SoLID Ecal Weekly 20230427

Ecal Weekly Meeting April 27, 2023

Discussion on tracking

• Xinzhan's presentation on GEM alignment fitting/optimization:
  • using theta angle (not slope) cut from Ye's simulation as a constraint to GEM optimization;
  • slide 6: fitted chisq is very good but the x and y results are too small (too good to be true given we installed the GEMs by hand)
  • slide 7: toy model.
  • slide 8: Jimmy said by hand measurement is within +/-1cm
  • last column: “wrong value” is +/-2mm for the last layer of the true value, (so Jimmy’s 1cm is quite large, i.e. fitted value is too good to be true)
  • for our test, accuracy is within a few mm. Millipede with constraint track recon is already implemented, probably nothing more to do → write a note to sum up everything.
  • Would ECal position help? → suggestions for students to look at? -- followup on this on May 18: probably not worth it because ECal will only constrain the track position and reduce algorithm time. For our beam test, the setup is so small that using ECal constraint will bring no reduction in time.
  • Conclusion is that alignment optimization is not possible without precision survey

Discussion on simulation

• Presentation by Ye
  • check Jixie's timing database, LASPD timing is good!
  • Also studied Preshower integral dependence on the integration time, >= +/- 4bins and above give the same result;
  • Photon rejection is 5/1, studied using preshower spectra with and without LASPD cut (>0), in particular the MIP area, but the factor depending on energy. Comments:
    1. the timing window is universal in the analysis shown, i.e. when it changes it does so for all detectors. However, denominator need fixed timing window for the other detectors (not LASPD) photon rej calculation;
    2. need to correct for pions (using SCD) and correct for high-E electrons
  • Ye is not doing LASPD timing yet
  • LASPD timing for SoLID: we need faster FADC and perhaps double-up with TDCs

Discussions on Analysis

• Jixie is working on pulse deconvolution. Will do all detectors and include the procedure in the technical note
• Tim working with Mike on PID cuts
• Mike continues on the run list
  • Showed reconstructed z from GEM: Xinzhan has theta cut in the latest tracking but data not cooked; could we do a cut on z? Is mean value consistent with survey pointing? (2cm?)