Commissioning and running of sPHENIX

[Jamie Nagle <jamie.nagle AT colorado.edu>]

Hello sPHENIX Collaboration,

sPHENIX is now starting "Cryo-Week #6".  sPHENIX has declared "Physics Running" for photon & jets!     

We are now running all systems (GL1, MBD, EMCal, HCal, sEPD, ZDC/SMD, MVTX, INTT) except (TPC/TPOT) at up to 15 kHz with high livetime (>90%).    Getting to  this point represents a lot of effort by a lot of people, so a good milestone to appreciate.    I also noticed the nearly full moon outside, just as we had about one month ago when collisions started.

For this part of the program, we now need to finish polishing the OnlineMonitoring and maintain an attentive shift crew.    Multi Event Buffering (MEB) is now working that enables the high rate with simultaneous high livetime, and thus the combination of rare photon triggers and plentiful minimum bias triggers.     Validation of the rare event triggers, led by Dan Lis,  is underway.    Significant work remains to improve run reliability, and additional features are needed for GL1 and MVTX error recovery, but we are on the road to physics.

C-AD has been struggling particularly with power supply failures, and at  the  same time the beam luminosity  has been steadily increasing -- though  remains a factor of five below where sPHENIX needs it to be.    Vacuum issues are significantly improved via scrubbing and now they are working to  understand emittance growth, in part by having  runs with more spaced bunches (56x56 and now 74x74).   

The TPC has not found a High Voltage working point meeting gain metrics without damaging the detector.    A mini-review was chaired by John Haggerty on Monday, May 20, 2024.    The agreed outcome is to revert the resistor chain back to Op1 point, with  much  lower ion backflow (IBF), along with addressing problematic areas - to be done during the Maintenance Day on Wednesday, May 21, 2024.     The TPC will start operating at a lower Voltage, which  impacts efficiency and momentum  resolution (see slides below), but enables much of the physics program and to start to move it towards continuous running with Big Partition, i.e., with all the other detectors.   In parallel, the TPC has additional avenues to pursue to improve the gain.     Tests of TPC/TPOT zero suppression have been done with new firmware and that needs to move forward at full speed.

Below are the sPHENIX slides shown at the weekly RHIC Coordination Meeting.

https://indico.bnl.gov/event/20768/contributions/91757/attachments/54686/93556/sPHENIXRunCoordinator_RHICCoordinationMeeting20240521.pdf

sPHENIX welcomes a new, intrepid shift crew (pictured below) and new Period Coordinator Hugo (pictured below).    Extra thanks to our outgoing Period Coordinator Tony Frawley!

Stay connected.    Call into the Daily Shift Change Meetings (SCM) at 3:30 pm ET -- details below.

https://bnl.zoomgov.com/j/1614645041?pwd=bmE4STBRZk5tVVVUUC8zRnQxSlFyQT09

https://drive.google.com/drive/folders/1isP7lZPovnRTfLxBQVAuC64Cz_djisbO

Sincerely,

Jamie

sPHENIX Run Coordinator 2024

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|| James L. Nagle   
|| Professor of Physics, University of Colorado Boulder

|| EMAIL:   jamie.nagle AT colorado.edu
|| SKYPE:  jamie-nagle        
|| WEB:      http://spot.colorado.edu/~naglej 
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