Tuesday, July 30, 2024
From SBS wiki
Agenda:
- All: round table updates/discussion
- GEP SBS DIG and SimDecoder status.
- Initial working version pushed to github.
- Eric was on vacation until yesterday, getting back to work
- Kip: continued work on reconstruction/hadron filter scenarios
- Increasing urgency of GEP Trigger simulations for lower Q2 points (Kip/Sarah/Jacob?):
- Define logic and lookup tables for the three lower Q2 points. Determine maximum safe thresholds for ECAL and HCAL to give high elastic efficiency.
- Estimate single arm and coincidence trigger rates (real and accidental) using full logic with lookup tables. Test multiple background generators:
- PYTHIA
- Beam (needs enormous statistics to populate the energy regime relevant for trigger formation)
- wiser inclusive pi+ pi- pi0 for ECAL and HCAL: useful for singles and accidental rate estimates
- Inelastic generator (electron in ECAL and hadron in HCAL): useful for singles and accidentals and partial contribution to real coincidences
- Elastic generator (rates very high for lower Q^2 points).
- Benchmark different generators against observed rates during GMN/GEN-RP LH2 data (GEN less relevant because Helium-3 target)
- Also need acceptance matching studies for the new low-Q2 point. In particular, ECAL distance could be optimized, perhaps made a bit larger to reduce trigger rate.
- Jiwan: Status update on HCAL calibration/gain matching efforts: Cosmics plus beam. Working with students and existing data from GEN-RP/etc.
- Andrew: Update on SBS optics calibrations
- BigBite optics calibrations DONE for GEN-RP.
- SBS optics calibrations work in progress:
- Zero-field alignment of SBS done, but possible ambiguities/spurious offsets may remain
- 4th-order optics model from Bogdan's TOSCA map (no rescaling) gives good but not perfect reconstruction initially when looking at LH2 elastic data compared to (calibrated) BigBite reconstruction
- Spurious offset and linear correlation with thetatarget observed in the deviation of target theta (vertical angle) from expectation. Could be the magnetic field description but the similarity to the vertical pitch angle of the GEM stack resulting from the zero-field alignment points to some issue with the alignment as the root cause.
- We could easily just remove the offset and spurious linear correlation with a simple ad-hoc correction, but it would be better to understand the underlying cause, especially since we need to rely on this alignment and field map for all of GEN-RP analysis and also to generate optics for K_LL analysis with multiple field settings.
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