# CPO-10 Abstracts

## Speaker: Asai, Hirotaka

**Authors:**Hirotaka Asai, Ryota Kawai, Fumiya Matsubara, Hidekazu Murata, and Eiji Rokuta

**Affiliations:**Faculty of Science and Engineering, Meijo University

**Keywords:**Nano tip; field ion microscopy; field emission microscopy

**Abstract Title:**

A high brightness field emitter by use of noble metal coated nano scale pyramid formed on tungsten tip

**Abstract:**

Nano tips have attracted large attention as the novel electron source with high brightness in high performance electron microscopes. In field emission electron guns, the brightness is improved as the width of electron source is decreased. This is because the electric field converges to the single atom at the tip end, resulting in a dramatic collimated electron beams. Tungsten (W) nanopyramids coated with monolayer films of noble metal (NM) are potential for a material of highly coherent electron sources. Sides of a tungsten (W) needle was coated with collodion containing powder of palladium oxide (PdO) at first. The W needle was subsequently annealed under ultrahigh vacuum to supply palladium (Pd) atoms to an apex of the W needle via surface diffusion and to produce a W nanotip coated with monolayer Pd films. Field ion microscopy (FIM) revealed {111} planes of the W nanotip were contracted by faceting {211} planes surrounding the {111} plane, of which the structural change is analogous to a formation of three sided W nanopyramids. General appearances of the W nanopyramids were the same as those shown by the existing naopyramids. The opening angle corresponding to FWHM of the beam profile of a nanopyramid with a top consisting of fifteen atoms was about 9.4 degree at extractor voltage of 711 V and emission current of 0.6 nA. In order to evaluate the brightness of the single atom tip, we adopted a regular triangle with a side of 0.18 nm was regarded as emission region and source area estimated 1.4E-14 cm^2. We evaluated the brightness of 2.0E4 A str^-1 cm^-2 V^-1. The evaluated value is higher than that of the conventional FE source (5.0E3 A str^-1 cm^-2 V^-1).

##
Speaker: Berg, Georg Peter - **
Invited Talk
**

**Authors:**G.P.A.Berg

**Affiliations:**University of Notre dame

**Keywords:**Spectrometer, Ion-optical design, Rare Isotopes

**Abstract Title:**

The ion-optical Design of the High Rigidity Spectrometer HRS for FRIB

**Abstract:**

With the ongoing construction of the Facility for Rare-Isotope Beams FRIB for the production of high-intensity rare isotopes (RI), several electro-magnetic experimental analysis systems are under construction and design to exploit these beams for a wide experimental science program. A large part of the science program can be executed using the HRS as outlined in the White Paper "HRS A High Rigidity Spectrometer for FRIB" (December 2014, ed. A. Gade and R. Zegers). The HRS will enable gains in luminosity for experiments with rare-isotope beams at FRIB by factors of 2-100, with the highest gains for the most neutron-rich isotopes, including those in the path of the astrophysical r-process. Therefore, the HRS will add tremendously to the discovery potential of FRIB. In this presentation the ion-optical design of a beam line/spectrometer system will be presented that satisfies all essential design requirements. This includes two modes of operation for missing mass experiments with MoNA-LISA and high-resolution spectroscopy. Both modes can operate with the Gamma Ray detector GRETA at the target and allow full dispersion matching of beam line and spectrometer for high resolution without dramatically reducing the beam intensity using momentum slits. The matching conditions also allow the reconstruction of the properties of the reaction products using the detector system. This work is supported by the U.S. Department of Energy Office of Science under Grant DE-SC0014554, ION-OPTICAL AND ASSOCIATED MAGNET FEASIBILITY STUDY OF A HIGH RIGIDITY SPECTROMETER.

## Speaker: Bimurzaev, Seitkerim

**Authors:**S.B. Bimurzaev, N.U. Aldiyarov, E.M. Yakushev

**Affiliations:**Almaty University of Power Engineering and Telecommunication

**Keywords:**lens-mirror objective, transmission electron microscope, spherical aberration, axial chromatic aberration

**Abstract Title:**

Lens-mirror objective for transmission electron microscope

**Abstract:**

A new electron-optical scheme of the lens-mirror objective for transmission electron microscopes (TEM), based on the special focusing regime (the so-called superimposed image mode) in the center of curvature of the deflecting magnetic field [1-3], is considered. The magnetic field does not cause an additional distortion of the image, and the problem of calculating the objective is reduced to calculating a relatively simple lens-mirror system with a common rotational symmetry axis. The new data on the parameters of specific lens-mirror systems composed of a well-known magnetic lens with a bell-shaped distribution of the axial field and an electrostatic mirror with electrodes in the form of a set of coaxial cylinders of equal diameter have been obtained. A rather wide family of mirror-lens electron-optical systems with a simultaneous compensation of the main types of aberrations (spherical and axial chromatic) with a large linear magnification has been found. The diffraction limit of the linear resolution of the lens-mirror objective has been evaluated under the joint action of the remaining fifth-order spherical aberrations and the diffraction of electrons by the beam-limiting diaphragm. It has been shown that full elimination of the third-order spherical aberrations can significantly increase the resolution of the transmission electron microscopes (TEM) and, even at moderate accelerating voltages about 100 kV, give high resolution values of less than one Angstrom, inaccessible for modern high-voltage TEM / STEM devices. 1. Bimurzaev S.B. and Yakushev E.M. (2013) Electron lens aberration corrector. // WIPO Patent Application WO/2013/077715 A1. 2. Yakushev EM. “Theory and Computation of Electron Mirrors: The Central Particle Method.” In Advances in Imaging and Electron Physics, Ed: Hawkes PW. Elsevier. 2013. V.178, P.147-247. 3. Bimurzaev S.B. Aldiyarov N.U. and Yakushev E.M. The objective lens of the electron microscope with correction of spherical and axial chromatic aberrations//Microscopy.-2017. – Vol. 66, Issue 5.- P. 356–365.

## Speaker: Bimurzaev, Seitkerim

**Authors:**S.B. Bimurzaev

**Affiliations:**Almaty University of Power Engineering and Telecommunication, Almaty, Kazakhstan

**Keywords:**mass spectrometer ,time-of-flight focusing, time-of-flight dispersion, electrostatic mirror

**Abstract Title:**

PLANAR MULTIREFLECTIVE TIME-OF-FLIGHT MASS SPECTROMETER OF A SIMPLE DESIGN

**Abstract:**

A scheme of an improved version of a planar multi-reflective time-of-flight mass spectrometer [1], based on the use of two-dimensional electrostatic mirrors and an ion source with an ion accelerator forming an inhomogeneous electrostatic field [2], which provide special focusing modes for ionic fluxes, is proposed. Numerical calculations have been used to determine the conditions that allow, along with the formation of a parallel ion flux, the time-of-flight focusing of ions in energy up to fourth order in the four-electrode ion accelerator in which the first electrode has a planar shape and can be combined with the exit window of the ionization region. The data that determine the conditions of time-of-flight focusing of ions in energy up to the third order inclusive in a three-electrode two-dimensional electrostatic mirror in the regime of a plane mirror have been obtained [3]. Mirror electrodes are pairs of parallel plates symmetrically located relative to the symmetry plane of the mirror field. Two variants of plane mirrors are considered: 1) when the forward and reverse branches of the trajectory coincide; 2) when the forward and reverse branches of the trajectory are symmetric with respect to the plane of symmetry. It is shown that the time-of-flight dispersion of the mirror by mass in the second variant is several times higher than in the first variant. The use of an ion source forming a parallel ion flux in combination with highly dispersive mirrors serves as the basis for simultaneous enhancement of resolution and sensitivity of the mass spectrometer. References 1. Nazarenko L.M., Sekunova L.M. and Yakushev E.M. SU Patent 1725289 A1 (1992). 2. Bimurzaev S.B., Yakushev E.M., Nazarenko L.M. Innovative package of the RK. Author's certificate No. 87127 (2015). 3. Kelman V.M., Fedulina L.V., Yakushev E.M. Deviation of parallel beams of charged parts by a plane electrostatic mirror // Zhurnal Tekhnicheskoi Fiziki, 41 (1971). P. 1825-1831.

## Speaker: Carneiro, Jean-Paul

**Authors:**J.-P. Carneiro, B. Hanna, L. Prost, A. Saini, A. Shemyakin, D. Sun

**Affiliations:**Fermi National Accelerator Laboratory

**Keywords:**Fast Faraday Cup, Bunch Length, Longitudinal Emittance

**Abstract Title:**

Longitudinal Beam Dynamics Studies at the PIP-II Injector Test Facility

**Abstract:**

The Proton Improvement Plan, Stage Two (PIP-II) is a program of upgrades proposed for the Fermilab injection complex, which central part is an 800- MeV, 2-mA CW-compatible SRF linac. A prototype of the PIP-II linac front end called PIP-II Injector Test (PIP2IT) is being built at Fermilab. As of now, a 15-mA DC, 30-keV H- ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1-MeV CW RFQ, followed by a 10-m Medium Energy Beam Transport (MEBT) have been assembled and tested. A Fast Faraday Cup (FFC) installed in the MEBT measures the length of a beamlet cut out of the bunch by a small-size entrance hole of the FFC. The information about the bunch length measured at various settings allows for reconstruction of the longitudinal beam dynamics and optimization of injection into the first cryomodule. These measurements are compared with simulations by the beam dynamics codes TRACEWIN and TRACK. The paper describes the experimental procedures of the bunch length measurements with the FFC, presents the measurement results, and compares them with simulations. One of important experimental observations, confirmed by simulations, is the dependence of the FFC beamlet length on the radial position across the beam.

## Speaker: Edwards, David Jr

**Authors:**David Edwards Jr

**Affiliations:**IJL research center

**Keywords:**Finite Difference Method, FDM, order 4 algorithm, nine point algorithm

**Abstract Title:**

The order 4 algorithm for cylindrically symmetric electrostatics

**Abstract:**

It has been ~60 years since Emile Durand first reported the fourth order algorithm for cylindrically symmetric electrostatics (1957). It was immediately clear that using this algorithm the potential could be calculated with precisions significantly higher than the standard 5 point or order 2 algorithm. The solution came at a price however and the price was that it was essentially impossible to implement for boundaries not lying on rows and columns of meshpoints. And this situation is basically the same today as it was 60 years ago in spite of the many attempts at incorporating this algorithm into electrostatics. However in 2014 a solution for the curved boundary problem was found for FDM. Unfortunately as the emphasis in that work was on the higher order algorithms and these were entirely too complex to be detailed no explicit formulations could be given. This significantly limited the usefulness of that work. It has become clear however that the fourth order algorithm, which when implemented by the process for curved boundaries as described in the 2014 report would provide significant gains in precision over the order 2 algorithm and likely compete favorably with the current BEM and FEM formulations. It is thus to provide such a description of that implementation that the present work is directed. In particular it will allow all points within the geometry, independent of their proximity to the boundary, to use the same 4th order algorithm, the one of Durand. Also the construction employed will in fact be more direct than that used in the standard order 2 implementation for curved boundaries at a cost of only a relatively insignificant increase in computational time. In addition the treatment of boundary singularities by a multi-region construction will be described as such singularities can negate any gains that the order 4 algorithm might yield.

## Speaker: Fedurin, Mikhail

**Authors:**Mikhail Fedurin

**Affiliations:**Brookhaven National Laboratory Accelerator Test Facility

**Keywords:**masked beam, ultrashort bunch, micro-bunching

**Abstract Title:**

Advanced beam optic options for Brookhaven National Laboratory Accelerator Test Facility beamline

**Abstract:**

The Accelerator Test Facility (ATF) at Brookhaven National Laboratory operates as a National User Facility supported by the Accelerator Stewardship Program in the US DOE's Office of High Energy Physics. The facility presently provides high brightness 70 MeV electron beams and terawatt-class CO2 laser capabilities to support wide program in advanced accelerator R&D. Present design of ATF beamline transport with beam manipulation tools and beam diagnostics together with proposed schemes to generate ultrashort and flat electron bunches will be discussed.

##
Speaker: Fujita, Shin - **
Invited Talk
**

**Authors:**Shin Fujita

**Affiliations:**Shimadzu Asia Pacific Pte Ltd.

**Keywords:**ray tracing, numerical calculation, cathode lens

**Abstract Title:**

Generalization of paraxial trajectory method for the analysis of non-paraxial rays: electron gun designs in terms of optical parameters

**Abstract:**

The paraxial trajectory method has been generalized for application to the cathode rays inside electron guns. The generalized method can handle rays that initially make a large angle with the optical axis. The key to success of the generalization is the adoption of the trigonometric function sine for the trajectory slope specification, instead of the conventional use of the tangent. An improved assignment of paraxial trajectory to the actual ray becomes possible by the new slope specification. It is possible to relate the ray emittance condition (the combination of position and slope of rays at reference planes) on the cathode to those at the crossover plane using polynomial functions, whose coefficients can be used as the optical parameters in electron source characterization. The most important among the parameters is the Electron Gun Focal Length, which can be used for quantitative estimate of both the crossover size and the angular current intensity. Electron gun simulation program G-optk has been developed based on the generalized paraxial trajectory theory. The program calculates the principal paraxial trajectories, optical parameters, as well as virtual emittances solely from the axial potentials and fields. It gives a clear physical picture of electron sources and can be used for the gun design optimization.

## Speaker: Fujita, Shin

**Authors:**Shin Fujita

**Affiliations:**Shimadzu Asia Pacific Pte Ltd.

**Keywords:**phase space, periodic potential, Mathieu-Hill equation, eigen-trajectory

**Abstract Title:**

Elucidation of Ion Motion in Quadrupole Mass Filter by Bloch Function: improved Pre-rod design for efficient ion injection

**Abstract:**

In the optimization of the quadrupole mass filter (QP filter), the understanding of ion motion in terms of the phase space (the combined representation of the trajectory coordinate and momentum) is useful. The phase space representation can give an ‘ensemble’ behavior of ions inside the filter. Even though each ion trajectory does not have the RF periodicity of the applied voltages to electrodes, the phase space evolution does. It is only when appropriate ensemble ions are considered together that a proper QP filter characterization is possible. We here report a new calculation framework for the phase space of the QP filter. The Mathieu-Hill equation is first solved for ‘complex number’ eigen-trajectory that has pseudo RF periodicity (Bloch Function). It is then shown that the acceptance phase space can be derived from Bloch Function without a need to calculate each ion trajectory. The ensemble behavior of ions can be estimated from one Bloch Function. The application of the Bloch Function method to the pre-rod effects revealed that the ion injection efficiency may significantly be improved by an appropriate choice of pre-rod (q, a) condition. Proper addition of DC voltage component will result in the phase space transformation in the pre-rod that enables the efficient ion injection.

