sPHENIX bulk physics topical group

["Perepelitsa, Dennis" <dvp AT bnl.gov>]

Hi Ron and all,

Thanks for the productive meeting.

I just wanted to add one more item for the record, which reflected some offline discussion after the meeting. 

In lieu of a ZDC trigger, having just a clock trigger in the trigger menu/mix that fires on filled bunch crossings might be a very effective way to select an orthogonal set of events to check the MBD trigger behavior in very peripheral Au+Au events and thus provide another constraint on the total cross-section.

Even if the trigger is being recorded at a small rate, the statistics would not be an issue, since we would need it only for relatively simple studies: evaluating the MBD efficiency given various other minimal conditions such as an offline ZDC requirement, a reconstructed vertex in the tracker, etc. 

Dennis

On Mar 22, 2023, at 7:27 PM, Ron Belmont <belmonrj AT gmail.com> wrote:

Hi All,

Many thanks to Peter and all involved for a very interesting and lively discussion.  Here’s a brief synopsis.

There is potential interest in adding a ZDC LL1 trigger.  The question is, do we *need* one?  Based on the discussion in the meeting as well as some follow up emails with Mickey, the answer is no.  A ZDC LL1 trigger would be very nice to have for many different reasons, but nothing (under the Bulk TG umbrella) requires it.

The main thing we discussed in the meeting was whether determining the MB efficiency needs it.  The accelerator department does Vernier scans periodically for various reasons, and this can be used to determine the efficiency - and yes, the Vernier scan can be done and is done in Au+Au in addition to p+p.  Based on simulation studies, the MB efficiency is expected to be about 90%, similar to the 92% in PHENIX.  That means the Glauber+NBD modeling can be regarded as safe and reliable.  The only drawback is that this is model dependent, whereas the Vernier scan is not.  It would be *beneficial* but it is not *necessary* to cross-check the Vernier scan with the ZDC trigger.

We talked about UPC physics.  Studies are ongoing, but there is a plan to use the streaming data with a software trigger to do UPC physics.  A dedicated UPC trigger using ZDC LL1 would be beneficial but does not seem to be required.

We briefly talked about polarimetry.  No Cold QCD experts were present, so Peter is going to follow up with the Cold QCD folks about that question.

Cheers,

Ron

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Ron Belmont (he/him/his)
RHIC/AGS Users' Executive Committee
Assistant Professor, Department of Physics & Astronomy
University of North Carolina at Greensboro
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On Mar 17, 2023, at 3:07 PM, Ron Belmont <belmonrj AT gmail.com> wrote:

Hi All,

We’ll plan to have the usual Bulk TG meeting this coming Tuesday March 21 at 9am EDT.  Please let me know if you’d like to present.

Agenda: https://indico.bnl.gov/event/18481/

Zoom: https://bnl.zoomgov.com/j/1613525277?pwd=TExaWUJYUHJMcERCV2ZLQW1OajExZz09 

Regards,

Ron

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Ron Belmont (he/him/his)
RHIC/AGS Users' Executive Committee
Assistant Professor, Department of Physics & Astronomy
University of North Carolina at Greensboro
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Dennis V. Perepelitsa
Associate Professor, Physics Department
University of Colorado Boulder
on sabbatical at Brookhaven National Laboratory