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Analysis of Pion beam test. R.Sawada 20/Jan/2004 on VRVS. Q.E. estimation Energy Resolution Timing Resolution. Absorption. distance dependence of number of photoelectrons at each PMT normalized with MC. Xenon was very pure !. Q.E. estimation. - PowerPoint PPT Presentation
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Analysis of Pion beam testR.Sawada
20/Jan/2004on VRVS
Q.E. estimationEnergy ResolutionTiming Resolution
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Absorption
Xenon was very pure !
distance dependence ofnumber of photoelectrons at each PMT normalized with MC.
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Q.E. estimation
gasalpha in gas
TERAS in 2003gain ~ 5e6
liquidalpha in liquid
PSI in 2003gain ~ 1e6
beam on (FSH52 =125)
We have ever used gas data for Q.E. estimation.But now we can also use liquid data because Xe is pure.
Q.E. (liquid ~ -105℃) ~ 0.74 * Q.E. (gas ~ -85℃)
4
Comparison between data and MC
alpha Pi0->2gamma
Q.E. estimated from liquid alpha data was used in MC.
The peak position is well reproduced by this MC code.
data
MC
data
MC
Energy Resolution
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Data Condition
with paraffin shield
Collimator sizeXenon 9.5 cmNaI 11.5 cm
FSH52 DAC value(beam intensity)
125
PMT gain 1e6
7
cut & correction
Nfpmt(0.5) is used as depth parameter for correction and cut.
Nfpmt : number of PMTs which occupy the half of Qfront.
sigma2<90 is also applied to remove very deep events.
MC
Nfpmt(0.5)>4
rejected
accepted
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Energy Resolution
FWHM = 4.5 ± 0.3 (left:2.7 + right:1.8) %
•Depth cut and correction.
•55 MeV gamma is selected by NaI energy cut.
•Impinging position cut is also applied
•(sqrt(x_average^2 + y_average^2)< 1.5cm)
(sigma of the right part is 1.53%)
9
Position dependence of resolution
FWHM [%]
4.3±1.0
4.8±0.4
4.6±0.7
4.5±0.6
4.5±0.3
4.5±0.6
4.1±0.9
5.0±0.5
5.0±1.6
center ofthe detector
center ofF14
center ofF21
center ofF20
center ofF15
There is no positioin dependence of resolution.
10FWHM is constant if depth > ~4cm
Resolution is estimated with slicing with depth parameter. Correspondence of depth parameter and the depth is calculated from MC.
11
Masking effect
1 without masking
2 mask: edge of front
3 mask: edge of front top,bottom
4 mask: edge of front top,bottom right,left
gamma
Some PMTs are masked to simulate the curved shape of the final detector. Curved shape is corresponding between 1 and 3 (it depends on how to put PMTs).
Timing Resolution
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Data Condition
without Amplifier
Collimator sizeXenon 9.5 cmNaI 11.5 cm
FSH52 DAC value(beam intensity)
125
PMT gain ~5e6
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Timing Counter (TC)
Timing resolution of the timing counter
is 60 psec
•Time walk correction.•virtex correction with Nphe(light)/Nphe(right)
•2 × 5cm × 5cm × 1cm BC404• 4 × 1-inch finemesh type PMTs• 5cm × 5cm × 0.6 cm lead target
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Algorithm
Timing correction of each PMT•time walk
•vertex (x_average,y_average,sigma2)
Timing of each PMT is shifted so that mean become 0.
Taking the average with•software threshold : 20 nphe•weight : sqrt(ADC)
TDC’(i) = TDC(i) - TDC(TC)
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Timing resolution (right - left)
Resolution is 75 ± 4 psec (5e6 gain)
•Depth cut is the same as energy analysis.
•No impinging point cut is applied.•Energy cut for selecting 55MeV gamma is applied.
Compared the timing of each part after
dividing the detector to right and left.
(fluctuation from the first conversion depthdistribution is not included in this resolution)
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Timing resolution (Xe - TC)
Resolution issqrt(128^2-60^2) = 113 psec
(5e6 gain)
Time resolution is also estimated from the difference between the Xenon and the timing counter.
The difference from the analysis(right-left) can be the resolution of depth reconstruction (~70psec).
Timing has no correlation with depth because it is corrected for each PMTs before taking the average. If we don’t correct depth correlation, it is like the right figure.
18
Timing resolution with 1e6 gain + Amplifier
gainbeam
intensity(FSH52 DAC)
time resolution
(right - left) [psec]
time resolution (Xenon - tc)
[psec]
w/o Amp 1e6 350 391 ± 11 426.8 ± 11
w/ Yuri’s Amp 1e6 125 251 ± 6 295 ± 6
w/ Lecce Amp 1e6 125 246 ± 6 300 ± 7
w/o Amp 5e6 125 197 ± 6 256 ± 7
Time resolution using 8 PMTs which is applied amplifiers.
Amplifier improve the resolution at 1e6 gain.
19
Summary
Q.E. is estimated from liquid data to take into account the decrement of it under backgrounds.
Energy resolution is estimated as 4.5 ± 0.3 %. There is no strong dependence on impinging position or depth. (if depth > ~4cm)
Energy resolution is estimated with masking some PMTs to simulate curved shape. The effect must not be so large.
Timing resolution of (right -left) is 75 psec
Timing resolution of (Xe - TC) is 113 psec. We need more sophisticated way to reconstruct the depth.
Amplifier will improve timing resolution at 1e6 PMT gain.