## Speaker: Greenzweig, Yuval

**Authors:**Yuval Greenzweig, Roy M. Hallstein, Minh P. Ly, Yariv Drezner, Rick H. Livengood, Shida Tan, and Amir Raveh

**Affiliations:**Intel Corporation

**Keywords:**Circuit Edit, Focused Ion Beam (FIB), Coldbeam, Cold FIB, Magneto-Optical Trap Ion Source (MOTIS), Low Temperature Ion Source (LoTIS)

**Abstract Title:**

Cs and Rb Ion Coldbeams Suitability for Circuit Edit

**Abstract:**

Semi-conductor applications of Focused Ion Beams (FIB) have long been enabled by Ga Liquid Metal Ion Source technology, but have been challenged by device density doubling every two years for the last 2-3 decades. One such application, Circuit Edit, has been critically losing performance due to density scaling in the recent past. The emergence of several new FIB source technologies such as gas field ionization and Coldbeam sources having much smaller probe sizes than Ga LMIS, and in some cases higher secondary electron (SE) yields, promise a revival of FIB capability for Circuit Edit. We report herein the results of our testing of Cs and Rb cold ion beams and their suitability for Circuit Edit. Testing of the Cs coldbeam was performed at ZeroK Nanotech, and Rb testing was performed at TU Eindhoven. We characterized Cs image resolution, beam profile, minimum sizes of micro-trenches etched in SiO2, and material properties of Cs deposited dielectric and metalization. For both Cs and Rb we measured residual ion contamination levels and SE yields from several common micro-electronic materials. We established the lack of invasiveness of Cs and Rb for Circuit Edit related operations on 14nm Intel transistors. Lastly, using the Cs coldbeam with gas chemistries for etching and deposition, we demonstrated the first ever Cs based real Circuit Edits, which we performed on Intel 10nm chips.

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Speaker: Grinfeld, Dmitry - **
Invited Talk
**

**Authors:**D. Grinfeld, H. Stewart, M. Skoblin, E. Denisov, A. Makarov

**Affiliations:**Thermo Fisher Scientific, Bremen, Germany

**Keywords:**mass-spectrometry, space charge

**Abstract Title:**

Orbitrap mass spectrometry and nonlinear space charge dynamics

**Abstract:**

The Orbitrap (TM) mass analyzer belongs to the family of Fourier transform mass spectrometers (FT MS) in which the ions are trapped between two spindle-like electrodes. The quadro-logarithmic field [1,2] provides the quadratic effective potential in the axial direction, in which the oscillatory frequency is independent of the orbital parameters (e.g. the amplitude) so that ions with same mass-to-charge ratios (m/z) preserve their common phase in the course of 1e5 ÷ 1e6 oscillations. On the other hand, ions with different m/z ratios oscillate with different frequencies, and Fourier analysis of the induced-current signal produces a mass spectrum with a resolving power of up to one million [3]. If the number of injected charges is large, however, the ion motion is affected by Coulomb forces. Though the space-charge field constitutes only ~1e-4 of the trapping field, the interaction between ions with equal or close m/z is amplified under the resonance conditions and results in sophisticated, sometimes counterintuitive, ion dynamics. For example, the Coulomb interaction between same charge ions, being repulsive by its nature, generates an effective attraction force. Detected FT peaks of ions with different but close m/z appear shifted towards each other in frequency. Ultimately, it leads to complete frequency synchronization, referred as coalescence, when the ions oscillate as a single bunch. Coalescence makes the involved ionic species undistinguishable in the FT spectrum and thus deteriorates the mass resolving capability. Basing on the perturbation theory, we have developed a multi-body model and an algorithm characterizing ion dynamics in the presence of Coulomb interactions. Systems of multiple ions were simulated near and beyond the coalescence threshold. It was shown that small non-idealities (~1e-5) of the trap's field substantially alter the ion dynamics, decreasing or increasing the threshold by a factor of ten. This observation suggests approaches to improving space charge capacity of the mass analyzers and, therefore, their dynamic range.

## Speaker: Guo, Xiaoli

**Authors:**Ali Mohammadi-Gheidari, Xiaoli Guo and Pieter Kruit

**Affiliations:**Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands

**Keywords:**Electron optics, Multi-beam inspection, High throughput, High resolution

**Abstract Title:**

Electron optics of a multi-beam source (MBS)

**Abstract:**

In the field of Charged Particle Optics, more than 50 years of research and development have been devoted to improving the resolution of these systems. Present day systems can easily obtain subnanometer resolution in imaging and sub 10nm resolution in patterning. To preserve the high resolution the current in the probe should be low, only tens of pico-Amps to a few nano-Amps. This makes the throughput of these systems too low for applications such as 3D imaging or wafer inspection. Multi-electron beam systems, in which not one but many electron beams are focused onto the sample simultaneously, can enhance the throughput to a great extent. A Multi-Beam Scanning Electron Microscope (MBSEM) that delivers 196 focused beams onto the sample, based on an FEI Nova-Nano 200 SEM electron optical column was designed and built at the CPO group in Delft University of Technology[1]. The multi-beam source (MBS) for this system, presented by Zhang et al.[2], was based on the principle of the "zero-strength" lens, where the deflection and collimation of the off-axis beams take place in a conjugate plane of the source in order to avoid chromatic deflection aberrations, astigmatism and coma. In further theoretical investigations and simulations, however, it was found that even if the net deflection at the aperture array plane is zero, the axial spherical and chromatic aberrations of the field in front of the aperture array plane can lead to unacceptable astigmatism and extra contributions to the field curvature in the image plane of the array. Therefore, in the design of the MBS, it is not the zero deflection at the aperture plane that should be respected but the minimization of its spherical and chromatic aberration coefficients. In general, the aberrations of round electron lenses cannot be made arbitrarily small or negative. However, the unique property of the present lens allows the aberrations to be made close or even equal to zero! A comprehensive and detailed analysis and design of the MBS will be presented here. [1] A. Mohammadi-Gheidari, C.W. Hagen and P. Kruit, JVST B 28(6) 2010. [2] Y. Zhang and P. Kruit, Physics Procedia 1 553, 2008.

##
Speaker: Herfurth, Frank - **
Invited Talk
**

**Authors:**Frank Herfurth

**Affiliations:**GSI Helmholtz Centre for heavy ion research

**Keywords:**deceleration, highly-charged ions, low energy storage ring, penning trap

**Abstract Title:**

Deceleration of heavy ions, HITRAP and CRYRING@ESR

**Abstract:**

To perform precision experiments on exotic ions, if highly charged or rare, it is mandatory to provide means to link high-energy production schemes with low energy storage and measurement schemes. Only low energy storage in rings and traps ensures the required extended observation time and well controlled environment. At GSI/FAIR in Darmstadt/Germany, heavy, highly charged stable and rare ions up to bare uranium are produced in large quantities. Medium charged ions at a few 100 MeV/nucleon will be stripped of all electrons when sent through a thin foil or fragmented in nuclear reactions when interacting with enough material in thicker targets. The deceleration down to MeV/nucleon, keV/nucleon and finally sub meV requires several steps involving storage rings and finally a dedicated linear decelerator coupled to ion traps. Two facilities, the linear decelerator facility HITRAP and the low energy storage ring CRYRING@ESR, will be introduced with planned experiments and status of installation.

## Speaker: Hesam Mahmoudi Nezhad, Neda

**Authors:**N. Hesam Mahmoudi Nezhad1*, M. Ghaffarian Niasar2, A. Mohammadi Gheidari1, T. Janssen3, C.W. Hagen1, P.Kruit1

**Affiliations:**1Delft University of Technology, Fac. Appl. Sciences, Dept. Imaging Physics, Charged Particle Optics Group, Lorentzweg 1, 2628 CJ Delft, The Netherlands- 2 Delft University of Technology, Faculty of Electrical Engineering, DC systems, Energy conversion and Storage, Mekelweg 4, 2628 CD Delft, The Netherlands -3 Delft University of Technology, Faculty of Applied Mathematics, Optimization, Mourik Broekmanweg 6, 2628 XE, The Netherlands

**Keywords:**Electrostatic lens Optimization, Second Order Electrode Method (SOEM), Genetic Algorithms (GAs)

**Abstract Title:**

Multi-electrode Lens System Optimization Using Genetic Algorithms

**Abstract:**

In electron lens design, finding the optimum lens system for the application at hand, is still quite a challenge. The situation becomes especially more complicated when many lens electrodes are involved, because the number of free parameters of the optimization, such as electrode thickness, radii, gaps between electrodes and voltages, increases rapidly. Therefore, fast optimization routines are needed to tackle the problem. In the past, there have been some attempts to develop such optimization programs. Szilagy et al. [1] and Adriaanse et al. [2], have published some results in 1989 on rough optimization of electrostatic lenses. However, using the above-mentioned methods, one could not get very accurate results. Now that we have more powerful computers and significantly better software, we revisit the problem. First we applied the so called "SOEM" (Second Order Electrode Method) [2] for a fast (~0.1sec) calculation of the axial potential. However, the results of the optimization were not accurate enough. To improve the accuracy of the SOEM-based optimization, we integrated a finite element based potential calculation method (using COMSOL). This way the potential calculation and the objective function calculation is more accurate, although the optimization becomes much slower. We propose a new approach that improves on the low speed of optimization while keeping the high accuracy results of the finite element method based potential calculation. This is done by first using a rough optimization based on the SOEM approach, resulting in a few approximately optimized systems. Then, using the parameters of the systems found, new sets of systems were defined using a small range of values around these parameters. Then the more accurate, COMSOL-based optimization was applied to this set of limited systems. We have tested our method on multi electrode systems up to 7 electrodes. We succeeded to very accurately optimize these systems within a few hours, with the electrode radii, gaps and voltages as free parameters, and the focus position as a constraint. [1] M.Szilagi. Yakowitz and M. Duff, Appl. Phys. Lett. 44, pp. 7-9, 1984. [2] J.P. Adriaanse, H.W.G Van der Steen and J.E. Barth, J.Vac. Sci. Technol. B7, pp. 651-666, 1989.

##
Speaker: Hoang, Hung Quang - **
Invited Talk
**

**Authors:**Hung Quang Hoang, Jean-Nicolas Audinot, Santhana Eswara, Tom Wirtz

**Affiliations:**Advanced Instrumentation for Ion Nano-Analytics (AINA), MRT Department, Luxembourg Institute of Science and Technology (LIST), 41 rue du Brill, 4422 Belvaux, Luxembourg

**Keywords:**Correlative microscopy, secondary ion mass spectrometry, helion ion microscopy, transmission electron microscopy, scanning probe microscopy

**Abstract Title:**

Correlative Microscopy based on Secondary Ion Mass Spectrometry for High-Resolution High-Sensitivity Nano-Analytics

**Abstract:**

Nano-analytical techniques and instruments providing both excellent spatial resolution and high-sensitivity chemical information are of extreme importance in materials science and life sciences for investigations at the nanoscale. New characterisation tools need to anticipate these research trends, but as more and more techniques approach their fundamental limits it is only by combining multiple techniques that disruptive advances may be made. While techniques such as Electron Microscopy, Helium Ion Microscopy and Scanning Probe Microscopy are commonly used for high-resolution imaging, they provide no or only limited analytical information. In particular, both Energy-Dispersive X-Ray Spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS) that are routinely used in electron microscopy have limited sensitivity, neither can distinguish isotopes and both have difficulty with light elements. In contrast, Secondary Ion Mass Spectrometry (SIMS) offers extremely high chemical sensitivity, but it typically suffers from poorer lateral resolution. However, by combing SIMS with one of these high resolution microscopy techniques, these intrinsic drawbacks may be overcome [1]. Therefore, in order to get chemical information with a highest sensitivity and highest lateral resolution, we developed integrated instruments combining SIMS with Transmission Electron Microscopy [2], Helium Ion Microscopy [3-5] and Scanning Probe Microscopy [6] and developed associated correlative methodologies and workflows. These workflows allow TEM, SE and SPM images of exactly the same zone analysed with SIMS to be acquired easily and rapidly, followed by a fusion between the SE and SIMS data sets [7]. In this talk, we will present the concepts, describe the instruments and discuss their performance characteristics. We will then present a number of examples taken from various fields of materials science and life science to show the powerful correlative microscopy possibilities enabled by these new in-situ methods. [1] T. Wirtz, P. Philipp, J.-N. Audinot, D. Dowsett, S. Eswara, Nanotechnology 26 (2015) 434001 [2] L. Yedra, S. Eswara, D. Dowsett, T. Wirtz, Sci. Rep. 6 (2016) 28705 [3] T. Wirtz, D. Dowsett, P. Philipp, Helium Ion Microscopy, edited by G. Hlawacek, A. Gölzhäuser, Springer, 2017 [4] D. Dowsett, T. Wirtz, Anal. Chem. 89 (2017) 8957-8965 [5] P. Gratia et al, J. Am. Chem. Soc. 138 (49) 15821-15824, 2016 [6] Y. Fleming et al., Beilstein J. Nanotechnol. 6 (2015) 1091 [7] F. Vollnhals, J.-N. Audinot, T. Wirtz, M. Mercier-Bonin, I. Fourquaux, B. Schroeppel, U. Kraushaar, V. Lev-Ram, M. H. Ellisman, S. Eswara, Anal. Chem. 89 (2017) 10702-10710

## Speaker: Hoque, Shahedul

**Authors:**S. Hoque1,2), R. Nishi1), H. Ito1,3), A. Takaoka1)

**Affiliations:**1) Osaka University, 2) Hitachi High Technologies America, Inc., 3) Hitachi High-Technologies Corp.

**Keywords:**Spherical aberration, Hexapole corrector, Sextupole corrector, N-SYLC

**Abstract Title:**

Spherical aberration correction with in-lens N-fold symmetric line currents

**Abstract:**

We have shown that N number of line currents placed symmetrically about the optic axis generate 2N-pole fields [1]. We call this structure N-fold symmetric line currents, or, N-SYLC in short. We have proposed simple aberration corrector models based on N-SYLC for scanning electron microscopes (SEM) [2][3][4]. The most important feature of N-SYLC is that it is free of magnetic material, thus in principle eliminates the problems of hysteresis, non-uniformity, and magnetic saturation suffered by conventional magnetic multipoles. We have shown theoretically that the conventional multipoles of sextupole doublet model of H. Rose [5][6] can be replaced with 3-SYLC to correct spherical aberration [2]. Here, we consider a new structure superimposing N-SYLC on rotationally symmetric lens fields, which is only possible because N-SYLC is free of magnetic materials. This simplifies the corrector structure, and allow for miniaturization and more versatile design. We call this structure in-lens N-SYLC. We show by analytical calculation that by adjusting certain parameters of the system, in-lens 3-SYLC can generate negative spherical aberration with high sensitivity, so that it can be used to correct the spherical aberration of objective lens. We also verify the results by computer simulation [7]. [1] Nishi R., Ito H., Hoque S.: Wire corrector for aberration corrected electron optics, (IMC2014), IT-1-P2984, pp.200-201. [2] S. Hoque, H. Ito, R. Nishi, A. Takaoka, E. Munro: Spherical aberration correction with threefold symmetric line currents, Ultramicroscopy 161, (2016) 74-82. [3] S. Hoque, H. Ito, A. Takaoka, R. Nishi, Axial geometrical aberration correction up to 5th order with N-SYLC, Ultramicroscopy 182, (2017) 68-80. [4] P. W. Hawkes and E. Kasper, Principle of Electron Optics, Volume 2: Applied Geometrical Optics, second edition, chapter 41, p. 986-988, Academic Press, 2017. [5] H. Rose, Correction of aperture aberrations in magnetic systems with threefold symmetry, Nuclear Instruments and Methods in Physics Research 187, 187-199 (1981). [6] M. Haider, H. Rose, S. Uhlemann, B. Kabius, and K. Urban, Towards 0.1 nm resolution with the first spherically corrected transmission electron microscope, Journal of Electron Microscopy 47, 395 (1998). [7] Spherical aberration correction with an in-lens N-fold symmetric line currents model, Ultramicroscopy 187, (2018) 135-143.

