sPHENIX is a new detector at RHIC.

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

Hello sPHENIXians,

Just a quick update from the sPHENIX BUP Taskforce.    We are making finishing edits towards the final BUP due on Monday, August 31, 2020.

In the process of checking and re-checking numbers, we found an error in the pp luminosities.    I had used the 26% value from C-AD as the fraction of the luminosity projected for 0 crossing angle that one gets within |z| < 10 cm with a 2 mrad crossing angle for AuAu as well as pp.  However, the final calculation from C-AD has 26% for AuAu, but only 16% for pp (mea culpa).   Thus, the 2024 and 2026 trigger sampled luminosities change from 101 pb^-1 and 130 pb^-1, respectively, down to 62 pb^-1 and 80 pb^-1.   All projection figures have been updated to reflect this change.    There was also a minor change in the O+O and Ar+Ar luminosities in the upward direction by ~10-20% for the sampled luminosities.

The Taskforce does believe that additional pp running would be very useful - which could be in 2026 or from more cryo-weeks in 2024.   The option of eliminating the p+Au running in 2024 in favor of more pp running that year was discussed, but it was decided not to make such a change in the BUP at this late stage.     I believe that the ALD and the Program Advisory Committee expects that there will be tweaks to this beam plan in the coming years, particularly in light of running and new physics at RHIC and the LHC in the meanwhile.

Sincerely,

Jamie, for the sPHENIX BUP Taskforce

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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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