Agenda

1. Realistic GEM tracker in Remoll (Bill) [1]

Concern with using CAD imported volumes for GEMs us computational expense (and verification of lack of problems due to overlaps) when GEANT 4 runs with a a highly-tesselated geometry. Decide it is probably better to use GEANT 4 "primitive volumes" that are described with only a few parameters (i.e. the GEM active region approximated by simple "wedge" slices), even if is not exact geometry. Could use software cuts on the simulation to remove events that hit regions where the geometry is not exactly modeled. Also, could study the effect of the frames by turning material to air and comparing - if we see a significant effect, then we can improve the accuracy of the model of the frames.

2. Blocker and Sieve collimator and power deposition (Kate).

Working out some bugs with how to use beam generator properly
We don't really worry much about power deposition on sieve collimator, since we will not need to run that with thick target and high power - but we do want ability to run blocker with lH2 target and high beam current. Maybe we can get away with no active cooling if we run at reduced beam (say 30 muA)? Need to ask engineers how much power can blocker tolerate without water cooling.
Blocker that Kate has been simulating has no azimuthal gaps, but KK points out that if we any to minimize power deposition, can have gaps in blocker where the solid parts of collimator 2 are, so the beam power is split between the two. Collimator 2 (Chandan) sees about 950 W at 65 muA beam.
Need to ensure that there are overlaps so that we don't get "slit scattering" background from apertures in blocker that make their way into the acceptance of collimator 2 (Kate is already working on this issue for the inner radial dimension, need to extend to phi).
Question (Cip): what about power deposition on blocker when in parked position? Good question, need to define where blocker will be horizontally when parked, and whether it is in shadow of Pb that is between target and collimator region.

Attendance

Meeting ID 970 3027 1000

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