STAR TOF MRPC Mass Production & Q.C. (USTC)

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

3. 1. Status Monthly output Totally, 1283 MRPCs were produced.

4. 1. Status 1210 MRPC shipped to U.S. Time schedule (at USTC) manufacturing Q.C.

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.

6. Photos of MRPC production

7. 2. Quality control in production

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 • ……

9. 2.1 checks on materials The case of glass • 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.

10. 2.1 checks on materials Photos of faults on materials

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 !

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.

13. 2.4 final checks Mean: 211.9 RMS: 0.078 Mean: 18.14 RMS: 0.219 Mean: 94.05 RMS: 0.096 Measurements of dimensions • Standards: • Length: 212.0 ± 0.5 mm • Width: 94 ± 0.5 mm • Thickness: 17.9 ± 1.0 mm

14. 3. Performance test

15. 3. Performance test 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.

16. 3. Performance test Upper limit: 50 Hz

17. 3. Performance test Lower limit: 80% The statistics of small signal ratio — a parameter used to evaluate the percentage of avalanche signal.

18. 3. Performance test Lower limit: 90%

19. 3. Performance test Mean 100.3 RMS 11.4 Mean 94.0 RMS 11.2 Mean 99.9 RMS 10.5 Upper limit: 120ps Mean 97.7 RMS 12.2 Mean 95.0 RMS 12.0 Mean 101.5 RMS 12.1 Time resolution of each pad.

20. 3. Performance test Production date

21. 3. Performance test The database is available at: http://mrpc.ustc.edu.cn

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!

23. Backup slides

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 4.1 RMS 2.2 Mean 4.5 RMS 2.2 Mean 6.3 RMS 3.2

25. Small signal ratio of each pad Mean 92.7 RMS 5.2 Mean 93.0 RMS 4.5 Mean 92.4 RMS 4.9 Mean 93.2 RMS 4.7 Mean 92.7 RMS 5.0 Mean 91.2 RMS 6.5

26. Design of MRPC for TOFr 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