Report on beam test results of high-rate MRPCs
Jingbo WangDepartment of Engineering Physics, Tsinghua University, Beijing, China
Index
• April test Two high-rate prototypes Test setup HV scan Rate scan
• August test Three prototypes (one is high-rate prototype) Test setup HV scan Horizontal scan Vertical scan Multi-hit analysis
2
Accelerator
3
April test
• MRPC design (two high-rate prototypes)
• Test setup
• HV scan
• Rate scan (focus on the rate capability)
4
MRPC_1 6-gap
5
60mm
Parameters
• Gap number: 6-gap
• Glass type: silicate
• Gap width: 0.22mm
• Glass thickness: 0.7mm
• Gas mixture:
Freon/iso-butane/SF6
96.5%/3%/0.5%
The same as the standard STAR module
Low-resistive silicate glass
3~4×1010 Ωcm
MRPC_2 10-gap
6
30mm
31.5mm
• Number of gaps: 10
Negative HV
Positive HV
Test setup
7
• The platform is movable. Different rates can be obtained by moving the chambers up and down.
2.5GeV Proton
Top view
8
A B
PMT1
PMT2
PMT3
PMT4 PMT0
Silicon
Scintillator
PMT
Ordinary-glass RPC
10-gap high-rate MRPC
6-gap high-rate MRPC
2×4 cm2
Counting rate
9
• PMT rate: 0.8~20 kHz/cm2
• MRPC rate: 2~30 kHz/cm2
Rate profile
Time difference
10
HV scan at low rate: 6-gap MRPC
11
2.2 2.3 2.4 2.5 2.6 2.740
50
60
70
80
90
100
Efficiency(%) 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)
800Hz/cm2
2.3 2.4 2.5 2.6 2.7 2.870
75
80
85
90
95
100
Efficiency(%)Resolution(ps)
Applied voltage(kV/gap)
Effi
cien
cy(%
)
50
60
70
80
90
100
110
120
130
140
Tim
e re
solu
tion(p
s)
HV scan at low rate : 10-gap MRPC
12
800Hz/cm2
0 5 10 15 2050
60
70
80
90
100
6-gap MRPC
10-gap MRPC
Effi
cien
cy(%
)
PMT rate (kHz/cm2)
Rate scan
13
0 5 10 15 20
60
70
80
90
100
110
120
130
6-gap MRPC10-gap MRPC
Tim
e re
solu
tion(p
s)
PMT rate(kHz/cm2)
Summary
Two prototypes were tested.
14
6-gap MRPC
• Low rate: 800Hz/cm2
Efficiency>93%, Time resolution: ~80ps
• High rate: 20kHz/cm2
Efficiency: ~75%, Time resolution: ~110ps
10-gap MRPC
• Low rate: 800Hz/cm2
Efficiency>95%, Time resolution: ~70ps
• High rate: 20kHz/cm2
Efficiency: ~90%, Time resolution: 80~85ps
August test
15
• MRPC design MRPC_1: common-glass prototype MRPC_2: high-rate prototype
• Test setup
• HV scan
• Horizontal scan
• Vertical scan (study the crosstalk)
• Multi-hit analysis MRPC_3: long-strip prototype
MRPC_1 and MRPC_2
16
1.5mm5mm
Diameter:1.5mmHole size:0.5mm
Width:0.508mmTop and bottom layers
240mm22mm
3mm
Guarding line
• Glass type: common / silicate
• HV electrode: colloidal graphite
• Number of gaps: 10
• Gap width: 0.25mm
• Glass thickness: 0.7mm
• Gas mixture:
Freon/iso-butane/SF6
96.5%/3%/0.5%
colloidal graphite
Test Setup
Main beam
Target
10 m
PM12
PM34
Tsinghua RPC
USTC RPC
PM5
Silicon
17
• Common-glass MRPC_1
• High-rate MRPC_2
95 100 105 110 11520
30
40
50
60
70
80
90
100
Eff: MRPC_1
Eff: MRPC_2
Timediff
/1.414
Effi
cien
cy(%
)
Applied voltage(kV/cm)
60
70
80
90
100
110
120
130
140
Tim
e re
solu
tion(p
s)
HV scan: Both prototypes
18Tdiff =T MRPC_1-T MRPC_2 , σMRPC_1 ≈ σMRPC_2 ≈ σdiff / sqrt(2)
Horizontal Scan: Common-glass MRPC
• Beam Position: 14.9mm, 34.9mm, 54.9mm, 74.9mm, 94.9mm. 19
Trigger area: 2 ×4 cm2
0100
0 20 40 60 80 10080
85
90
95
100
Eff: left end (%)
Eff: right end (%)
Time resolution(ps)
Effi
cien
cy (%
)
Beam position(mm)
60
70
80
90
100
110
Tim
e re
solu
tion (ps)
0 10 20 30 40 50 60 70 80 90 100 1102180
2190
2200
2210
2220
2230
slope=0.140
slope=-0.155
Tim
e-ri
ght (3
5ps/
chan
el)
Tim
e-le
ft(3
5ps/
chan
nel
)
Beam position(mm)
Average time: left end
Average time: right end
2390
2400
2410
2420
2430
2440
Horizontal Scan: Common-glass MRPC
20
0100Transmission time = 5.4ps/mm
-20 -10 0 10 20 30 400
20
40
60
80
100 "or" eff
strip1
strip2
strip3
"and" eff
Effi
cie
ncy(%
)
Height(mm)
Vertical Scan: Common-glass MRPC
gap gap
strip1strip2strip3
21
• “cross-talk” of the 1st neighbor: 6%
• “cross-talk” of the 2nd neighbor: 3%0
Trigger area: 2 ×4 cm2
-20 -10 0 10 20 30 400
20
40
60
80
100
"or" eff
strip1
strip2
strip3
"and" eff
Effi
cien
cy(%
)
Height(mm)
Vertical Scan: High-rate MRPC
22
gap gap
0• “cross-talk” of the 1st neighbor: 15%
• “cross-talk” of the 2nd neighbor: 3%
strip3 strip2 strip1
Vertical Scan: Both prototypes
23
-20 -10 0 10 20 30
70
80
90
100
110 strip1
strip2
strip3
Tim
e re
solu
tion(p
s)
Height(mm)
strip1strip2strip3
• Time diff / 1.4140
Summary
24
Common-glass MRPC
• Efficiency: ~95%,
• Time resolution: 70~80ps
• Crosstalk at the 1st neighbor: 6%
• Crosstalk at the 2nd neighbor: 3%
High-rate MRPC
• Efficiency: ~95%,
• Time resolution: 70~80ps
• Crosstalk at the 1st neighbor: 15%
• Crosstalk at the 2nd neighbor: 3%
Multi-hit analysis: Long-strip MRPC
25
Multi-hit
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
Strip1
Strip2
Strip3
Strip4
Strip5
Strip6
• Particle position of strip1: T1-T7
• Beam position of strip3: T3-T9
• Position difference: (T1-T7)-(T3-T9)
100cm
2.5cm
Not to scale!
Position difference
26
Cut out the correlated peaks
no double hitdouble-hit in any of 1st neighborsdouble-hit in any of 2nd neighborsdouble-hit in any of 3rd neighbors
Resolution of the fired strip
1-m long counter, 12-gap, mirrored and shielded