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

OUTLINE Status Quality Control in mass production Statistics of cosmic test results Summary 2018/11/28

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. 2018/11/28

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 2018/11/28

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. 2018/11/28

Photos of MRPC production 2018/11/28

2. Quality control in production 2018/11/28

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 …… 2018/11/28

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. 2018/11/28

Photos of faults on materials 2.1 checks on materials Photos of faults on materials 2018/11/28

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 ! 2018/11/28

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. 2018/11/28

Measurements of dimensions 2.4 final checks Measurements of dimensions Mean: 18.14 RMS: 0.219 Mean: 211.9 RMS: 0.078 Mean: 94.05 RMS: 0.096 Standards: Length: 212.0 ± 0.5 mm Width: 94 ± 0.5 mm Thickness: 17.9 ± 1.0 mm 2018/11/28

3. Performance test 2018/11/28

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. 2018/11/28

3. Performance test Upper limit: 50 Hz 2018/11/28

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. 2018/11/28

3. Performance test Lower limit: 90% 2018/11/28

3. Performance test Time resolution of each pad. Upper limit: 120ps Mean 100.3 RMS 11.4 Mean 94.0 RMS 11.2 Mean 99.9 RMS 10.5 Mean 97.7 RMS 12.2 Mean 95.0 RMS 12.0 Mean 101.5 RMS 12.1 Upper limit: 120ps Time resolution of each pad. 2018/11/28

3. Performance test Production date 2018/11/28

3. Performance test The database is available at: http://mrpc.ustc.edu.cn 2018/11/28

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! 2018/11/28

Backup slides 2018/11/28

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 2018/11/28

Small signal ratio of each pad Mean 92.7 RMS 5.2 RMS 5.0 Mean 93.0 RMS 4.5 Mean 92.4 RMS 4.9 Mean 91.2 RMS 6.5 Mean 93.2 RMS 4.7 2018/11/28

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 2018/11/28

2018/11/28