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