##
Speaker: Hornung, Christine - **
Invited Talk
**

**Authors:**Timo Dickel, Christine Hornung

**Affiliations:**Justus-Liebig-University, Giessen, Germany / GSI Helmholzcenter for Heavy Ion Research, Darmstadt, Germany

**Keywords:**TOF-MS, RF traps, mass measurements

**Abstract Title:**

High-precision mass measurements with MR-TOF-MS

**Abstract:**

At the FRS Ion Catcher at GSI, projectile and fission fragments are produced at relativistic energies at the FRS, separated in-flight, range-focused, slowed-down and thermalized in a cryogenic stopping cell and transmitted to a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). The MR-TOF-MS can perform direct mass measurements of exotic nuclei, to provide an isobarically and isomerically clean beam for further experiments, and as a versatile diagnostics device to monitor the production, separation and manipulation of exotic nuclei. At the Justus Liebig University, Giessen, Germany similar MR-TOF-MS have been developed for the ISOL facility TRIUMF, Vancouver, Canada and for applications in analytical mass spectrometry. These MR-TOF-MS consist of an injection RF trap to form the ns ion bunches, a coaxial isochronous TOF analyzer, and a TOF detector for mass measurement and a Bradbury-Nielsen-Gate for spatial mass separation. Several novel principles further enhance the performance and versatility of the MR-TOF-MS, including (i) a post-analyzer reflector, (ii) a dynamical time-focus shift technique and (iii) mass-selective re-trapping in the RF trap. Thus extremely versatile MR-TOF-MS with mass resolving powers beyond 600,000 (FWHM), high transmission efficiency, ion capacities of more than a million ions per second and cycle frequencies has high as 1kHz have been developed. The MR-TOF-MS can also be used as their own isobar separator. Mass measurements of uranium projectile and fission fragments produced at the FRS at 1000 MeV/u have been performed using the MR-TOF-MS of the FRS Ion Catcher. More than 30 short-lived ground state masses have been measured with high mass accuracies (down to 6E-8). The excitation energies of isomers and isomeric ratios were determined using mass spectrometry, and, for the first time, an isomeric beam was prepared using an MR-TOF-MS. The unique combination of performance parameters make the MR-TOF-MS the system of choice for measuring the masses of very exotic nuclei and for the search for new long-lived isomeric states.

##
Speaker: Jiao, Yi - **
Invited Talk
**

**Authors:**Yi Jiao, Gang Xu, Qing Qin

**Affiliations:**Institute of High Energy Physics, CAS

**Keywords:**High Energy Photon Source, diffraction limited storage ring, linear optics, nonlinear dynamics

**Abstract Title:**

Lattice design of the HEPS

**Abstract:**

The High Energy Photon Source (HEPS) is the first high-energy diffraction-limited storage ring (DLSR) light source to be built in China,with a natural emittance of a few tens of picometers and a circumference of 1360 m. After 10 years' evolution, the accerlator physics design of the HEPS has been determined. The latest HEPS lattice consists of 48 hybrid-7BAs with a few modifications, such as, antibends, superbends, and alternating high- and low-beta sections. These modifications promises a 34 pm design with high brightness. In this report we will introduce the status of the HEPS acclerator physics design and the linear optics and nonlinear dynamics of the latest HEPS lattice.

## Speaker: Jiruse, Jaroslav

**Authors:**Jaroslav Jiruse

**Affiliations:**TESCAN Brno

**Keywords:**SEM, detection system, secondary electrons, backscattered electrons

**Abstract Title:**

Detection systems in scanning electron microscope

**Abstract:**

Controlling surface sensitivity is becoming increasingly important in SEM. We will present results obtained with ultra-high resolution columns developed recently with extended detection systems optimized for low energies. These systems allow angular filtering of secondary electrons and both angular and energy filtering of backscattered electrons. These filtering possibilities lead to enhanced surface sensitivity of the detected signal.

##
Speaker: Kahl, Frank - **
Invited Talk
**

**Authors:**Frank Kahl, Heiko Müller, Martin Linck, Richard Schillinger

**Affiliations:**CEOS GmbH, 69126 Heidelberg, Germany

**Keywords:**post-column energy filter, ESI, EELS, Electron-Spectroscopic-Imaging, Electron-Energy-Loss-Spectroscopy, spectroscopy

**Abstract Title:**

Design of a High-Performance Post-Column Imaging Energy Filter for (S)TEM Instruments

**Abstract:**

CEOS developed a high-performance post-column imaging energy filter for transmission electron microscopy. It can be used for Electron-Spectroscopic-Imaging (ESI) and Electron-Energy-Loss-Spectroscopy (EELS) for beam energies from 30kV to 300kV. It has been designed as a multi-purpose instrument for zero-loss filtering with large field of view, low-loss and core-loss spectroscopy with highest energy resolution, angle-resolved EELS, and fast STEM-EELS mapping applications. Its exceptionally low remanence and drift effects allow for switching from high-resolution EELS to ESI or another EELS dispersion back and forth with only very little shift or defocus. The excellent stability of the filter supply minimizes the need for regular re-tuning. The filter is supported by a python-based image processing platform featuring automated tuning for maximum ease of use. The users can run their own python scripts, having access to all acquired images plus image processing and display functionality via an Application-Programmers-Interface (API). Third party software can be integrated very easily. The detector interfaces are designed for flexibility. In ESI mode an entrance aperture of up to 12 mm can be used. The filter supports post-filter cameras with detector sizes up to 64 mm side length and fits into the mounting space of all modern (S)TEMs. Three ESI magnifications are supported, imaging a quadratic field of views of 8 mm, 10 mm and 12 mm diagonal length in the entrance aperture plane onto the detector. For those three magnifications the non-isochromaticities, maximum distortions and maximum chromatic distortions are (0.13 eV, 0.9 %, 0.22 %), (0.44 eV, 1.0 %, 0.23 %) and (1.7 eV, 1.4 %, 0.26 %), respectively, for an energy window of 50 eV at 200 kV. The regular EELS aperture is 5 mm. The pre-slit alignment is kept almost identical for the different ESI and EELS modes. Additional spectroscopy modes supporting an extremly large spectral range of up to 4 keV at 200 kV and dedicated alignments for omega-q mapping at higher dispersions are possible. For highest energy resolution a dispersion of 2 meV/channel for 4k x 4k detectors with pixel sizes at the order of 15 um is available. In order to minimize the non-isochromaticity of an ESI image and to improve the quality of focus of the Zero-Loss-Peak (ZLP) in EELS mode, the diameter of the ZLP in the slit plane formed by all electrons over the entire entrance aperture must be as small as possible in the dispersive direction. This is equivalent to minimize the geometric aberrations in the slit plane, which is achieved by combining a sector magnet whose geometry has been optimized for minimum intrinsic geometric aberrations with a set of sextupole, octupole, decapole and dodecapole fields allowing for correcting all residual geometric slit aberrations up to third order and certain aberrations of fourth and fifth order. The aberrations are measured by scanning the ZLP over the edge of one selection slit, recording the attenuation pattern and fitting the aberration coefficients from that. The pre-slit setting shared by all ESI magnifications is optimized for low residual chromatic distortions in the image while the pre-slit setting shared by all regular EELS modes uses an additional pre-slit sextupole to correct for the spectrum inclination. For all ESI magnifications the projective corrects or adjusts the distortion coefficients of first order, the three intrinsic coefficients of second order, one critical intrinsic coefficient of third order and finally the chromatic distortion coefficients of first degree. Its excellent performance is achieved by an optimized design comprising a minimalistic design of only four main quadrupoles, two weak rotated quadrupoles for correcting parasitic aberrations and three sextupoles. The measureable residual distortions for the 12 mm entrance field of view are very predictable and can optionally be removed by online distortion dewarping.

## Speaker: Katsap, Victor

**Authors:**Victor Katsap

**Affiliations:**NuFlare Technology America

**Keywords:**e-beam lithography, shot noise, acid deficit

**Abstract Title:**

On significance of 50 kV e-beam shot noise in lithography application

**Abstract:**

In e-beam mask writers, 50-keV e-beam having dynamically controlled rectangular shape strikes mask blank surface. Mask blank consists of thin layers of resist and metal atop of massive quartz substrate. Primary and secondary electrons expose resist by colliding inelastically with resist molecules. Beam dwell time depends on beam spot current density and resist sensitivity. Noise is often defined as ratio of SQRT(var) to MEAN value. For e-beam shot noise, it's 1/SQRT(Ne), Ne being number of electrons in process considered. In a simplified way, e-beam resist exposure may be looked at as a sequence of 3 steps: Ne electrons enter resist > Na acids get de-protected > Np polymer molecules get exposed in Post-Exposure-Baking (PEB) step. In each step, limited number of particles is involved, and so each process may be described with Poisson-type statistics. These 3 statistics can be summed up to evaluate resulting noise in e-beam exposed and developed resist: SQRT(var)/MEAN = SQRT(1/Ne + 1/Na + 1/Np) This means that step with the least number of particles would dominate resulting noise in the exposed feature, thus defining exposure quality. Typically, Na is smallest of 3 values, facilitating so called "acid deficit". Under realistic conditions, e-beam noise is 1/4 of total, while acid noise may reach 70% of total noise. This could explain a difference in exposing resist with low- and high-energy e-beams: - with low-energy beam, acid yield is close or greater than 1 acid per primary electron, hence no acid deficit, and e-beam noise dominates. - with high-energy beam, acid yield is less than 1 acid per primary electron, hence acid deficit, and e-beam noise is minor factor. However, because of using thinner and thinner resist in commercial process, e-beam noise may become major component of the total exposure noise.

##
Speaker: Kazantseva, Erika - **
Invited Talk
**

**Authors:**Erika Kazantseva, Oliver Boine-Frankenheim, Helmut Weick

**Affiliations:**Technische Universitaet Darmstadt

**Keywords:**Super-FRS, high-order aberrations, realistic Taylor transfer maps

**Abstract Title:**

High-order aberrations of large aperture magnets and applications to the Super-FRS project at GSI

**Abstract:**

The magnets of the charged particle spectrometers and separators play a decisive role in the beam quality and transmission percentage, especially for the systems with large geometrical and momentum acceptances. In the case of the Superconducting Fragment Separator (Super-FRS), a core part of the FAIR project being built at GSI, the undesired high-orders aberrations are expected due to the large usable apertures of the magnets (38x19 cm^2 in the main dipoles and 19x19 cm^2 in the multipoles) and wide operation rigidity range of 2-20 Tm. In this work we will analyse the aberrations introduced by the normal conducting dipole magnet of the Super-FRS preseparator. The methods of generating the high-order Taylor transfer maps from the 3D magnetic field distributions and taking the magnetic rigidity into account will be discussed.

## Speaker: Khan, Sameen Ahmed

**Authors:**Ramaswamy Jagannathan and Sameen Ahmed Khan

**Affiliations:**Chennai Mathematical Institute and Dhofar University

**Keywords:**Quantum Mechanics, Charged Particle Beam Optics

**Abstract Title:**

Quantum Charged-Particle Beam Optics

**Abstract:**

Though the classical charged-particle beam optics is very successful, in designing and operating numerous charged-particle beam devices from electron microscopes to particle accelerators, it is natural to look for the quantum theory of such systems handling beams of microscopic particles for which quantum mechanics should be relevant. With the curiosity of understanding how the classical charged-particle beam optics is so successful, the quantum charged-particle beam optics (QCPBO) is being developed by Jagannathan et al. QCPBO is seen to reproduce the classical charged-particle beam optics exactly for the paraxial and aberrating systems in the classical limit of dropping the additional quantum correction terms which depend on the Planck constant and are, of course, extremely small compared to the classical terms. In the classical limit the quantum formalism reproduces the well-known Lie algebraic formalism of classical charged-particle beam optics. QCPBO based on the Klein-Gordon equation is applicable to spin-0 and spin-less particles. The formalism of QCPBO based on the Dirac equation provides a unified treatment of orbital and spin dynamics of a Dirac particle with anomalous magnetic moment being transported through magnetic optical elements accounting for the orbital phase-space transfer maps, including the Stern-Gerlach effect, and the Thomas-Bargmann-Michel-Telegdi spin motion. QCPBO based on the nonrelativistic Schrödinger equation emerges as the approximation of the relativistic formalisms based on both the Klein-Gordon and the Dirac equations.

