1DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

Analysis of Oct. 04 Test Beam RPC Data

Jay Hauser, Martin von der MeyJay Hauser, Martin von der Mey

University of California Los AngelesUniversity of California Los Angeles

2DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

ME1/1

RE1 on ME1/2

ME2/2ME3/2

RE2, RE3 behind

3DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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 13 in readout

• N.B. RE1 seems the healthiest chamber

4DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

5DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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 (?)

6DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

7DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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 0-923 0 0 0

2 0-923 924-1847 0 12 12

3 0-923 1848-2771 0 8 8

4 0-791, 792-923

2772-3563, 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

8DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RPC Bunch Crossings - Data• TMB vs RPC see perfect agreement with

expectations.• At least, ALCT/CLCT bx reset/bx0 protocol =

Link board protocol

9DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RPC BX from different RPC Chambers?

• Nice diagonals, but offsets (2, 7 bx) due either to TTCrx offset or reset timing at Link board

10DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

Beam Spot Size• Data triggered by SP covers roughly 30x30 cm• (Scintillators are 10x10 cm)

Key ½-Strip

Key

½-S

trip

Key Wire Group

11DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

RPC Pad

Key

½-S

trip

12DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

13DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RE2 Pad Data Quality• Same comparison• Active part of chamber appears far from beam centerlow statistics• Fiducial region: select half-strips 10-50

Key

½-S

trip

RPC Pad

14DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RE2 Efficiency Within Fiducial Region• This RPC chamber not so efficient

Key Wire Group

15DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RE3 Pad Data Quality• Same comparisons• Fiducial region: select half-strips 80-115

Key

½-S

trip

RPC Pad

16DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RE3 Efficiency Within Fiducial Region• RE3 efficiency reaches a high value, but is not

flat with wire number

Key Wire Group

17DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

RE1RE2

RE3

18DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

RPC Afterpulsing?• Number of time bins per chamber per event• RE1 and RE2 good, RE3 shows considerable

after-pulsing:

RE1RE2

RE3

19DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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

RE1

RE2RE3

20DRAFT version Oct. 15, 2004 Hauser/Mey UCLA

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?