GEMs for CMS Upgrade
• Muons are quite central to most of the Physics
that would unfold from “CMS”
• Triggering and tracking with muons, is therefore
a challenging task :
Detector R&D (Hardware techniques)
Instrumentation and
Trigger generation (Software development)
• Muon detectors are in the peripheral regions
of the calorimeter, they tend :
to be large sized in areas ( 1 to 2 m2)
to have a larger granularity in the forward region
with excellent timing capabilities
 wide acceptance and robust triggering
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Physics for high eta region
• Standard Model precision measurement :
• high-η : Z production for backward-forward asymmetry
studies (important for pdf)
• precise measurements of electroweak processes where
barrel is not enough (low-pT : J/ψ, Υ)
• Exotica (new physics at 7-8 TeV mass scale) :
• Heavy-resonances
(with possible multi-leptons signatures)
• New heavy HSCP which may need precision timing
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Initial RPC end-cap system
Reduced RE
system
|η| < 1.6
η =2.4
η=2.4
Scenario with a double GE1/1 and a single GE2/1 station
in each endcap
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Forward Muon RPC Trigger system
The Forward Muon RPC trigger system is equipped with detectors at η < 1.6,
the high η region of CMS is presently vacant and presents an opportunity to instrument
it with a detector technology that could sustain the environment and be suitable for
operation at the LHC and its future upgrades.
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
4
The harsh environment
Rates Hz/cm2
RPC Region
LHC
(1034 cm2/s)
High Luminosity
LHC
(2.3 x LHC)
(1035cm2/s)
Phase II SLHC
??
RB
30
Few 100
kHz (tbc)
RE 1, 2, 3,4 h < 1.6
30
Few 100
kHz (tbc)
Total Expected
Charge in 10 years
0.05 C/cm2
0.15 C/cm2
 C/cm2
RE 1,2,3,4 h > 1.6
500 Hz  kHz
few kHz
few 10’s kHz
Total Expected
Charge in 10 years
(0.05 - 1) C/cm2
few C/cm2
few 10’s C/cm2
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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3 GEM layers on either side
h = 1.6
h = 2.1
GE 2/1
Single station
10o chambers
1 x 36 = 36
GE 1/1
Double station
20o chambers
2 x 18 = 36
72 + 8 spares = 80
GE 1/1
Double station
20o chambers
2 x 18 = 36
72 + 8 spares = 80
GE 2/1
Single station
10o chambers
1 x 36 = 36
Total 160 chambers @ 7 kCHF
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
6
Cost of GEM based upgrade
160 GEMs in 3 layers ()
1 kCHF  Rs. 50,000/SN
Item
Cost (kCHF)
1
Detector : 160 @ 7 kCHF
1120
2
Electronics
2200
3
Power Supplies & Cables
480
4
Mechanics and Services
600
5
Gas mixing and distribution systems
6
Total
7
Contingency (15%)
8
Grand Total
9
75
4475
671.25
5146.25
Rounded
5000
Total Cost : 5 MCHF  Rs. 25 Crore
This is in additional to 65 MCHF total given in the upgrade technical proposal
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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The GEM collaboration
• The GEM collaboration currently comprises
– 76 collaborators
– 14 institutions
Bari (INFN & Univ.), Beijing, CERN, Delhi, Florida Tech, Frascati, Gent, Islamabad (NCP),
Kolkata, Mumbai (BARC & TIFR), Napoli, INFN Pisa/Siena, Warsaw, and Wayne State
– 7 countries (plus CERN)
Belgium, China, India, Italy, Pakistan, Poland, USA + CERN
• Additional groups are interested in joining:
–
–
–
–
ULB Brussels, Belgium (Gilles De Lentdecker)
Tsinghua U., China (Chunhua Jian)
Panjab University, India (Jasbir B. Singh)
KODEL, Seoul, Korea (Sung Park)
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Present need for resources
In the present project stage resources are needed/used for :
 construction of small and large prototypes
(mechanics, electronics, HV dividers, detector mockup ...)
 lab equipment and consumables
 instrumentation and running during test beam campaigns
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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GEM double mask vs. single mask
Base material : Polyimide 50 µm + 5 µm Cu on both sides
•Double mask
•Single mask
•Base material
•Hole patterning in Cu
•Polyimide etch
•Bottom electro etch
•Second Polyimide Etch
• limited to 40 cm x 40 cm
• mask precision
L. M. Pant
• limited to 2 m x 60 cm
India CMS Meeting, BARC, 28 July 2011
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Present GEM foil : 1.2 m x 0.6 m
Future GEM foils : 2m x 0.6 m
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Proposed Indian contribution
GE 2/1, Single station,
Cost
10o
chambers, 1 x 36 = 36
: 1125 kCHF (22% of the projected cost)
:  Rs. 6 Crore
L. M. Pant
h = 1.6
h = 2.1
Institutes
: NPD-BARC, PU-Chandigarh, SINP, ?, ?
