SBS GEM Test · 01/19/17 3 GEMs Scintillator Calorimeter Target chamber direction Parastic test at...
Transcript of SBS GEM Test · 01/19/17 3 GEMs Scintillator Calorimeter Target chamber direction Parastic test at...
Danning Di
University of Virginia
Jan.19.2017
SBS GEM Test
Hall A collaboration meeting
01/19/17 2
● Test setup
● Two crucial GEM characteristics for high occupancy situation– Charge sharing
– Time correlation
● Hit reconstruction method– Tracking
– Charge correlation of test data
– Timing correlation of test data
● GEM efficiency
● GEM spacial resolution
● Summary
Overview
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GEMs
Scintillator
Calorimeter
Target chamber direction
● Parastic test at 70° from beam in Hall A during DVCS/GMP experiment in Fall 2016.
● 5 60x50 cm SBS GEM modules spaced by ~13 cm
● Gas mixture: Ar/CO2 (75/25%) at flow rate ~5L/h
● GEM HV: ~4100V● Calorimeter size: 30x30 cm● The occupancy of GEMs during test was
around 1.5%.● DAQ rate was about 40Hz(MPD 3.0) reading
about 15k channels, data rate ~12MB/s
Setup in Hall A at JLab
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Scintillator
5 SBS GEMs
Calorimeter
Setup in Hall A at JLab
● Parastic test at 70° from beam in Hall A during DVCS/GMP experiment in Fall 2016.
● 5 60x50 cm SBS GEM modules spaced by ~13 cm
● Gas mixture: Ar/CO2 (75/25%) at flow rate ~5L/h
● GEM HV: ~4100V● Calorimeter size: 30x30 cm● The occupancy of GEMs during test was
around 1.5%.● DAQ rate was about 40Hz(MPD 3.0) reading
about 15k channels, data rate ~12MB/s
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Charge sharing and time correlation of GEM
σ~10 ns
Signal arrive time in Y plane
10 ns wide band
Sig
na
l arr
ive
tim
e in
X p
lan
e
Signal arrive time in Y plane
Sig
na
l arr
ive
tim
e in
X p
lan
e
Signal arrive time in x(y) plane
Signal arrive time in x/y planeCluster charge ratio X/Y
Charge sharing Time correlation
BeforeAfter correct trigger phase in APV clock
Plots are from cosmic data in 2015
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Real hits buried in accidental hits and cross-talk clusters and mismatching clusters(incorrectly paired x/y clusters)
Real hits, small part of accidental hits, cross-talk clusters andpart of mismatching clusters
cut in charge correlation and timing correlation
Hit Reconstruction
Do tracking in x/y plane
Real hits
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GEM 3
GEM 4
GEM 2
GEM 1
GEM 0
Tracking Snapshots
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Charge Correlation
Due to electronics cross talk
Due to Mismatching of clusters
Tracking remove most of mismatching clusters
Not showing up here because cross talk happens mainly in Y direction
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Charge Correlation
Due to Mismatching of clusters
Electronics cross talk removed
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Correcting the phase of trigger in APV clock Cut off weakly timing
correlated clusters
Timing Correlation
From fit of 6 time sample
σ~6 ns
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Efficiency
HV: 4100V
HV from 4000 V to 4150 V with step of 25 V
Efficiency drop due to spacer
Overall efficiency HV scan
X Plane(mm)
Y P
lan
e(m
m)
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Spatial Resolution
σ~80 μm
σ~233μm
Inclusive residual in X
Exclusive residual in XExclusive residual in X
σ~230μm
Slope of tracks
● Tracks varies in direction● Work in progress to get better offsets
to align the GEM modules
Cosmic data results(preliminary)
mm
mm
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Spatial Resolution
σ~110 μm
Inclusive residual in X
Exclusive residual in X
σ~44 μm σ~69μm
σ~170μm
Inclusive residual in X
Exclusive residual in X
perpendicular tracks Non-perpendicular tracks
Simulation resultsAssuming resolution of 70 μm
mm
mmmm
mm
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Summary
● A GEM tracker of 5 modules are tested at about 1.5% occupancy. By combining tracking and cuts on charge correlation and timing correlation can successfully remove the accidental hits and mismatching clusters.
● The spacial resolution is calculated and needs further work on finding more accurate offsets to better align GEM modules for better results.
● It is definitely beneficial to our knowledge and experience on dealing with high occupancy in future if there is chance to take data with this simple tracker under higher occupancy that is comparable with the expected SBS run condition.