production and quality control of rpcs for the cms muon barrel system
DESCRIPTION
Production and Quality control of RPCs for the CMS muon barrel system. Davide Piccolo – INFN Napoli. RPCs in the CMS experiment. RPCs are used as muon trigger both in barrel and endcap system. 5 Wheels 12 sectors per wheel 6 RPC station per sector 8/7 chamber per sector. RPCs. - PowerPoint PPT PresentationTRANSCRIPT
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Production and Quality control of RPCs for the CMS muon barrel
system
Davide Piccolo – INFN Napoli
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
RPCs in the CMS experiment
RPCs are used as muon trigger bothin barrel and endcap system 5 Wheels
12 sectors per wheel6 RPC station per sector8/7 chamber per sector
RPCs
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
RPCs as trigger detector
Pattern of fired stripsis compared to predefinedpatterns corresponding to specific Pt
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
RPC chamber layout
RB4 120 chambers (2 double gaps per chamber)
RB3 120 chambers (2 double gaps per chamber)
RB2 60 chambers (2 double gaps per chamber) + 60 chambers (3 double gaps per chamber)RB1 120 chambers (2 double gaps per chamber)
Forward UP
Forward Down
Backward UP
Backward Down
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber productionSeveral steps areinvolved in thechamber production.
GTHT: Napoli
Bari
Pavia
Sofia
PanPlaCERNISR
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber production
PaviaPanPlaBakelite is
producedat PanPla factory
Bakelite production and QC
PanPla factory
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber production
GT
Bari
Single gaps and Double gaps producedat General Tecnica factory
General TecnicaSingle gap
Double gap
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber production
GTHT: Napoli
Bari
Sofia
RB1 assembled in HT (napoli)RB2 assembled in GTRB3 assembled in Bari and SofiaRB4 assembled in GT
Chamber assembly
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber test (phase I)
Bari
Pavia
Sofia
RB1 tested in PaviaRB2/RB4 tested in BariRB3 tested in Sofia
Cosmic ray test
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber test (phase II)
Chamber tested arrive at CERN.A final test is donebefore install chambers.Big effort has been doneto increase Quality Controlbefore final installation
Bari
Pavia
Sofia
CERNISR
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Bakelite production and QC
Bakelite sheets are produced at PanPla factory.Production and QC are under the control of the Pavia group
• ADC resolution: 12 bit
• python strength: 70 kg
• readout electrode diameter : 5 cm
• 9 measurement points
• humidity and temperature monitored
• ADC resolution: 12 bit
• python strength: 70 kg
• readout electrode diameter : 5 cm
• 9 measurement points
• humidity and temperature monitored
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Bakelite production (.. Continue)
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Bakelite resistivity distribution
Resistivity is corrected for temperaturedependency according to:(T)/(20) = e -(T-20)/7.8
bakeliteresitivity
accepted
Accepted bakelite platesbetween 1 and 6 1010 •cm
Resitivityprecision
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Bakelite coupling in RPCs
Bakelite plateswith similar resistivityare coupled together
Resistivity Difference Between gap electrodes
Average Resistivityof gap electrodes
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Single gap production
Single gaps are produced at General Tecnica
Produced 1655
Accepted 1082
Rejected 283
Under test 265
Spare/on wait
25
Total to install 2040
Accepted 1082
Accepted/To install
53.04 %
Critical issues:• Spacers gluing
- problem has been solved washingand brushing bakelite surfacewith dimethylketon
• Oiling- good quality, rpcs are opened one per
sample to check quality of the surfacesUpdated to may 15
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Quality control of single gaps
SG assembled by GTSG assembled by GT Gas leakage testGas leakage test
Overpressure testOverpressure test
Control the gap “bubbles” in 30 sControl the gap “bubbles” in 30 s
Reach an inside overpressure of 20 mbar: check if spacers or frame detach
Reach an inside overpressure of 20 mbar: check if spacers or frame detach
GT connects the HV wire ... The SG type (Right/Left) is assigned
GT connects the HV wire ... The SG type (Right/Left) is assigned
Bring the SG at 9500V and measure the current:
reject if I > 5 A
Bring the SG at 9500V and measure the current:
reject if I > 5 A
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Single gap QC resultsRejection
s
Pressure test and leak test
188 66 %
HV test 95 34 %
Spacers already detached
Rejected sg
cut
Overpressure (mbar)
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Double gap productionTwo single gaps are joined together with strips runningin the middle.
Produced 501
Accepted 458
Rejected 15
Spare/On wait 3
Total to install 1020
Acceped 458
Accepted/to install
44.90 %
DG production status
Updated to may 15
Single gap down
Single gap up
strips
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Double gaps Quality control
DG assembled by GTDG assembled by GT Gas leakage testGas leakage test
Control the gap “bubbles” in 30 sControl the gap “bubbles” in 30 s
Bring the DG at 9500V and measure the current:
reject if I > 5 A per single gap
Bring the DG at 9500V and measure the current:
reject if I > 5 A per single gap
2 SG validated by previews step2 SG validated by previews step
SG couplingSG coupling
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Critical issues on double gaps
Average current absorbed by a SG (in DG) before PET:
2.32 µA @ 8 kV
Average current absorbed by a SG (in DG) after PET:
0.83 µA @ 8 kV
Discharges: in some DG, a discharge between the gap edge and the copper ground plane has been found (mostly on the side were solderings with the termination resistors are made). This was evident at a later stage, when DG had already been included in Chambers.
