Assembly and Testing of RPCs in Pakistan
Transcript of Assembly and Testing of RPCs in Pakistan
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Assembly and Testing of RPCsin Pakistan
Hafeez HooraniNational Centre for Physics
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Layout
• Introduction• RPCs in CMS• RPC: From Lab to Detector• Assembly• Testing• QA & QC• Installation and Commissioning
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Resistive Plate Chambers
PAST• Used in several HEP
experiments: L3, BaBar, Belle
• No wires• High efficiency• Fast response• Position measurement • Low production cost• Large surfaces
PRESENT• LHC experiments:
ATLAS, CMS, ALICE, LHCb
• Cosmic rays experiments: (ARGO)
• High rate capability• Low gas gain operation• Long term performance
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Developed by R. Santonico (Roma) in the early 80’
bakelite resistivity 10 10- 10 12 ΩcmCoated with linseed oil
• Gap: 2 mm• HV electrodes : 100 µm graphite • Gas pressure : ~ 1 Atm• Gas mixture: 70% Ar, 29% iso-Butane, 1% Freon• Gas flow: 0.1 vol/hour
Resistive Plate Chambers
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E
SPARK COUNTER
RESISTIVE PLATE CHAMBERS
AVALANCHE CHAMBERS
The avalanche size depends on the anode distance
RPC is not a proportional counter
Different regimes with different HV
The signal is induced on theread-out electrodes
Operating Regimes
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EBp
Aep
−=
α
α = first Townsend coefficient
Gain
Korff approximation
Primary e-
λα 1= λ: free mean pathxEenxn )(
0)( α=
== ∫d
dxxnnM
00
)(exp α
The Avalanche Regime
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ded
kq = >(d)Q<
d
kq< elee
ηλη
ληη +
>= 0n
- k= (εr d/s)/( εr d/s +2) - qel is the electron charge- no is the average size of the primary cluster- λ is the cluster density in the gas mixture- εr is the relative dielectric constant- d is the gap width- s is the electrode thickness
- k= (εr d/s)/( εr d/s +2) - qel is the electron charge- no is the average size of the primary cluster- λ is the cluster density in the gas mixture- εr is the relative dielectric constant- d is the gap width- s is the electrode thickness
λ should be large to achieve high efficiency-------> C2H2F4 gas mixturesλ should be large to achieve high efficiency-------> C2H2F4 gas mixtures
s
d
qs
+
-
-
n 0ve
qe
Qe
High rate environment require low gas gain (avalanche operation)
The Avalanche Regime
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E
5 mV/div
20 mV/div
20 mV/div
50 mV/div
E
E
Volts !
Avalanche:
The electric field is such that the electron energy is larger than the ionising potential
Streamer
Spark
The separation avalanche-streamer decreases with increasing HV
The Streamer Regime
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Streamer
Avalanche
Rate capability increases by a factor 10!
RPC in Avalanche
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εtot = ε1 + ε2 - ε1ε2
Front-end
BakeliteHV
Bakelite
Bakelite
Bakelite
Gas
GasHV
_
_
Double gap geometry improves the efficiency and allows safer operation at higher threshold. Also the time resolution improves.
Double gap geometry improves the efficiency and allows safer operation at higher threshold. Also the time resolution improves.
