1. STAR TOF MRPC Mass Production & Q.C. (USTC)
Yongjie Sun
University of Science and Technology of China

2. OUTLINE Status Quality Control in mass production
Statistics of cosmic test results
Summary
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3. 1. Status 2006 2007 Total 230 1053 Totally, 1283 MRPCs were produced.
Monthly output
2006
Month
Output
2007
Jun. 12
Jan. 58
Jul.
120 64
Feb. 24
Aug.
Sep. 55
Mar. 83
119
Oct. 35
Apr. 80
121
Nov. 42
May.
126
Dec. 22 82
Total
230
1053
Totally, 1283 MRPCs were produced.
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4. Time schedule (at USTC)
1. Status
1210 MRPC shipped to U.S.
Time schedule (at USTC)
manufacturing
Q.C.
2006
2007
2008
1/2
3/4
5/6
7/8
9/10
11/12
Production begin 
40 MRPCs
+192 MRPCs
+326 MRPCs
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5. 1. Status
100 m2 Clean Room (Class 100K) with conditioned temperature (25°C) and humidity (<40%)
Detailed documents for construction and quality control
Qualified workers and technicians
 Over 95% modules meet the STAR requirements.
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6. Photos of MRPC production
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7. 2. Quality control in production
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8. 2.1 checks on materials
Glass: surface quality, dimensions, thickness, …
Electrode PCB: dimensions, pad surface, …
Honeycomb board: surface quality, dimensions, thickness, …
Support pillar: thickness
Mylar: surface quality, dimensions,…
Graphite: surface resistivity
Fish line: diameter uniformity ……
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9. 2.1 checks on materials The case of glass Inner glass 36% 1-2% 4-5%
Faults on received
broken when polished
Picked out after cleaning
Broken during assembly
usable
Inner glass
36%
1-2%
4-5%
<1%
6415
Outer glass
15% 3% 2%
2566
The glass were checked carefully on the surface quality first. The dimensions and thickness were also measured. The glass with faults were returned to the factory.
Then, the edges and corners of glass were polished. A small amount of glass were broken or scraped in this procedure.
The polished glass were checked again after have been cleaned. The glass with faults were picked out (but would not be returned back to the factory).
Some wastage of glass during assembly, especially the outer glass broken when pasting the graphite layer.
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10. Photos of faults on materials
2.1 checks on materials
Photos of faults on materials
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11. 2.2 HV check on electrodes
Electrodes, which mainly contains the pcb and outer glass with the graphite layer between them, are applied with up to 12 kV HV in pure Nitrogen.
The leak currents are monitored.
Leak current > 2 nA
 reject !
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12. 2.3 module thickness check
After a MRPC is assembled, the thickness (from pcb to pcb) was measured at 14 points.
Abnormal thickness at certain points indicates problems in assembly.
This step helps find assembly problems earlier and ensures the uniformity of the gas gaps.
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13. Measurements of dimensions
2.4 final checks
Measurements of dimensions
Mean: 18.14
RMS:
Mean: 211.9
RMS:
Mean: 94.05
RMS:
Standards:
Length: ± 0.5 mm
Width: 94 ± 0.5 mm
Thickness: 17.9 ± 1.0 mm
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14. 3. Performance test
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15. 3. Performance test Tow cosmic ray test systems were built.
Cosmic ray test setup
Tow cosmic ray test systems were built.
8 MRPCs can be tested per day.
All the produced modules take time resolution test.
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16. 3. Performance test
Upper limit: 50 Hz
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17. 3. Performance test The statistics of small signal ratio
Lower limit: 80%
The statistics of small signal ratio
— a parameter used to evaluate the percentage of avalanche signal.
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18. 3. Performance test
Lower limit: 90%
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19. 3. Performance test Time resolution of each pad. Upper limit: 120ps
Mean 100.3
RMS
Mean 94.0
RMS
Mean 99.9
RMS
Mean 97.7
RMS
Mean 95.0
RMS
Mean 101.5
RMS
Upper limit: 120ps
Time resolution
of each pad.
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20. 3. Performance test
Production date
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21. 3. Performance test
The database is available at:
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22. Summary Totally, 1283 MRPCs have been produced in USTC site.
With strict implements of the Quality Control throughout the mass production, over 95.1% MRPCs achieve the required performances.
1210 MRPCs (30% of STAR TOF) have been sent to U.S.
Thank you!
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23. Backup slides
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24. Noise rate statistics of each pad
Mean 6.4
RMS 3.5
Mean 4.3
RMS 2.2
Mean 4.1
RMS 2.0
Mean 4.5
Mean 6.3
RMS 3.2
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25. Small signal ratio of each pad
Mean 92.7
RMS
RMS
Mean 93.0
RMS
Mean 92.4
RMS
Mean 91.2
RMS
Mean 93.2
RMS
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26. Design of MRPC for TOFr Time resolution <100ps Efficiency  90%
Module size： 21.2×9.4×1.79 cm3
Gas gap：6×0.22mm
Time resolution <100ps Efficiency  90%
High granularity
MRPC strip size：
3.15cm×6.30cm
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27. 2018/11/28