## Speaker: Khursheed, Anjam

**Authors:**Xiuyuan Shao, Wei Kean Ang, and Anjam Khursheed

**Affiliations:**Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore

**Keywords:**Energy distribution, Boersch effect, Graphene

**Abstract Title:**

A low-energy spread graphene coated nickel electron source for low-voltage scanning electron microscopy

**Abstract:**

Field emission energy distribution characteristics of graphene coated nickel emitters have been experimentally measured as a function of cathode extraction voltage and tip radius. These emitters have been recently reported to have significant advantages over conventional cold field tungsten emitters for electron microscopy/lithography applications. Full-width at half-maximum values for their energy spectra were experimentally measured to vary between 0.16 to 0.39 eV. By subtracting the calculated total energy distribution (TED) in the thermal field regime from the experimental spectra, the energy spread broadening due to Coulomb interactions (Boersch effect) was obtained, and found to increase with increasing extraction voltages and decreasing the tip sizes. These results are of particular interest for low-voltage scanning electron microscopy applications where chromatic aberration of the objective lens is the main factor limiting spatial resolution.

##
Speaker: Kim, Jongwon - **
Invited Talk
**

**Authors:**Jongwon Kim, Brahim Mustapha

**Affiliations:**Institute for Basic Science, Korea, Argonne National Laboratory, USA

**Keywords:**Superconducting linac, Heavy-ion beam, Rare isotope beam

**Abstract Title:**

Considerations on beam optics of superconducting heavy ion linacs for a rare isotope beam facility

**Abstract:**

The rare isotope science project (RISP) was started in Korea from Dec. 2011 to establish an accelerator facility based on superconducting linacs for nuclear and applied science studies under the auspices of the Institute for Basic Science (IBS). The current design was frozen in 2013 in terms of the facility layout and the civil construction began in 2016. In fact, some considerations on alternative linac design were made in 2016 together with the linac development group of Argonne National Lab in search of further optimized configuration of the driver linac, which should have sound lattice design against realistic machine errors. Results of beam optics simulations and error analysis for an alternative design will be presented. Also, considerations on optimized design and operation scheme of the superconducting linac which can accelerate both stable and rare isotope beams simultaneously, will be presented.

##
Speaker: Kozak, Martin - **
Invited Talk
**

**Authors:**Martin Kozak, Timo Eckstein, Norbert Schönenberger, Peter Hommelhoff

**Affiliations:**Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 12116 Prague 2, Czech Republic, Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstrasse 1, 91058 Erlangen, Germany

**Keywords:**Ultrafast control of electron pulses, attosecond physics

**Abstract Title:**

Ponderomotive generation and detection of attosecond electron pulses

**Abstract:**

In this contribution we will discuss recently developed technique for generation and detection of attosecond electron pulses via inelastic ponderomotive scattering of electrons at an optical traveling wave formed by two laser pulses at different frequencies. This scheme represents an analogy to the classical Kapitza-Dirac effect [1], in which the roles of the transverse and longitudinal directions (with respect to electron propagation) are reversed. We demonstrate a large modulation of the kinetic energy of subrelativistic electrons with initial kinetic energy of 29 keV, achieving a peak acceleration gradient of G=2.2 GV/m (energy gain/travelled distance) [2]. A time-correlated modulation of electron energy leads to a ballistic compression and formation of attosecond electron pulses. Detection of the sub-cycle temporal structure of the electron pulse train was performed via energy streaking using a second phase-controlled traveling wave [3]. Measured spectrograms (spectrum as a function of relative phase) and their comparison with numerical calculations allow monitoring the evolution of the electrons' longitudinal phase space distribution. [1] P. L. Kapitza, and P. A. M. Dirac, Proc. Cambridge Philos. Soc. 29, 297 (1933). [2] M. Kozák, T. Eckstein, N. Schönenberger, and P. Hommelhoff, Nat. Phys. 14, 121-125 (2018). [3] M. Kozák, N. Schönenberger, and P. Hommelhoff, Phys. Rev. Lett. 120, 103203 (2018).

##
Speaker: Krivanek, Ondrej - **
Invited Talk
**

**Authors:**N. Dellby1, A.L. Bleloch1, M.V. Hoffman1, T.C. Lovejoy1, C. Su2 and O.L. Krivanek1,3

**Affiliations:**1. Nion R&D, 11511 NE 118th St, Kirkland, WA 98034, USA 2. Nuclear Science and Engineering Department, MIT, Cambridge, MA 02139, USA 3. Department of Physics, Arizona State University, Tempe, AZ 85287, USA

**Keywords:**spectrometers, monochromators, aberration correction

**Abstract Title:**

Correction of Aberrations in Electron Monochromators and Spectrometers

**Abstract:**

Electron energy loss spectroscopy (EELS) in the electron microscope has progressed remarkably in recent years. In our monochromated microscope system, we have reached 4.2 meV energy resolution at 30 keV, measured as the full-width at half-maximum of the monochromated zero loss peak (FWHM of ZLP), and 5.9 meV at 60 keV - i.e., energy resolution better than 1 part in 10^7. In both the monochromator and the spectrometer, the energy spectrum contains a small image of the electron source, and the attainable energy resolution is given by ER = d / D, where d is the diameter of the source image and D the energy dispersion. Reaching better energy resolution thus requires making d smaller, or increasing D. The second path employs sizable energy-dispersing devices with concomitant weight and mechanical stability issues. We have chosen the more practical first path to better energy resolution, and we pay particular attention to three performance aspects: 1) stability of the source image position, 2) demagnifying the source sufficiently (while retaining a useful electron current), and 3) increasing the convergence angle, to minimize the diffraction limit, and to maximize the probe current. The third aspect requires that aberrations be kept under tight control. Our latest spectrometer design corrects all geometric aberrations up to 5th order, plus mixed chromatic-geometric aberrations up to third rank. It also includes autotuning that measures individual aberration coefficients and corrects them. The talk will review the methods we use to optimize performance aspects 1) and 2), and then focus on the correction of aberrations in the monochromator and the spectrometer. It will also describe our recent work on optimizing probe corrector performance.

## Speaker: Kruit, Pieter

**Authors:**Pieter Kruit(1) and Hideto Dohi(2)

**Affiliations:**(1)Delft University of Technology and (2)Hitachi High-Technologies Corporation

**Keywords:**scanning electron microscope; aberration corrector;MEMS electron optical components

**Abstract Title:**

Double Mirror Aberration Corrector

**Abstract:**

The resolution of scanning electron microscopes (SEMs) is limited by aberrations of the objective lens, mainly the chromatic aberration. It is well known that both spherical and chromatic aberrations can be compensated by placing an electron mirror in the beam path before the objective lens. The effectiveness of this has been proven in LEEM systems. Nevertheless, this approach has not led to use of these aberration correctors in SEMs, probably because aberrations of the bending magnet can be a serious problem. We have proposed a mirror corrector with two mirrors placed perpendicularly to the optic axis of an SEM and facing each. As a result, only small-angle magnetic deflection is necessary to guide the electron beam around the top mirror to the bottom mirror and around the bottom mirror to the objective lens. The deflection angle is only in the order of 50 mrad, and thus sufficiently small to avoid deflection aberrations. In addition, lateral dispersion at the sample plane can be avoided by the correct choice of deflection fields. In order to keep such a corrector system simple, the incoming beam should pass the top mirror at a distance in the order of millimeters. It is proposed that condition can be satisfied with micro-scale electron optical elements fabricated using MEMS technology. Extensive optical calculations were performed. Aberrations of the micro-mirrors were analyzed by numerical calculation. Dispersion and aberrations of the deflectors were calculated by using an analytical field model. We concluded that the proposed corrector system could be a candidate for aberration correction in low-voltage SEMs. We have started the construction of a system to be tested in an existing SEM. Reference: Hideto Dohi and Pieter Kruit, Design for an aberration corrected scanning electron microscope using miniature electron mirrors, Ultramicroscopy 189 (2018) 1-23.

## Speaker: Kruit, Pieter

**Authors:**Pieter Kruit and Maurice Krielaart

**Affiliations:**Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands

**Keywords:**interaction-free measurement, quantum electron microscope, electron mirror, electron phase manipulation

**Abstract Title:**

Some Designs for Quantum Electron Microscopy

**Abstract:**

Following a recent suggestion [1] that interaction-free measurements may be possible with electrons, we have analyzed the opportunities to use this concept for imaging of biological specimen with reduced damage in a Transmission Electron Microscope. This requires that part of the electron wave travels multiple times through the same position on the specimen. We expect this to be an interesting challenge in charge particle optics. We have made preliminary designs for an atomic resolution interaction-free electron microscope, or "quantum electron microscope" [2] . The designs require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times. A two-state-coupler has the function of moving the electron wave slowly between the reference beam and the specimen beam, as in a Rabi-oscillation. We have suggested and are now investigating, both in simulation and in experiment, whether an electron mirror with a diffraction grating on the reflecting surface can accomplish the two state coupling while at the same time forming part of the resonator. The experimental design consists of many MEMS elements. The same mirror unit might be used for a more advanced manipulation of the electron wave front. This research is funded by the Gordon and Betty Moore Foundation. 1] Putnam, W.; Yanik, M. Phys. Rev. A 2009, 80, 040902. 2] Kruit, P.; R. G. Hobbs, C-S. Kim, Y. Yang, V. R. Manfrinato, J. Hammer, S. Thomas, P. Weber, B. Klopfer, C. Kohstall, T. Juffmann, M. A. Kasevich, P.Hommelhoff, K. K. Berggren. Ultramicroscopy (2016), 31-45 3] Elitzur, A. C.; Vaidman, L. Found. Phys. 1993, 23, 987-997.

## Speaker: Kruit, Pieter

**Authors:**Leon van Kouwen, Dustin Laur and Pieter Kruit

**Affiliations:**Delft University of Technology, Lorentzweg 1, Delft, The Netherlands

**Keywords:**Ion source; brightness; mirror charge

**Abstract Title:**

Nano Aperture Ion Source

**Abstract:**

Ion production in the Nano Aperture Ion Source (NAIS) is based on electron impact gas ionization inside a sub-micron sized gas chamber [1]. An important part of recent efforts [2] was devoted to understanding how the relevant physical processes determine the ion beam performance. This has led to interesting insights in charged particle optics. The influence of initial velocity and position distributions of the neutral gas particles, their ionization cross sections, the electron current density, ion-neutral scattering, Coulomb interactions and the electric fields around the double membrane structure are studied by analytical models, numerical calculation, and ray tracing. An unexpected effect is that the low energy ions are deflected by their mirror charge when they exit the submicron sized orifice of the gas chamber. An important finding is that the ion current and the brightness tend to keep increasing with increasing particle density, despite increasing ion-neutral scattering. Ion-to-ion Coulomb repulsion is found to pose a final limit to the achievable brightness. In a realistic configuration, the simulations predict a brightness of about 3 x 106 A/m2srV in combination with an energy spread of 1 eV. In experiments we have now demonstrated a brightness of 1 x 105 A/m2srV, which we consider a milestone result because it is already a competitive brightness when compared to a Ga LMIS while there is clearly room for improvement. [1] David S. Jun, Development of the Nano-Aperture Ion Source, PhD Thesis TU Delft, 2014. [2] Leon van Kouwen, The Nano-Aperture Ion Source, PhD Thesis TU Delft, 2017

##
Speaker: Luiten, Jom - **
Invited Talk
**

**Authors:**Wouter Verhoeven, Jasper van Rens, Peter Mutsaers, Jom Luiten

**Affiliations:**Eindhoven University of Technology

**Keywords:**dynamic electron optics, ultrafast electron microscopy, microwave cavities, time-of-flight eels

**Abstract Title:**

Longitudinal phase space manipulation of electron beams using microwave cavities

**Abstract:**

At Eindhoven University of Technology we are developing resonant microwave cavities as dynamic charged particle optics for electron microscopy (EM). We employ miniaturized and power-efficient dielectric 3 GHz pillbox deflection cavities in TM-110 mode both for creating femtosecond electron pulses by chopping a continuous beam and for measuring pulse lengths by streaking electron pulses across a detection screen. Cavities in TM-010 mode are used as longitudinal lenses to both compress electron pulses (positive focal length), to improve the temporal resolution, or stretch them (negative focal length), to reduce the uncorrelated energy spread. If properly used, microwave cavities do not affect the electron beam quality. The microwave phase can be accurately synchronized to femtosecond lasers, enabling ultrafast pump-probe experiments. Combining a high-quality continuous electron gun with a special configuration of two TM-110 cavities and two TM-010 cavities, time-of-flight EELS can be realized with few-10-meV energy resolution and few-ps time resolution. This new method does not require femtosecond lasers and may constitute an interesting alternative to magnetic electron spectrometry. The use of microwave cavities is therefore not restricted solely to the burgeoning field of ultrafast EM. In fact, it may become increasingly relevant to EM in general.

## Speaker: Lyman, Charles

**Authors:**Charles E. Lyman and Robert L. Price

**Affiliations:**Dept. of Materials Science and Engineering, Lehigh University, Bethlehem, PA (1991 MSA President) and University of South Carolina Medical School, Columbia, SC (2018 MSA President)

**Keywords:**microscopy society, scientific conference, electron and ion optics, peer-reviewed journal, education

**Abstract Title:**

For the promotion of microscopy and microanalysis in all relevant scientific disciplines: the Microscopy Society of America

**Abstract:**

The Microscopy Society of America (MSA) is pleased to support student travel to the 10th International Conference on Charged Particle Optics. Such support is a natural fit for MSA given our mission statement, an excerpt of which forms the title above. Founded 76 years ago, our Society has been a forum for discussion of electron optics, from the early days of the TEM to aberration-correction technology; indeed, the original name of the society was the Electron Microscope Society of America. Today our purview also includes ion optics with presentations and publications that include focused ion beam (FIB) and atom probe tomography (APT) instrumentation and techniques. The Society promotes microscopy and microanalysis in several ways. The Microscopy & Microanalysis (M&M) conference in August is the largest annual microscopy meeting and instrument exhibition in the world. M&M 2018 featured 1236 scientific papers and attracted attendees from 40 countries. Among the many students and post-doctoral scholars attending the meeting, 55 received competitive travel awards. Our student council members are learning leadership skills by independently organizing an annual pre-meeting congress.

*Microscopy and Microanalysis*, our peer-reviewed research journal covering both the life and physical sciences, ranks high among microscopy journals in terms of Impact Factor and number of pages published per year. Our technical trade magazine,

*Microscopy Today*, reaches a large audience and provides news and research summaries that emphasize advances in instrumentation and methods, as well as hints and tips for novice and experienced microscopists. In addition to the above, our educational efforts include short courses and tutorials at the M&M meeting, a technologist certification program, undergraduate research scholarships, and several outreach programs for students in middle school and high school. Finally, membership in MSA is cost-effective since dues cover subscriptions to our publications and registration discounts at the M&M meeting.

