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

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

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.

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

agenda
- hardware status
- software updates
- calibration review

 minutes:

hardware
- the west laser had a LV power supply with a bad fuse. Alexie got an access fand fixed in < 1 hour
- Alexei monitor gas and will adjust methan concentration slightly.
- new hot channel in sector1. Have asked Tonko to mask out

FF request.
Gene summarized the FF request as it had emerged from the calibration review. It is important to run FF setting to seperate alignment, E*B distortins
but having data from both polarities. Yuri & Gene confirm that the 20M RF is a good sample from RFF and it was concluded we should request a change as soon as practical and on Wednesday access day at latest. Alexei brought up request to at at the time of switch that a high stat laser run ~20k is taken jest before magnet change and another one is taken with FF after the change, and magnet stabilized.

Yuri showed the dedx for his run 20 calibration for collider data and fixed target.There is some room for improvement in particular for the FXT target data.
Yuri showed that the readout of the magnets current fluctuate on a 15 sec time sacle between two distinct values. Current code only has one magnet value per run so it gives rise to distinct bands of say K0_as there is a scale factor between current read and Field suggest to use average value for future.

Gene discussed a Minor problem in sector alignment distortion correction as shown in attached slide on web page.
Looked at run 18 distortion maps and notice a missing featue that he expected namely spikes missing between inner and outer sector. This is due to an un intentional change of code in 2014. Demonstrated with differences that these effect are likely small. One measure of #primary tracks is sub-promille.

aAgenda
- hardware status
- run progress
- software
- TPC Review Planning


Charge to committee

  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)


Talks and subject area.
Geometry & alignment (Yuri)
•  Drift velocities
•  dE/dx
•  Specifics for Run 19
•  Cosmic data
•  Beam data
•  Laser data
•  What is the procedure for alignment; How is it documented
•  Bottleneck in timely calibrations
•  Validation procedures and QA
•  Lessons and procedures learned from iTPC prototype commissioning
•  Present/summarize clearly the open/unknown issues and potential concerns (all talks)

Surveys done (Flemming)
• Alexei, Jim and Yuri (operation survey)
• Other detectors as calibration tools (GMT, TOF,  BEMC)
• How they are included in the calibration procedure

Correction Distortions (Gene)
• Dynamic distortions: SpaceCharge & GridLeak
• Static distortions

Resources for Online and express stream (Hongwei)
•  Recap of resources
•  Activities
•  Relation to FastOffline

Calibration (Irakli)
•  T0
•  Long bunch timing, FXT and collider BES-II
•  How is express and fast offline used in calibration
•  Resource/tools/datasets use

QA,QC (BES-II)   (Dan)
•  Recap of resources
•  How are working groups involved in this
•  Feedback, requirements to calibrations

 agenda
-- hardware
-- run preparation
-- software
    + Gene: Residuals with the iTPC

TPC meeting Jan 20, 2021

 

Hardware:

Inspection walk tru done. Checked HV. Leak rate is good < 2l/min after rep of valve.

Prepare for low Ar flow Friday, high flow Sunday. Blue sheet Monday

Laser Need to replace 3 windows- ordered. East side very good West some rafters missing due to windows.

 

Run Prep:

DB for TPC should be initialized. Yuri

Discussed HLT running for cosmics. HLT will be commissioned during cosmics, files should be kept as they are useful.

 

Discussed the proposal for running FF. With the current  schedule for beam injection Friday evening in Blue, and Gas flow starting Tuesday morning at best one can get about ~ 1 day worth maybe 10M. As it will also be the first day of running it will probably be used for commissioning (e.g GMT triggers) the sample can be less. The EPD and BBC installation will also take place Thursday/Friday when magnet has to be off.  Yuri said it could be useful for checking but not enough for full calibration.

 

Gene presented his ongoing study of inner-outer matching looking at very low-luminosity run from 19.6 , and under different conditions. See blog https://drupal.star.bnl.gov/STAR/blog/genevb/residuals-itpc

The 2020 calibration gives large track residual at the lowest pads (1-6 or so), while the ‘old’ does not show this but slightly larger values. Irakli pull up some plot and see similar effects in some of his results (from maybe a year ago).

 

Yuri is working on alignment. No results yet.