Simulation Issues - and - MICE Interim Report on MANX after MICE (Two talks for the price of one.)

1. Simulation Issues- and -MICE Interim Report on MANX after MICE(Two talks for the price of one.) Tom Roberts Muons, Inc. Illinois Institute of Technology Simulation Issues / MANX After MICE

2. Simulation Issues • As author of one of the primary simulation programs used in current muon collider design studies, I am keenly aware of some of the limitations of current simulation codes. And I am surely blind to others! • As an example, extrapolating from current measurements of energy loss and multiple scattering to a full cooling channel has a ratio comparable to extrapolating from a rifle to 0.1 c. Clearly some humility is needed! Or rather, some EXPERIMENTS are needed… Simulation Issues / MANX After MICE

3. Simulation Issues • All programs are prone to “garbage in, garbage out”Complex simulation programs are even more prone to this.− This is old hat and I won’t discuss it • Simulation programs make many approximations.− This is old hat and I won’t discuss it • Simulation programs have many parameters to select.− This is old hat and I won’t discuss it • Simulation programs require enormous CPU resources.− This is old hat and I won’t discuss it • Real systems are very complex and difficult to represent in a simulation program− This is old hat and I won’t discuss it • Etc…. Simulation Issues / MANX After MICE

4. Simulation Issues • Existing programs do not implement all relevant physics phenomena.− This is worth a discussion • Electromagnetic processes – the essence of muon cooling • Accurate multiple scattering models (tails become important…) • Accurate energy straggling model • Correlation between multiple scattering and energy loss • Effect of magnetic field on multiple scattering • Thick vs. thin absorbers • Realistic 3-d EM fields (e.g. waveguide ports, HOM correctors, …) Simulation Issues / MANX After MICE

5. Simulation Issues • Collective processes (vacuum) • space charge  in progress • wake fields • coherent synchrotron radiation • beam-beam interactions • electron cloud effects • Collective processes (in matter)  starting • space charge screening by material • bunch-induced polarization of material causing intensity-dependent energy loss and instability • effects of matter on wake fields • coherent bremstrahlung • for all the above, consider dependency on material properties, head-tail differences, and bunch-to-bunch effects (i.e. time dependence) Simulation Issues / MANX After MICE

6. Simulation Issues • Decays and Interactions in macroparticle models • Polarized muon processes • Normalization uncertainties • Pion production models • Distortions of mercury target In short, there are many known physics processesnot implemented in current simulation programs.Some are surely important for muon collider design. Many of them have never been measured. Measuring EM processes in a thick absorber is a good start. Simulation Issues / MANX After MICE

7. MICE Interim Report onMANX After MICETom Roberts, IIT “The MICE collaboration members generallystrongly support the idea of a follow-up experimental program in ionization cooling studies. […] The concept of helical cooling channel seems very promising and the synergy with muon colliders is exciting.” − Alain Blondel, MICE Spokesperson • This is a summary of a report presented by Malcolm Ellis at the recent MICE Collaboration Meeting (Jan. 14, Harbin, China). Prepared by: John Cobb (chair), Chris Rogers, Malcolm Ellis, Yoshi Kuno Simulation Issues / MANX After MICE

8. MANX After MICE • MICE has convened a committee to consider follow-on possibilities; MANX is by far the most advanced, and the only one considered at this time • The questions suggested by the MICE Executive Board: • Space-consistency in the MICE hall • Scope and adequacy of proposals in view of existing • MICE instrumentation, and • Infrastructure • Consistency of time scales • Comment on resources available from MANX and MICE • Good use of MICE infrastructure resources Simulation Issues / MANX After MICE

9. MANX After MICE • MANX proposal assumes much of MICE will exist • MICE is a collaboration • Infrastructure is not (yet) a facility • Operated by MICE collaborators • Instrumentation is not owned ‘in common’ by MICE • Individual owners of instrumentation may have own preferences or funding agency constraints • ‘MICE’ itself cannot agree to support any new initiative – a new collaboration would be needed • MANX – or any new cooling experiment – at RAL would probably require substantial UK involvement • RAL is small part of MICE • Not same relationship to users as CERN or Fermilab Simulation Issues / MANX After MICE

10. MANX After MICE • Two possible configurations: • MANX with matching • Off-Axis MANX – reduces cost of the magnet • 350 MeV/c  150 MeV/c • New fiber tracker planes inside matching and HCC • New high-resolution TOF counters (<5 psec resolution) • Being developed Simulation Issues / MANX After MICE

11. Off-Axis MANX • The MICE committee did not consider the off-axis configuration of MANX, believing the spectrometer solenoids had not been designed to handle off-axis forces • This is not actually a show-stopper: “The cold mass support system for the spectrometer solenoid is quite robust. […] I think that the supports can carry 200 kN in the radial direction while carrying 450 kN in the axial direction.” − Mike Green • Of course the overall system must be properly engineered, including quench forces • The off-axis configuration puts the downstream spectrometer closer to the iron magnetic shield wall, which must be considered (forces, field distortions, infrastructure) Simulation Issues / MANX After MICE

12. MANX After MICEConclusions – I • MANX with matching fits in the MICE hall • Off-Axis MANX should also fit • effects of the magnetic shield wall? • MICE spectrometers appear more than adequate for transverse planes • Large volume of LHe needs new infrastructure; ditto for LH2 • Placement of new TOF counters needs to be considered • The down-stream PID detectors may be too small, if the downstream TOFs need additional space Simulation Issues / MANX After MICE

13. MANX After MICEConclusions – II • 350 MeV/c is within the magnet capabilities of the beamline • Higher pi/mu ratio at 350 MeV/c makes particle ID important • MICE Cherenkov counters may be inadequate • Investigating – can probably be made to work • TOF1-TOF0 give ~7 sigma separation for pi/mu at 350 MeV/c • Also: larger absorber means higher pi/mu ratio may be OK • Matching from spectrometer to HCC at 350 MeV/c probably cannot be done with the current design • Needs to be considered in the MANX magnet design • Perhaps reducing initial momentum to 240 MeV/c reduces or eliminates the problems with 350 MeV/c Simulation Issues / MANX After MICE

14. MANX After MICEConclusions – III • Timescale to follow MICE in 2013 seems rather optimistic • Need selection of configuration • Need engineering of HCC itself and in MICE hall • Need to construct the HCC magnet • Need simulations of performance, resolutions, etc. • Need high-resolution TOF development • Resources are very tight Simulation Issues / MANX After MICE

15. MANX After MICEConclusions – IV • MICE is not a facility, and MICE as a collaboration cannot commit to a follow-on experiment • A new collaboration is required • All groups must agree on a program & apply for new funding • Within the MICE collaboration, there is qualified support for MANX (and for other potential follow-on experiments) • The MICE committee believes that STFC would most likely support a new initiative No show-stoppers have been found. Simulation Issues / MANX After MICE

16. MANX After MICE “The MICE collaboration members generally strongly support the idea of a follow-up experimental program in ionization cooling studies. […] The concept of helical cooling channel seems very promising and the synergy with muon colliders is exciting.” − Alain Blondel, MICE Spokesperson Simulation Issues / MANX After MICE