Cost / Institute
: Rs. 2 Crore [12th plan (2012-2017); 13th plan]
Other Indian
Institutes
Joining
: cost per institute reduces or
: one could take up extra layers
India CMS Meeting, BARC, 28 July 2011
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NPD-BARC and GEMs : 1 of 4
1.
NPD-BARC has expressed its interest (EoI) :
Sep 2010 workshop on MPGDs at CERN
2.
The necessary infrastructure exists at NPD-BARC for handling the project
3.
BARC, as a whole, is planning to join the RD51 collaboration
(procedures in the pipeline)
4.
A triple GEM (10 cm x 10 cm) procured from CERN is being configured in
RPC Lab., at NPD-BARC
5.
Gas mixing system arranged for the GEM (Ar:CO2 :: 70:30)
6.
Reactive Ion Etching of polymide surface being studied with RF plasma in
a local industry
7.
Clean volume for GEM operation being augmented
8.
Linkages to the existing programmes : RPCs for CMS
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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NPD-BARC and GEMs : 2 of 4
200 X magnification of a GEM foil
• Rejected Gem foil
• Cu etched on one side
Cu
• Polyamide film visible
within the circles
• Hole diameter  70 µm
70 µm
• Pitch  140 µm
• Equilateral triangle
symmetry
• The surface quality of GEM does not appear to be good
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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NPD-BARC and GEMs : 3 of 4
Preparations for dry etching of GEM foils
RIE machine for dry etching of polymide
surface between the etched copper in a
local industry
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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NPD-BARC and GEMs : 4 of 4
To do : Triple GEM to be configured for tests
•
•
•
•
•
•
•
GEMs active area: 10 x 10 cm2
Double mask triple GEM
1D readout (128 ch on X)
Strip pitch = 0.8mm
Gas mixture : Ar/CO2 (70/30)
Gas flow :  5 litres per hour
Test with an X-ray source
Drift
GEM3T
GEM3B
GEM2T
GEM2B
GEM1T
GEM1B
Anode
L. M. Pant
Drift gap
3.00 mm
T1
1.00 mm
Manpower
1.00 mm
 Scientist : 2
 Assistant : 1
T2
Induction gap
1.00 mm
India CMS Meeting, BARC, 28 July 2011
 Need student : 1
16
Assembly procedures : 2-3 hours
GEM foil with the
protection resistors
Read-Out board, bottom
plane
Read-Out board, top plane,
connector
Frame for stretching
Placing the foil
Mounting the frame and
stretching
Stretched GEM foil
Placing the Read-Out
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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GEMs for CMS
Saha Institute of Nuclear Physics
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Fields of Interest
Simulation
Experiment
 Characteristic responses:
gain and signal in magnetic
field
 Dynamics related issues:
transparency, efficiency, ion
back-flow, efficiency,
charging up, gas flow
 Effect of design parameters:
spacer, drift electrode
 Gas composition
 Optimization of design
parameters:
spacer and drift electrode
 Measurement of detector
dynamics:
gain, ion back-flow, gas
flow
In-Beam Tests
Data Analysis
L. M. Pant
India CMS Meeting, BARC, 28 July 2011
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Resources
Expertise
 Experiment: experience of working in both low energy and high energy
nuclear physics experiments at various national and international
accelerator facilities, operation and testing of detectors (gaseous,
solid state, scintillator), fluid dynamics, data analysis
 Programming and simulation: development of electrostatic field solver
(neBEM), interface of neBEM with GARFIELD (RD51 collaboration
WG4), detailed field and response simulation of MPGDs, fluid dynamics
Personnel (current status)
 Faculty: 3
 Student: 1
 Technician: 2
L. M. Pant
Infrastructure:
 MPGD laboratory with necessary
gas flow unit and electronics, XYZ
precision positioning system
 Blade servers, high-end work
stations
India CMS Meeting, BARC, 28 July 2011
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