The STAR experiment

agenda
- hardware status
- operations
- calibration status

TPC meeting April21 minutes

 

Present:

Alexei,Babu, Flemming,Gene,Hongwei,Yuri

 

TPC running well. The pizo driver for the laser failed , no power,was adjusted during quick ccess, and then rebooted today during access. Lost about one laser run during. Will investigate how remote reboot can be done. Such failure has happened 1-2 per run.

 

Flemming present a few more observation on the single bad pad hot due to values this seem to have pedestal subtracted incorrectly. This is intermittent and usually, but not always clears on next run. Also it only 5-10% of events with this failure. See  https://drupal.star.bnl.gov/STAR/blog/videbaks/tpc-qa-2021
for more details

 

The 19.6 GeV calibration sample is complete. Includes dynamic space charge, and event by event t0 correction. EPD had time offsets calibrated/changed at some point in time during the 19.6 GeV data sets. This change is now in DB.  The 14.5 GeV  should be done by the weekend. Babu will start looking at the run 20 soon.

 

The sample(s) can now be checked for BTOF calibrations, and dE/dx.

If the mass square difference seen in east persists with the DbTpcMaker that was updated, there will be additional work to identify this issue. The TOF group will not sign off with a mass split of approx. 1%.

 

 

Agenda
- hardware update
- operations
- calibration updates

Agenda

-hardware
-operation
- test production progress
- AOB

agenda
- hardware status
- operations
- software
 - big events
 - update on test productions

Minutes:
hardware: There was a failure of LV for TPX. broken fan; replaced with spare available in IR.
Have ordered 3 more fans, special. 3 mo. delivery

After a massive trip, one HV section 20-4 itpc seem not to have been brought up and not noticed. Asked David
to check the readouts during this event.

We see very large events in run 19 reconstruction, and in current data taking
a) current activity is related to the beat-squeeze; discussed also at ops meeting. Under discussion what to happen
b) run-19 reco is related to some store with BMM running throughout some runs.

Discussion on TPC calibration. Good progress is being made. Additional discussions later this day.

agenda
- hardware status
- operations
- software
  - cluster quantization
  -update on test productions

Minutes

No issue with TPC hardware
-Have adjusted methan content to make Vdrift more constatnt; there were several period in Feb with variations.
- powerdips and magnet trips during last weeks running.

The two runs in day 38 and 66 had outer sector 19 exhibit large excess of charge that extended for all pad and rows for about 150 timebins. See blog entries in https://drupal.star.bnl.gov/STAR/blog/videbaks/tpc-qa-2021 near top of page

Most likely a faulty GG driver board . Alexei suggested looking at signals from board during next maintanence day (unless it get really bad). Will talk to Tim on this.

Gene reported looking at laser un running 7.7 GeV for local clock vs. coll clock. Did not see any different between laser positions. Now looking at prompt hits for two conditions, (UPDATE: small shifts seen for the entire TPC by 14.1 ns, but not on the scale of 1 time bucket; documentation is here)

Yuri show plots 
these are references for plots which we discussed today
1. Comparison RF and FF  https://drupal.star.bnl.gov/STAR/system/files/TpcCSTransformations_0.pdf
-- the FF has only 34k events.Alignment same for two settings.
2. QA plots for RunXXI (express production) : https://www.star.bnl.gov/~fisyak/star/BES/
---
3. Lasers for different fields
-- no clear pattern. Sector 20 seems consistent for all fields. 20 has best lasers
4. Prompts for different VPD timing cuts
-- shows dependence on collisions timing (sum of VPD timing)
The last plots on meeting page only

Meeting minutes:

GMT - the code stransferrend to dev compiles, but crashes. The reasons seems to be forbidden access to the tree data structure. David will test if the is also tru in  .DEV2

Robert Licenik managed to recreate the embedding Pythia in to zero bias pp data. The results are different from what Dima showed. The reason could be that Dima was using a private reproduction of the data.

K->3pi update. The  bump in the reconstruction efficiency as a function of transverse radius is also in the MC. Possible cause could be a track splitting. It was suggested to check the invariant mass. It could also be a feature if the KFP when extrapolating into a region without hits. Need to try changing the KFP cut values.