new mrpc prototypes developed in tsinghua unversity
DESCRIPTION
New MRPC prototypes developed in Tsinghua Unversity. Huangshan Chen (Tsinghua Unversity). Outline. High rate MRPC modules Performance of low resistivity silicate glass Pad readout MRPC Strip readout MRPC MRPC module for STAR-MTD Module structure Cosmic-ray test setup and result - PowerPoint PPT PresentationTRANSCRIPT
New MRPC prototypes developed in Tsinghua Unversity
Huangshan Chen (Tsinghua Unversity)
Outline High rate MRPC modules
Performance of low resistivity silicate glass Pad readout MRPC Strip readout MRPC
MRPC module for STAR-MTD Module structure Cosmic-ray test setup and result Beam test setup and result
Summary
2011/03/31STAR MTD Workshop, USTC, Hefei, China2
High rate MRPC modules
2011/03/31STAR MTD Workshop, USTC, Hefei, China3
FAIR – CBM TOF
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CBM
Full TOF system:
Time resolution sT ~ 80 ps
Efficiency > 95 % Rate capability < 20 kHz/cm2
Acceptable cross-talk and charge-sharing. Low power electronics (~75.000 channels).Sufficient space resolution
Timing RPC :
Active area: A = 170 m2
Counter time resolution: sT ~ 50 ps
Rate capability: R ~ 0.5 - 20 kHz/cm2
Granularity: DA ~ 6 - 100 cm2
Operation mode: free running
World map of MRPC’s rate capability
2011/03/31STAR MTD Workshop, USTC, Hefei, China5
108 109 1010 1011 1012 1013102
103
104
105
106
Floatglass
Semi-conductive
glass
Ceramics
BeijingCBM Requirement
lip Coimbra AlICE-muon LHCb ATLAS Warsaw CMS-forward CMS-barrel CERN+Bologna CERN+Rio Lip+USC ALICE-TOF Lip+USC Beijing Dresden INR+CBM STAR-Beijing
Max
Counting R
ate(
Hz/
cm2)
Volum Resistiviey(cm)
Specification of low resistivity silicate glass
2011/03/31STAR MTD Workshop, USTC, Hefei, China6
Specifications:Maximal dimension: 50cm×50cmBulk resistivity: ~1010.cmStandard thickness: 0.5mm--2mmThickness uniformity: 0.02mmPermittivity : ~10Surface roughness: <10nmDC measurement: very stable
Scanned images of low resistive silicate glass
2011/03/31STAR MTD Workshop, USTC, Hefei, China7
2-D image 3-D image
L
X
Y
Ry i
0
1 L
Ra y x dxL
2
0
1 L
Rq y x dxL
iRy Max Ry
Ra=0.873 nm Rq=1.10nm Ry=9.30nm
0 5 10 15 20 25 30 35
1
2
3
4
5
67
Current(A)
Bulk resitivity(1010cm)
Time(days)
Curr
ent(A
)
2
3
4
5
678910
Bulk
resis
tivity(1
010
cm)
8
0 200 400 600 800 10001E8
1E9
1E10
1E11
Applied voltage(V)
Bulk
resis
tivity(
cm
)
20°C 30°C 40°C 50°C 60°C 70°C
Using low resistive silicate glass instead of common glass is an innovative way of improving the rate capability of Resistive Plate Chambers.
Bulk resistivity: 3-4×1010 ΩcmThe accumulated charge was 1 C/cm2, roughly corresponding to the CBM life-time over 5 year operation at the maximum counting rate.
T = 28 C°HV = 1kV
Low resistive silicate glass
2011/03/31STAR MTD Workshop, USTC, Hefei, China
Pad readout MRPC – MRPC #1
HV electrode Graphite tape
Readout pad 31.5mm×60 mm×6
Glass type Low resistive silicate glass
Glass thickness 0.7mm
Gas gap 0.22mm×6
2011/03/31STAR MTD Workshop, USTC, Hefei, China9
60mm
31.5mm
3mm
Pad readout MRPC – MRPC #2
HV electrode Graphite tape
Readout pad 31.5mm×30 mm, 15.5mm×30mm
Glass type Low resistive silicate glass
Glass thickness 0.7mm
Gas gap 0.22mm×10
2011/03/31STAR MTD Workshop, USTC, Hefei, China10
30mm
31.5mm 15.5mm
3mm
11
Tests were performed at GSI-Darmstadt under uniform irradiation by secondary particles stemming from proton reactions at 2.5 GeV.
