The status of LMRPC production at USTC

1. The status of LMRPC production at USTC Yongjie Sun State Key Laboratory of Particle Detection & Electronics Center of Particle Physics and Technology, USTC

2. Outline • Introduction • LMRPC mass production • The quality assurance • Summary and the plan The status of LMRPC production at USTC

3. Introduction MRPC MRPC (Multi-gap Resistive Plate Chamber) is a major new detector technology first developed by the ALICE experiment. The concept first published on Nucl. Instr.& Meth. A374 (1996) 132 by M.C.S.Williams et al. • Advantages: • Good time resolution • High efficiency • Low cost • Large area coverage Good candidate for large area Time-of-Flight system. Have been used in STAR/TOF, ALICE/TOF … The status of LMRPC production at USTC

4. The STAR MTD • A large area Muon Telescope Detector (MTD) at STAR • based on the long-strip MRPC technology • good timing performance • moderate spatial resolution • Cost-effective • using the iron bars as absorber • Requirement on the MRPC • Time resolution: < 100 ps • Spatial resolution: ~ 1 cm • High efficiency Z. Xu, BNL LDRD 07-007; L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001 The status of LMRPC production at USTC

5. The prototype design • First prototype: 2006, USTC • Strips: • 2.5 cm wide • 90 cm long • Two ends readout • Gaps: • 10 x 250 um • Two stacks • Performance: • Efficiency > 98% • Time resolution < 70ps • Spatial resolution ~ 1 cm • Operated on STAR from RUN7 The status of LMRPC production at USTC

6. The final design • Module  • Bigger • More strips • Strips wider • Gaps  less 38 6 inner glass = 543 Licron electrode = 551 outer glass / honeycomb = 559 PC board = 580 The status of LMRPC production at USTC

7. The mass production • After the MTD Hefei workshop 2011, the mass production started. • Most of the TOF MRPC facilities are re-used for MTD. • Some of the techniques and procedures are modified, and new equipments are installed. • Clean room • same as that for the TOF production, with controlled temperature and humidity. • two ventilation desks with both sides open, for the big module assembly The status of LMRPC production at USTC

8. The mass production • The electrodes production • Graphite spray method used. • Operate in a separate room • A fan blows outside continuously • Cosmic test system • Gas: Freon + iso-butane • Trigger: 20 x 5 cm2 • Daq: VME based ADC +QDC • HV: N471a The status of LMRPC production at USTC

9. A new clean room • A new clean room has been built. • A flat table of 4m x 1.5m is installed. • Already been used for the production. The status of LMRPC production at USTC

10. The mass production • The materials • Ready for the rest 30 LMRPCs • The man power • glass washing: 1 worker 6 pie./day, 75% cleaned. • electrodes spray: 1 worker 2 pie./day, 60% sprayed. • Assembly: 4 students 2 modules/week, 40% produced. • Cosmic test: 1 student 2 modules/week, ~40% tested. The status of LMRPC production at USTC

11. The performance • The thickness • without honeycomb • In total • The uniformity is in good condition. • The variation in each module is less with the production. <±0.3mm The status of LMRPC production at USTC

12. The performance The noise rate • The noise rate is less than 200 Hz/strip for most of the channels. • High noise rate comes mainly from the environment. • HV filter, the isolation transformer  copper shielding The status of LMRPC production at USTC

13. The performance • The small signal ratio • The small signal ratio is higher than 80% for 98% channels. The status of LMRPC production at USTC

14. The performance • The efficiency • The efficiency is stably around 85% without the geometric correction. 85% / 0.91 = 93.4% > 90% The status of LMRPC production at USTC

15. The performance • The time resolution • For 96% channels, the time resolution is less than 120ps. The status of LMRPC production at USTC

16. Further improvement The environment noise. • High noise rate observed on some random channels, especially during the day time. • A electromagnetic shielding is under design with copper mesh. The status of LMRPC production at USTC

17. Further improvement The trigger size. • A trigger of 20 x 5 cm2 is used now. • Only half of one module (5 strips) can be covered. • A pair of 55 x 5 cm2 scintillators have been ordered. • 6 gas boxes is on hand, can be used for the HV training and cosmic test. The status of LMRPC production at USTC

18. Database • The database is available at http://mtd.ustc.edu.cn • The structure is similar but different to the TOF MRPC database. • Any suggestion or comments are welcome and appreciated. (account: guest:guest) The status of LMRPC production at USTC

19. Summary and the plan • The MTD LMRPC mass production progresses smoothly at USTC. • Experience learned from the beginning phase. Techniques improved and procedures modified. • Performances are stable. Improvement with the progress. • 20 modules have been built, 30 modules to be made. • The rest LMRPCs will be produced according to the timetable of installation. Thank you! The status of LMRPC production at USTC