New MRPC R&D in Tsinghua University

STAR regional meeting, October 22-23 @Shandong UniversityWang Yi, Tsinghua University

New MRPC R&D in Tsinghua University

Outline:• Introduction of MRPC• MRPC for RHIC STAR-TOF• LMRPC for STAR-MTD• High rate MRPC for CBM-TOF • Conclusions

1

Wang YiDepartment of Engineering Physics

Tsinghua University

STAR regional meeting, October 22-23 @Shandong UniversityWang Yi, Tsinghua University 2

Introduction of MRPC

Large area, high granularityGood time resolution<100psHigh efficiency> 95%Low cost

Was used or will be used in ALICE, STAR, FOPI, HADES HARP, CBM and NICA-MPD


• 4 gaps, used in HADEs-TOF

• 6 gaps, used in STAR-TOF

• 10 gaps, used in ALICE-TOF

Four kinds of MRPC prototypes

90cm

3.8cmGap 6mm

• 6gaps, used in STAR-MTD


MRPCs used in hadron experiment

95/0/5

23040


QCD phase diagram

The goal of hadron experiments are to search the QGP and find the origin of cosmology.

Our goal is to develop high quality Time of Flight system for these hadron experiments!

RHIC-STARFAIR-CBMNICA-MPDJLAB upgrade project…..



MRPC used in STAR barrel TOF

Long side view


Glass: ～ 4×1012.cmCarbon tape: 500k /Gas gap: 6×0.22mmWorking gas: 95% F134a+5% iso-butane

Time resolution: 70psEfficiency >95%

3cm

6cm

Readout pad

Performance of STAR-TOF MRPC

PID of TOF:

/k ~1.6 GeV/c

(,k)/p ~ 3.0 GeV/c


1/2 3/4 5/6 7/8 11/129/10 1/2 3/4 5/6 7/8 11/129/10 1/2 3/4 5/6 7/8

2006 2007 2008

Prod Start

132 MRPCs

768 MRPCs

1856 MRPCs

2944 MRPCs

4032 MRPCs

MRPC production scheme

MRPC production was finished in September of 2008. In Tsinghua: 3100 MRPC have been produced; 2951 Modules passed QA, yield >95% ; 2840 modules shipped to UT Austin .

Great

success!


A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of•di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, possible correlations of quarks and gluons as resonances in QGP, and Drell-Yan production

•single muon from the semi- leptonic decays of heavy flavor hadrons

•advantages over electrons: no conversion, much less Dalitz decay contribution, less affected by radiation losses in the detector materials, trigger capability in Au+Au

•trigger capability for low to high pT J/ in central Au+Au collisions excellent mass resolution, separate different upsilon states e-muon correlation to distinguish heavy flavor production from initial lepton pair production

STAR Muon Telescope Detector


Iron bars

• Muon penetrates iron bars, other particles are stopped• Good Time Resolution (60-70ps): rejects background greatly• 1 hit per 5 head-on Au+Au: Dimuon trigger• Large coverage: diameter of 7 meters

Simulation: Hadron Rejection and Muon Trigger at STAR


Concept of Design of the STAR-MTD

A detector with long-MRPCs covers thewhole iron bars and leave the gaps in- between uncovered. Acceptance: 45% at ||<0.5

117 modules, 1404 readout strips, 2808 readoutchannels

Long-MRPC detector technology, HPTDCelectronics (same as STAR-TOF)