##
Speaker: Mankos, Marian - **
Invited Talk
**

**Authors:**Marian Mankos1, Stewart A. Koppell2, Brannon B. Klopfer2, Thomas Juffmann3, Vladimir Kolarik4, Khashayar Shadman1 & Mark A. Kasevich2

**Affiliations:**1 Electron Optica, 1000 Elwell Court #110, Palo Alto, California 94303, USA 2 Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA 3 Universitaet Wien, Campus Vienna Biocenter 5, 1030 Vienna, Austria 4 Delong Instruments, Palackeho trida 3019/153b, Brno, Czech Republic

**Keywords:**electron optics, multi-pass transmission electron microscopy, electron mirror

**Abstract Title:**

Electron optics for a multi-pass transmission electron microscope

**Abstract:**

Recent advances in cryo-electron microscopy (cryo-EM) and direct electron detection have spurred renewed interest in the development of novel electron imaging techniques for applications in structural biology at atomic resolution. The challenge with imaging unstained biological specimens is that they provide a low scattering cross-section to the probing electrons because they are composed primarily of low atomic number elements. Hence, high electron doses are needed to obtain sufficient signal-to-noise ratios (SNR). Such doses, however, severely damage the specimens. Multi-pass transmission electron microscopy [1] is a promising approach that can reduce the required electron dose for a desired SNR by exploiting the change to the phase of the electron wave that is imparted by the specimen. In this approach, the electron beam interacts elastically with the specimen multiple times so that the change in the phase accumulates before reaching the detector. Here we examine the electron-optical design of a practical implementation of a multi-pass transmission electron microscope (MTEM), which is currently under construction. In MTEM, an electron pulse, triggered by an ultrafast laser beam, is focused by the illumination optics and transmitted by the entrance electron mirror, rendered transparent by a voltage pulse synchronized with the laser beam. The transmitted electron pulse enters an electron resonator, bounded by the entrance and exit mirrors. The resonator includes two objective and field lenses that sandwich the specimen. The electron pulse is collimated by the upper field and objective lens onto the specimen, and refocused by the lower objective and field lens onto the exit mirror, which reflects it back symmetrically so that the electron pulse is collimated again at the specimen. This reflection is carried out multiple times until a second voltage pulse renders the exit mirror transparent to allow the electron pulse with the accumulated phase to proceed into the projection optics, which magnifies the image at the exit mirror onto the detector. Past simulations have predicted an improvement in resolution and sensitivity for a range of electron microscopy imaging techniques, and an order-of-magnitude reduction in damage at equivalent resolution[2]. 1 T. Juffmann, B. B. Klopfer, T. L. Frankort, P. Haslinger, and M. A. Kasevich, Nat. Commun. 7, 12858 (2016). 2 T. Juffmann, S. A. Koppell, B. B. Klopfer, C. Ophus, R. M. Glaeser, and M. A. Kasevich, Sci. Rep. 7, 1699 (2017).

##
Speaker: Maxson, Jared - **
Invited Talk
**

**Authors:**Jared Maxson, William Li

**Affiliations:**Cornell University

**Keywords:**UED, photoinjector, time resolved diffraction

**Abstract Title:**

Ultrafast electron diffraction using the CBETA photoinjector

**Abstract:**

In this talk, I will describe perspectives and simulations of the photoelectron injector for the CBETA accelerator (Cornell-BNL Energy Recovery Test Accelerator) as a high average brightness source of short-pulse electrons for femtosecond time-resolved electron diffraction. Specifically, I will discuss the ability of the CBETA photoelectron gun to take advantage of novel high coherence photocathode materials, as well as the extreme flexibility of the RF acceleration system. The acceleration system is composed of five superconducting cavities each with independent phase and amplitude control, which I will show is critical for a number of applications, including longitudinal phase space linearization in velocity bunching, as well as ultrafast time of arrival measurements when used in conjunction with a high resolution spectrometer. These capabilities make the CBETA photoinjector an excellent candidate for use in high spatiotemporal resolution electron scattering experiments.

##
Speaker: McClelland, Jabez - **
Invited Talk
**

**Authors:**J. J. McClelland(1), J. R. Gardner(1,2), W. R. McGehee(1), A. Schwarzkopf(3), B. Knuffman(3), and A. V. Steele(3)

**Affiliations:**(1) CNST, National Institute of Standards and Technology, Gaithersburg, MD, USA; (2) IREAP, University of Maryland College Park, College Park, MD, USA; (3) zeroK NanoTech, Gaithersburg, MD, USA

**Keywords:**ion sources; laser cooling; high brightness; focused ion beams

**Abstract Title:**

Cold atom ion sources

**Abstract:**

Ionization of laser-cooled atoms has emerged as a new approach to constructing high brightness ion sources for applications such as focused ion beam (FIB) microscopy and milling. While conventional sources, such as the Ga liquid metal ion source (LMIS) or the gas field ionization source (GFIS), attain brightness by emitting from a very sharp tip, cold atom sources reach high brightness through reducing the transverse velocity spread. With the ultracold, microkelvin-range temperatures achievable with laser cooling, the corresponding velocity spread can lead to a brightness significantly higher than typical LMIS values. Moreover, the phase-space shape of the emittance of the source - narrow in velocity, wide in space - brings new opportunities for ion optical design. For example, high currents can be obtained without the high current density present in sharp tip sources. This can result in fewer Coulomb effects, such as increased emittance and broadened energy spread (Boersch effect). In addition, the absence of a sharp tip eliminates a sensitivity to source stability. Other advantages of this type of source include insensitivity to contamination, access to new ionic species, inherent isotopic purity, and fine control over emission, down to the single ion level. To date, sources have been demonstrated with Cr, Li, Rb, and Cs ions. In this talk I will review progress in the field, focusing on our work with a Li FIB microscope for battery studies and a Cs FIB with brightness 24 times higher than the LMIS.

## Speaker: Munro, Eric

**Authors:**Eric Munro, John Rouse, Haoning Liu and Catherine Rouse

**Affiliations:**Munro's Electron Beam Software Ltd, 14 Cornwall Gardens, London SW7 4AN, United Kingdom

**Keywords:**Electron mirrors, boundary element method, aberration computation, direct ray tracing

**Abstract Title:**

A new simulation program for electron mirrors using the boundary element method

**Abstract:**

Electron mirrors have many applications in charged particle optics, e.g. aberration correctors, beam separators, time-of-flight spectrometers. Optimization of electron mirrors requires high accuracy computation of electric fields, trajectories, focal properties, and geometrical and chromatic aberrations, including both spatial and temporal aberrations. The simulations are more difficult than for electron lenses, because the ray slopes become infinite at the reflection plane, so the trajectories and aberrations have to be computed using time, rather than axial position, as independent variable. This paper present a new electron mirror simulation software using the Boundary Element Method. This method computes the electric charge distribution generated on the electrode surfaces, by dividing the electrodes into rotationally symmetric rings, and generating a matrix equation expressing the potential on each ring as a weighted sum of the surface charges on all the rings. Since the potentials on each ring are the known electrode potentials, a matrix equation is obtained whose solution yields the ring charges. The potential at any point in the mirror can then be computed by numerical evaluation of a sum of elliptic integrals of the ring charges. This method has several beautiful features: (1) Data input is simple, because only the electrode surfaces need to be discretized, not the intervening space; (2) Numerical accuracy can be verified by evaluating the potential at check-points on the electrodes and comparing these with the known values; (3) The axial potential distribution and its derivatives can be obtained with great accuracy; (4) From these axial functions, all the optical properties can be computed, including geometrical and chromatic aberrations, both temporal and spatial, using a differential algebraic method; (5) The potential and fields at any off-axis point can be computed using elliptic integrals which have great accuracy and stability, and the results are an exact solution of Laplace's equation; (6) These off-axis fields can be used to compute aberrations by direct ray-tracing, providing an independent check on the differential algebra results. The program will be described in detail, and illustrated with practical examples, and the results compared with those from our previous electron mirror program, which used finite element method and Hermite series fits.

## Speaker: Murata, Hidekazu

**Authors:**Hidekazu Murata, Seiji Watanabe, Takahiro Ikeda, Hirotaka Asai, Eiji Rokuta, and Hiroshi Shimoyama

**Affiliations:**Faculty of Science and Technology, Meijo University

**Keywords:**electron ray tracing; three-dimensional boundary charge method; Runge-Kutta-Fehlberg 4th order method; field emission spectroscopy; cylindrical deflection angle

**Abstract Title:**

Electron Ray Tracing in a Cylindrical Deflector Analyzer for Field Emission Spectroscopy

**Abstract:**

Field-emission spectroscopy (FES) is a technique that acquires an energy spectrum of the electrons emitted from a field emitter. A cylindrical deflector analyzer (CDA) is often used for FES. Assuming that the electric field in the CDA is an ideal cylindrical field, it is known that the optimum deflection angle is 127°. In fact, there is a deviation from an ideal cylindrical field in the CDA. In particular, a fringing field occurring at the vicinity of entrance and exit of slits is not negligible. Therefore, herein, we performed three-dimensional (3D) electric field calculations and electron ray tracing using a 3D boundary charge method (BCM) that we developed previously. Furthermore, for this purpose, we improved the calculation method of the electron ray tracing. So far, we had used Runge-Kutta-Gill method (RKG method) for the electron ray tracing. In the method, the step size is fixed due to the specification of the method. Therefore, to perform an electron ray tracing with high-accuracy, the step size must be finer. However, extremely-long calculation time is required for the electron ray tracing. Hence, to improve this obstacle, we introduced Runge-Kutta-Fehlberg 4th order method (RKF4 method) into the electron ray tracing calculation so that suitable step size can be controlled automatically while keeping high-accuracy. As a result, we have found that the improved method can reduce the calculation time while keeping high-accuracy. In addition, as a result of the election ray tracing in the CDA, we also have found that when the potential difference between the inner and outer electrodes is 0.353 V (= 2 E0/e log 1.8) and the initial energy E0 of the electrons is 0.3 eV, the optimum deflection angle of the CDA is ~109 degree.

## Speaker: Nesteruk, Konrad P.

**Authors:**K. P. Nesteruk, C. Calzolaio, A. Gerbershagen, D. Meer, V. Rizzoglio, M. Seidel, and J. M. Schippers

**Affiliations:**Paul Scherrer Institut, Villigen PSI, Switzerland

**Keywords:**Beam optics design; proton therapy; superconducting gantry;

**Abstract Title:**

Large momentum acceptance beam optics of a superconducting gantry for proton therapy

**Abstract:**

In proton therapy, the last part of the beam transport system is installed on a rotatable gantry, so that the beam can be aimed at the tumor from different angles. Since such a gantry system consists of many dipole and quadrupole magnets, it is typically a 200 ton device of more than 10 m in diameter. The use of superconducting (SC) magnets for proton therapy allows gantries to be significantly lighter and potentially smaller, which is attractive for this medical application. In addition to that, SC combined function magnets enable beam optics with a very large momentum acceptance. The latter can be advantageous for patient treatment, since the irradiation time can be significantly reduced by avoiding magnet current changes. A new prototype of a SC gantry with a momentum acceptance of +/- 15 % is under development at PSI. To design such an achromatic system, precise high-order calculations have been performed. In order to reach the required accuracy and to check consistency of the obtained results, we have used several simulation tools in our iterative design approach. Here we will describe how we have combined an initial standard first order calculation with more detailed calculations using the higher order code COSY Infinity and particle tracking using OPAL (open source software from PSI) in 3D field maps obtained from detailed magnet calculations performed in OPERA. A comparison of the results from the beam-optics calculations helped to determine the next iteration step in the design of the SC gantry.

## Speaker: Neustock, Lars Thorben

**Authors:**L. T. Neustock, P. C. Hansen, Z. E. Russell, L. Hesselink

**Affiliations:**Stanford University, Ion Innovations

**Keywords:**optimization, electrostatic lens design, finite element method, inverse design, electrostatic field solver, adjoint variable method, charged particle optics, einzel lens, velocity verlet

**Abstract Title:**

Adjoint variable method for rapid design optimization of electrostatic lens systems

**Abstract:**

We have implemented a generative algorithm for design optimization of electrostatic charged particle optical devices using the discrete adjoint variable method. In this work, we optimize a series of electrostatic lenses to minimize spherical and chromatic aberrations and perform beam steering. To the best our knowledge, these are the first charged particle optics systems designed by an adjoint variable based algorithm. Physical systems with many designable parameters (e.g. dimension, shape and applied voltages) are computationally burdensome to optimize. To efficiently improve the device design it is crucial to know how its performance changes under all designable perturbations to its shape, dimensions, and operating conditions. This sensitivity of the design to its design parameters can be obtained by simulating each potential perturbed device in turn. This is a computationally costly approach requiring at least one extra full-system calculation per design parameter. In contrast, adjoint design sensitivity analysis is a method to obtain sensitivities to all design parameters at once through an algorithm with nearly-fixed computational cost. Thus, adjoint methods enable rapid optimization of complex systems. This has led to the pervasive use of these methods in aeronautical, structural and photonic design. To obtain such a rapid algorithm for charged particle optics, we derived and implemented a fully discrete adjoint system solver for the nonlinear, coupled system comprising the Laplace equation for the electric potential and an equation of motion based on the Lorentz force law and Newton's second law, using a custom-built electrostatic finite-element method and a charged particle dynamics simulator based on Verlet integration. This solver allows for arbitrary selection of initial designs and number of design parameters and calculates the sensitivity of the design to charged particle trajectories for each of these parameters. The method demonstrated can be applied to miniaturizing complex systems and optimizing multi-beam applications such as lithography.

