Difference between revisions of "Start Counter Background Studies"

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* Seema and Sasha's Old Background Study: [https://halldweb1.jlab.org/talks/2012-2Q/background/SC_simulations.pdf]
+
* Seema and Sasha's Old Background Study: [https://halldweb.jlab.org/talks/2012-2Q/background/SC_simulations.pdf]
−
* Sasha's Howto [https://halldweb1.jlab.org/wiki/index.php/HOWTO_to_generate_electromagnetic_background]
+
* Sasha's Howto [https://halldweb.jlab.org/wiki/index.php/HOWTO_to_generate_electromagnetic_background]
  
−
=== Pure EM Background ===
+
=== EM Background Rates ===
  
−
* Generated 100K dummy events using  
+
* Generated 10K dummy events using  
  
−
  '''$ genphoton -M 100000 -Pmax 0.00001 -Pmin 0.000005 -Thetamin 0. -Thetamax 0.001 -o file_out.ascii'''
+
  '''$ genphoton -M 10000 -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
 
* Convert the ascii events into HDDM format and smear the z-vertex across the entire 30cm long target
Line 13: Line 13:
 
  '''$ genr8_2_hddm -V"0 0 50 80" file_out.ascii'''  
 
  '''$ 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) [https://halldweb1.jlab.org/talks/2012-2Q/background/em_control.in]
+
* Use the following control.in file options to process the events through HDGEANT (from latest sim-recon version)
 
** 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 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 background rate is set appropriately depending on the threshold:
 +
*** For <math>10^7 \gamma/s</math> use '''BGRATE 1.1''' (HDGEANT scales the BGRATE to 2.22)
 +
*** For <math>10^8 \gamma/s</math> use '''BGRATE 11.0''' (HDGEANT scales the BGRATE to 22.2)
 
** The photon pileup window is set to 100ns: '''BGGATE 0. 100.'''
 
** The photon pileup window is set to 100ns: '''BGGATE 0. 100.'''
 
** The following EM processes are turned on:
 
** The following EM processes are turned on:
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and <math>N</math> is the number of events generated.  
 
and <math>N</math> is the number of events generated.  
  
−
* Plots
+
* Plots <math>10^8 \gamma/s</math>
−
** Rates [https://halldweb1.jlab.org/talks/2012-2Q/background/em_paddle_1.png]
+
** Rates [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/paddle_rate_1.png]
−
** Hit Multiplicity [https://halldweb1.jlab.org/talks/2012-2Q/background/em_mult_1.png]
+
** Hit Multiplicity [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/hitmult_1.png]
−
** R vs Z hit [https://halldweb1.jlab.org/talks/2012-2Q/background/em_rz_1.png]
+
** R vs Z hit [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/rz_1.png]
−
** Y vs X hit [https://halldweb1.jlab.org/talks/2012-2Q/background/em_yx_1.png]
+
** Y vs X hit [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/yx_1.png]
 +
** Energy [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/energy_1.png]
  
 +
* Plots <math>10^7 \gamma/s</math>
 +
** Rates [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/paddle_rate_2.png]
 +
** Hit Multiplicity [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/hitmult_2.png]
 +
** R vs Z hit [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/rz_2.png]
 +
** Y vs X hit [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/yx_2.png]
 +
** Energy [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/energy_2.png]
  
−
* This study was done for the nominal running luminosity of <math>10^7 \gamma/s</math>
+
=== Hadronic Rates ===
−
* For the high luminosity running of <math>10^8 \gamma/s</math>, 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
+
  
−
<math>f_{2} = 11.0/2.2</math>
+
* To study the hadronic rates, a similar method is used compared to the EM background study.
 +
* 395K background events are generated using '''bggen'''. <!----The bggen card options are: [https://halldweb.jlab.org/talks/2012-2Q/background/hadronic_bggen_run.ffr]---->
 +
* These events are then passed through HDGEANT
 +
** The BGRATE and BGGATE options are turned off as we don't want to look at additional photon pile-up (double counting)
 +
** The same EM processes as above are turned on
 +
** The BEAM options are still '''BEAM 12. 9. 0.0012'''
 +
** The output is again smeared using mcsmear
 +
* No normalization factor is applied
 +
* The following rates are observed:
 +
** Rates [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/paddle_rate_1.png]
 +
** Hit Multiplicity [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/hit_mult_1.png]
 +
** R vs Z hit [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/rz_1.png]
 +
** Y vs X hit [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/yx_1.png]
 +
** Energy [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/energy_1.png]
  
−
* 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
 
  
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=== Pure Hadronic Rates ===
+
====Energy Cuts====
−
 
+
* E > 0.2 MeV
−
* To study the pure hadronic
+
** EM only [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/paddle_rate_0.2mev.png]
 +
** Hadronic [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/paddle_rate_0.2mev.png]
 +
* E > 0.3 MeV
 +
** EM only [https://halldweb.jlab.org/talks/2012-3Q/sc_background/em/paddle_rate_0.3mev.png]
 +
** Hadronic [https://halldweb.jlab.org/talks/2012-3Q/sc_background/had/paddle_rate_0.3mev.png]
  
  

Latest revision as of 21:54, 31 March 2015

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

EM Background Rates

  • Generated 10K dummy events using 
$ genphoton -M 10000 -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 options to process the events through HDGEANT (from latest sim-recon version)
    • 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 is set appropriately depending on the threshold:
      • For 10^{7}\gamma /s use BGRATE 1.1 (HDGEANT scales the BGRATE to 2.22)
      • For 10^{8}\gamma /s use BGRATE 11.0 (HDGEANT scales the BGRATE to 22.2)
    • 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 10^{8}\gamma /s

Hadronic Rates

  • To study the hadronic rates, a similar method is used compared to the EM background study.
  • 395K background events are generated using bggen.
  • These events are then passed through HDGEANT
    • The BGRATE and BGGATE options are turned off as we don't want to look at additional photon pile-up (double counting)
    • The same EM processes as above are turned on
    • The BEAM options are still BEAM 12. 9. 0.0012
    • The output is again smeared using mcsmear
  • No normalization factor is applied
  • The following rates are observed:


Energy Cuts


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