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%.

TPC minutes April 5, 2021

Present: Alexei, Hongwei, Gene, Turi and Flemming

Hardware:

-       TPC running well.

-       Used access to put pizo driver on remote PS

-       Adjusted methane content.

Operation:

Sector 20 RDO 3 had to be masked out. Unfortunately, the crew did not reboot iTPC on run control, so there are ‘fake’ cluster in the data. The manual for masking out has been updated to remind people to get this done. 

There is currently no code to perform masking in the offline code. i.e. skipping hits in masked sectors.

Calibrations:

Gene summarized impressions from S&C calibration discussion. There are small deviations in M**2 plot with newest calibration. The deviation seen corresponds to order 0.2% in momentum. Indicates imperfect calibrations in TPC and/or BTOF. What are requirements to physics analysis to be performed? PWG should define?

It is important to have clarifications if current alignment and calibrations is sufficient to do physics for at least some physics analysis, since redoing / improving alignment will take several months

Yuri iterated the deviation is ~40% (at what momentum?) of mass**2 width. Have requested plots from BTOF group to get additional finer divided information. Is not convinced its TPC; Needs additional info to separate. Example: plotting tray numbers rather than phi.

Babu has done first pass on run-20 9.2 GeV dynamic distortions. Run 19 is done.

Yuri is revisiting dE/dx for both 19 and 14.5 GeV. Not satisfied with aging effect treatment.

If I recall, there was an early fast drop after installation of iTPC reported by Yuri long time ago.

Dear All,

  We just formed the STAR TPC calibration review committee. It is timely and critical to look at the offline calibration tasks and issues. The committee is charged to evaluate the readiness of the TPC calibration for the BES-II data production and provide answers to the following questions by the end of March 2021:

1. What is the status of the tracking and production calibration? 
2. Where is the bottleneck of the TPC calibration procedure? 
3. Are there enough collaboration manpower and resources for the tasks? 
4. How are the online/operation/fast-offline/PWGs efforts coordinated to accomplish the goals? 
5. Is there a clear document of procedures in calibration and what are the unexpected and expected issues in BES-II datasets? What are the steps in calibration, and how are the current responsibilities assigned?
6. What is the timeline and path toward completion of whole BES-II calibration for production? 
7. Any lesson learned toward future runs?

The members are:

Zhangbu Xu (Chair)

Bill Christie

Carl Gagliardi

Frank Geurts

Marian Ivanov

Ivan Kisel

Tonko Ljubicic 

Maria Stefaniak

Jim Thomas

Qinghua Xu

Xin Dong (ex officio)

Rongrong Ma (ex officio)

Hardware status:

HV systems ok. GG drivers fixed/swapped modules and the noisy channels reported earlier is gone. Laser ok.  Will work on gas systems, ongoing plan to have Ar flowing by next mid-week, getting blue sheet by Mon 25.

Methan gas flow starting with shifts on Tuesday 26 at 8 am.

Alexei mentioned Jeff had asked for some positions of laser – will forward e-mail to Yuri.

Gene has requested sets of run with GMT trigger that was created for run20, but where commissioning was not complete. A software (trigger code had a flaw, but is now fixed).

The MTD will be available for the startup phase, and for possible other physics runs like O+O should they happen.

Yuri brought up that it will be very useful to have about 3 days of FF cosmics. He was requested to come with a specific goal for tracks/triggers that we can forward to ops group.

Q: When did we last have FF cosmic data?

Gene reminded us that DB should be initialized for this run. Will ask Irakli if he had scripts from last year to do this and get hold of them.

Flemming mentioned that Star ops mgt and star mgt will like to have a review for TPC focused on calibrations and tracking. As Gene pointed out this has not been done in about a decade. It will be an internal STAR committee chaired by Zhangbu.

Yuri informed us that there was an error in his calculations (code, not formulae) and that the

Results presented last week on asymmetric corrections are wrong. They are symmetric in East/West, Thus the issues on the alignments and calibrations still stands as un-resolved.

Gene has started a study of looking at residuals in low-luminosity 19.6 Gev runs and see a split between inner and outer. Seems related to padrow40 correction i.e static distortion due to the gridleak wall. Gene will present results at a later stage of the study.