## Speaker: Nishi, Ryuji

**Authors:**R. Nishi(1), S. Hoque(1, 3), H. Ito(1,2) and A. Takaoka(1)

**Affiliations:**(1) Osaka University, (2) Hitachi High-Technologies Corp., (3) Hitachi High-Technologies America, Inc.

**Keywords:**chromatic aberration, symmetric line currents, SEM, aberration correction

**Abstract Title:**

Investigation of electromagnetic-SYLC for chromatic aberration correction

**Abstract:**

We are studying a simple aberration corrector for scanning electron microscopes (SEM). We have proposed SYLC (SYmmetric Line Currents) corrector in which parallel line currents are symmetrically arranged instead of usual magnetic multipoles to correct spherical aberration [1, 2, 3]. The main feature of SYLC is being free of magnetic material, thus eliminating the problems of hysteresis, nonuniformity and magnetic saturation of the magnetic material. In addition to spherical aberration, correction of chromatic aberration is also necessary for low acceleration voltage SEM. Therefore, SYLC is expanded to incorporate electrostatic multipole field with magnetic multipole field. Applying positive and negative electrostatic potentials alternately to the conducting lines of SYLC yields a superposition of electrostatic and magnetic 2N-poles, which we call an electromagnetic-SYLC. Moreover, since the direction and distribution of 2N-pole electric and magnetic field are the theoretically same, the number of poles can be reduced by half comparing with a conventional electromagnetic multipole. We show that chromatic aberration can be corrected by a model in which the conventional multipoles of the quadrupole 4-stage corrector proposed by H. Rose [4] are replaced by the combination of electro-and magnetic-SYLC. [1] Nishi R., Ito H., Hoque S., (IMC2014), IT-1-P2984, pp.200-201 [2] S. Hoque, H. Ito, R. Nishi, A. Takaoka, E. Munro, Ultramicroscopy 161, (2016) 74-82 [3] P. W. Hawkes and E. Kasper, Principle of Electron Optics, Vol.2 : Applied Geometrical Optics, 2nd ed., chap. 41, pp. 986-988, Academic Press, 2017. [4] H. Rose, Optik 32, (1970) 144

## Speaker: Ogawa, Takashi

**Authors:**Takashi Ogawa

**Affiliations:**Korea Research Institute of Standards and Science

**Keywords:**Monochromator, Cylindrical lens, Electron microscope

**Abstract Title:**

Evaluation of a Monochromator with Offset Cylindrical Lenses for Electron Microscopy

**Abstract:**

Monochromators (MCs) have been indispensable optical components for advanced electron microscopes [1-3]. MCs can improve image resolutions at low energy conditions and energy resolutions of EELS spectra. Both are achieved by narrowed energy spreads of electron beams. At the CPO9 conference, a new MC with cylindrical lenses (CLs) was proposed [4]. The MC consists of two CLs in offset layout with the middle plane symmetry. The strongly excited CLs generate large energy dispersions, which enables the MC optics with high performance and simple structure. Based on theoretical studies on the MC [5-7], a prototype of the MC has been constructed at high mechanical accuracy and combined with highly stable electronics. The MC achieved the energy resolution of 73 meV by measuring energy distributions with an additional energy analyzer [8]. Observation in two conditions with or without the MC confirmed fine beam profiles because of the symmetry of the MC. The results assure applicability of the MC to electron microscopes. At the conference, recent evaluation results of the MC will be presented. References: [1] H. Rose, Ultramicroscopy 78 (1999) 13. [2] H.M. Mook, P. Kruit, Ultramicroscopy 81 (2000) 129. [3] O.L. Krivanek, et al., Nature 514 (2014) 209. [4] T. Ogawa, et al., Microsc. Microanal. 21 (S4) (2015) 112, Proceedings of CPO9. [5, 6] T. Ogawa, B. Cho, Nucl. Instrum. Methods. A 772 (2015) 5, 800 (2015) 18. [7] T. Ogawa, et al., J. Vac. Sci. Technol. B 33 (6) (2015) 06FJ01-1-11. [8] T. Ogawa, Y. Takai, J. Vac. Sci. Technol. B 36 (3) (2018) 032902.

## Speaker: Oral, Martin

**Authors:**Martin Oral

**Affiliations:**Institute of Scientific Instruments of the CAS, Kralovopolska 147, 612 64 Brno, Czech Republic

**Keywords:**linear quadrupole Paul trap, Coulomb crystals, optical atomic clock, micromotion, trajectory simulation

**Abstract Title:**

Simulation of motion of many ions in a linear Paul trap

**Abstract:**

The quadrupole linear Paul trap is one of the key instruments in building highly stable atomic clocks. However, a frequency reference based on a single trapped ion is limited in stability due to the time needed for the interrogation cycle which cannot be further shortened. A promising strategy is the utilization of multiple trapped ions. The ions of the same kind then repulse each other with the Coulomb force, which is countered by the ponderomotive force of the time depended field in the trap. A few ions form a chain along the axis of a linear Paul trap. Adding more ions (a few tens or hundreds) gives rise to Coulomb crystals. We created an efficient simulation code which calculates the motion of such collections of ions in quasistatic radiofrequency fields of real linear quadrupole traps (including the micromotion). We attempt to take into account various methods of cooling the ions. The simulation tool can be used to study the formation and the dynamics of Coulomb crystals under conditions corresponding to various experimental set-ups.

## Speaker: Ose, Yoichi

**Authors:**Yoichi Ose and Makoto Ezumi

**Affiliations:**Hitachi High-Technologies Corp.

**Keywords:**SEM, auto-focus, self-inductance, aftereffect

**Abstract Title:**

Simulation for the development of precise auto-focusing of SEM lenses

**Abstract:**

The latest SEMs in industrial product lines should meet the demands of higher resolution and higher throughput. The higher resolution objective lenses have the shorter depth of focus which require the more precise adjustment of their coil current. The duration of auto focusing should be shorter to obtain higher throughput then the precision of auto-focusing is subject to the delay of current response with the self-inductance and the aftereffect of magnetization. We propose a response function based on those two delay mechanisms while the ratio of the aftereffect is estimated comparing experimental delay times with simulated ones. A function to calculate self-inductance has been built onto an in-house electron optics simulator "EMB2D" which shows the saturation of self-inductance over the permeability of 1000. We demonstrate the ratio of the aftereffect 0.06 with time constant of 1.0 sec. is plausible in this case and our proposed response function is useful to improve the precision of auto-focusing.

## Speaker: Pranesh, Balamuniappan

**Authors:**Balamuniappan Pranesh, Ang Wei Kean, Anjam Khursheed

**Affiliations:**National University of Singapore

**Keywords:**annular focused electron/ion beams, aberration correction, electric sectors

**Abstract Title:**

Wide-angle annular electron beam focusing column.

**Abstract:**

There are many applications in electron microscopy, electron spectroscopy, as well as accelerator physics that require the combination of minimizing a focused electron beam's probe size, while maximizing its beam current. This paper describes how it can be done through the use of annular focused electron beam column designs and cold field emission sources, where an electron beam is propagated and focused in the form of a ring beam. For relatively small probe semi-angles, where the central angle lies between 1° to 2°, a 3 stage deflector-corrector in combination with an objective lens will be presented. The objective lens design can be either magnetic or electric. For probe semi-angles above say 20°, a column consisting of 2 identical electric sectors and 2 identical focusing lenses functioning with odd symmetry will be presented. The column is designed to cancel energy dispersion while limiting geometric aberrations to be of 3rd order at the point of final focus. Both designs predict to have over two orders of magnitude higher beam current than their corresponding conventional electron beam focused columns for the same final probe size. For a 1.2 keV annular electron beam with a semi-angular spread of 45° +- 0.1146° semi-angle, simulation results predict a final spot size of 5.7 nm at a working distance of 3.4 mm, giving approximately three orders of magnitude larger probe current than its corresponding conventional on-axis electron beam column for a similar probe size.

## Speaker: Qin, Bin

**Authors:**Bin Qin

**Affiliations:**Huazhong University of Science and Technology

**Keywords:**Proton therapy, beam optics, superconducting gantry beamline, high order effect

**Abstract Title:**

Comparison of beam optics for normal-conducting and superconducting gantry beamline applied to the proton therapy system

**Abstract:**

Due to the unique 'Bragg peak' dose distribution characteristics of the proton beam, the proton therapy is recognized as one of the most precise and effective radiotherapy method for tumors. A gantry is required to project the beam on tumors with various angle for multiple fields radiation, and a superconducting beamline can significantly reduce the size and the weight of the gantry. A proton therapy system is under development in HUST. This paper will introduce the comparison study of the beam optics for normal-conducting and superconducting gantry beamline. Beam simulation study which demonstrates the influence of high order magnetic field effect in the beamline, will also be described.

##
Speaker: Radlicka, Tomas - **
Invited Talk
**

**Authors:**Tomas Radlicka

**Affiliations:**Institute of Scientific Instruments CAS

**Keywords:**differential algbraic method, correctors, aberrations, parasitic aberrations

**Abstract Title:**

Differential algebraic method in electron optical design

**Abstract:**

The differential algebraic method is standardly used in particle accelerator design. It provides the high order transfer map needed for simulations of the long-term ring stability. On the other hand, the electron optics community prefers methods having a solution in the form of the aberration integral which provides a deeper view of the effect of each element on the electron optical properties of the system but they became too complicated with increasing aberration order, which is not a case of the differential algebraic method. We show the potential of the differential algebraic method on a design of electron optical systems. The first part deals with simulation of the axially symmetrical systems where the effect of the fringing field regions must be handled to obtain correct values of aberration coefficients. The next part shows the application of the method on aberration corrector design, we propose the efficient combination of the trajectory method used for a qualitative description of the primary aberration behavior and the differential algebraic method providing the quantitative description of electron optical properties. Instead of the aberration integrals the shape of the aberration coefficients is used for estimation of the effect of each electron optics element. The approach is used in the analysis of parasitic aberrations and optimization of the system with corrector. The last part shows the application on the systems whose symmetry was perturbated by the general 3D elements of the in-lens detector.

## Speaker: Rosenbusch, Marco

**Authors:**M. Rosenbusch (1), Y. Ito (2), P. Schury (3), M. Wada (3), H. Wollnik (4), and the SHE-Mass Collaboration

**Affiliations:**(1) RIKEN Nishina Center (RNC), (2) Japan Atomic Energy Agency (JAEA), (3) KEK - Wako Nuclear Science Center (WNSC), (4) New Mexico State University (NMSU)

**Keywords:**Multi-Reflection Devices, Precision Mass Spectrometry, Mass Calibration, Nuclear Masses

**Abstract Title:**

Recent successes of multi-reflection devices at RIKEN's RIBF facility and some thoughts about highly accurate mass calibration using ion traps

**Abstract:**

By the use of coaxial ion mirrors, very long flight paths of ions to a time-of-flight detector were possible since the early 90's, when multi-reflection time-of-flight mass spectrometry (MRTOF MS) was invented [1]. The development and usage of MRTOF mass spectrographs has been performed intensely at nuclear-physics on-line laboratories at later time and is still being continued. Due to the high precision of ion masses achieved in times <10 ms, and the single-ion sensitivity achievable for TOF MS, this technique became attractive for high-precision mass determinations of rare and short-lived nuclei. Due to minute production rates and insufficient beam emittances provided by the existing facilities, the MRTOF technique has been developed in combination with ion-trapping techniques, i.e. quadrupole ion traps as accumulators, ion coolers, and injectors into the MRTOF device. At the super-heavy element (SHE)-mass facility of RIKEN-KEK [2] the exotic isotopes of 249-253Md [3], many other rare species like 210-214Ac/Ra [4] and about 70 other isotopes have successfully been mass determined with precisions down to several hundred ppb [5]. Reaching extremes for mass precisions, new considerations of the effect of ion traps on the mass calibration of an MRTOF mass spectrograph may become important and have been calculated. Here, the success of a MRTOF MS at RIKEN's RIBF facility will be presented and later-on, some thoughts on mass calibrations for precisions beyond the so far achieved ones will be discussed. [1] H. Wollnik and M. Przewloka, IJMS Ion Proc. 96, 267 (1990) [2] P. Schury et al., Nucl. Instr. Meth. B 335, 39 (2014) [3] Y. Ito et al., Phys. Rev. Lett. 120, 102501 (2018) [4] M. Rosenbusch et al., Phys. Rev. C 97, 064306 (2018) [5] S. Kimura et al., IJMS 430, 134 (2018)

## Speaker: Seidling, Michael

**Authors:**Michael Seidling, Philipp Weber, Robert Zimmermann and Peter Hommelhoff

**Affiliations:**Friedrich-Alexander University

**Keywords:**Electron Guiding,Electron Beam splitter,Laser triggered Schottky-emitter,Paul trap,Coherence

**Abstract Title:**

Towards a microwave based beam splitter for a quantum electron microscope

**Abstract:**

The current status of development of a beam splitter for low-energy electrons (eV range) is reported. The beam splitter is based microwave electric fields applied to micro-structured chips. A coherent electron beam splitter is necessary to establish interaction-free measurements [1] with free electrons [2]. A possibility to guide electrons is provided by the Paul trap principle [3]. The electrons are confined in the two directions perpendicular to the direction of motion by fast alternating electric fields. The so formed pseudopotential guides the electrons in its minimum. The form and assembly of the electrodes design the desired pseudopotential, which allows constructing a beam splitter for electrons. Based on the initial designs of guides [4, 5], we have developed an electron beam splitter[6]. We can now split electrons with energies of up to 200 eV, however, we have not demonstrated coherent splitting. Properly designed, the beam splitter is predicted to split electrons coherently. To demonstrate this and for excellent electron beam control we have placed the guiding chip inside of an SEM. To establish phase control over electrons and microwaves at the guiding chip, femtosecond laser pulses trigger the Schottky-emitter of the SEM. This way, the electrons can be injected in to guide at a certain microwave phase. The current status of the experiment will be reported. The goal is to show interaction-free measurements [1] with free electrons, which would pave the way for the development of a quantum electron microscope [2, 7]. [1] P. Kwiat et al.; Phys. Rev. Lett. 74, 4763 (1995) [2] W. P. Putnam and M. F. Yanik; Phys. Rev. A 80, 040902(R) (2009) [3] W. Paul; Rev. Mod. Phys. 62, 531 (1990) [4] J. Hoffrogge et al.; Phys. Rev. Lett. 106, 193001 (2011) [5] J. Hoffrogge and P. Hommelhoff; New J. Phys. 13, 095012 (2011) [6] J. Hammer, et al.; Phys. Rev. Lett. 114, 254801 (2015) [7] P. Kruit et al.; Ultramicroscopy 164, 31–45, (2016)

## Speaker: Shadman, Khashayar

**Authors:**Khashayar Shadman, Marian Mankos

**Affiliations:**Electron Optica, 1000 Elwell Court #110, Palo Alto, California 94303, USA

**Keywords:**nonlinear ordinary differential equation solver, ray-optical simulator

**Abstract Title:**

An algorithm for characterizing the geometric optics of charged particle instruments

**Abstract:**

The proper design of charged particle instruments requires accurate simulations of the particle trajectories within the applied electromagnetic fields. Of interest, in particular, are the small deviations in the trajectories from the optical axis of the instrument. These deviations have linear and nonlinear dependencies on the initial conditions of the particles whose coefficients define the optical properties of the instrument. These coefficients can be computed directly, circumventing the need to simulate the individual trajectories. The traditional methods apply perturbation theory to the equation of motion to manually derive integral expressions for the primary nonlinear (aberration) coefficients. However, the manual procedure is difficult to extend for the computation of the higher order aberrations as the algebra becomes intractable. This difficulty has been overcome by the differential algebraic method, which uses a structure from nonstandard analysis to compute the series expansions of the electromagnetic forces about the optical axis in an automated manner. Here, an algorithm is presented that uses a standard mathematical technique, the binomial theorem, to codify this calculation. This algorithm gives the evolution of the coordinates along the optical axis as a series expansion in their initial values. The series coefficients can be derived up to any order in one of two ways, by either accumulating them serially along the optical axis via the solution to a difference equation or in parallel over the entire region of interest via an iterative solution of an integral equation. The algorithm is not limited to the equation of motion. It can be applied to higher order nonlinear, ordinary differential equations for the evolution of the dependent variables in the neighborhood of a principal path.

