Commissioning and running of sPHENIX

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

Hello sPHENIXians,

This week marks the start of cryo-week #13 (out of 19 + 6).     John Haggerty made the interesting point that the sPHENIX 3-year run plan was for 28 cryo-weeks in each year:  2023, 2024, 2025.       At this point, adding the cryo-weeks from 2023 and now in 2024 adds up to 11+12 = 23 weeks.   sPHENIX has a lot to be proud of in this short amount of running time, and at the same time needs to optimize within the current reality.

Extra thanks to Virginia Bailey (picture below) who is doing an excellent job as Period Coordinator.     We also welcome our latest intrepid sPHENIX shift crew (pictured below).

Zero crossing angle running continues to yield high luminosity with very low backgrounds.    Over the past few days, C-AD has been injecting ever higher bunch intensities and bringing only sPHENIX into collision.    After 1-2 hours, when the intensities go below a fixed point related to the beam-beam limit, STAR is brought into collision.      Just in the last week, sPHENIX has integrated 10 pb^-1 over all z-vertices and approximately 16% of that within |z|<10 cm.   Updates to the MBD and Photon/Jet triggers look good and increase our overall efficiency.    sPHENIX is fully sampling the highest luminosities delivered with  livetime ~ 97%.      In addition, a small 100 Hz Clock Trigger has been included for cross checks, and the MBDNS>=1, vtx<10 cm is now taking most of the minimum bias bandwidth (with a smaller fraction without the vertex cut for trigger checking).   The  ZDCNS bandwidth has been increased to > 300 Hz.      I encourage the Collaboration to push on checks with the "tracklets" (vertex, INTT, MVTX and perhaps connecting to TPOT or EMCal) that should provide important physics in the data already taken.

The MVTX and INTT are working on run stability, and the Offline QA is coming into shape to examine the overall data quality.
That Offline QA output needs to be checked every day and then fed back into our operating procedures.    We are now tracking the overall data taking efficiency and need to also quantify the data quality.

"The nitrogen admixture for the TPC improved the working point, and at the same time does not allow for a robust, stable physics detector.     Thus, the push is to get safety approval for an isobutane admixture -- the earliest that might happen is next week and then would take a number of days to evaluate a new working point.    Fingers crossed."   -- You might note that I  wrote these exact same words last week.     The TPC effort is working hard in parallel to check for precursors of the sparking by running full streaming at lower Voltage, working on firmware/FEE issues, and preparing for the gas change when approved.

Lastly, there are a lot of questions about when the AuAu run might start, if the TPC is not working do we end the  run early, what if the isobutane is not approved, etc., etc.       Right now the team in 1008 and the Collaboration are focussed on taking high quality data with the detector currently in place, and working to efficiently bring the TPC into the physics fold.      It is premature to address these larger questions until we have more information on the TPC options and performance.

Below are links to the weekly RHIC Coordination meeting presentations from sPHENIX and C-AD.   The slides have lots of answers to your questions 😬

https://indico.bnl.gov/event/20768/contributions/93858/attachments/55734/95293/sPHENIXRunCoordinator_RHICCoordinationMeeting2024_07092024.pdf

https://indico.bnl.gov/event/20768/contributions/93857/attachments/55741/95302/RHIC_Coordination_Meeting_XXIV.pdf

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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