Commissioning and running of sPHENIX

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

Hello sPHENIXians,

This week marks the start of cryo-week #14 (out of 19 + 6).     

Extra thanks to Virginia Bailey who did just an amazing job as Period Coordinator, and we welcome Sanghoon Lim as the new Period Coordinator (pictured below).     We also welcome our latest unstoppable sPHENIX shift crew (pictured below).

Zero crossing angle running continues to yield high luminosity with very low backgrounds.    sPHENIX continues to take good quality physics data with all detectors (except the TPC).    The triggers are sampling the full luminosity and can also take higher interaction rates.     We are focussing on data taking efficiency with good work by the shift crews and help from many experts.     This past week the collision rates provided by C-AD were lower than the week before in part due to larger emittance growth, which they will try to remedy via a Machine Development on this coming Thursday.    A Vernier scan was also performed last Thursday and hopefully that will pin down our MBD and ZDC cross sections.   The integrated luminosity over all z-vertices now exceeds 27 pb^-1, and a decent sample exceeding 4 pb^-1 within |z| < 10 cm is now in the bag.    I  was encouraged by the potential tracking using MVTX, INTT and even TPOT shown at last week's PCM.

Joe Osborn has led a key effort on the offline QA, and more eyes on this QA and low-to-high level checks on the data are needed.   

For the TPC, Kin and John Haggerty have been leading the effort to enable isobutane to be in the TPC gas mixture.    The safety approval process is painful to watch, and they are attempting to thread the needle.    In parallel, preparations for that running, including key  work on the firmware and readout are underway.    Predicting when the isobutane will be approved and start flowing is challenging as this process at BNL is highly non-linear and non-monotonic.   The most optimistic scenario would be to turn on next week.   Many schedule items, and decisions regarding crossing angle, AuAu running time, etc. hinge on this timeline and the results of isobutane on the TPC working point.    We need the collaboration to remain engaged and have the important presence at Brookhaven in 1008 to take advantage of the limited remaining cryo-weeks.

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/94164/attachments/55873/95555/sPHENIXRunCoordinator_RHICCoordinationMeeting2024_07162024.pdf

https://indico.bnl.gov/event/20768/contributions/94163/attachments/55872/95554/RHIC_Coordination_Meeting_XXV.pdf

Lastly, there are open shifts in September and October that need filling.    If each institution can look at these openings and each pick up one more shift that would be very helpful.

Stay engaged!

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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