XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 1 Results from...
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Transcript of XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 1 Results from...
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 1
Results from development ofGlass RPCs for INO detector
B.Satyanarayana(For INO Collaboration)
TIFR, Mumbai
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 2
Plan of the presentation
Introduction Principle of operation of a glass RPC Overview of the field Our prototype designs and fabrication RPC gas mixtures and gas system Cosmic ray muon telescope Data acquisition system Preliminary results RPC aging problem Future work plan
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 3
Introduction
Neutrinos are one of the fundamental particles of matter. Electrically neutral and were initially thought to be mass less. Three types or flavors (eof neutrinos known.
Recent evidence indicates that neutrinos have mass and also experience mixing among these flavors.
Neutrino oscillations can explain the discrepancy between theory and observations about its flux; can be used to estimate its mass.
Pioneering experiments at the KGF underground laboratories. Formation of Indian Neutrino Observatory (INO) collaboration. Feasibility studies for setting up of a neutrino experiment in India
is in progress.
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 4
Proposed INO detector
Magnetised iron calorimeter
Iron
RP
C
140
laye
rs
RPC dimension: 3m X 2m
No of chambers: 11K
No of channels: 220K
No of TDC channels: 3K
35KTons
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 5
Principle of operation of a RPC
Two 2mm thick float glassesSeparated by 2mm spacers
2mm thick spacer
Glass plates
Graphite coating on the outer surfaces of glasses
Pickup strips
V-I model
Each discharge locally deadens the RPC. The recovery time is approximately
l
A
A
lRC
s 2)10 x (8.85 x 4 x )10 x ( -1210
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 6
Our prototype designs: Single gap
Gas inlet
HV terminals
Graphite coat
Gas outlet
Spacer
Two versions
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 7
Our prototype designs: Double gap
Double gap RPC for better detection efficiencies
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 8
Jigs for RPC fabrication
A glued RPC
Resistivity measurement jig
A finished small area RPC
RPC fabrication jig
Glue and dispensers
Glass handlers
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 9
Gas mixing and flow control unit
Gas mixing unit
Flow monitor
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 10
P1P2
P3
P4P5
P6
Glass RPC under test
Muon Trigger =654321 PPPPPP
Schematic of Cosmic ray muon trigger
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 11
Cosmic ray muon telescope setup
Mounting structure for flexible and precise telescope alignment
Paddle alignment detail
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 12
Schematic of data acquisition system
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 13
Data acquisition system electronics
NIM CAMAC
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 14
V-I characteristics
Small RPC Large RPC
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 15
Typical RPC pulse profile
RPC pulse
Muon trigger
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 16
Noise rate and efficiencies
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 17
Charge performance
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 18
Timing performance
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 19
Charge-time linearity
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 20
RPC aging problem
Drop in efficiency, increase in noise rate and chamber current seen after a few weeks of continuous operation
Reports in the literature (Monolith, Belle etc)
Moister contamination in Freon gas, the culprit?
Use of SF6 instead of Freon preferred
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 21
Controlled humidity test
Carlo Gustavino et al, LNGS
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 22
AFM images of damaged electrodes
2scans 10scans
Damaged electrodes
Damaged electrodes
Raw glass
Raw glass
¶ 500nm structures of 100nm thick seen in the images
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 23
SEM image of damaged electrode
6scan 2scan
Damaged electrode Fluorine: 38%
Raw glass Fluorine: 4%
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 24
Future work plan
Systematic study of RPC stability problemFabrication of more large area RPCs and studiesDetailed studies on timing, spatial resolution, cross-talkOptimization of detector gas composition INO prototype detector; needs about 16 large area RPCsPerformance studies of prototype detector; comparison
of results with those from simulation studiesRPC Parameter inputs for electronics and data
acquisition system designFull pledged RPC device simulations
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 25
Backup slides
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 26
RPCs of modern designs
Multi gapHybrid RPC Micro RPC
Applications in HEP research
Cosmic ray experiments: EAS-Top, Cover-Plastex, Argo, Auger
Accelerator based experiments: Belle, Babar, Star, Harp
Future experiments: Alice, ATLAS, CMS, LHCb
Medical applications etc
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 27
Telescope stability monitoring
100000
120000
140000
160000
180000
200000
220000
240000
260000
280000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Time, Hours
Tele
scop
e pa
ddel
rat
es
P1
P2
P3
P4
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 28
Preliminary cross-talk measurements
Gas Mixture Tele window
(mm)Cross talk (%)
62:8:30 10 6.8
62:8:30 15 6.7
62:8:30 20 6.2
57:8:35 20 6.5
52:8:40 20 5.9
46:8:46 20 6.3
XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004 29
Recovery of a damaged RPC
Purging with pure Argon at high flow rate.
Bubbling pure Argon through pure ethyl alcohol.
Bubbling pure Argon through 3% Ammonia solution for 24 hours with high voltage off.
Recovers efficiency and brings down noise rate.