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Analysis of Oct. 04 Test Beam RPC Data

Detailed analysis of RPC data from the test beam, focusing on RPC chambers RE1, RE2, RE3 in relation to RAT and TMB boards. Investigation of pad data, bunch crossings, efficiency, and timing discrepancies. Suggestions for future analysis and setup improvements.

charlesmoss
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Analysis of Oct. 04 Test Beam RPC Data

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  1. Analysis of Oct. 04 Test Beam RPC Data • Jay Hauser, Martin von der Mey • University of California Los Angeles

  2. RPCs in Test Beam • 1 RE1/2 (call it RE1) • 2 free-standing (call them RE2, RE3) • Readout info for experts only: • RPC0  RE1 • RPC3  RE2 • RPC2  RE3 • RE2, RE3 behind • RE1 on ME1/2 • ME3/2 • ME2/2 • ME1/1 m-

  3. Link Board to RAT Board Setup • RAT receives 4 cables, one from each RPC chamber • Cables 0, 1, 2 were connected • Appears that phasing RAT-TMB incorrect, so that 0  2 and 13 in readout • N.B. RE1 seems the healthiest chamber

  4. RPC-RAT Interface • RAT receives 4 cables with 20 pairs each (3 cables active at test beam) • For each cable/RPC chamber implemented: • 4 bits of bunch crossing • 12 bits of RPC pad data • 1 clock • (FYI CMS specification is 16 pads, 2 bx, 1 clock, 1 GND) • New full-size backplane was used

  5. Data Conditions • Run conditions: • Link boards arrived Saturday p.m., run ended Sunday evening • Runs 535-548 have RPC data. • Data triggered by Sector Processor, not scintillators • Beam spot roughly 30 cm each dimension • RAT latches bits on falling edge of 40 MHz clock where they are stable • Analysis conditions: • Comparison CSC chamber always ME3/2 - part of SP trigger (ALCT&CLCT required) • Run 548 taken Sunday. • Corrupted RPC events not included • Seen at 1% level • Symptom: as if no RPC cables connected to RAT (?)

  6. TMB Bunch Crossings - Data • Flat Distribution seen 0-15 (4 bits): • N.B. no ALCT or TMB data transmission errors (CRC check) seen in these runs

  7. RPC Bunch Crossings - Expectations • Emu electronics used orbit=924 bx, RPC used orbit=3564 bx • These are incommensurate. • What are lowest 4 bits if synch is perfect? • Therefore, expect various differences in jumps of 4 bx • In general, there can also be an offset due to time delay of BX0

  8. RPC Bunch Crossings - Data • TMB vs RPC see perfect agreement with expectations. • At least, ALCT/CLCT bx reset/bx0 protocol = Link board protocol

  9. RPC BX from different RPC Chambers? • Nice diagonals, but offsets (2, 7 bx) due either to TTCrx offset or reset timing at Link board

  10. Key ½-Strip Key Wire Group Key ½-Strip Beam Spot Size • Data triggered by SP covers roughly 30x30 cm • (Scintillators are 10x10 cm)

  11. Key ½-Strip RPC Pad RE1 Pad Data Quality • Compare ME3/2 (rear chamber) CLCT key half-strips (not strips) to RE1 pad (vertical dimension) • Good position agreement (one dead pad) • Modest RPC efficiency within readout region • Fiducial region for RE1 select half-strips 65-100

  12. Key Wire Group RE1 Efficiency Within Fiducial Region • Unsure exactly where pads are, so plot efficiency versus CSC wire group • This RPC chamber fairly efficient

  13. Key ½-Strip RPC Pad RE2 Pad Data Quality • Same comparison • Active part of chamber appears far from beam centerlow statistics • Fiducial region: select half-strips 10-50

  14. Key Wire Group RE2 Efficiency Within Fiducial Region • This RPC chamber not so efficient

  15. Key ½-Strip RPC Pad RE3 Pad Data Quality • Same comparisons • Fiducial region: select half-strips 80-115

  16. Key Wire Group RE3 Efficiency Within Fiducial Region • RE3 efficiency reaches a high value, but is not flat with wire number

  17. RE2 RE3 RE1 RPC versus ALCT Timing • First RPC hit per chamber: • RE1, RE2 all in one BX • RE3 not as good • Note RE1 later by 1 BX

  18. RE2 RE3 RE1 RPC Afterpulsing? • Number of time bins per chamber per event • RE1 and RE2 good, RE3 shows considerable after-pulsing:

  19. RE2 RE3 RPC Pads Hit • Pads hit per event (summed over time bins) • All look okay (RE1 slightly more pads) RE1

  20. Summary • RPC Link Board to RAT-TMB data transmission worked well • RPC pads well correlated to CSC position • Timing looks strange on one RPC chamber • RPC efficiency hard to study • Instrumented region was small • Gas was not optimal due to safety concerns • Will be useful to do simultaneous analysis of RPC data taken through Link board readout – is it possible to double-check? • N.B. time for doing tests was way too short. Is there some way to set up a cosmic ray test bench for a longer time?

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