1. Report on beam test results of high-rate MRPCs Jingbo Wang Department of Engineering Physics, Tsinghua University, Beijing, China

2. Index April test  Two high-rate prototypes  Test setup  HV scan  Rate scan August test  Three prototypes (one is high-rate prototype)  Test setup  HV scan  Horizontal scan  Vertical scan  Multi-hit analysis 2

3. Accelerator 3

4. April test MRPC design (two high-rate prototypes) Test setup HV scan Rate scan (focus on the rate capability) 4

5. MRPC_1 6-gap 5 60mm  Parameters Gap number: 6-gap Glass type: silicate Gap width: 0.22mm Glass thickness: 0.7mm Gas mixture: Freon/iso-butane/SF6 96.5%/3%/0.5% The same as the standard STAR module Low-resistive silicate glass 3~4×10 10 Ωcm

6. MRPC_2 10-gap 6 30mm 31.5mm Number of gaps: 10 Negative HV Positive HV

7. Test setup 7 The platform is movable. Different rates can be obtained by moving the chambers up and down. 2.5GeV Proton

8. Top view 8 AB PMT1 PMT2 PMT3 PMT4PMT0 Silicon Scintillator PMT Ordinary-glass RPC 10-gap high-rate MRPC 6-gap high-rate MRPC 2×4 cm 2

9. Counting rate 9 PMT rate: 0.8~20 kHz/cm 2 MRPC rate: 2~30 kHz/cm 2 Rate profile

10. Time difference 10

11. HV scan at low rate: 6-gap MRPC 11 800Hz/cm 2

12. HV scan at low rate : 10-gap MRPC 12 800Hz/cm 2

13. Rate scan 13

14. Summary  Two prototypes were tested. 14  6-gap MRPC Low rate: 800Hz/cm 2 Efficiency>93%, Time resolution: ~80ps High rate: 20kHz/cm 2 Efficiency: ~75%, Time resolution: ~110ps  10-gap MRPC Low rate: 800Hz/cm 2 Efficiency>95%, Time resolution: ~70ps High rate: 20kHz/cm 2 Efficiency: ~90%, Time resolution: 80~85ps

15. August test 15 MRPC design  MRPC_1: common-glass prototype  MRPC_2: high-rate prototype Test setup HV scan Horizontal scan Vertical scan (study the crosstalk) Multi-hit analysis  MRPC_3: long-strip prototype

16. MRPC_1 and MRPC_2 16 1.5mm 5mm Diameter:1.5mm Hole size:0.5mm Width:0.508mm Top and bottom layers 240mm 22mm 3mm Guarding line Glass type: common / silicate HV electrode: colloidal graphite Number of gaps: 10 Gap width: 0.25mm Glass thickness: 0.7mm Gas mixture: Freon/iso-butane/SF6 96.5%/3%/0.5% colloidal graphite

17. Test Setup Main beam Target  10 m PM12 PM34 Tsinghua RPC USTC RPC PM5 Silicon 17 Common-glass MRPC_1 High-rate MRPC_2

18. HV scan: Both prototypes 18 T diff =T MRPC_1 -T MRPC_2, σ MRPC_1 ≈ σ MRPC_2 ≈ σ diff / sqrt(2)

19. Horizontal Scan: Common-glass MRPC Beam Position: 14.9mm, 34.9mm, 54.9mm, 74.9mm, 94.9mm. 19 Trigger area: 2 ×4 cm 2 0100

20. Horizontal Scan: Common-glass MRPC 20 0100 Transmission time = 5.4ps/mm

21. Vertical Scan: Common-glass MRPC gap strip1strip2strip3 21 “cross-talk” of the 1 st neighbor: 6% “cross-talk” of the 2 nd neighbor: 3% 0 Trigger area: 2 ×4 cm 2

22. Vertical Scan: High-rate MRPC 22 gap 0 “cross-talk” of the 1 st neighbor: 15% “cross-talk” of the 2 nd neighbor: 3% strip3strip2strip1

23. Vertical Scan: Both prototypes 23 strip1strip2strip3 Time diff / 1.414 0

24. Summary 24  Common-glass MRPC Efficiency: ~95%, Time resolution: 70~80ps Crosstalk at the 1 st neighbor: 6% Crosstalk at the 2 nd neighbor: 3%  High-rate MRPC Efficiency: ~95%, Time resolution: 70~80ps Crosstalk at the 1 st neighbor: 15% Crosstalk at the 2 nd neighbor: 3%

25. Multi-hit analysis: Long-strip MRPC 25 Multi-hit T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 Strip1 Strip2 Strip3 Strip4 Strip5 Strip6 Particle position of strip1: T1-T7 Beam position of strip3: T3-T9 Position difference: (T1-T7)-(T3-T9) 100cm 2.5cm Not to scale!

26. Position difference 26 Cut out the correlated peaks

27. no double hit double-hit in any of 1 st neighbors double-hit in any of 2 nd neighbors double-hit in any of 3rd neighbors Resolution of the fired strip

28. 1-m long counter, 12-gap, mirrored and shielded