sPHENIX discussion of physics

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

Hello All,

When we have been taking AuAu data with the MVTX in triggered mode, the default trigger latency is about 3.7 microseconds.    The auto-recoveries are substantially reduced relative to streaming mode depending on the DAQ rate.   There is a concern that this triggered mode might be clipping the signal from high-charge-deposit signals - which might predominantly be from lower momentum kaons and protons.     There are some initial indicators that in this triggered mode, the MVTX hits are being recorded from most pions (which is a good sign).   See the slides below that were shown at a meeting with C-AD last week.

Thus, I have a physics question, if in triggered mode with this latency the hits were lost for the range on the dEdx figure > 150 (arbitrarily chosen), then sPHENIX might have lower efficiency for kaons with p  < 0.4 GeV (total momentum) and protons with p < 0.7 GeV (total momentum).      For the open heavy flavor program (D0, D_s, Lambda_c) what would be the impact on the acceptance as a function of eta and pT for reconstruction of these decays?     A first look might be useful just from PYTHIA (without GEANT) and calculate with nominal sPHENIX acceptance and then with these cuts.

As an aside, sPHENIX was running last night with AuAu 111x111 bunches at 1 mrad with a DAQ rate of 1.5 kHz.     The MVTX was in triggered mode with the 3.7 microsecond latency and the number of auto-recoveries was very small -- see below (almost all green, and not red).     This running last night represents the best sPHENIX AuAu sample at higher luminosity for checking the triggered mode -- see the run list below.    This all means we still need significant reduction in backgrounds (factor of 10) from C-AD to run at 10-15 kHz next year, but triggered versus streaming gives us a big part of the step towards running.     That is why the question above is important.    

Sincerely,

Jamie

Run = 54925 Evts = 0.373 M,  Duration = 5.27 min. Start = Sat Oct 19 18:14:01 2024 EDT
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Run = 54934 Evts = 2.82 M,  Duration = 17.1 min. Start = Sat Oct 19 21:45:20 2024 EDT
Run = 54935 Evts = 4.63 M,  Duration = 60 min. Start = Sat Oct 19 22:13:59 2024 EDT
Run = 54936 Evts = 4.19 M,  Duration = 59.9 min. Start = Sat Oct 19 23:19:28 2024 EDT
Run = 54937 Evts = 4.73 M,  Duration = 60 min. Start = Sun Oct 20 00:23:57 2024 EDT
Run = 54938 Evts = 4.55 M,  Duration = 60 min. Start = Sun Oct 20 01:27:45 2024 EDT
Run = 54944 Evts = 5.32 M,  Duration = 60 min. Start = Sun Oct 20 03:01:36 2024 EDT
Run = 54945 Evts = 4.79 M,  Duration = 56.7 min. Start = Sun Oct 20 04:05:44 2024 EDT
Run = 54948 Evts = 4.49 M,  Duration = 57.7 min. Start = Sun Oct 20 08:34:43 2024 EDT
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Run = 54951 Evts = 3.92 M,  Duration = 55.6 min. Start = Sun Oct 20 11:13:07 2024 EDT
Run = 54952 Evts = 3.79 M,  Duration = 55.8 min. Start = Sun Oct 20 12:11:16 2024 EDT
Run = 54953 Evts = 1.85 M,  Duration = 27.9 min. Start = Sun Oct 20 13:09:12 2024 EDT

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