[Nps] NPS VTP Trigger thresholds for KinC_x60_4

[Charles Earl Hyde]

Hello,
We are currently running with the following VTP thresholds
Single Photon (NPS_T1) 1400 MeV
TwoPhoton (each, NPS_T6) 650 MeV
With 20 uA on LD2, the OR of these two triggers (with EDTM)
is hTRIG1 = 1.9e6
https://logbooks.jlab.org/entry/4248473
The endpoint energy (gamma or pi0) of the current KinC_x60_3 setting is
4.4 GeV.
So a symmetric pi0 decay of two photons of 650 MeV has a SIDIS
z=1.3/4.4 =

in NIM hardware, the output of hTRIG1 is fanned out with a 160 nsec pulse
width.  Thus in current running on LD2 we have a 30% probability of
pile-up in the trigger.

In our next setting (starting tomorrow afternoon), KinC_x60_4,
the endpoint energy will be 5.2 GeV.
I would like to raise the NPS-VTP trigger thresholds as follows
Single Photon raise to 1600 MeV
Two photon raise to 800 MeV
Looking at the cluster energy spectra, I think this will lower the NPS
nTRIG1 rate by a factor of 2.
The SIDIS range would be approximately 1.6/5.2 =0.31, so essentially
unchanged.


Sincerely
Charles E. Hyde
University Professor  and Eminent Scholar
Department of Physics
Old Dominion University
www.odu.edu/~chyde