Commissioning and running of sPHENIX

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

Hello sPHENIXians,

This week marks the start of cryo-week #21 (out of 19 + 6 + 2 = 27).     With the two week extension of the run, the current pp data collection goes until September 30, 2024 followed by 3 weeks of AuAu, i.e., until October 21, 2024.    There are two weeks of watch shifts after that, though the sPHENIX magnet will have to be turned off just one day after beam time ends.    Please consider having your institution sign up for one more shift beyond your quota!

https://www.sphenix.bnl.gov/ShiftSignupRun2/

sPHENIX continues running at +1.5 mrad with approximately 50% of the collisions within |z|<10 cm.    C-AD has delivered consistent, good luminosity stores over the past week.    The consensus at the sPHENIX General Meeting last Friday was to request that C-AD have no more machine development for the beta squeeze nor for intensity improvements -- the best path to maximizing sPHENIX physics is to run under the current beam conditions with high uptime.

Five days ago, additional optimizations and data compression enabled up to 35% tracker data streaming (with the TPC in trigger + 50 microsecond extended readout).      This was sPHENIX engaging the data-bandwidth hyperdrive.     However, to quote Han Solo:

"We've come out of hyperspace, right into a meteor shower... or an asteroid field or something. It's not on any of the charts!"

In last week's message, I emphasized that "Key checks on the overall data quality are underway and are on the critical path to ensuring that we are taking the highest quality bits to disk.    This point cannot be emphasized enough."     JaeBeom stayed up all night for a few cycles and determined that the TPC was dropping substantial amounts of data, and after conferring with Jin and others, it seems that six stores worth of data are likely unanalyzable.    Sunday early morning, sPHENIX set a new run point at 20% streaming and so far checks by JaeBeom, Sam, Michael P, Chris, Joe indicate reasonable data quality.   A real offline QA process remains a critical priority.

Our current data taking with the TPC has a tracking acceptance that is changing through the running period in part due to remaining data dropping as well as auto-masking of FEEs and other issues.     Charles and Takao in particular have been covering around the clock to maintain the TPC readout.    Experts are working on stabilization and a careful assessment of potential FELIX firmware fixes/changes and potential busy logic is needed.     Note that our current data rate is consistent with the goals sPHENIX presented under the +2-week extension, and so balancing additional gains versus lost development time must be weighed.

The graph below shows a summary of the run so far and the time remaining.    The graph shown below excludes the data taken during the failed "hyperdrive" period where substantial TPC data was being dropped.

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

https://indico.bnl.gov/event/20768/contributions/96172/attachments/57012/97840/sPHENIXRunCoordinator_RHICCoordinationMeeting2024_09032024.pdf

https://indico.bnl.gov/event/20768/contributions/96171/attachments/57013/97841/RHIC_Coordination_Meeting_XXXI.pdf

Lastly, welcome to our new sPHENIX shift crew (picture below) and continuing Period Coordinator Yeonju Go (picture below).   

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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