The STAR experiment

agenda
- hardware status
    Gene: humidity impacts seen on inner field cage currents. See image shown further down, below agenda. More on this topic in general in my blog.
- operations
- calibration status

TPC meeting May 12, 2021

 

Present: Alexei, Gene, Yuri, Hongwei and Flemming

 

Hardware:

Basically in good shape. Struggled with HV GUI’s likely due to ITD scanning during the access day. Sector 20 outer was repaired by Tonko and Mike, bad RORC card.

Has observed the part short of west filed cage.

 

Alexei has the calibrated NMR in house.

 

Operations:

The O+O running  very clean. The 1.5mrad crossing angle and levelling at ~3-4kHz Mbias results in very little if any dynamic space charge.

This  bodes well for the FF setting to be run in about a week.

For the central collisions to be run right after the RFF 400 M Mbias the Mbias rate will be possibly ~20kHz.

 

Calibrations:

 

Gene looked at h+/hi ratios vs. pt for the 19.6 Gev au+au and reports seeing sector to sector variations;

https://drupal.star.bnl.gov/STAR/blog/genevb/h-h-run-19-196-gev

These variations are at similar level as after run 12 alignment calibrations i.e little overall effect but sector to sector variations.

The sectors showing largest effect correlates with Zaochen's findings in mass² splitting in BTOF

Thus the variation is most likely due to TPC calibrations.

Yuri commented that until we have the FF data  its unlikely that underlying reason, and improved calibration can be made. It is also likely to be a large effort, not a few weeks.

 

Yuri reported that dE/dx calibration for 14.5 and 19.6 is completed

It was also reported to S&C management

https://drupal.star.bnl.gov/STAR/system/files/19%20and%2014p5%20GeV%20dEdx%20Calibration.pdf

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.

agenda
- hardware status
- operations
- calibration status