TDC test beam data analysis
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Transcript of TDC test beam data analysis
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TDC test beam data analysisTDC test beam data analysisB. AngelucciB. Angelucci
Università di Pisa & INFN PisaUniversità di Pisa & INFN Pisa
01/04/200901/04/2009• Introduction
• Hit distribution & noisy channels
• Missed hits in algo A & B
• PMT time resolution
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Layout of 400PMT RICH Prototype test
TELL1
TDCB
TDCB
TDCB
TDCB GBE
PC &
STORAGE
NIN
O
CA
RD
S
Laser Ext trigger
~400 PMs
~25 cables
1 Gb channel
• Test with 400 PMs
• Laser and defocusing lens, ~30PMT fire each laser pulse
• Variable frequency (~Hz - ~MHz )
• Only one GBE output channel (max 1GBit/s)
• ~2% channels masked
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Setup
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channel channel
ch91
ch76
10 kHz 100 kHz
Noisy channels
Evidence of a difference between 10kHz and 100 kHz runs, for some channels (33, 42, 63, 69, 76, 91, 111, 137, 139, 155,
159, 169, 177, 179, 222, 258, 396, 417, 424)
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Noisy channels
window of absolute time ~20s
Events all channels
channel 91
channel 90
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Noisy channels
Events all channels
channel 91
channel 90
100us
Noise independent from events’ rate: more relevant in 10kHz runs
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Missed hits in Algo A
10 kHz 100 kHz
Number of words per event
Number of words per event
• It is expected only an even number of words (leading & trailing edge)
• From data: uniform distribution (odd/even) in 10kHz runs, even predominance in 100kHz runs
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Missed hits in Algo A
100 kHzDifference between number of trailing and leading per event for 100kHz runs
•The peak at dTL=0 indicates the predominance of an even number of words
• An odd |dTL| means an odd number of words
• dTL≠0 shows the presence of unpaired leading or trailing
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30 leading 26 trailing
3 trailing from next event
Missed hits in Algo A
120 clk edges readout window
adjustable offset
Algo A scheme
Example of event in which dTL= -4
• The leak of trailing words is partially recovered from next event
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ALGO A 10kHz
9% 1%
90%
good events
leading recovered
leading not justif ied
ALGO A 10kHz
15%
49%
36% good events
trailing recovered
trailing not justif ied
ALGO A 100kHz
32%
7%61%
good events
leading recovered
leading not justif ied
ALGO A 100kHz
43%
44%
13%
good events
trailing recovered
trailing not justif ied
Missed hits in Algo A
• Good events means no unpaired leading or trailing
• Not justified means not totally recovered
• Under analysis: debugging using pattern generator in progress
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Missed hits in Algo B
10 kHz 100 kHz
Number of words per event
Number of words per event
trigger
Readout window
data flux in LB
Wait trigger on data
Algo B scheme
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Missed hits in Algo B
• Good events means no unpaired leading or trailing
• Not justified means not totally recovered
ALGO B 10kHz
13%
72%
15%good events
leading recovered
leading not justif ied
ALGO B 10kHz
6% 5%
89%
good events
trailing recovered
trailing not justif ied
ALGO B 100kHz
40%
50%
10%
good events
leading recovered
leading not justif ied
ALGO B 100kHz
22%
8%
70%
good events
trailing recovered
trailing not justif ied
• Under analysis: debugging using pattern generator in progress
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Differences Trailing time – Leading time
<tT – tL> for each channel σ[tT – tL] for each channel
threshold
tL tT
The difference tT-tL is rather proportional to signal’s amplitude
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Resolution (ref ch14)
Offset <∆t(chx-ch14)>
for each channel
Raw resolution
for each channel
Offset and raw resolution: analizing the time difference ∆t(chx-ch14) for each event with both chx and ch14
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Slewing correction for time resolution
∆t(ch31-ch14) vs (tT – tL)ch31 for each event
mean of each binx content
fit function
(2nd degree)
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Raw & corrected resolutions
∆t(ch31-ch14) raw ∆t(ch31-ch14) corrected
σraw ~ 540 ps σcorr ~ 200 ps
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A detailed analysis of test beam data has been presented
Comparison between 10kHz and 100kHz runs points out the presence of ~5% noisy channels (due to front-end electronics)
Most of the events show no more than one lost hit over ~ 60 at the edges of the readout window. Probable bug in the firmware under investigation
Single photo-electron time resolution of PMTs in fair agreement with measurements with CAEN TDCs (<250ps)
Next step: systematic measurements using fast and high resolution pattern generator
Conclusions