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1. VDC: u1,u2,v1,v2
2. Gas Cerenkov,
3. Scintillator: S1&S2
4. Pion Rejector: pr1,pr2
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Gas Cerenkov
Scan through Production Runlist
This scan only apply for run from 2858 to 3450, cover the He4 production, kinematics 1, all
kinematics 2, and kinematics 3. (From Mar 15, 2011, 22:24 to April 13, 2011, 4:47)
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description: The gas Cerenkov detector is used to separate the electron from other particle, i.e. pion-.
Calibration:
1. raw ADC -> ADC pedestal correction : Change Offset in db_L.cer.dat
2. ADC single PE alignment: ADC_p-> ADC_c: Change Coeff in db_L.cer.dat
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Calibration 1: pedestal Scan.
1.1 The raw ADC offset is calculate using run 3091 (and will later be done for 1run/day)
424 368 374 392 518 458 475 432 411 396
1.2 Now scan for all the production run. (explain above).
The following figure set (figure 1) is the example of what has been done. I check the alignment
of the pedestal peak in the variable a_p where the alignment should be at zero. The red line show
where the pedestal peak is for each Cerenkov PMT. (10 PMTs in total).
Note that any negative value will not be use in term of calculating any further information, i.e. a_sum .
Figure 1
The x-axis is the ADC pedestal subtracted value (in channel).
The cut required is “DBB.evtypebits==8 && DBB.edtpl[0]==0” (left arm trigger only without edtm)
(top left is pmt 0, top right is pmt 1, bottom left is pmt 8 and bottom right is pmt 9.)
Then the value set for each “good” run is extracted and compare to see the change from one run to
others. The fluctuation is between 0+/-2. The red line is zero. The green is +2. and the black is -2.
With this, I see no need to change pedestal value from what I already has done in the 1.1 step.
Figure 1.2 pedestal value (y) vs run number (x)
Calibration 2: SPE alignment Scan.
2.1 Try to align the single PE at channel = 100. The coefficient is calculated with the following
relation.
The SPE ideal channel = Coeff * (mean PE)
The initial attempt is done with the same run 3091. Only focus on the peak identified by the red
line at value 100.
Figure 2.1 overlap of all the L.cer.a_c[i] for i=0 to 9
2.2 The SPE peak is then scan for all the run list.
2.2.1
The SPE peak fit with Gaussian for each PMT is shown below for a single run
3425 as an example.
Figure 2.2 The fit of SPE peak for each PMT.
The the value is then extract with mean and sigma to show the change through the run list.
Figure 2.3 The mean peak value with sigma as the 'error' bar. There clear to be three district set of data
which has to fit separately.
2.2.2
I also do the overlap between run xxx0 to xxx0+10 to make sure that I didn't let
any thing slip. The following is the example of the overlap of the normalized ADC
value.
Figure 2.4 The overlap of the normalized ADC value for each PMT for 11 runs all together to ensure
the consistent of the SPE peak location. This show the consistent for all 11 runs.
Figure 2.5: This is the example of the 11 runs that has two district (different) coefficients as the
distribution lines clearly not overlap.
With the second scan, I also conclude with three set of the run that will have different coefficient
factors.
Here is the run numbers in each setting.
Setting
1
2
3
run number
2800 – 3022
3025 – 3052
3053 – 3450
2.2.3
For each setting, the histograms are sum to ensure the large statistic. The value of
the SPE peak is then extract.
Figure 2.6 : The sum of the ADC value for setting 1 of Cerenkov PMT-0.
The SPE is fit at (mean) 186.02 +/- (sigma) 64.90
There seem to be another peak there where I am not sure what it is. This also occur in all the PMT and
can only be seen when we have large statistic.
Figure 2.7: The sum of the ADC setting 1 for all the PMT.
The final gain factor:
Setting
1
2
3
run number
2800 – 3022
3025 – 3052
3053 – 3450
gain factor
0.430 0.216 0.199 0.272 0.267 0.386 0.281 0.486 0.477 0.332
0.547 0.387 0.408 0.522 0.444 0.561 0.493 0.594 0.546 0.485
0.803 0.674 0.813 0.852 0.767 0.924 0.889 0.804 0.799 0.761
Figure 1.2: The corrected sum of the adc after correction for the pedestal then the gain factor.
Run 3901 only.