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 m- RE2, RE3 behind RE1 on ME1/2 ME3/2 ME2/2 ME1/1
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: Analysis conditions:
Link boards arrived Saturday p.m., run ended Sunday evening
Runs 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. Internal RPC BXN diff BXN difference for consecutive
RPC data arriving at TMB
Always incrementing by 1.

8. No CRC errors for TMB/ALCT
ALCT CRC
TMB CRC

9. 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?
Orbit
Emu BX
RPC BX
Emu starts (mod16)
RPC starts (mod16)
Difference (mod16) 1
0-923 2 12 3 8 4
0-791,
, 0-131
0, 8
4, 0
4, 8
Therefore, expect various differences in jumps of 4 bx
In general, there can also be an offset due to time delay of BX0

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

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

12. Test clock sent to TMB
Inverted RPC clock
sent to TMB (Runs=553,554)

13. Reset with SPS Orbit Better agreement (run=563)
Still issues to understand

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

15. RPC configuration
Run 562
(Wires 0-11)
Run 548
(Wires 9-20)

16. 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
RPC Pad
Key ½-Strip

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

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

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

20. RE3 Pad Data Quality Same comparisons
Fiducial region: select half-strips
Key ½-Strip
RPC Pad

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

22. RPC timing versus TMB
RE2
RE3
RE1

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

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

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

26. 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?