Optics Meeting Aug 9 2022 230PM ET

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1. Quick 2D GEM Electron Path Simulation (Nathan) [1]

2. Initial look at GEM resolution effects on optics study (Kate) [2]


David, KK, Kate, Vassu, Zuhal, Jim F., Nathan Shankman, Ciprian


  1. Nathan showed initial steps toward code that will check to see if tracks we are interested in (from Moller scattering, e-p, or e-12C scattering could hit "dead zones" (due to the high voltage spacers) in more than one GEM layer... if they do, then we may wish to adjust the exact radial/azimuthal location of the different layers. In posted figure, the GEM active regions are in green, the orange lines are the (horizontal) spacers, and the yellow line is an arbitrary track that does hit one spacer (and is forced to end there). The next steps will include reading in actual simulated tracks for the relevant processes. Vertical spacers are not yet included.
  2. Kate showed initial results which did a post-facto "smearing" of the simulated GEM coordinates to see effect on the ability to image sieve collimator holes. Results are encouraging - the different holes are still clearly separable. The width of the reconstructed theta residuals only increases by about 20% due to this rather large smearing (1 mm in r). There was discussion of ways to do the smearing that was more consistent (i.e. not smearing x,y and r independently, since r can be obtained from x and y) and of what the GEM resolutions are expected to be (sub mm in both r and phi). Smearing in phi of one degree is much larger than realistic, likely more like 1 mm in x,y leading to 0.1 degree at GEM outer radius, 0.6 degree at inner radius. Eventually, should smear input to actual reconstructed tracks.
  3. General discussion of planning for GEM track reconstruction code for a) simulated data and b) real data. Might be able to re-use SBS tracking code and/or PREX-II GEM tracking code. Need to understand advantages/disadvantages of both. Need to decide at what stage the tracking codes "merge" for real and for simulated data - do we want to digitize GEM data at the strip level to look like the raw data, or should we start at the "hit level", i.e. start with (r,phi) values at each GEM layer as generated by GEANT4?
  4. Should look at GEM resolution effects not only on optics reconstruction, but on ability to image individual rings and quartz tiles (for Q^2 and for determination of dilutions of ep events under Moller peak, etc.

Meeting link information

Meeting URL


Meeting ID: 972 5975 5403

Passcode: 4937

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