The higher rates can be obtained by moving the RPCs up closer to the main beam.
Gas mixture: Freon/iso-butane/SF6 : 96.5%/3%/0.5%
2.5GeV
Beam test setup at GSI-Darmstadt
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The beam comes in spills.We take the mean of the PMT and MRPC measurements as a sound reference for rate estimation :
•PMT rate: 0.8~20 kHz/cm2
•MRPC rate: 2~30 kHz/cm2
•Mean rate: 1.4~25 kHz/cm2
Counting rate
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Timediff =TMRPC#1-TMRPC#2
Time difference
2011/03/31STAR MTD Workshop, USTC, Hefei, China
Resolution of time difference become worse with the raise of rate.
14
MRPC#2: 10-gap
With rate increasing, the average charge decreases, which leads to a relativity lower efficiency.
Charge distribution of MRPC#2
2011/03/31STAR MTD Workshop, USTC, Hefei, China
2.3 2.4 2.5 2.6 2.7 2.870
75
80
85
90
95
100
Efficiency(%)Time resolution(ps)
Applied voltage(kV/gap)
Effi
cien
cy(%
)
50
60
70
80
90
100
110
120
130
140
150
Tim
e re
solu
tion(p
s)
15
The efficiency is higher than 90% and the time resolution remains below 90ps once at the efficiency plateau.
By means of using more gas gaps, the 10-gap RPC shows a better performance.
2.2 2.3 2.4 2.5 2.6 2.740
50
60
70
80
90
100
Efficiency(%) Time resolution(ps)
Applied voltage(kV/gap)
Effi
cien
cy(%
)
60
70
80
90
100
110
120
130
140
150
Tim
e re
solu
tion(p
s)
MRPC#1: 6-gap MRPC#2: 10-gap
HV scan at 1.4kHz/cm2
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0 5 10 15 20 2550
60
70
80
90
100
6-gap MRPC
10-gap MRPC
Effi
cien
cy(%
)
Counting rate (kHz/cm2)
90%
76%
0 5 10 15 20 2560
70
80
90
100
110
120
130 diff/210-gap
6-gap
Tim
e re
solu
tion(p
s)
Counting rate (kHz/cm2)
110ps
85ps
The efficiencies and time resolutions deteriorate with the counting rate.MRPC#2 yields much better results: 90% efficiency, 85ps resolution at the rate of ~25 kHz/cm2.
Rate scan
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240mm22mm
interval: 3mm
Strip readout module structure: MRPC#3 & MRPC#4
HV electrode colloidal graphite
Readout strip 22mm×240 mm×3
Glass type Low resistive silicate / common
Glass thickness 0.7mm
Gas gap 0.25mm×10
2011/03/31STAR MTD Workshop, USTC, Hefei, China
Surface resistivity distribution of electrode
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20 points: minimum: 2.9M /□ maximum: 5.8M /□ average: 4.3M /□
Main beam
Target
10 m
PM12
PM34
Tsinghua RPC
PM5
Silicon
19
MRPC#3 : silicate glassMRPC#4: common glass
Beam test layout
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5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.220
30
40
50
60
70
80
90
100
Eff: MRPC#3 Eff: MRPC#4
diff/2
Applied voltage(kV)
Effi
cie
ncy(%
)
60
70
80
90
100
110
120
130
140
Tim
e r
esolu
tion(p
s)
Tdiff =T MRPC#3-T MRPC#4
HV scan
EffMRPC#3 ≈ EffMRPC#4 > 95%, σMRPC#3 ≈ σMRPC#4 ≈ σdiff / sqrt(2) < 80ps
2011/03/31STAR MTD Workshop, USTC, Hefei, China
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2 3 1
Rpcy