Double Gaps
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Compact Muon Solenoid
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LHC output 109 Hz (total)106 Hz (muons)
3 104 Hz (total)1.5 104 Hz (muons)
LV1
LV2
Storage unit
100 Hz (total)30 Hz (muons)
RPC
sorter
• bunch separation of 25 ns
• high background of n and γ
• long term operation with high irradiation
CMS environment
Dedicated Trigger
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Red dashed line is at 10 Hz/cm2Red dashed line is at 10 Hz/cm2
Rate in the shadow region (η ≤1.6) is ≤ 10 Hz/cm2
Background
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ChinaChinaKoreaKorea PakistanPakistan
Gap production
KoreaGap production
Korea
Front-end electronics
PakistanFront-end electronics
Pakistan
HV/LV system
PakistanHV/LV system
Pakistan
Endcap Overview
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Ring REi/1
Ring RE i/3
Ring REi/2
RE1/1 StagedRE1/2 and RE1/3 in production at CERN
RE1/1 StagedRE1/2 and RE1/3 in production at CERN
RE2/2 and RE2/3 under production in PakistanRE2/2 and RE2/3 under production in Pakistan
RE1/1
RE1/2
RE1/3
RE2/1
RE2/2
RE2/3
RE3/1
RE3/2
RE3/3
RE4/1
RE4/2
RE4/3
No. of chambers 36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2
RE3/2 and RE3/3 to be produced in PakistanRE3/2 and RE3/3 to be produced in Pakistan
Endcap Overview
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Gap (c)
Gap (a)
Gap (b)
Gap ( a ) Gap ( b )
Sensitive Volume (Gaps) made in Korea
All other chambersRE3/1, RE4/1
BottomBottom
Top WideTop Wide
Top Top Narrow
Narrow
Endcap Overview
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BakelitePurchase Italy
Cut Clean Ship to S. Korea
Gaps Built in Seoul QC Ship to CERNPakistan
FEBs, Adaptor Boards
Procured from Italy Ordered by Pakistan Ship to PakistanCERN
Chamber Assembly
QC Construction Database
CERN/Pakistan
Storage Point 5 InstallationProductionDatabase
Mechanics Kit prep in ChinaPakistan
Procurement Cables and pieces
Assembly at CERNPakistan
Endcap Organization
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Organizational Structure• Project Managers Tariq Solaija/Hafeez Hoorani• Technical Coordination Zia Aftab• Mechanics M. Shariq Khan• Design & Fabrication Javed A. Jan• Assembly M. Iftikhar/M. Saleh• Installation M. Shariq Khan• Cosmic Testing Waqar Ahmed• DAQ Software Sajjad Asghar/Hassan Shahzad• Analysis M. Irfan/M. Saleh• QA & QC Imran M. Awan/Hafeez Hoorani
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Oiling FacilityHot melt of PET film
KODEL
KODEL
Oiling procedure successfully transferred to Korea 2003
Gap Production
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~ 100 Gaps
Schedule for Gap Delivery
Delivered in 12/2004
Not yet delivered
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RPCs from Lab to Detector• Research & Development• Prototyping• Pre-Production
– Mockups, Retrofitting• Production
– Quality Assurance• On-site Installation• Commissioning• Maintenance
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Prototyping• PK-01/99 400*400 mm2 double gap RPC, Italian bakelite 1999. (non-oiled)
• PK-02/00 Full-size RE 2/2 chamber, tested at GIF in 2000, phenolic bakelite gaps fabricated in Italy ( ρ ≅ 10 9 Ωcm). (non-oiled)
• PK-03/01 Full-size RE 2/2 chamber, tested at GIF in 2001, melaminic bakelite gaps ( ρ ≅ 10 10 Ω cm). (non-oiled)
• PK-04/02 Full-size RE 2/2, tested at GIF in 2002, gaps supplied from Korea ( ρ ≅ 10 10 Ω cm) (non-oiled)
• PK–05/03 Full-size RE 2/2, tested at GIF in 2003, gaps supplied from Korea ( ρ ≅ 10 10 Ω cm) (Oiled)
Good results were achieved in all beam tests.
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First Prototype RPC
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RPC Prototype in 2002
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Front End Board for RPC
ASIC0.14 µBi CMOS
32 ChannelsFEB
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CMS Criteria for good RPC
• Good Rate Capability > 1 KHz/cm2
• Efficiency > 95%• Good Time Resolution < 3 ns• Small Cluster Size < 3 • Operational Plateau > 300 V• Streamer Probability < 10%
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Beam Test Results -I
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Beam Test results-II
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Beam Test Results-III
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Beam Test Results-IV
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RPC LayoutFinal Gas mixture used in all tests95.5 Freon 3.5 Isob 0.3 SF6 + RH 50% = 5000 ppm
GAPMechanics
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Full-Scale RPC
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40 ° Sector with Services
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RE */1
RE */2 RE */2
RE */3 RE */3
20 ° Sector of Station 2, 3 & 4
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RE */2 dimensions
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RE */3 dimensions
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Assembly Procedure
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Assembly Procedure
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Assembly Procedure
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Storage
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Chamber Production in Pakistan
0102030405060708090
01.04.20
0515.0
4.2005
01.05.20
0515.0
5.2005
01.06.20
0515.0
6.2005
01.07.20
0515.0
7.2005
01.08.20
0515.0
8.2005
01.09.20
0515.0
9.2005
01.10.20
0515.1
0.2005
01.11.20
0515.1
1.2005
01.12.20
05
No.