LMRPC for STAR-MTD


LMRPC for STAR-MTD

•Readout strips: 3.8cm x 90cm x 12

•Inter-strip separation: 6 mm

•Gas gaps: 0.25 mm x 6•Outer glass: 1.1 mm•Inner glass: 0.7 mm

•HV electrode: colloidal graphite

~4 MΩ/

Strip length: 90cm

Strip width: 3.8cm

Inter-strip separation:0.6cm

1

2

3

4

5

6

7

8

9

10

11

12

Filter circuit


Surface resistivity distribution of electrode

20 points, average: 4.3M /□ minimum: 2.9M /□ maximum: 5.8M /□


System layout of cosmic ray

2cm*2cm*4cm scintillatorsabove and below the module

123456789

101112

5cm*5cm*20cm scintillatorsAbove and below the module

Efficiency: determined by S3, S4, LMRPC

Resolution: calculated with S0,S1, S2,LMRPC

PMT0

PMT1

PMT3

PMT2

PMT4

PMT5

PMT6

LMRPC

s1

s0

s2

s3

s4


5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.630

35

40

45

50

55

60

65

70

75

80

85

90

95

100

105 Efficiency @ 95% Freon + 5% iso-Butane Time resolution @ 95% Freon + 5% iso-Butane Efficiency @ 94% Freon + 5% iso-Butane + 1% SF6 Time resolution @ 94% Freon + 5% iso-Butane + 1% SF6

High Voltage (kV)

Effi

cien

cy (

%)

70

75

80

85

90

95

100

105

110

115

120

Tim

e resolution (ps)

90%

Efficiency and time resolution

@7.5kV, 4000 events, time is 65ps

95%Freon/5%iso-butane : efficiency>90% @ 7000V, time resolution <100ps

94%Freon/5%iso-butane/1%SF6 : efficiency>90% @ 7200V, time resolution ~ 75ps


Noise rate

Noise < 0.4 Hz/cm^2 @ 7200V


Uniformity

94%Freon/5%iso-butane/1% SF6 @ 7500V

Efficiency ~ 95% Time resolution 60~80ps Not bad uniformity!


Particle e+, e-,+,-,p

momentum

e 200MeV/c~1.3GeV/c

400MeV/c~900MeV/c

p 500MeV/c~1GeV/c

rate 3~4Hz

Beam-test area in IHEP


Detector system at experiment area

Trigger and PID position T0(trigger) and MRPC

C0 MWPC MRPC

PMT1&2 PMT3&4

MRPC


Efficiency & time resolution for proton

Efficiency > 95% @ 6600V Time resolution ~ 70ps


12

11

10

9Trigger: 2cm x 4cm Move trigger: 5mm/step@7200V

EfficiencyTime resolution

Trigger scan -- vertical


12

11

10

9

Move trigger: 5cm/step@6800V

Good uniformity!!

Efficiency ~ 99%

Time resolution ~ 55ps

Trigger scan -- horizontal


Signal propagation velocity

T_diff/2 = x0+dx/v1/v = 56 ps/cm

Good linearity

Charge at two ends of one strip @ 6800V


1/2 3/4 5/6 7/89/10 11/12 1/2 3/45/6 7/8 9/10 11/12

Plan 2011 2012

Start20 LMRPCs40 LMRPCs60 LMRPCs80 LMRPCs

100 LMRPCs115 LMRPCs

LMRPC manufacture milestones

Tsinghua : 65USTC: 50We want to duplicate STAR-TOF’s success!


• Full system time resolution T ~ 80 ps• Efficiency > 95 %• Rate capability ~ 20 kHz/cm2

• Acceptable cross-talk and charge-sharing• Pile-up < 5%• Occupancy < 5 % • Spatial resolution

FAIR-CBM TOF

CBM


Possible Solution:

– Timing RPC with low resistivity glass ~1010 Ωcm

– Center: pad-readout

Outside: strip-readout

CBM-TOF requirement

1 2 3 4 5

20kHz/cm2

8kHz/cm2

3.5-8kHz/cm2

1.5-3.5kHz/cm2

0.5-1.5kHz/cm2


World map of MRPC’s rate capability

108 109 1010 1011 1012 1013102

103

104

105

106

Floatglass

Semi-conductive

glass

Ceramics

Streamer mode

Warm glass

BeijingCBM Requirement

Beijing

INR+CBM

lip Coimbra

ALICE-muon

LHCb

ATLAS

Warsaw

CMS-forward

CMS-barrel

CERN+Bologna

CERN+Rio

Dresden

STAR

ALICE-TOF

Lip+USC

Max

Counting R

ate(

Hz/

cm2)

Volume Resistivity(cm)

