Nov 16, 2021 PrimEx-Eta (informal) Calibration & Analysis Meeting
Time and Place
- Time: Tuesday, November 16, 2021 at 10:30 am EST.
- Room: Online
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- Status of Calibrations
- Run Validation phase I -- https://halldweb.jlab.org/wiki/index.php/RunPeriod-2019-01_Validation
- Run Validation phase II -- https://halldweb.jlab.org/wiki/index.php/RunPeriod-2021-08_Validation
- Calibration Updates:
- Tagger (Tyler)
- PS & Alignment (Sasha)
- FCAL (ig)
- CCAL (Drew)
- Analysis Updates:
- Experimental Systematics (Drew)
- Experimental Angular Resolution (Tyler)
- Background suppression (ig)
- MC simulation Updates
- Production (ig)
- Matching data/simu FCAL response (Sasha)
Present: Drew, Tyler, & ig
We discuss the:
- Calibration status
- Tagh, since Sean automatic online calibration did a pretty good job, Tyler thinks only the time walk correction needs some work that can be done pretty fast. If Tyler is confident, he should post new tables directly on the main DB. After discussing with Sean, Tyler realized that the ADC time offset is not an issue,
- Tagm, Tyler will work on calibrating the microscope asap, offsets tend to be good. Mostly needs to focus on timewalk.
- ig asked Tyler to plot a summary quantity for the tagm & tagm vs run number so we can evaluate the quality of the calibration
- ig will check the pedestal for each run
- Currently, the PrimEx-eta phase II is divided into 28 periods out of which 6 corresponds to empty target, so there are currently 22 different gain tables that will need to be changed if the pedestals have to be updated
- Altogether, pedestal, gain matching, energy dependence correction, QA/QC will take 2 to 3 months, any updates will be available directly & immediately on the main DB
- Drew noted that the elasticity peak position for the 2019 & 2021 data sets are more or less the same and are quite shifted. ig will have to study this. A possibility is the energy dependence correction is wrong for cluster energies above 3 GeV. It is worth noting that the Compton DeltaE/K is slightly off wrt to Primakoff i.e. for FCAL clusters of 3 GeV or below the energy dependence correction might be good enough.
- Drew needs a couple of weeks to finish the calibration
- Time offset calibration is more or less finished, some work needs to be done on the time walk correction. Drew cannot use the values of the 2019 data sets and think the snake scan will not give the proper new constants
- Energy calibration can be done in two ways with FCAL (if FCAL is well-calibrated) or if the beam spot and detector positions are known without FCAL. Drew will work on determining the FCAL and CCAL positions.
- Analysis status
- ig shows the data/simu comparison for the eta polar angle distribution. It looks good but there are some systematics differences which is due to a mismatch between data/simu & also possibly physics (interference contribution depends on the phase for example and we do not know it). By just looking at the data & simu diphoton invariant mass, one can see the resolution in data is worse and theta dependent.
- Drew will focus on determining the systematics (target density, flux, & efficiency vs run number) with the Compton process. This process can also be used to study the BCAL and TOF systematics by including them in the analysis as veto or to ID charge particle/neutral.
- Tyler will focus on determining the data angle resolution with pi0 and see how the resolution change as a function of the polar & azimuthal angles. Tyler might not be able to determine the resolution for small-angle but might be able to extrapolate the resolution from the dependence of the resolution vs (larger) angles. Tyler could also determine the energy resolution.
- ig will focus on matching data/simu