of C
ham
bers
Actual Production
Goal
8 ch./week2 ch./week Retrofitting 4 ch./week
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Quality Assurance& Control
• Gas flow & leakage test• Dark current test • Cosmic ray test
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Cosmic Test Facility• Testing of chamber done using Cosmic Rays• VME based Data Acquisition System used:
– 64 Channels TDC– NI Crate Controller
• Trigger is generated using scintillators– Top & Bottom Layer consist of 8 scintillator each– Scintillators are ORed in a layer– Trigger is the AND of two ORed top & bottom
layers• Events are read automatically, stored and analyzed
for chamber performance
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Each chamber consist of 96 readout channels10 Chambers are tested in parallel• Gas System is working (10 Chambers can be connected)
– Gas Mixture (96% Freon, 3.5% Iso-butane, 0.5% SF6)• HV Available for Chamber ( 5 modules CAEN, 1526N)• LV is available for 30 FEBs• 15 TDCs are available, each can read 64 channels• Two Layers of scintillators, each layer consist of 8 scint.• Most Scintillators have efficiency great than 90% Scint.
trigger is working properly
Cosmic Test Facility
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Scintillators
• Dimension – 195x20x1 cm• Can work up to 180 cm• 18 scintillators• For the trigger we need 18 scintillators + some
spare• 2 layers – 8 scint. each + 2 additional scint.
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Trigger set-up
• Two movable scintillators to match the chamber’s dimension
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TimingTrigger
Cable 52 nsAmplifier 26 nsDiscriminator 12 nsCoincidence 16 nsPMT 40 nsTotal Delay Trigger 146 ns
RPCRPC + FEE 16 nsCable 25 nsTotal Delay RPC 41 ns
Scintillator trigger is late by 100 ns compare to signal from RPC
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Quality Assurance
• Each component has a unique identifier• All information is stored in a central
database “Construction Database”• For each step of movement a traveler’s
sheet is filled and signed by the person responsible for QA
• All test results are stored in the database
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Quality Assurance (Gaps)
• Visual Test– Random check of dimensions– HV connectors and gas inlet/outlet
• Leakage Test– Checked with 20 mbar over pressure
• Spacer Test– Template sheet is used, 5 N pressure is applied
• Dark Current (V vs I)– Gaps with current more than 5 µA are rejected
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RE-2/2 Gaps QC (Total 120 Gaps)
0
2
4
6
8
10
HV Test Leak Test Spacer Test Mech. Faults
Gap QC Test
No.
of G
aps
TNTWFG
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RE-2/3 Gaps QC (Total 120 Gaps)
0123456
HV Test Leak Test Spacer Test Mech. Faults
Gap QC Test
No.
of G
aps
TNTWFG
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• All chambers are inspected visually after assembly
• Chambers are conditioned using the gas mixture, 8 volume changes
• HV of 8.6 kV is applied for 6 hours and the behavior of dark current is observed. More than 0.5 µA variation chamber is rejected
Quality Assurance(Chambers)
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• HV is varied:– 8.6, 8.8, 9.0, 9.2, 9.3, 9.4, 9.5 & 9.6 kV
• For each HV point 20,000 events are taken• Using the data following parameters are
obtained:– Strip Occupancy– Efficiency– Cluster Size
Quality Assurance(Chambers)
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• Strip Occupancy– Noisy and/or dead channels are identified– More than 2 noisy or dead channels, chamber is
rejected• Efficiency
– Chamber is rejected if ε < 95%• Cluster Size
– Chamber is rejected if cluster size is greater than 3.0
Quality Assurance(Chambers)
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Jan 06
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Summary
• We started in 1999 with the notion, RPCs are cheap and easy to make. None is correct.
• Chambers are now produced at a constant rate.• For assembly we have gone over the learning
curve.• For the testing (QA/QC), still some problems
but situation is under control and improving.• Testing of 70 chambers in 6 weeks.