Transcript Characterization of Micro-Pattern Gas Detectors for

Characterization of Micro-Pattern Gas
Detectors for Application in the CMS Muon
Detection System
D. Abbaneo1, S. Bally1, H. Postema1, A. Conde Garcia1, J.-P. Chatelain1, G. Faber1, L. Ropelewski1, E. David1, S. Duarte Pinto1, G. Croci1, M. Alfonsi1, M. van Stenis1, A. Sharma1, S. Bianco2, S.
Colafranceschi2, L. Benussi2, F. Fabbri2, G. Saviano2, N. Turini3, E. Oliveri3, G. Magazzu3, A. Marinov4, M. Tytgat4*, N. Zaganidis4, M. Hohlmann5, K. Gnanvo5, Y. Ban6, H. Teng6, J. Cai6
1
CERN, Geneva, Switzerland
2
LNF Frascati, Frascati, Italy 3 Universita' Degli Studi di Siena - INFN Sezione di Pisa, Pisa, Italy 4 Dept. of Physics and Astronomy, University of Gent, Gent, Belgium
5 Dept. of Physics and Space Sciences, Florida Institute of Technology, Melbourne, Florida, USA 6 Peking University, Beijing, China
* [email protected], presenter of this contribution
CMS Endcap Resistive Plate Chamber Muon System
Use Micro-Pattern Gas Detectors for CMS Muon Endcap System ?
Micro Pattern Gas Detectors :
 Spatial resolution ~ 100 m (track< 45°)
 Time resolution ~ 4-5 ns
 Efficiency > 98%
 Rate capability ~104/mm2
 Non-flammable mixtures (like Ar-CO2)
 Good gain stability for high particle fluxes
 No ageing effects seen for high doses
Endcap chambers are double-gap Bakelite
RPCs with strip readout, operating in
avalanche mode at 9.5kV with a C2H2F4iC4H10-SF6 (96.2-3.5-0.3) gas mixture
GEM
Ions
Multi-GEM
I+
e-
40 %
Induction gap
e-
60 %
Electrons
η = 2.4
Staged
No. ofchambers
 Improve contribution to CMS Muon Trigger Efficiency
 Combine triggering and tracking functions ?
 Instrument the vacant (RE1-4/1) zones in forward CMS endcap
region, 1.6 < |η |<2.4
 Enhance and optimize the readout (η-φ) granularity by
improved rate capability
RE RE RE
RE RE RE RE RE RE RE RE RE
1/1 1/2 1/3
2/1 2/2 2/3 3/1 3/2 3/3 4/1 4/2 4/3
36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2
 At present RPC endcap system limited to |η|<1.6
 RPC Endcap completion phase 1, RE4/2-3, in 2012
 Need other technology for RE1-4/1 region to
sustain high LHC/SLHC rates of several kHz/cm2!
Micromegas
10x10 cm2 Triple-GEM Prototypes
Small prototypes were produced and tested at
CERN in EN-ICE surface treatment workshop and
RD51 lab :
Standard double-mask triple-GEM
 Triple-GEM detectors with 10x10cm2 active area
 GEM and cathode foils glued on fiberglass frames
GEM3
GEM2
CONFIG. 1: 12mm(Drift) / 12mm(T1) / 12mm(T2) / 12mm(Induction)
and mounted inside gas-tight box
 Double/single mask GEMs
Use of single-mask technique to avoid alignment problems during
etching of holes in top/bottom of GEM foils
 2 gap size configurations : 3/2/2/2 & 3/1/2/1 mm
 Strip pitch = 0.8mm
Drift
3.00 mm
Drift gap
GEM1
Anode
Honeycomb triple-GEM
Single-mask triple-GEM
T1
T2
1.00 /2.00 mm
Induction gap
1.00 /2.00 mm
Use of honeycomb spacer frames in gaps
could avoid the need for GEM foil
stretching
Different honeycomb structures
(drift/T1/T2/induction) :
Config 1 : 12 / 12 / 12 / 12 mm
Config 2 : 6 / 12 / 12 / 12 mm
Config 3 : 6 / 0 / 0 / 0 mm
2.00 mm
Drift
 Different gap configuration for double mask GEM
GEM3
 Use of honeycomb spacers
GEM2
GEM1
Anode
 Gain and discharge probability measurements
Drift gap
3.25 mm
T1
2.215 mm
T2
2.215 mm
Induction gap
2.15 mm
Measurements @ CERN SPS H4 Beamline
Prototypes were tested during several RD51 test beam
campaigns in the CERN SPS H4 beamline with 150 GeV
muons or pions
 Gas flow ~5 l/h for different mixtures :
Ar-CO2 (70-30, 90-10)
Ar-CO2-CF4 (45-15-40, 60-20-20)
 VFAT based readout from INFN Siena-Pisa
 RD51 triple-GEM beam telescope used for tracking
RD51 triple-GEM beam telescope
VFAT readout
 3 Standard triple-GEM detectors with 10x10 cm2 active area
 Gas mixture Ar-C02 70-30%
 Strip pitch = 0.4 mm; 4x128 strips (2X-2Y)
 VFAT readout
 Always operated at a gain > 104
Tracker GEM 3
Tracker GEM 2
DIGITAL AND
SYNCHRONOUS
 Trigger
function
provides
programmable “fast OR” information
based on the region of the sensor hit
Tracker GEM 1
Beam
direction
Standard GEM
ANALOG AND
ASYNCHRONOUS
 VFAT (TOTEM) is a digital on/off
chip for tracking and triggering with an
adjustable threshold for each of the
128 channels
 Output signals synchronous
40MHz (25ns) clock
Single-Mask /
Honeycomb
GEM
with
Data Analysis Results
Muon and pion beam profile
Standard GEM Performance
Single-mask GEM Performance
Efficiency ~98%
VFAT threshold scan
Resolution ~270μm
compatible with
0.8mm strip pitch
Tunable HV divider allowed Drift and Induction field scans
4ns time resolution obtained
after correction for 25ns
VFAT jitter
Honeycomb GEM Performance
 Different prototypes fully
operational without major
problems
 Observed efficiency loss due to
honeycomb spacers
 Efficiencies :
 Config 1 ~ 50%
 Config 2 ~ 75%
 Config 3 ~ 75%
 Single-mask GEM reaches similar performance
level as standard GEM
 Efficiency plateau at ~98%
 Time resolution of 4ns obtained with 3/1/2/1
configuration and Ar-CO2-CF4 (45-15-40)
 Very high gain > 104 reachable
Clear effect of gain, gas
mixture and gap sizes on
cluster size
General conclusions
Prototypes demonstrated :
 High efficiency and high gain
 Good time resolution
 Fast electronics
 Single-mask GEM technology works well
 Honeycomb GEM needs further tuning of efficiency
IEEE
Nuclear Science Symposium and Medical Imaging Conference, Oct. 30 – Nov. 6, 2010 – Knoxville, Tennessee
www.PosterPresentations.com
TEMPLATE DESIGN © 2008
First CMS Size GEM Prototype
 First full-size triple-GEM
prototype for CMS was
produced and tested in SPS
H4 beamline during October
18-28 RD51 test beam
campaign
 Single-mask GEM technology
 4x256 readout strips, 35
GEM HV sectors, 4 η
partitions