-20 -10 0 10 20 30 400
20
40
60
80
100 "or" eff
strip1
strip2
strip3
"and" eff
Effi
cien
cy(%
)
Rpcy(mm)-20 -10 0 10 20 30
70
80
90
100
110strip1
strip2
strip3
Tim
e re
solu
tion(
ps)
Rpcy(mm)
-20 -10 0 10 20 30 400
20
40
60
80
100 "or" eff strip1 strip2 strip3 "and" eff
Effici
ency
(%)
Rpcy(mm)
MRPC#3
MRPC#4
Position Scan
2011/03/31STAR MTD Workshop, USTC, Hefei, China
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Position resolution
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T1 T2
DeltaT=(T2-T1)/2
• Using the tracking, we get the signal propagation velocity:
~ 61ps/cm• Position resolution: <5 mm
5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2
40
50
60
70
80
90
100
110
Eff_tracking(%) Eff_original(%)
Effi
cien
cy (%
)
High voltage (kV)
5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2
40
50
60
70
80
90
100
110
Eff_tracking(%) Eff_original(%)
Effi
cien
cy (%
)
High voltage (kV)
23
2×4 (cm2) 1×2 (cm2)
Efficiency: 95% 97%
MRPC#3 MRPC#4
Efficiency correction with tracking
2011/03/31STAR MTD Workshop, USTC, Hefei, China
MRPC module for STAR-MTD
2011/03/31STAR MTD Workshop, USTC, Hefei, China24
Module structure
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Strip length: 900mm
Strip width: 38 mm
Interval: 6 mm
1
2
3
4
5
6
7
8
9
1011
12
Inner glass: 524 mm × 890 mm
Outer glass: 550 mm × 912 mm
Mylar layer: 560 mm × 920 mm
Honeycomb: 568 mm × 920 mm
PC board: 580 mm × 930 mm
Strip: 38 mm × 900 mmInterval: 6 mm
Spacer: fishing lineGas gap: 0.25 mm
Inner glass: 0.7 mmOuter glass: 1.1 mm
PC board: 0.9 mm Graphite paint: 0.01 mm
Mylar: 0.18 mm Strip: 0.045 mm
HV electrode colloidal graphite ~5 MΩ/
Readout strip 38mm x 900 mm x 12
Interval 6mm
Glass type Float Glass
Glass thickness 0.7mm(inner), 1.1mm(outer)
Gas gap 0.25mm x 6
Cosmic-ray test system layout
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2cm*2cm*4cm scintillatorsabove and below the module
123456789
101112
5cm*5cm*20cm scintillatorsAbove and below the module
Gas mixture:
95%Freon/5%iso-butane Or
94%Freon/5%iso-butane/1%SF6
Gas flow: 50ml/min
Efficiency and time resolution
95%Freon/5%iso-butane : efficiency>95% @ 96.3kV/cm (HV=±7.22 kV), time resolution <100ps
94%Freon/5%iso-butane/1%SF6 : efficiency>95% @ 98.3 kV/cm (HV=±7.37 kV), time resolution ~ 75ps
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76 78 80 82 84 86 88 90 92 94 96 98 10030
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
Efficiency @ Freon/iso-Butane/SF6 : 95%/ 5%/0% Time resolution @ 95%/5%/0% Efficiency @ 94%/ 5%/1% Time resolution @ 94%/ 5%/1%
E (kV/cm)
Effi
cien
cy (%
)
95%
70
75
80
85
90
95
100
105
110
115
120
Tim
e resolu
tion (p
s)
Noise level
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Filter circuit
0 1 2 3 4 5 6 7 8 9 10 11 12 130.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Nois
e (H
z/cm
2)
Strip number
• Having a filter circuit on HV electrode, the noise is reduced to a very low level!
• Most of noise level are smaller than 1.0 Hz/cm2.
