2004 Workshop on Muon Collider Simulation

Miami Beach, December 12 16, 2004

Purpose - see below

Program

Click here to view the schedule (preliminary and subject to updates).

Location / Accommodation

The meeting will take place at Fontainebleau Hilton Resort, Miami Beach, Florida, USA. More Information about the hotel can be found here. We have negotiated a special rate of 85$/night for meeting participants. This discounted rate is available three nights both prior to and after the event. Room reservations can be made at 1-305-538-2000 (Fontainebleau Reservations) by referring to "Michigan State University". Please make a reservation by December 1 to get the special rate.

--- Beyond December 1, when having trouble making a reservation at Fontainebleau Hilton Resort with the workshop special rate, contact Johannes Grote (grotejoh@msu.edu) with your arrival and departure information. We will negotiate with the hotel. ---

Note that reasonable parking is available only via the hotel's valet service at a rate of $18 per night.

Organization

We plan to begin each day with several hours of presentations and progress reports. We will then break up for individual or small working group sessions, where actual calculations or simulations can take place. High speed internet access will be available at the workshop. Hopefully each participant will use the workshop as an opportunity to work intensely on some approach to designing a muon collider.

Purpose

Muon colliders represent one approach to the development of TeV-scale lepton-antilepton colliders. High energy electron-positron colliders must be linear to avoid excessive synchrotron radiation losses, but with current technologies such machines must be very long. Since TeV muons can still be stored in rings, the footprint of a muon collider is much smaller and there is therefore some hope that a muon collider could be less expensive than an equivalent-energy electron collider. Muon colliders also have the desirable features that the beam energy can be determined very accurately, the energy spread resulting from the beam-beam interaction is small, and direct coupling to s-channel Higgs particles is large.

The problem that has hindered the development of this type of machine is, of course, that, unlike the electron, the muon is an unstable particle, which does not exist normally in nature. The muons must first be created, either from pion decay from high energy interactions in matter, or from some very high energy radiative process. These muons must then be collected and formed into a useable beam in a very short period of time, determined by the muon lifetime.

Much progress has be made over the past 20 years in developing methods for capturing muons, reducing their energy spread, cooling their transverse and longitudinal emittance, and accelerating them to high energies. A few sections of plausible accelerator systems have been simulated in great detail. This gives some hope that it may be possible to build a full system with useful luminosity. Much effort has gone into the development of ionization cooling, which appears to be the most practical method for cooling low-energy, large-emittance muon beams. In addition Fixed Field Alternating Gradient (FFAG) accelerators look like a very promising approach for rapid acceleration of large-momentum-spread beams. A summary of the current state of these calculations and simulations can be found in two recent status reports [1,2].

However, in spite of this remarkable progress, significant difficulties still remain with simulating the performance of a muon collider. There has never been a full end-to-end simulation of the front end of a muon collider. This crucial piece starts with the production target and continues through all the required phase rotation, cooling and emittance exchange systems until the beam is sufficiently well-behaved for injection into an accelerator chain. Until this very difficult task has been accomplished, it is not possible to state with confidence what the ultimate luminosity of a muon collider will be.

We plan in this workshop to review the various approaches that have been suggested for designing a muon collider, including simulation tools for particle tracking through material, Taylor transfer maps, field solvers, and other tools. Hopefully people will select a promising approach, have active discussions with the other participants, and start an active program of muon collider simulations. One important intermediate goal might be to work on an accelerator front-end that can achieve the performance goals assumed in reference [1]: a muon yield of 0.16 muons/incident proton with a normalized 6-dimensional emittance of 0.17 mm^3. How well we can achieve these front-end goals will have a major impact on the design of all the following systems.

Because no complete simulation exists yet, it is important to keep an open mind about speculative approaches that were not seriously examined in the status reports. For example, this may be an ideal time to reexamine a collider front-end based on frictional cooling or gas-filled helical cooling channels. Alternatively we might consider starting with a long muon bunch train, as in the U.S. neutrino factory design, and recombine the bunches later. Channels containing lithium lenses are also a promising approach.

Ring coolers are likely to play an important role in the front-end design. There has been a lot of progress in this area over the past few years, but these studies have so far taken place mostly in isolation. This could be an opportunity to benchmark the overall performance of a self-consistent series of realistic cooling rings. The feasibility of the injection/extraction system must also be addressed when using small-diameter rings with large-emittance beams.

Beyond the front-end there are many options and open questions in the acceleration and storage ring. Cost will become a major factor when considering TeV acceleration. Beam loading, heating from muon decays, beam-beam tune shift correction, and optical stochastic cooling are among the topics that need to be studied further.

[1] C. Ankenbrandt et al, Status of muon collider research and development and future plans, Phys. Rev. Special Topics 2, 081001 (1999).

[2] M. Alsharo’a et al, Recent progress in neutrino factory and muon collider research within the Muon Collaboration, Phys. Rev. Special Topics 6, 081001 (2003).

Links

MSU Beamtheory web site

Third International Workshop on Taylor Methods, Miami Beach, December 16-20, 2004

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