Star-tpc-l mailing list

[videbaek <videbaek AT bnl.gov>]

TPC meeting March 16,2023
Present:  Gene, Tommy, Yuri, Alexei, Jim and Flemming

-Hardware
 Alexei complete East laser alignment; Laser system is now ready for 
upcoming run
 Next week will install ‘new’ magnetic sensors for additional 
monitoring.
 Q: can these be interfaced to Slow Control (Monitoring)

-       Electronics
-	The TPX s8-3 RDO issue turned out to be a network card problem in the 
DAQ PC. West is ok a few FEEs are masked off for run
-       East TPC should also be ready.

Gating grid tests
-	Gene is proposing that we test the effectiveness (transparency) of the 
GG under different beam conditions.
-	Aim to take short runs (<1 min) with 2,3,4,5kHz rate for MB data 
taking and similar for High lumi running later in the runs.
-	Gene will talk to Jeff on setting up run configs so it can easily be 
run by crew. And with JG on beam conditions.
-       The equest will be added to the TPC reafiness status

Pre run calibrations
Had long discussion on FF/RFF information that should be extracted. STAR 
magnet is currently wired for FF.
Yuri would like, now that Alexei has installed detector to monitor 
possible movement , that we switch a couple of times between FF , 0 , 
and RFF to see if a) there is a movement and b) if it is reproduceable. 
This does not need COSMIC data
It was not clear how this knowledge would translate into improved 
calibrations of TPC. Jim pointed out that (some) E-B mis alignment is 
already included in space charge distortions (static?). Gene commented 
that the main geometry calibration issue/uncertainties is related to the 
super sector to super sector alignment.
Yuri iterated that understanding if there are movements of TPC between 
FF and RFF will help for calibrations methods.
WWill bring the proposal up at readiness for TPC, but expect to get push 
back to the ‘cost’ (time, people,..) of doing multiple filed switches.

De/dx calibrations
Yuri pointed to the presentation at last S&C meetins that identified at 
FF/RFF difference between a correction that has been used previous for 
de/dx vs. position along wire attributed to wire to pad plane diff. See 
https://drupal.star.bnl.gov/STAR/system/files/RunXXI%20OO200GeV.pdf

FV raised the issue why this shows up in OO at 200 GeV which has about 
equal positive and negative charge tracks with opposite curvatures.




+ Run 21 dAu200 SpaceCharge
  - Babu continues to find essentially no asymmetry between east and 
west, despite historically seeing ~20% more in east
  - Gene sees asymmetry in the lower luminosity Run 21 dAu data, but it 
disappears at high luminosity
  - Recommendation from Gene was for Babu to process more high 
luminosity data to help investigate dependencies further

- Run 22 pp500 SpaceCharge
  - Babu has plenty of SpaceCharge work to do even without Run 22, plus 
his physics analysis
  - Gene has asked the PWGs to provide an additional helper to 
investigate possible fill-by-vill variations as seen in Run 17
  - Good to educate more people about SpaceCharge anyhow, even if Babu 
does find  time to work on it

+ New cluster finder
  - Tonko expects it to be not just different, but "better"
  - Tommy proposed a test with embedding to see if momentum resolution 
and acceptance improves as Tonko hopes
  - Yuri suggests not to focus on momentum resolution, but rather 
efficiency
  - Tommy will discuss with Tonko more

+ dE/dx adjustments by analyzers
  - Tommy brought up artificial, empirical dE/dx nsigma shifting by 
analyzers for BES-I datasets
  - Yuri says that's ok as a band-aid for older productions of iTPC era 
data, but that the new dE/dx model introduced last year should help 
avoid this
  - Tommy is willing to work on a standard version of the empirical 
band-aid for people to use, and no one objected


--
Flemming Videbaek
senior scientist, emeritus
videbaek @ bnl.gov
Brookhaven National Lab
Physics Department
Bldg 510D
Upton, NY 11973

phone: 631-344-4106
cell     :  631-681-1596