MRPC Beam Test @ GSI

Yongjie Sun

University of Science and Technology of China

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Index

Test setup Preliminary results of 3 prototypes Summary

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Accelerator

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Setup

Our Beam Test Experiment

FOPI at Cave B

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6m

Setup

ProtonBeam

Pb

2m

42 cmPMT 1,2PMT 3,4

PMT 5,6TSU MRPC

USTC MRPC

Platform PlatformPlatform

xy

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Photo of the setup

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Beam

Proton beam,Kinetic energy: 3.5 GeV/c

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DAQ Logic

T

D

C

Q

D

C

PMT 1-4(5)

DiscriminatorNIMECL VULOM, Logic

Delay NIMECL

LMRPC1-6 (left)7-12(right)

FEE

Delay Discriminator NIMECL

Delay

Delay

Gate

Trigger area: 2 cm x 4 cm (without back_scint.)

STOP

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Index

Test setup Preliminary results of 3 prototypes Summary

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MRPC structure (endview)

5 x 250μm gaps

5 x 250μm gaps

Readout strips

HV

2.5cm

Readout strips: 2.5 cm x 50 cmHV electrode: Licron spray ~40 MΩ/□

Made of window glass of 0.7 mm thick

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MRPC #1 (topview)

55 cm

24.1cm

2.5cm

0.6cm

Gaps between strips: 0.6 cm

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MRPC #1

+iso-butane 5%+Freon

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ADC1 ADC2

ADC3 ADC4

<t 1

-(t 3

+t 4

)/2>

ADC1

<t 2

-(t 3

+t 4

)/2>

ADC2

<t 3

-(t 1

+t 2

)/2>

ADC3ADC4

PMT calibration

<t 4

-(t 1

+t 2

)/2>

((t3+t4)-(t1+t2))/4

Resolution~67 ps

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T-(t1+t2+t3+t4)/4

T-(t1+t2+t3+t4)/4

T-(

t1+

t2+

t3+

t4)/

4ADC

<T-(

t1+

t2+

t3+

t4)/

4>

ADC

MRPC CalibrationIntrinsic timing resolution = 67 ps (including momentum spread)

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Efficiency and resolution plateau

65 ps

97%

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Position scan (±7 kV)

No significant efficiency drop in the gap

Trigger Area: 2 cm wide

From both “charge sharing” and cross talk.

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Cross Talk

Trigger on the strip center:

“Cross talk” at neighbor strips: 3%

Trigger Area: 2 cm wide

“Cross talk” at next-to-neighbor strips: ~2%

Require valid TDC on two ends

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TDC vs. QDCValid TDCs and valid QDCs (3 sigma above pedestal)

Valid TDCs

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MRPC #2 (topview)

Top/bottom pcb

The readout strips are “hollowed-out” alternately.

Removed: 5 mm x 4

Left: 1 mm x 5

Removed: 2.5 mm x 9

Left: 0.25 mm x 10

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MRPC #2

Valid TDCs and QDCs

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Efficiency vs. Position

Valid TDCs

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Valid TDCs and valid QDCs (3 sigma above pedestal)

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MRPC #3 (topview)

55 cm

24.1cm

2.5cm0.7cm

Gaps between strips: 0.7 cm (upper part)

0.8 cm (lower part)

0.8cm

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MRPC #3

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Efficiency vs. Position

Valid TDCs

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Summary

Three prototypes were successfully tested. Efficiency: > 97% Time resolution: 60-70 ps Cross talk: < 3%

With position from silicon detectors, the data will be further analyzed.

Thank

you!

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Longitudinal

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Double hit