Star-tpc-l mailing list

["Fisyak, Yuri V" <fisyak AT bnl.gov>]

Hi Jamie, 

1. Yes, the occupancies are depended on multiplicity, but not only of multiplicity.
2. Number of compromised (deconvoluted) cluster is increase with occupancy.
3. Higer ADC clusters (wider ) trend to be compromised more often. 
4. Rejecting compromised clusters create a bias to low dE.

The problem is to find a good measurement which characterized the occupancy. 

                                            Yuri Fisyak

STAR                             Phone: +1 631 344 3913
Brookhaven National Laboratory  Fax:    +1 631 344 4206
510A/1-161
http://www.star.bnl.gov/~fisyak       E-mail: fisyak AT bnl.gov

From: Dunlop, James C <dunlop AT bnl.gov>
Date: Friday, November 21, 2025 at 1:44 PM
To: Fisyak, Yuri V <fisyak AT bnl.gov>
Cc: Dunlop, James C <dunlop AT bnl.gov>, Witt, Richard CIV USNA Annapolis <witt AT usna.edu>, Star-tpc L <Star-tpc-l AT lists.bnl.gov>
Subject: Re: [[Star-tpc-l] ] TPC Meeting Minutes

Hi Yuri,

  Repeating Rongrong's speculation, are you sure this isn't just a side effect of a multiplicity (actually occupancy) dependence?

i.e. possible logic

 

i) the mtd trigger selects higher multiplicity than minbias  

ii) Higher multiplicity leads to higher occupancy 

iii) Higher occupancy leads to more deconvoluted clusters.

iv) Excluding deconvoluted clusters biases the dE/dx downwards

        -- PS do you know why this bias happens?  I guess because you cut off some fluctuations to high ADC? 

Reason I say occupancy is that there is also the complication in, say, the high lumi dataset of pileup, where the

occupancy doesn't just depend on the multiplicity of the triggered event but also the level of pileup, i.e. instantaneous lumi.

--J

On Nov 21, 2025, at 10:44 AM, Fisyak, Yuri V <fisyak AT bnl.gov> wrote:

Hello,  it looks like that I found the reason for dE/dx degradation in mtd stream.

See  https://drupal.star.bnl.gov/STAR/system/files/Run%20XXII%20dEdx%20comparison%20st_physics%20and%20st_mtd%20%20stream_0.pdf

The conclusion is that we need trigger dependent dE/dx correction.

                                            Yuri Fisyak

STAR                             Phone: +1 631 344 3913
Brookhaven National Laboratory  Fax:    +1 631 344 4206
510A/1-161
http://www.star.bnl.gov/~fisyak       E-mail: fisyak AT bnl.gov

From: star-tpc-l-request AT lists.bnl.gov <star-tpc-l-request AT lists.bnl.gov> on behalf of Richard Witt <Star-tpc-l AT lists.bnl.gov>
Date: Thursday, November 20, 2025 at 12:29 PM
To: Star-tpc L <Star-tpc-l AT lists.bnl.gov>
Subject: [[Star-tpc-l] ] TPC Meeting Minutes

This Message Is From an External Sender

This message came from outside your organization.

 

Present: Alexei, Flemming, Jim, Yuri, Gene, Rongrong, and myself

== Hardware

— all is going well for the most part

— was small hiccup with laser (prior repair work appears to be holding)

— current concentration seems to provide as stable 5.52 cm/us drift velocity

— cathode interlock is now behaving

== Electronics

— still the usual losses and repairs of RDOs and FEEs (usual 15% dead on average)

— lost 5 or 6 RDOs in last five days, most were fixed yesterday

— Gene reminded us that due to SL farm outage coming on Monday and Tuesday there will be a delay in fast offline processing

== Software

— hit error work for AuAu23 DAQ 5000 (2023) with different fields (RF, RHF, and ZF)

— see https://drupal.star.bnl.gov/STAR/event/2025/11/20/Weekly-TPC-Meeting

— Run23 dE/dx in physics and MTD streams

— see https://drupal.star.bnl.gov/STAR/event/2025/11/20/Weekly-TPC-Meeting

— MTD stream data presents ~1% difference in dE/dx MIP position

— seems to be attributable to the inner sectors, but not yet fully understood

— Rongrong suggest looking at shift vs. RefMult due to central bias of MTD trigger

== AOB

— Nothing new for this week.

Best Regards,

  Richard

Sent from my iPad

-- 
"Education is the most powerful weapon which you can use to change
the world."

--Nelson Mandela

~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~
 Richard Witt, Professor of Physics     Phone (USNA): 410-293-6675
    United States Naval Academy         Email: witt AT usna.edu
~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~~~***~