[Primexd] [New Logentry] CCAL rates

[somov at jlab.org]

Logentry Text:
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We have performed a study of rates in the CCAL detector.

Beam conditions:

Amorphous 10^-4  R.L. radiator, 750 um converter, beam current 100 - 350 nA.

(PrimEx nominal current - 320 nA assuming runs with the 10^-4  R.L. radiator)

Trigger type: FCAL & CCAL, total energy deposition > 2 GeV

SETUP:    hd_all.tsg_ccal_fcal
CONFIG:  CCAL_FCAL_TAGGER.conf


Fig. 1 CCAL scalers for the run with  350 nA

Fig. 2 CCAL scalers  for the run with 350 nA (energy threshold 30 MeV)

The maximum rate of CCAL modules is 240 kHz for 30 MeV energy threshold. 

The maximum rates seems to tolerable (acceptable) for the compton calorimenter.
The rate is relatively close to that predicted by Monte Carlo simulation, see Fig 3.

Fig. 3 Simulation of rates in the Compton calorimeter (slide from the experimental readiness
review). 

The PS rate for  runs  with a 350 nA current is 7.3 kHz (for 750 um converter). The beam transmission 
(estimated by comparing PS rates) seems to be 'similar' to that for GlueX runs with the amorphous 
radiator. Note, the PS acceptance has to be corrected due to the smaller beam energy of 10.3 GeV.

We took data to check the PMT gain stability on rate. An  LED pulser operated at 20 Hz was added to the
production trigger

run 52193   - 350 nA current

run 52194   - 200 nA 

run 52195  - 100 nA 

run 52196  -  no beam







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