I have implemented a new set of subroutines for the gsim package that
simulate target related background events. This code was directly derived
from Volker Burkert's background routine in the old geant simulation.
These routines produce background event distributions that are based on an
EGS simulation of the target. These distributions are stored in an HBOOK
file and sampled randomly. The code will generate electron, photon
(including bremstrahlung) and positron background events.
I have not yet recompiled libgsim.a and gsim_int, gsim_bat on
all the platforms. I currently don't have the disk quota to do this and
install new versions.
If you are not interested in background events, no need to read further.
Regards,
Maurik Holtrop
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Modifications to gsim:
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New behavior:
The kine switch ( ffread key or gsim command-line) now accept new values
which are equal to the original kine value +10 ( -10 for negative kine
values). This turns on the background event generator. Thus, kine=1 reads
events from mcin, kine=11 reads events from mcin, plus generated
background events. A new value, kine=4, does nothing so that kine=14
generates only background events.
The following new ffread keys were defined:
NTARG - Select target type: (defaults to 1)
NTARG = 1 - Hydrogen gas dens. 0.007g/cm3, length 76mm
reads file $CLAS_PARMS/h_76mm_g.hst
NTARG = 2 - Hydrogen liquid dens. 0.07g/cm3 , length 76mm
reads file $CLAS_PARMS/h_76mm_l.hst
NTARG = 3 - NH3 solid dens. 1g/cm3 , lenght 15mm
reads file $CLAS_PARMS/nh3_15mm.hst
NTARG = 4 - Cu solid dens. 8.9 g/cm3 , lenght 10microm
reads file $CLAS_PARMS/cu_10um.hst
NTARG >= 5 - User supplies background information,
set ZTAR,ATAR,RHOT,TLENG and supply a file
bckgr.hbook.
LUMEN - Luminocity, (defaults to 1E-32)
TIMDC - Time that one event is sensitive to background.
(defaults to 250E-9 sec)
NINCE - Number of events used to generate background file.
(defaults to 100000000)
ZELEM - Z of target.
ATOM - A of target.
RHOT - density of target (g/cm3)
TLENG - lenght of target (cm)
New files: (in gsim.lib/s )
clas_bckgr.F - Contains the routines to calculate background events.
ffky_bckgr.F - Handles the new keys (ffread) for target description.
ffpar_bckgr.inc - Contains common block that controls clas_bckgr routine.
Modified files:
clas_kine.F - Now calls clas_bckgr when the flag ikine (kine command
on gsim command line) is set to previous kine value +10
- A new "event generator", kine=4, was defined which does
nothing. Thus kine=4 does nothing, kine=14 gives only
background events.
clas_ffky.F - Now also calls ffky_bckgr