[Nps] Constraints on DVCS kinematic settings

[Charles Earl Hyde]

Hello,
(Reposting from my JLab email)


I am making a few tweaks to the DVCS kinematic settings, with the
following objectives:
1) Reduce the number of settings requiring full HMS optics studies
.....by reducing xB=0.5 to 0.48, we can use the pionLT calibration at 6.8 GeV
....by reducing xB=0.6 to 0.58, we can use the pionLT calibration at 5.878
GeV
.... we still need a ~quick optics run (single foil thick C) at each
setting to check for fringe field effects from NPS sweep magnet
2) Adjust the low-x settings to satisfy:
.....HMS angle >/= 11.7 deg
....HMS-SHMS separation >/= 23.5 deg.  This is particularly difficult at E
= 10.558 GeV, Q2<3.0 GeV2, and xB~0.24
3) Minimize the number of settings with calorimeter at extremely small
angles (concern for radiation damage to PMT base amplifiers).
.... currently there is one setting (x=0.36) with theta_Calo = 7.4 deg and
2 (of 4)  xB=0.24 settings at theta_Calo=8.7deg
.... all other settings have theta_Calo>/= 9.9 deg

With these changes, we need new comprehensive HMS calibrations at electron
energies of
5.0 GeV, 5.25 GeV, and 6.12 GeV.
Does anyone know of prior (e.g. 6 GeV era) optics studies at or near 5.0
GeV in HMS?
The closest thing I can find is a logentry from Mark Jones:
https://logbooks.jlab.org/entry/3554200
which seems to imply all is well with standard optics matrix at 5.1 GeV



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