94%Freon/5%iso-butane/1% SF6, E=104 kV/cm (HV=±7.8kV)
Noise level
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94%Freon/5%iso-butane/1% SF695%Freon/5%iso-butane
Noise < 0.6 Hz/cm2 @ (HV=±7.2kV, eff~95%) Noise < 0.6 Hz/cm2 @ (HV=±7.4kV, eff ~95%)
0 1 2 3 4 5 6 7 8 9 10 11 12 1330
40
50
60
70
80
90
100
Efficiency Time resolution
Strip number
Effi
cie
ncy (%
)
20
40
60
80
100
120
140
160
180
200
Tim
e re
solu
tion (p
s)
Uniformity94%Freon/5%iso-butane/1% SF6 @ 100 kV/cm (HV=±7.5 kV)
Efficiency ~ 95% Time resolution :60~80ps Not bad uniformity!
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Beam-test area at IHEP, BEIJING
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Particle e+, e-,+,-,p
momentum
e 200MeV/c~1.3GeV/c
400MeV/c~900MeV/c
p 500MeV/c~1GeV/c
rate 3~4Hz
Detector system at experiment area
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C0 MWPC MRPC
PMT1&2 PMT3&4
MRPC
Gas mixture: 90%Freon/5%iso-butane/5%SF6 @ 150ml/min
SC2SC1 MWPCC0
PMT1
PMT2
PMT3
PMT4
MRPC
e, , p
50cm 50cm 60cm
T0(trigger) and MRPCpositionTrigger and PID
Beam
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Trigger = SC1+SC2-C0+T0 + p (600MeV)
Rate ~ 1-20/min
Distinguish between pion and proton using the charge spectrum of PMTs
PMT4Entries 2592Mean 2895RMS 1010
ADCchannel0 500 1000 1500 2000 2500 3000 3500 4000 4500
Coun
t
0
20
40
60
80
100
120
140
PMT4Entries 2592Mean 2895RMS 1010
PMT4
proton
pion
Efficiency & time resolution for proton
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Efficiency > 95% @ ~87 kV/cm (HV= ±6.525 kV) Time resolution ~ 70ps
78 80 82 84 86 88 90 92 94 96 98 100 102 10450
55
60
65
70
75
80
85
90
95
100
Efficiency Time resolution
E (kV/cm)
Effi
cie
ncy (%
)
50
60
70
80
90
100
110
120
Tim
e re
solu
tion (p
s)
95%
-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
20
30
40
50
60
70
80
90
100
strip# B
Effi
cien
cy (%
)
Position (cm)
strip# A strip# B strip# A AND B strip# A OR B
strip# A
-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.560
70
80
90
100
110
120
strip# B
Tim
e re
solu
tion (ps)
Position (cm)
strip# A
Trigger scan -- vertical
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12
11
10
9Move trigger: 5mm/step@ 96kV/cm (HV=±7.2kV)
Efficiency Time resolution
-2 0 2 4 6 8 10 12 14 16 18 20 2270
75
80
85
90
95
100
105
110
Efficiency Time resolution
position (cm)
Effi
cie
ncy (%
)
30
40
50
60
70
80
90
100
110
120
Tim
e re
solu
tion (p
s)
Trigger scan -- horizontal
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12
11
10
9
Move trigger: 5cm/step@ 90.67 kV/cm (HV= ±6.8 kV)
Efficiency ~ 100%Time resolution ~ 55ps
0 5 10 15 20
3600
3800
4000
4200
4400
4600
4800
0.5*Time_diff Linear Fit of 0.5*Time_diff
0.5
*Tim
e_diff
(ps)
position (cm)
y = a + b*xParameter Value Errora 3634.5 2.853b 55.96 0.211
T_diff/2 = t0+dx/v1/v = 55.96 ps/cm
Summary High rate MRPC modules
Low resistive silicate glass ~1010.cm, <10nm, stable DC measurement
MRPC #2 (10-gap, pad readout, silicate glass) >95%, <70 ps @ 1.4 kHz/cm2; ~90%, ~85 ps @ 25 kHz/cm2
MRPC #3 (10-gap, strip readout, silicate glass) ~97%, ~75 ps, <5mm
MRPC module for STAR-MTD >95%, ~75 ps in cosmic-ray test; ~100%, ~70 ps in beam test Low noise level Good uniformity across the different strips and along the strip
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That’s all! Thank you!