An additional “C” made of PET has been added;
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber production
2 Double gaps (3 for RB2-3) arecoupled in a mechanicalframework
Chamber isdressed withfront end boards,cables, gas tubesand cooling pipes
Preloaded bars mantain RPCsin the mechanicalframework
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Chamber assembly QCDouble gaps inventory
DB update
Check list filling
Chambers assembled in several sites:RB1 in HT near NapoliRB2 in GT RB3 in Bari and now in SofiaRB4 in GT
Cooling system test Gas flow test
electronic test Kapton-FEB connectivity test
QC during assembly
assembly
Status of production:
Chamber type
assembled
Assembled/total
RB1 52 43 %
RB2 45 37.5 %
RB3 54 45 %
RB4 14 12 %
HV test:I vs HVI vs time
Noise rate strip by strip
QC after assembly
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
QC results at HTHV scan
0
0,5
1
1,5
2
2,5
3
3,5
4
1
11 21 31 41 51 61 71 81 91
101
111
121
131
141
151
161
171
181
191
201
211
221
231
241
251
261
271
281
291
301
311
321
time (10 sec)
I (uA
)
forw up
forw down
back up
back down
1000 V
2000 V
4000 V
3000 V
9500 V
9200 V
9000 V
8000 V
7000 V
6000 V
5000 V
CHAMBER 173
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
1
10 19 28 37 46 55 64 73 82 91
100
109
118
127
136
145
154
163
172
181
190
199
208
217
226
235
244
253
262
271
280
289
298
307
316
HV (Volts)
I (uA
)
ant sup
ant inf
post sup
post inf
Temp 22 degrees
Chamber accepted if:
• <I(@9500V)> < 5 A per gap,• I not increasing in one hour• (I) < 1 A per gap.
For each HV pointmeasure average andrms of current
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Selection criteria on assembled chamber
cut
cut
Nu
mb
er
of
gap
s
Nu
mb
er
of
gap
s
Average current
rms current
Gas mixture used inassembling sites:C2H2F4 96 %Iso_C4H10 4 %
Gas mixture used inassembling sites:C2H2F4 96 %Iso_C4H10 4 %
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Problems during assembly
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Cosmics testsFinal test with cosmic rays in Bari, Pavia, Sofia.
BARI test site(10 slots)
Gas mixture
Pavia test site(5 slots)
SF6 ..…… 0.3 %I-C4H10 .. 3.5 %C2H2F4 … 96.2 %
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Test procedure
• gas flow @ 4 volumes/day per 4 days with gas mixture humidified at 50 %• HV conditioning scan (1 kV/15 min)• dark current vs HV measurement• Take data with cosmic rays (gap Up, Down, both)
• Efficiency vs HV • single rate vs HV• cluster multiplicity vs HV
• monitor of T, P, H• measure of stability: dark current vs time
• gas flow @ 4 volumes/day per 4 days with gas mixture humidified at 50 %• HV conditioning scan (1 kV/15 min)• dark current vs HV measurement• Take data with cosmic rays (gap Up, Down, both)
• Efficiency vs HV • single rate vs HV• cluster multiplicity vs HV
• monitor of T, P, H• measure of stability: dark current vs time
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Some results
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Efficiency distribution: summary
50 % Efficiency HV
CorrectedFor T and P
Maximum Efficiency
<>dg = 97 %<>sg = 95 %
Double gaps
Single gaps
Double gaps
Single gaps
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Test performances with tracking
RPCs under test can be used to reconstruct the cosmic track.(Bari test station)
Select tracks with at least 4layers (do not require layer under test)
Shift due to geometry and sample purity
Tracking
No tracking
Work in progress
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Dark current distribution
Dark currentat working voltage9400 Volts
Current of 2 gaps
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Noise rate distribution
Average singlerate at 9400 V.
Most of these rates are due to a singlenoisy channel. Chamber accepted
Double gaps
Single gaps
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Cluster size distributionNo cut on cluster size:Trigger algorithm usescluster baricenter
Mean cluster size vs HV
Mean clustersize at 9400 V.
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Final test at CERN (ISR)Chambers from Bari, Pavia, Sofia CERN
Chambers at ISR 116
Tested chambers at ISR
59
Under observation 1
Rejected 5
Storage/test area • I vs. V • Noise rate• Cluster size• Current stability for ~30 days• Chambers suspicious have been monitored for > 1 month • Upgrade: cosmics test
Test at ISR
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Test at Cern
A
Dark current @ 9400 V.
Noise rate @ 9400 V.
Hz/cm2
Cluster size @ 9400 V.•Forw •Back•Middle-total
•up•Down-total
HV not corrected for T and P
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
Dark current stability
Suspicious chambers
Davide Piccolo - INFN Napoli
SIENA 23-26 maggio 2004
ConclusionsProduction and quality certification of CMS RPC chambersinvolve several steps.
• 1655 single gaps have been produced (total 2040)• 165 chambers have been assembled (total 480)• 116 are at moment at ISR • 59 are ready to be installed