Commissioning and running of sPHENIX

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

Hello sPHENIXians,

This week marks the start of cryo-week #15 (out of 19 + 6 = 25).     

Extra thanks to Sanghoon Lim as our Period Coordinator (pictured below) and also welcome to our latest heroic sPHENIX shift crew (pictured below).    The continued commitment of many people in 1008 and beyond has directly translated into improved data taking efficiency and higher quality data.

The Time Projection Chamber has been off for the better part of a week as preparations are essentially complete to add isobutane to the gas mixture.     In a Byzantine process of safety approval, the end may be in sight.    Kin, John Haggerty, Joel led a safety walk through today and there is a "final" list of requirements.      Numerous people are working hard to address the listed items and David Mohamed (an Authorization Basis Engineer from C-AD) has been helping enormously.     Once approval is given, there will be a two-day period for turning the gas over and then we expect to first have cosmic data taking without beam, and then low bunch number stores to systematically understand the new working point for the TPC.     It is notable that the firmware is not yet complete to readout the TPC in a physics mode, and there is significant instability with the EBDC and buffer box system at the highest rates -- which is going to be further stress tested tomorrow during APEX.   

For the other detector subsystems, 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).    This past week the collision rates provided by C-AD were much higher due to Machine Development work reducing the emittance growth by almost a factor of two.     The integrated luminosity over all z-vertices is now almost 40 pb^-1, and almost 6 pb^-1 within |z| < 10 cm.    MVTX and INTT are in full streaming but DMA transfer issues are resulting in lost data and down time in the first 1-2 hours of stores.     Tests turning off MD5 checking and turning on data compression are underway.   These checks are crucial in anticipation of TPC running in full streaming mode.

Note that once the TPC HV can be turned on, we will likely have significant downtime for commissiong and the rate of accumulated statistics for the other detectors will be much lower.   The highest priority will be the TPC establishing a working point, and then most likely switching to +1.5 mrad and running physics.   A test of +1.5 mrad was carried out successfully yesterday.

Below are links to the weekly RHIC Coordination meeting presentations from sPHENIX and C-AD.  

https://indico.bnl.gov/event/20768/contributions/94456/attachments/56021/95859/sPHENIXRunCoordinator_RHICCoordinationMeeting2024_07232024.pdf

https://indico.bnl.gov/event/20768/contributions/94455/attachments/56018/95853/RHIC_Coordination_Meeting_XXVI.pdf

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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