Commissioning and running of sPHENIX

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

Hello All,

Just a quick update in between my weekly sPHENIX Tuesday emails.

1)    After a heavy-lift effort by many, the isobutane usage was fully signed off and then Saturday morning Rob Pisani, Joel, John H carefully checked everything and turned on the isobutane flow to the TPC -- flow turn on time was 3 pm.   The current plan is to have 6 hours without beam on Monday, July 29, 2024 from 1 pm - 7 pm for raising the TPC high voltage and taking cosmic ray data triggered by the HCal.         The exact time and duration of the "no beam" depends on the TPC results, and we will take as much time as needed.      During that same time, the INTT group led by Raul will be testing new streaming readout firmware to address the BCO issues observed over the past week.

2)    Looking ahead, the plan is to have a low bunch number store (6x6) at zero crossing (to ensure stable, low background beam) for TPC next step tests.     This may occur on Tuesday, or potentially after the Wednesday Maintenance Day, on Thursday.   Again, this is highly dependent on the first results and the ability to get offline feedback as soon as possible.    It is critical that the offline results be well labeled and clear not just to the TPC group, but to the Collaboration.    These studies must be very systematic and not rushed.

3)   It is likely that the TPC may need one or two long periods of access to the IR for resistor changes, and we will schedule those as needed (and not be waiting for Maintenance Days).

4)   The isobutane additive is not magic - it has benefits and also down sides.     The Collaboration should be patient as the TPC group carefully steps through various tests.    Also, there are critical firmware changes needed to run the TPC in physics mode and it is not yet clear at what rate data can be logged (initial tests from the last week's APEX day were done by Jin, JaeBeom, and Dan).

5)   Until the TPC reaches a physics data taking mode, we will continue running with injecting beam starting with zero crossing and when not doing TPC tests, sPHENIX will continue to collect high statistics data with the other detectors.   

Sincerely,

Jamie

||------------------------------------------------------------------------------------------
|| 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 
||------------------------------------------------------------------------------------------