## Speaker: Shchepunov, Vyacheslav

**Authors:**V. Shchepunov, M. Rignall, R. Giles, R. Fujita, H. Nakanishi, and H. Waki

**Affiliations:**Shimadzu Research Laboratory (Europe) Ltd, Manchester, M17 1GP, United Kingdom

**Keywords:**Mass analyzer, TOF mass spectrometer, Ion optics, Aberrations

**Abstract Title:**

A High Resolution Multi-turn TOF Mass Analyzer

**Abstract:**

Ion optical design of a high resolution Multi-turn TOF Mass Analyzer (MT-TOF MA) is presented. The analyzer has rotational symmetry of the main electrodes, which allows higher density of turns in the azimuthal (drift) direction compared to MT-TOF MA's linearly extended in the drift direction. The analyzer geometry has mid-plane symmetry and comprises a pair of polar-toroidal sectors S1 (lower) and S3 (upper), a toroidal sector S2 located at the mid-plane of the system, a pair of polar (trans-axial) lenses, and a pair of conical lenses for longitudinal and lateral focusing, each pair of the electrodes being mirror symmetric with respect to the mid-plane. Additionally, drift focusing segments embedded into S2 electrodes are used to provide focusing and spatial isochronicity in the drift direction. Due to an open reference trajectory and static electric fields the analyzer retains the full mass range of the injected ions. Geometry and potentials of the analyzer electrodes are optimized for 5-8 keV ions to provide transverse focusing and isochronicity with some higher order corrections of TOF aberrations. Ion optical properties of the analyzer are described in detail. Several operational modes of the analyzer are feasible. At small turn numbers (up to ~10-12 turns) focusing in the drift direction is not required, and the turn number can be varied by simple injection steering. Maximum m/dm in this mode is ~50-60 k (fwhm). At larger turn numbers the drift focusing must be used. The ions' drift in the azimuthal direction can be reversed by using a pair or dedicated reversing deflectors. This gives possibility of multiple passes in the drift direction. It was demonstrated earlier that ~200 k (fwhm) of mass resolving power is feasible after 2 passes in the drift direction (forward and reversed). Further optimization of the analyzer for 4 passes allowed us to increase m/dm up to ~400-500 k (fwhm). Respective numerical simulations are presented. Apart from TOF operational modes the analyzer can be optimized for the use as an electrostatic trap with Fast Fourier Transform (FFT) mass analysis.

## Speaker: Shchepunov, Vyacheslav

**Authors:**V. Shchepunov, M. Rignall, R. Giles, R. Fujita, H. Nakanishi, and H. Waki

**Affiliations:**Shimadzu Research Laboratory (Europe) Ltd, Manchester, M17 1GP, United Kingdom

**Keywords:**FFT mass spectrometry, Mass analyzer, Ion optics, Aberrations

**Abstract Title:**

FFT and TOF Operational Modes of a Hybrid Mass Analyzer

**Abstract:**

It was demonstrated earlier that a rotationally symmetric mass analyzer can achieve mass resolving power of ~200 k (fwhm) in a multi-turn TOF operational mode. The analyzer geometry has mid-plane symmetry and comprises a toroidal sector S2 located at the mid-plane, a pair of polar-toroidal sectors S1 and S3, pairs of trans-axial and conical lenses for lateral and longitudinal focusing, each pair being mirror symmetric with respect to the mid-plane. In the multi-turn TOF operational mode drift focusing segments are used to provide focusing and spatial isochronicity in the drift direction. In this work we present results of simulation studies demonstrating that analyzers with similar geometries can be used as (i) a pure Fast Fourier Transform (FFT) mass analyzer with image charge detection providing m/dm of at least ~800 k (fwhm), (ii) a pure multi-turn TOF mass analyzer with m/dm of at least ~200 k (fwhm), and (iii) a hybrid instrument providing either m/dm ~100 k (fwhm) in multi-turn TOF mode or m/dm ~800 k (fwhm) in FFT mode. Analyzers of three different sizes (500 mm, 250 mm and 120 mm of external diameter of S2) have been studied numerically for ions at 5-8 keV energy. The largest analyzer is the best for the use in the multi-turn TOF mode. Its simulated m/dm for 400 Da ions at 5 keV is ~200 k (fwhm) at typical flight times of about 1.1 ms. Large size makes the analyzer rather slow for running it in FFT mode. On the contrary, the smallest analyzer is the fastest of the three and the most appropriate for the use in the FFT mode. The 5th harmonic of the FFT signal provides m/dm of ~800 k (fwhm) after 1 sec of measurement time. Its estimated m/dm in the multi-turn TOF mode is only ~15-20 k. Hybrid anayzer of the intermediate size (250 mm of S2 diameter) demonstrates m/dm ~100k (fwhm) in the multi-turn TOF mode or m/dm of ~800 k (fwhm) at 2.1 s measurement time in the FFT mode. Similar instruments can be run in one of the two complimentary modes - the multi-turn TOF mode with lower m/dm and faster mass analysis, or the FFT mode with higher m/dm and slower mass analysis. Corporate software and SIMION program were used in the studies.

## Speaker: Shirasaki, Yasuhiro

**Authors:**Yasuhiro Shirasaki and Momoyo Enyama

**Affiliations:**Hitachi, Ltd. Research and Development Group

**Keywords:**SEM, magnetic sector, simulation

**Abstract Title:**

Robustness Calculation of Magnetic Sectors using Differential Algebraic Method

**Abstract:**

In electron microscopes, beam separators are important electron optical components used to separate the signal electrons. In particular, magnetic sectors have a long history of being used for low energy electron microscopes, and in recent years have also been considered for use in scanning electron microscopes (SEMs). To be able to use magnetic sectors, the aberrations introduced must be negligible compared to that introduced by other optical components [1]. Furthermore, the magnetic sectors must be robust enough so that they can be fabricated and operated under practical machining and current source precisions, respectively. Aberrations introduced by magnetic sectors can be calculated using the differential algebraic method to solve the electron beam trajectory as a function of its initial conditions, which are position, direction, and energy [2]. However, to assess their robustness the aberrations must be calculated for many cases, each with different pole piece shapes and excitation currents caused by the machining error and the current source noise. This becomes tedious and increasingly difficult as the number of pole pieces becomes large. To make the assessment of robustness possible, we have developed a simulator that treats the angles of the grooves forming the pole pieces and the excitation currents of the pole pieces as parameters that are part of the initial condition. Therefore, in addition to the initial conditions of the beam, the aberrations can be calculated also as a function of the groove angles and the excitation currents. Using this simulator, we evaluated the robustness of a chicane-type magnetic sector [3], which only deflects the secondary beam, and found that this chicane-type magnetic sector can be useful for electron optical systems with straight optical axes such as SEMs. References: [1] Y. Shirasaki et al., EIPBN 2016 (2016). [2] M. Berz, Modern Map Methods in Particle Beam Physics. Academic Press (1999). [3] V. Kolarik et. al., "Close packed prism arrays for electron microscopy", Optik 87, 1 (1991).

## Speaker: Spivak-Lavrov, Igor

**Authors:**I.F. Spivak-Lavrov, O.A. Baisanov, A.A. Nurmukhanova, T.Zh. Tleubaeva

**Affiliations:**Kazakhstan, Russia

**Keywords:**prismatic mass-spectrometer, transaxial lens

**Abstract Title:**

Prismatic mass spectrograph with a conical achromatic prism and transaxial lenses

**Abstract:**

The conical achromatic prism (CAP) has a record angular dispersion equal to about 50 radians per 100% of mass variation [1]. In CAP, electric and magnetic fields are realized whose potentials in a spherical coordinate system depend only on angular variables. The particles of a homogeneous planar parallel ion beam move in the middle plane of the CAP along similar trajectories and maintain parallelism at the exit from the CAP. The CAP also focuses on energy, and the parallelism of the volume beam is maintained due to its telescoping in the vertical direction. CAP can be used in a prismatic mass spectrometer, which in its scheme is similar to a prism light-optical spectrometer equipped with a collimating and focusing lens. The linear dispersion of the prism spectrometer is equal to the angular dispersion of the CAP multiplied by the focal length of the focusing lens. A prismatic device is designed in which three-electrode transaxial lenses are used as a collimating and focusing lens. Due to the large mass dispersion by using a positional detector located in the focal plane of the focusing lens, a mass spectrograph can also be implemented in such a device. 1. Spivak-Lavrov I.F. Analytical Methods for The Calculation and Simulation of New Schemes of Static and Time-of-Flight Mass Spectrometers. - Advances in Imaging and Electron Physics. - Vol. 193, Burlington: Academic Press, 2016. - P. 45-128.

## Speaker: Stewart, Hamish

**Authors:**Dmitry Grinfeld, Christian Hock, Hamish Stewart, Alexander Makarov

**Affiliations:**Thermo Fisher Scientific

**Keywords:**mass spectrometry, aberration correction, ion mirror

**Abstract Title:**

Drift control in isochronous multi-reflection ToF analyzer with elongated ion mirrors

**Abstract:**

Ion mirrors are employed to establish a many meters-long flight path in a table-size time-of-flight (ToF) mass spectrometer [1-3] to enhance the mass resolving power. This goal also requires isochronicity, i.e., independence of the travel time with respect to the ion's initial coordinates and velocities. The systems under consideration comprise a pair of ion mirrors facing each other in such a manner that the ions isochronously oscillate between them. To achieve spatial separation between the oscillations, the mirrors are elongated in the direction orthogonal to the line of oscillations. The ions are injected at an angle and slowly drift in the direction of elongation describing zigzag paths. An unavoidable spread of the drift velocities results, however, in the expansion of the ion bunch, and adjacent oscillations start overlapping after just a few reflections. To counteract the drift expansion, the 'ideal' isochronous 2D electrostatic field f0(z,x) should be given a relatively small perturbation df(z,x,y) that varies in the drift coordinate 'y'. Some designs [3] incorporate an array of three-electrode lenses placed after each reflection, while in other solutions [4] the mirrors are sectioned to reverse the drift direction and refocus the ion bunch. It should be noticed, however, that the y-dependent field breaks the reflection isochronism so that the time of flight becomes a function of the ion's injection position y(0) and the injection angle dy/dz, which should be avoided. In this presentation, we develop a perturbation theory of drift control and its impact on the oscillation isochronism. It is shown that some classes of field perturbations generated by inter-mirror electrodes and slight non-parallelism of the ion mirrors counteract the drift expansion while the isochronicity is practically retained. As simulations have demonstrated, these results may be used to build ToF mass spectrometers with improved mass resolving power and throughput. [1] Nazarenko L.M., Sekunova L.M., Yakushev E.M., USSR Patent SU1725289 (1989) [2] Wollnik H. and Casares A., Int. J. Mass Spectrom. 227 (2) (2003): 217-22 [3] Yavor M., Verentchikov A., et al., Physics Procedia 1 (2008): 391-400 [4] Sudakov M. and Kumashiro S., Nucl. Instr. Meth Phys Res. A645 (2011): 210-5

## Speaker: Stopka, Jan

**Authors:**Jan Stopka, Pieter Kruit

**Affiliations:**Institute of Scientific Instruments of the CAS, v. v. i.; Faculty of Applied Sciences, Delft University of Technology

**Keywords:**Multi-beam; Coulomb interactions; Trajectory displacement

**Abstract Title:**

Statistical Coulomb Interactions in Multi-Beam SEM

**Abstract:**

Statistical Coulomb interactions in conventional scanning electron microscopy mostly affect the probe size via energy spread and virtual source broadening in the emitter vicinity. However, in a multi-beam probe forming system such as multi-beam SEM, the trajectory displacement due to interactions in the whole column can give a major contribution to the final probe size. A theoretical description of trajectory displacement is only known for single-beam systems. It can be expressed using approximate analytical formulae for the total trajectory displacement in a beam segment (Jansen's theory) or by integrating contributions of infinitesimally thin beam slices (the slice method). We build on Jansen's theory of statistical Coulomb interactions and develop analytical formulae for the trajectory displacement in a multi-beam system. We also develop a more precise semi-analytical result using the slice method. We compare both approaches with a Monte-Carlo simulation and show a good agreement thereof. Finally, we discuss the implications of our results for the optical design of multi-beam SEM. In a multi-beam with probe size dominated by Coulomb interactions, an increase in the number of beamlets does not necessarily provide an increase of throughput, because the probe size is limited by the total current. Furthermore, we disprove the notion of "the fewer crossovers - the less coulomb interactions" by showing the quadratic dependence of trajectory displacement on segment length.

