sPHENIX cold QCD topical group

["Aidala, Christine" <caidala AT bnl.gov>]

Dear Itaru and all,

I quickly tried looking for explicit instructions on how to take the Vernier 
scan data from PHENIX days, but I couldn't find them, either.  In case it is 
helpful, I did find a 2005 "PHENIX Focus" didactic talk by Dave Kawall on how 
to measure absolute luminosity at RHIC.  

Christine

-- 
Christine A. Aidala
Professor, Department of Physics 
University of Michigan

-----Original Message-----
From: sphenix-cold-qcd-l-request AT lists.bnl.gov 
<sphenix-cold-qcd-l-request AT lists.bnl.gov> On Behalf Of Alexander Bazilevsky
Sent: Tuesday, July 9, 2024 8:50 PM
To: sphenix-cold-qcd-l AT lists.bnl.gov
Subject: Re: [[Sphenix-cold-qcd-l] ] Vernier Scan Instruction

Hi Itaru ans All,

Some correction to my proposal.
After looking more careful in the vernier scan analyses we did in the past, I 
found that the vertex distribution evolution vs different beam displacements 
was studied with ZDC triggers (as its efficiency is not z-dependent, unlike 
BBC/MBD which is z-dependent), so we'd better increase the collected 
statistics for ZDC-Coincidence. So, my corrected proposal for scaledowns:

CLOCK: 10k
MBD N&S >= 1: 10
ZDC Coincidence: 0

(actually almost the same as we run it in PHENIX)

and if we can afford collecting also single-side triggers (just in case):

ZDC-North and ZDC-South: 100
MBD S >= 1 and MBD N >= 1: 500

Regards,
Sasha.

On 7/9/24 9:51 AM, Alexander Bazilevsky wrote:
> Thanks, Itaru, for compiling the info!
>
> Besides the scaler (GL1P) data, we also need event data: as a maximal 
> set - for all triggers included in GL1P, and as a minimal set - for 
> MBD coincidence trigger and CLOCK (e.g. to study vertex distribution 
> at each beam position to understand the hour glass effect).
>
> Since during the vernier scan run our rates vary by a few orders of 
> magnitude, we can not set up reasonable trigger scaledowns which would 
> provide both good life time and good DAQ rate at each step. Therefore 
> we used to release the scaledowns for triggers we collect to saturate 
> the DAQ rate regardless the life time (with the goal to collect as 
> many as possible of triggers we want).
>
> So, I suggest the following scale downs:
>
> CLOCK: 10k
> MBD N&S >= 1: 0
> ZDC Coincidence: 0
>
> Not sure how useful could be the one-side trigger data, but if we can 
> afford enabling them, I'd suggest the scaledowns:
> ZDC-North and ZDC-South: 10
> MBD S >= 1 and MBD N >= 1: 50
>
> In this configuration, the major bandwidth will be occupied by CLOCK 
> and MBD N&S, and only a few % for all other triggers (not necessary, 
> but may be useful).
>
> Regards,
> Sasha.
>
>
>
> On 7/9/24 5:01 AM, Itaru Nakagawa wrote:
>> Dear Sasha and Ralf,
>>
>>  Here is the draft instruction for the vernier scan. Unfortunately I 
>> cannot find any instruction of the data taking in PHENIX, but here is 
>> what I think is the procedure. Please have a look and send me feedback.
>>
>> Best regards,
>>
>> -itaru
>>
>

--
Alexander Bazilevsky
Brookhaven National Laboratory, Bldg. 510D, 2-232 Upton, NY 11973 Tel: 
631-344-3712
Email: shura AT bnl.gov
-------------------------------------------------

Attachment: phenixfocus_07-jun-05_HowToMeasureAbsoluteLumi.pdf
Description: phenixfocus_07-jun-05_HowToMeasureAbsoluteLumi.pdf