STAR QA Board

["Van Buren, Gene" <gene@bnl.gov>]

Hi, all

I am attaching the plot that I assume is in question. I believe what you are seeing is the result of the following:

1) The FastOffline reconstruction uses the "BeamLine3D" option developed by Dmitri Smirnov several years ago, which allows the BeamLine constraint to be used with finite weighting. The "non-3D" "BeamLine" option, in contrast, gave the BeamLine infinite weight, such that plots like this only ever show a point for a non-tilting BeamLine definition, or a line for a tilting one. With the finite weighting of BeamLine3D, the reconstructed vertices lie in a reasonably tight cloud centered around the BeamLine...except...

Another feature of the BeamLine3D option is that if the tracks point to a vertex far enough away from the BeamLine, the BeamLine itself can be excluded from the fit. The end result of this is that there is usually an empty ring of no vertices just outside that tight cloud, beyond which vertices again appear. The various points we see randomly distributed out at several mm and beyond are this class of vertices.

2) When I sent the note to starops about the reconstructed BeamLine, I changed the BeamLine parameters in the database. Before that, the Beamline was all 0's, which means the z axis. After that, I settled (after a few iterations of trying to exclude pile-up vertices) on the following parameters:

   x0  = -0.053 cm
   dx/dz  = -0.00113
   y0  = -0.215 cm
   dy/dz  = 0.00023

(these are slightly different from my starops post as I decided to try one more iteration after that post).

Slide 2 of Yingjie's slides notes that the data presented is: "Run ID : 22349011– 22357028 (day 349-357, 167 runs)"

...which means that it includes data both before and after the database BeamLine parameters were changed by at the end of the day on Dec. 22 The effect of this is clear in the below plot: much of the data had one non-tilting BeamLine near (0,0), and the rest of the data passes through

(x0,y0) = (-0.053,-0.215)

with the tilt in this plot visible as

(dy/dz) / (dx/dz) = (dy/dx) = 0.00023 / -0.00113 = -0.2035

I assume that if Yingjie plots this data vs. run number, it will be more clear how _when_ the data was produced (which is highly, but not perfectly, correlated with when the data was taken) defines whether the vertices are generally in the upper or lower bunch.

Hope that helps,

-Gene

On Dec 26, 2021, at 6:39 PM, Ting Lin <tinglin@sdu.edu.cn> wrote:

Hi Geary:

I think Gene can comment on this. What they use are the Min-bias events from the fast production files (picoDst or MuDst files) generated by the production group.

There is Vx vs. Vy plot in fast offline, but do not get report if that is problematic. For the fast offline, Gene said that current setup require that there should be a primary vertex exist, then it is working.

As it is holiday, there is no expert present during the meeting, we will continue to check using this week's data and discuss in next QA board meeting (that will be Dec. 31th, Friday at noon BNL Time).

Thanks,
Ting

-----Original Messages-----
From: "Geary Eppley via STAR-QAboard-l" <star-qaboard-l@lists.bnl.gov>
Sent Time: 2021-12-27 07:04:27 (Monday)
To: STAR-QAboard-l <star-qaboard-l@lists.bnl.gov>
Cc:
Subject: Re: [STAR-QAboard] 2. Vz – vpdVz distribution is shifted by about 5cm.

HF & Bulkcorr QA reps:

The vertex Vx vs Vy plot doesn't look physical. Can the beam really do  
that? Do you understand why your plot looks so different than L4 for  
that period? Your central distribution is an order of magnitude more  
compact than the L4 plot.

Is your result consistent with the mean vertex position Gene sent out?  
What plot and analysis chain does Gene use? What analysis chain do you  
use? Is there a Vx vs Vy plot in Fast offline? If there a Vz VPD-TPC  
plot in fast offline?

Could you plot Vz VPD-TPC for just the central Vx vs Vy distribution?

-Geary


Re: Re: [STAR-QAboard] QA Board Meeting December 24

Date 12/24/2021 (10:51:06 PM CST)
From Ting Lin <tinglin@sdu.edu.cn>
To geary eppley <eppley@rice.edu>
text/plain Text (3 KB)
Hi Geary:

We found this issue from offline QA by HF and Bulkcorr group.

You can see the slide 3 from HF group by Yingzhou and Kaifeng below:
https://drupal.star.bnl.gov/STAR/system/files/1225_HF_QA_pp500_0.pdf

Also slide 3 from Bulkcorr group by Ashish:
https://drupal.star.bnl.gov/STAR/system/files/Bulkcorr_pp_500GeV_QA_week1_new.pdf

Best,
Ting



Ting Lin tinglin at sdu.edu.cn
Fri Dec 24 13:17:40 EST 2021
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Hi all:

A brief minutes for today's meeting:
https://drupal.star.bnl.gov/STAR/comp/qa/pwg-qa/run-22-qa

For Run-22 offline QA:

From Lanny Ray:

1. Offline QA software get stuck this morning.
2. Run 22355023 – 22357011 have excessive hits in various RDOs. Tonko  
power cycled the TPX FEE’s and that seems to have fixed the issue.  
This will very likely to affect the track quality. Need to check with  
TPC expert if we want to mark these as bad or not.
3. Mean dE/dx has been slowly decreasing since the first run  
e.g.22349015 with MIP at 2.4 keV/cm, which continued on days 351 &  
352, but then reduced to more normal values (2.2 keV/cm) on day 353 to  
the present. Also need to check with expert about the real reason if  
it happen again.

From pwg:

1. Most of the problematic runs have been identified by offline QA  
shift, also noted in the shift-log.
2. Vz – vpdVz distribution is shifted by about 5cm.
3. Vr shifted during the last few runs in day 356.

      BulkCorr (Ashish)
      LF (Chenliang)
      HF (Yingjie, Kaifeng)
      JetCorr (Tong)
      ColdQCD (Bassam): .

Best,
Ting


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