## Speaker: Tamaki, Hirokazu

**Authors:**Hirokazu Tamaki 1, Yoichi Hirayama 2, Hiromi Inada 2

**Affiliations:**1 Research & Development Group, Hitachi, Ltd., 2 Science & Medical Systems Business Group, Hitachi High Technologies Corporation

**Keywords:**Image Distortion, Aberration, Electron Optics

**Abstract Title:**

Accurate measurement and correction of image distortion in TEM without reference

**Abstract:**

As well known, transmission electron microscope (TEM) has the image distortion due to lens aberration, and it is not easy to remove. Image distortion lowers the accuracy of image scale and increases the error in computational image reconstruction such as Tomography, Single Particle Analysis, and Ptychography. One of the solutions to this problem is a distortion correction with a known information. However it is difficult to get an exact information of the distortion, because there are no suitable measurement references for high magnification in electron microscopes. To solve this problem, we developed a new method to quantitatively measure the image distortion without reference. This method uses multiple images which are taken in the different fields of view with some amount of overlap. Between each image, there are mainly two kinds of changes. One is a linear image shift which corresponds to the field of view movement and the other is a nonlinear image transformation which originates from the image distortion. From the nonlinear image transformations, differential component of distortion can be obtained, which is then used to calculate image distortion. From numerically generated test images, measurement error less than 0.1% was confirmed for radial distortion which is the main cause of barrel or pincushion distortion. Moreover, post-correction of the image distortion from the measured results and the applicability to experimental images were also confirmed to be possible. This method allows many kinds of typical specimen to be used for distortion measurement, and the result can be used for both optical system evaluation and real-time or post distortion correction.

## Speaker: Tarazona, David

**Authors:**David A. Tarazona, Martin Berz, Kyoko Makino

**Affiliations:**Michigan State University

**Keywords:**betatron resonance muon losses

**Abstract Title:**

Muon losses from betatron resonances at the Muon g-2 Experiment at Fermilab

**Abstract:**

The Muon g-2 Experiment at Fermilab (E989) is directed toward measuring the muon anomalous magnetic moment (a, also named as “anomaly”) with statistical and systematic relative errors smaller than 0.14 ppm. This new measurement will serve as strong indication of yet undiscovered particles beyond the Standard Model (SM) and validate or disprove other theoretical models beyond the SM. Of special interest is the reduction of muon losses to achieve the precision needed at the g-2 Experiment. For this purpose, we have developed a detailed and precise model of the g-2 Storage Ring using COSY INFINITY that considers measured inhomogeneities of the magnetic field; high-order representation of the Electrostatic Quadrupole System (EQS) electrostatic field at different stages of the experiment; injection to the ring based on measurements; and beam collimation. Specifically, we have performed numerical analysis of lost muons rates for several possible configurations of the EQS in order to find the best possible scenarios that minimize muon losses and understand the resonance mechanisms that contribute to betatron and possibly spin resonances. Additionally, comparisons with measurements have allowed to determine whether observed resonances come from anticipated features of the g-2 storage ring or from unexpected sources of error whose effect could be detrimental to the precision of E989.

## Speaker: Trbojevic, Dejan

**Authors:**D. Trbojevic 1, William Lou 2, Stephen Brooks 1, Francois Meot 1, and Nicholaos Tsoupas 1

**Affiliations:**1. Brookhaven National Laboratory 2. Cornell University

**Keywords:**Fixed Field magnets, large momentum acceptance, hadron cancer therapy, proton gantry

**Abstract Title:**

Optical Design of the Fixed Field Permanent Magnet Gantry for the Proton Cancer Therapy

**Abstract:**

We present an optical design of the proton therapy gantry with a very large momentum acceptance of dp/p=+-33%. This momentum range corresponds to the kinetic energy of protons within a range of 65-250 MeV - energies required for the patient proton radiation therapy moving the Bragg peak between 3.5-38 cm. The optics uses combined function magnets with a fixed linear magnetic field. The permanent magnets of the Halbach type, are made of Neodymium Iron Boron - NeFeB. Additional important optics properties is that the gantry is made of chromatically matched parts. The first achromatic part bends protons upwards. The central momentum particles travel in a perfect circle while the rest of them radially oscillate with orbit offsets of +14 -10 mm; positive offsets correspond to the higher while the lower energies, accordingly. The same magnets from the half of the first gantry part continue symmetrically upward but with opposite bending direction. The last part of the gantry brings focused proton beams to the patient. The last gantry magnet is more than 1.2 meters away from the patient. Two radially scanning magnets are placed within this space to allow +/- 10 cm in the horizontal plane at the patient. There are multiple advantages of this optical design: the large momentum acceptance allows fast energy change without magnetic field variation. The only variable magnetic field comes from the scanning magnets at the end of the gantry. The transverse scanning is significantly slower as the longitudinal energy scanning occurs for each radial position. The patient treatment time is shorter and the operation is simplified due to the fixed magnetic field. There is a significant reduction of power consumption as well as with the overall gantry cost; it is one order of magnitude reduced with respect to the other existing gantries. The weight and size of the magnets is significantly reduced allowing lighter rotating structures.

## Speaker: Tsoupas, Nicholaos

**Authors:**N. Tsoupas*, M. Blaskiewicz, H. Lovelace III, F. Méot, C. Montag, V. Ptitsyn, V. Ranjbar, S. Tepikian, W. Zhang, G. M.Wang, E. Wang, W. Weng, F. Willeke

**Affiliations:**Brookhaven National Laboratory

**Keywords:**Spin Rotator

**Abstract Title:**

The eRHIC Spin Rotator and the beam optics of the 400 MeV transfer line to RCS

**Abstract:**

The 400 MeV LINAC [1] is the first acceleration stage of the electron accelerator of the proposed eRHIC collider [1]. The second acceleration stage of the electron bunches is the Rapid Cycled Synchrotron (RCS) which can increase the energy of the electron bunches up to 18 GeV. The function of the transfer line between the LINAC and the RCS (LtRCS) is twofold, first to transfer the electron beam from the exit of the 400 MeV LINAC to the injection point of the Rapid-Cycled-Synchrotron (RCS) [1] and second to rotate the electron spin from the longitudinal direction to the vertical. We will describe the beam optics of the transfer line, and the required constrains on the beam line for the proper beam matching of the 400 MeV LINAC and the RCS and the spin rotation. A section will also be devoted to discuss the spin rotator. * tsoupas@bnl.gov [1] PCDR of eRHIC Brookhaven National Laboratory

## Speaker: Turchetti, Marco

**Authors:**M. Turchetti, N. Abedzadeh, A. Agarwal and K. K. Berggren

**Affiliations:**Massachusetts Institute of Technology

**Keywords:**quantum electron microscopy, aberration, ptychography, shadow imaging, ronchigrams

**Abstract Title:**

Development of a Diagnostic Setup for Quantum Electron Microscopy

**Abstract:**

Quantum electron microscopy is one of the most promising approaches that could overcome the resolution limit imposed by the radiation damage especially to biological samples. This microscopy scheme requires the design of novel components such as gated electron mirrors, and the development of a platform for diagnostics of ultra-fast electron optics. This testbed would allow time-resolved characterization of such elements either isolated or integrated into the system, both in transmission and in reflection modes. In this work, we propose a diagnostic setup comprised of a ptychography and shadow-imaging (Ronchigrams) platform to allow the evaluation of wavefront aberrations in transmission, and a procedure for beam characterization in reflection, which employs an electron mirror with tuneable spherical aberration.

## Speaker: Valetov, Eremey V.

**Authors:**Eremey Valetov and Martin Berz

**Affiliations:**Michigan State University

**Keywords:**electrostatic deflectors, transfer maps, aberrations, differential algebra

**Abstract Title:**

Analytic Aberration Formulas and Transfer Maps of Electrostatic Deflectors

**Abstract:**

Using an iterative perturbation method, we derived first and second order analytic aberration formulas for the electrostatic deflector, specified by the curvature radius, central angle, and inhomogeneity coefficients. We compared the results with those of numerical differential-algebraic (DA) integration of the ODEs of motion using COSY INFINITY. Additionally, we directly calculated the transfer map of the electrostatic spherical and cylindrical deflectors in the laboratory coordinate system using a Runge-Kutta integrator. For the electrostatic spherical deflector, we also calculated the transfer map analytically and in closed form using the properties of the respective elliptical orbits from Kepler theory. We compared the results with the DA transfer map of COSY INFINITY's built-in electrostatic and spherical deflector elements, as well as with the program GIOS.

## Speaker: Watts, Adam

**Authors:**Adam Watts, Carol Johnstone

**Affiliations:**Fermilab

**Keywords:**optics, tomography, transverse, phase space

**Abstract Title:**

Transverse Phase Space Tomography in Beamlines

**Abstract:**

Methods of reconstructing beam transverse phase space using computed tomography are compared and optimized in simulation to improve reconstruction accuracy. Errors and artifacts are shown for both Filtered Back Projection (FPB) and Simultaneous Algebraic Reconstruction Technique (SART) methods as a function of their respective free parameters. Finally, a theoretical discussion of common optics configurations and their effect on the feasibility of computed tomography is shared, and advice is given on choosing optimal sections of rings or beamlines to perform such reconstructions.

## Speaker: Webb, Stephen

**Authors:**Stephen D Webb

**Affiliations:**RadiaSoft, LLC

**Keywords:**free-electron lasers, reduced models

**Abstract Title:**

A Transverse Envelope Macroparticle Method for Modeling High-Gain Free Electron Lasers

**Abstract:**

Recirculating schemes for free-electron lasers, such as the regenerative amplifier FEL, require simulating thousands of passes through a high-gain FEL system. Modeling high-gain FELs accurately requires the inclusion of diffractive effects in the radiation field and transverse motion of the electron beam. Consequently, most simulation codes that study high-gain FELs are three-dimensional self-consistent codes. Using these codes in the aforementioned multi-pass system would be too computationally expensive to produce results in a reasonable amount of time. However, because the transverse dynamics for the electron bunch is largely comprised of linear motion through drifts and quadrupoles, it can be represented by carefully constructed reduced models. Here we present the use of macroparticles with a transverse gaussian envelope to map the three-dimensional problem to a quasi-one-dimensional problem, reducing the computational cost of simulating the high gain FEL. We present the derivation of the algorithm and preliminary benchmarking simulations against GENESIS for both accuracy and computational efficiency.

## Speaker: Weisskopf, Adrian

**Authors:**Adrian Weisskopf, David Tarazona, Martin Berz

**Affiliations:**Michigan State University

**Keywords:**Betatron tune shifts, moun g-2 ring, normal form, high-order transfer maps

**Abstract Title:**

Computation and consequences of high-order amplitude and momentum dependent tune shifts in the muon g-2 ring

**Abstract:**

Betatron tune shifts can influence the coherent betatron oscillation (CBO) frequency of a mismatched beam in an accelerator, in particular the muon beam in the storage ring of the Muon g-2 Experiment at Fermilab (E989). In this case, nonlinear electric fields from the electrostatic quadrupole system (EQS) installed within the storage ring to confine muons vertically and other nonlinearities due to slight errors in the uniformity of the magnetic field produce substantial amplitude-dependent tune shifts. In addition to this, the storage ring momentum acceptance of ±0.5 allows for momentum-dependent tune shifts. Motivated by these aspects and by the sensitivity of the final measurement precision at E989 to the CBO frequency, we present a normal-form based method for the calculation of high order energy/momentum as well as amplitude dependencies of horizontal and vertical tune in the storage ring of E989 using the differential algebra framework within COSY Infinity. First, the energy/momentum dependent reference orbit is calculated, which corresponds to the parameter dependent fixed point of the map representing the detailed simulations of the g-2 storage ring. Secondly, the fixed-point map is transformed into normal form coordinates to extract the high-order tune dependencies. Analytical estimations of those calculations are presented to benchmark the simulation results.

##
Speaker: Wieland, Marco - **
Invited Talk
**

**Authors:**Marco Wieland

**Affiliations:**Mapper Lithography

**Keywords:**maskless lithography, charged particle optics, MEMS, massively parallel

**Abstract Title:**

Massively parallel charged particle optics enabled by MEMS fabrication techniques

**Abstract:**

Mapper Lithography has developed a maskless lithography system, based on massively parallel electron-beam writing with high-speed optical data transport for switching the electron beams. The system, containing 65,000 parallel electron beams, has a 1 wph throughput at 300 mm wafers and is capable of patterning any resolution and any different type of structure all the way down to 28 nm node patterns. The large number of beams is realized by fabricating the electron optics using MEMS fabrication techniques such as lithography and deep dry etching. In this presentation we will discuss the various building blocks enabled by the MEMS fabrication techniques such as lens arrays, aperture arrays, deflector arrays, individually controllable deflectors and beam blanker arrays. Also we will describe how these building blocks are combined to make a massively parallel electron-beam lithography tool.

##
Speaker: Wollnik, Hermann - **
Invited Talk
**

**Authors:**H. Wollnik, M.Wada, P.Schury, M.Rosenbusch, Y.Ito. Kimura, H.Miyatake, S.Ishizawa

**Affiliations:**1 New Mexico State University, Las Cruces, NM 88001, USA 2RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan 3Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), 4High Energy Accelerator Research Organization (KEK), Wako, Saitama 351-0198, Japan 5Institut of Physics, University of Tsukuba, Ibaraki 305-8571, Japan

**Keywords:**Time-of-flight mass spectrographs, very precise mass determinations, masses of short-lived nuclei

**Abstract Title:**

Time-of flight mass spectrographs and the precise determination of masses of ions

**Abstract:**

The masses of charged atoms and molecules were first investigated by laterally dispersive sector field mass analyzers, which early on already achieved mass resolving powers m/Δm ≈100 000 and more. Equally high mass resolving powers were achieved by time-of-flight mass analyzers during the last decades. These measurements became possible when fast and precise electronic circuitries became available. Such techniques have been developed and used extensively for the mass analysis of short-lived nuclei, which mass values reveal insight in processes that describe the formation of elements in star explosions. Precise mass determinations of short-lived ions have been performed for energetic ions in large accelerator storage rings as well as for low energy ions in time-of-flight mass spectrographs with long flight paths. Similarly precise mass measurements can also performed for molecular ions that help to reveal the structure of molecules. In case of very high mass resolving powers the mass determination of molecular ions can be so high that the measured ion mass directly reveals the molecule's sum formula.

## Speaker: Zhou, Kaishang

**Authors:**Kaishang Zhou

**Affiliations:**Shanghai Institute of Applied Physics

**Keywords:**CSR EEHG fully coherent

**Abstract Title:**

Optimize the design of chicanes for EEHG scheme

**Abstract:**

The echo-enabled harmonic generation (EEHG) scheme in free electron lasers is one of the most promise ways to generate the fully coherent soft x-rays. However, the increased energy spread of the electron beam causing by the coherent synchrotron radiation (CSR) effect may smear the fine structure introduced by the external seeded lasers. Here, we optimize the design of the chicanes to reduce the increased enegy spread causing by CSR effect.