sPHENIX is a new detector at RHIC.

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

Hello sPHENIXians,

As you may know, last August 2021 the sPHENIX Collaboration submitted to the Associate Lab Director and the Program Advisory Committee a Beam Use Proposal (BUP) for the years 2023, 2024, 2025 under two scenarios (24 cryo-weeks per year and 28 cryo-weeks per year).   We are now requested to submit an updated BUP under two scenarios (20 cryo-weeks per year and 28 cryo-weeks per year).    The approach is to submit an Addendum (only 10 pages) to the earlier BUP and address what would be done in the 20 cryoweek scenario.    The draft document is available at the following link:

https://indico.bnl.gov/event/11884/

We would benefit from Collaborator input on the "Chapter 1 - Addendum" and would appreciate receiving all comments by Friday, May 21, 2021.     That will give the group time to address the comments and improve the document before final submission.  The final document is due on May 30, 2021 and the PAC meeting is June 22-23, 2021.

The short summary paragraph is included below and so we clearly must work hard to avoid the 20 cryo-week scenario.

"We detail the ramifications of a 20 cryo-week scenario in the following sections, and the broad effects of significantly shorter runs in 2023–2025 can be stated succinctly: there is increased risk to the sPHENIX science program, but particularly in the crucial commissioning year 2023; the entire p+Au run is lost; and there is a significant reduction in the statistics of the signature Au+Au program. We emphasize that many of the core sPHENIX physics measurements can still be made; however, there is substantial increased risk to the entire physics program."

Sincerely,

Jamie 

(for the sPHENIX BUP Taskforce)

Sasha Bazilevsky, John Haggerty, Jin Huang, Dennis Perepelitsa, and ex-officio Dave Morrison, Gunther Roland

Also particular thanks to Ron Belmont and Marzia Rosati

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|| James L. Nagle   
|| Professor of Physics, University of Colorado Boulder

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