Start Counter Background Studies

• Seema and Sasha's Old Background Study: [1]
• Sasha's Howto [2]

Pure EM Background

• Generated 100K dummy events using

$ genphoton -M 100000 -Pmax 0.00001 -Pmin 0.000005 -Thetamin 0. -Thetamax 0.001 -o file_out.ascii

• Convert the ascii events into HDDM format and smear the z-vertex across the entire 30cm long target

NB: This step is not necessary as HDGEANT automatically smears the vertex across all three dimensions

$ genr8_2_hddm -V"0 0 50 80" file_out.ascii 

• Use the following control.in file to process the events through HDGEANT (from latest sim-recon version) [3]
  • The minimum energy for the photon beam was lowered to 1.2 MeV to look at hits contribution in SC from 50 MeV photons: BEAM 12. 9. 0.0012
  • The background rate or flux for this minimum energy is 2.2e9 photons/s: BGRATE 2.2
  • The photon pileup window is set to 100ns: BGGATE 0. 100.
  • The following EM processes are turned on:
    • Compton Scattering: COMP 1
    • Pair Production: PAIR 1
    • Energy Loss: LOSS 1
• Additional cuts in HDGEANT:
  • The energy threshold in for hits in SC is 150 MeV (but is currently not applied in HDGEANT code)
  • The time window for two hit resolution is 25 ns
• The hits are then smeared using mcsmear (???)

• To obtain the appropriate scaling factor for the plots, use the following approach:

$f=1/\delta t/N$

where, $f$ is scaling factor, $\delta t$ is the time window (BGGATE) in seconds, and $N$ is the number of events generated.

• Plots
  • Rates [4]
  • Hit Multiplicity [5]
  • R vs Z hit [6]
  • Y vs X hit [7]

• This study was done for the nominal running luminosity of $10^{7}\gamma /s$
• For the high luminosity running of $10^{8}\gamma /s$, the BGRATE should be set to 11.0 instead of 2.2. One can either scale the above rates by applying an additional factor of

$f_{{2}}=11.0/2.2$

• Or, one can re-run the study with BGRATE set to 11.0. This "value will be scaled automaticaly

to the right value corresponding to the beam energy threshold defined by the BEAM card." - Sasha

Pure Hadronic Rates

• To study the pure hadronic

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