CLAS12 simulations with GSIM12/RECSIS12

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CLAS12 simulations with GSIM12/RECSIS12
H. Avakian

• GSIM12/RECSIS12 chain
• Event reconstruction
• Physics events
• Moller background
• Events with real background
• Conclusions

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CLAS GSIM12/RECSIS12
Code in /work/clas/pdisk6/dontcleanme/clasg8/gsim1
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Based on e1DVCS gsim/recsis Modifications by
Franz 1) DC for CLAS12 2) PID as in CLAS6 3)
Torus as in CLAS6 4) Solenoid field from CLAS12
(target at -180.0cm from CLAS center) 5) Moller
Shield for CLAS12
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GSIM12
Current view
Latest version will be available in CVS (Franz)
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Moller background

1. Direct simulation of Mollers in gsim with11 GeV
   beam 5cm target

Sol.Field no shielding, no pipe (air)
Sol.Field no shielding pipe (vacuum)
The shielding should be optimized using the
moller background shape with no air in the pipe!
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Steps in GSIM12 background studies
Compare the background extraction chain

• Real background from e1DVCS data
• Occupancies
• Track reconstruction efficiencies
• GEANT simulation from Vlassov
• Momentum and position of background particles in
  the region I DC

Produce occupancies for R1 DC of CLAS12 and
estimate the track reconstruction efficiencies as
a function of Lumi and occupancies
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Background account at high lumi
1r.ev1ph.ev95k beam el.
Bosmearge routne (Franz (DC) FX (IC,EC,CC,TOF)
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GSIM12 background studies

• GEANT simulation from Vlassov
• Momentum and position of background particles in
  the region I DC

Vlassov
gsim12
Most of the background in CLAS12 are photons (few
e/e-) GSIM12 (gean321) consistent with GEANT4
type GEANT (Degtiarenko)
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e1DVCS background studies
Background accounting procedure tested with e1dvcs
IC edge
shielding
target
e1dvcs GSIM-MC background consistent with data
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GSIM12 background studies
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GSIM12 background studies
CLAS12 occupancies and reconstruction
efficiencies in line with expectations
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summary

• GSIM12/RECSIS12 chain currently available for
  simulation of resolutions and background
• Consistent with e1DVCS data and GEANT background
  sim.
• Occupancies predicted
• Tracking efficiency extracted
• TODO list
• Update the torus field
• Optimize tracking parameters for high
  background conditions
• Update other detector components (update the
  PID part)
• Fix the parameters in FASTMC using
  GSIM12/RECSIS12