/1Rate


Performance of low resistivity glass

Specifications:Maximal dimension: 50cm×50cmBulk resistivity: ~1010.cmStandard thickness: 0.5mm--2mmThickness uniformity: 0.02mmDielectric constant: ~10Surface roughness: <10nmDC measurement: very stable


Scanned images of glass

2-D image 3-D image


MRPCs with different structure

2 cm2 cm

13 cm

97cm

2.5cm Gap 4mm


Beam test for rate capability

PMT: 0.8-20 kHz/cm2

MRPC: 2-30 kHz/cm2

Charge distributions of the 10-gap RPC for different particle fluxes at 2.64 kV/gap


Performance of high rate MRPC

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)

0 5 10 15 20 2580

85

90

95

100

Efficiency(%) Time resolution(ps)

Particle flux (kHz/cm2)E

ffici

ency

(%)

60

70

80

90

100

110

120

130

Tim

e re

solu

tion(p

s)

Efficiency and time resolution as a function of high voltage at a rate of about 800Hz/cm2

When the particle flux increases every 5 kHz/cm2, the efficiency decreases by 1% and the time resolution deteriorates by 4 ps.


HV scan (strip readout module)

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 ,

σMRPC#3 ≈ σMRPC#4 ≈ σdiff / sqrt(2)


Position Scan

2 3 1

Rpcy

-20 -10 0 10 20 30 400

20

40

60

80

100 "or" eff

strip1

strip2

strip3

"and" eff

Effi

cie

ncy(%

)

Rpcy(mm)

-20 -10 0 10 20 30

70

80

90

100

110strip1

strip2

strip3

Tim

e r

esolu

tion(p

s)

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


Crosstalk & charge sharing- doped glass

-1.5 -1.0 -0.5 0.0 0.5 1.00

10

20

30

40

50

60

70

80

90

100

Cha

rge(

ch)

Efficiency_2(%)

Crosstalk_3(%)

Charge_3(ch)

Effi

cien

cy(%

)

Rpcy(cm)

0

100

200

300

400

500

600

700

800

900

1000

2 3 1

Rpcy (cm)

-1.5 -1.0 -0.5 0.0 0.5 1.00

10

20

30

40

50

60

70

80

90

100

Efficiency_2(%)

Crosstalk_1(%)

Charge_1(ch)

Effi

cien

cy(%

)

Rpcy(cm)

0

200

400

600

800

1000

Cha

rge(

ch)

20%

10%

Crosstalk_1=counts(T2>0 && T1>0) / counts(trigger)


Crosstalk & charge sharing- common glass

-1.5 -1.0 -0.5 0.0 0.5 1.00

10

20

30

40

50

60

70

80

90

100

Rpcy(cm)

Cha

rge(

ch)

Effi

cien

cy(%

)

Efficiency_2(%)

Crosstalk_3(%)

Charge_3(ch)

0

200

400

600

800

1000

2 3 1

Rpcy (cm)

-1.5 -1.0 -0.5 0.0 0.5 1.00

10

20

30

40

50

60

70

80

90

100

Efficiency_2(%)

Crosstalk_1(%)

Charge_1(ch)

Cha

rge(

ch)

Effi

cien

cy(%

)

Rpcy(cm)

0

200

400

600

800

1000

2%2%

Crosstalk_1=counts(T2>0 && T1>0) / counts(trigger)


Position resolution

T1 T2

DeltaT=(T2-T1)/2

• Using the tracking, we get the signal propagation velocity:

~ 61ps/cm• Position resolution: <5 mm


Conclusions

• Development of 6-gap MRPC for STAR-TOF, time resolution<70ps, efficiency>95%

• 3100 MRPCs were assembled for STAR-TOF, yield>95%• Development of LMRPC for STAR-MTD, time resolution <70ps, efficiency>95%, noise rate<1Hz/cm2

• Development of low resistive glass with resistivity ~ 1010Ωcm

• Development of pad- and strip- readout high rate MRPCs, rate capability>25kHz/cm2, time resolution<80ps

• Application in NICA-MPD and Jefferson lab, .…


Thanks for your attention!

Documents

New MRPC R&D in Tsinghua University