new mrpc prototypes developed in tsinghua unversity huangshan chen (tsinghua unversity)

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


FAIR – CBM TOF


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


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


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


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


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


Gas gap 0.22mm×10


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


12

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


13

Timediff =TMRPC#1-TMRPC#2

Time difference


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


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


16

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


17

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


Gas gap 0.25mm×10


Surface resistivity distribution of electrode


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


20

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


21

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


22

Position resolution


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


MRPC module for STAR-MTD


Module structure


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


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


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


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


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!


Beam-test area at IHEP, BEIJING


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


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


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


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


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


12

11

10

9Move trigger: 5mm/step@ 96kV/cm (HV=±7.2kV)


-2 0 2 4 6 8 10 12 14 16 18 20 2270

75

80

85

90

95

100

105

110


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


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


That’s all! Thank you!

new mrpc prototypes developed in tsinghua unversity huangshan chen (tsinghua unversity)

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