[Lad_hallc] FW: electron singles rates

[Holly Szumila-Vance]

Hi all,

Dave Gaskell setup a new simc branch for us for generating the distributions and rates for the electron arm DIS electron.

I am passing this along to anyone who wanted to play with it. I will use this to start generating the comparison plots for our kinematics in the spectrometer quantities.

-Holly

From: Dave Gaskell <gaskelld at jlab.org>
Date: Monday, December 9, 2024 at 4:22 PM
To: Holly Szumila-Vance <hszumila at jlab.org>
Subject: electron singles rates
Hi Holly -

I made a branch of mc-single-arm that adds the cross section/weight to
the output so one can use it similar to simc to get the rates/yield.

https://github.com/gaskelld/mc-single-arm/tree/LAD

I've generated a cross section table using externals for the LAD
kinematics, and interpolate the values in the table to get a cross
section to put in the tree.  New variables in the tree are:

xsecv - vertex cross section in ub/sr/GeV
xsecr - radiated cross section in ub/sr/GeV
weight = xsecr*jacobian

where the jacobian is the small transformation from cartesian
(xprime,yprime) to spherical angles.

To get the yield, just weight all the events by *weight*normfac", where
"normfac" is printed out in the text output file.  That will give you
the number of counts for 1 mC of charge.

For the HMS/SHMS kinematics you sent me, I get:

P=4.4 GeV

HMS:
theta = 17 deg: 244 Hz
theta=13.5 deg: 899 Hz

SHMS
theta=17 deg: 277 Hz
theta=13.5 deg: 1050 Hz

for 1 uA of beam current.

I checked these values against my stand-alone program that ignores
radiative corrections, and they are in same ballpark.

Cheers,
Dave
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