Optics Meeting May 9 2023 200PM ET

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Attendance

Kate, Ciprian, David, Andrew, Michael D., Vassu, Zuhal, Bill, Tyler, Sayak

Minutes

1. Kate: has submitted simulation jobs to investigate the puzzle of why one of the symmetry-pair of holes does not have identical GEM positions for the case of default (ideal) B field. Might be GDML implementation bug, statistical fluke, or...? David suggests looking in detail at the fits to the histograms that give the mean values of the radial and phi positions.
2. Vassu: in the past we have been looking at the e-12C/Moller event separation at the GEM planes for the case of the Optics 1 DS foil target. Vassu presents now the Optics 1 US C foil target, and results are also fine; as for the case of the DS foil, the only case with overlaps between e-12C and Moller events is for some holes for pass 1. We discuss the idea of looking at a 3rd (single) optics target, located at the center of the target in Z.
3. David: Tyler will take on the task of repeating the optics reconstruction parameterization, but instead of using the exact GEANT 4 "truth" values for each track's theta, phi E', and Z, as input to the fits, to use only sieve hole information for theta and phi (i.e. the center of the holes in theta and phi, and knowledge of the foil position in Z to get theta and phi, and assumed "flat" E'. This will reduce our dependence on the GEANT 4 simulation, and will be what we can apply to the real data when we get it. Vassu and Kate will help Tyler get started with the reconstruction fitting code.
4. Vassu: will continue working on making the reconstruction fit parameters into smooth functions of beam energy.
5. David: initial discussion of tracking code requirements. Possible model: don't add detector (GEM, Trig. Scint.) digitization to remoll; instead, factorize between 1) GEANT 4 simulation 2) detector digitization 3) track reconstruction. Step 2 would be an "afterburner" code that would take GEANT 4 output (an ntuple of r and phi of charged particle intersections with the 4 GEM layers and the two TS planes), and then adds resolution smearing, offsets, and generates hit information that can be fed to track reconstruction code, in similar way to real data. We need to decide on an architecture for the tracking code: modify what Chandan had for the PREX-II GEMs? Modify SBS code? Some more general code base? Should discuss in detail in upcoming meetings.
6. David: Vassu and Kate to present Sieve design to simulations group this Thursday: sides are here: [1]
7. David: Tyler will take on the task of repeating Vassu's optics fitting results, but instead of using the "truth" values from the remoll thrown kinematics, he will use simply the z-location of the target, and the central r, phi of the relevant sieve hole. See if we the fitting parameters agree with those found by Vassu, and see if the resolution on extracted theta, phi are adequate. This is closer to a data-driven optics fit (i.e. can do with real data without recourse to G4 simulation).

Meeting link information

Meeting URL

https://cwm.zoom.us/j/97259755403?pwd=WTRqVHJnZ3RQa1IwNHdMQjJuQm9FZz09

Meeting ID: 972 5975 5403

Passcode: 4937

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