marcus hohlmann (florida institute of technology) with c. armaingaud, s. colafranceschi, r. de...

Marcus Hohlmann (Florida Institute of Technology)

with C. Armaingaud, S. Colafranceschi, R. De Oliveira, and A. Sharma

(CERN)

on behalf of the

CMS GEM Collaboration

Construction & Commissioning of Full-size GEM prototypes for the

CMS High- Muon System

Nov 1, 2012 2012 IEEE Nuclear Science Symposium, Anaheim, CA N38-6

11/1/2012 M. Hohlmann - Construction & Commissioning of Full-size GEM Prototypes for the CMS High-eta Muon System; IEEE NSS 2012, Anaheim, CA 2

MOTIVATION & INTRODUCTION


Premise for CMS GEM upgrade• CMS was designed with a “hermetic and redundant muon system” –

Joe Incandela, CERN “Higgs Discovery” Event, 7/4/12

• But: CMS currently has the least redundancy in the most challenging muon region, i.e. at |η| > 1.6:

RPCs descoped; only Cathode Strip Chambers currently present

• Long-term functioning of the muon system into LHC Phase II (beyond Long LHC Shutdown 3) is of vital interest for CMS. Use Phase I to evaluate muon technology for Phase II.

• The high-η muon region in particular will need robust and redundant tracking and triggering at the anticipated higher muon rates

Additional muon detectors with high spatial and temporal resolution in the high-η endcap region could bring benefits in triggering, reconstruction, and ID for muons: → GEMs


CMS GEM Endcap ChambersThe currently un-instrumented high- RPC region of the muon endcaps presents an opportunity for instrumentation with a detector technology that could sustain the radiation environment long-term and be suitable for operation at the LHC and its future upgrades into Phase II: GEM Detectors

GE3/1GE4/1

GE1/1 in YE1 nose

GE2/1 on back of YE1

CMS Detector


Method of Integration into CMS Four superchambers in their final position

Installation sequence:

A. Conde Garcia Mounting on yoke disk

Superchamber(Two Triple-GEMs)


Expected Benefits for Reconstruction & Trigger

M. Maggi (Bari) – GEM Workshop 3

Strip Readout granularity: # GEM strips / # RPC strips (orig. TDR)

Expected gains in momentum resolution at high-pT

Acceptance impact: distribution of 4 muons in H → ZZ → 4µ

Paolo Giacomelli (Bologna) & Markus Klute (MIT) – GEM Workshop 3

1.6<<2.4

for one GEM station

Expected CSC inefficiency at PU=400 due to Cathode LCT - Anode LCT timing mismatching

Staving off looming muon trigger inefficiencies at high-

Simulation

A. Safonov (Texas A&M)


CONSTRUCTION OF FULL-SIZE GEM PROTOTYPES


Evolution - GEM foil stretchingCurrent state-of-the-art: Self-stretching assembly without spacers (CERN)

Readout PCB

GEMs

Drift electrode

Tightening the horizontal screws tensions the GEMs& seals gas volume

Detector base pcb

R. De Oliveira, CMS-GEM/RD51Workshops CERN & U. Gent

Allows re-opening of assembled detector for repairs if needed.

only glue joint in assembly

2012


3rd CMS GE1/1 Prototype: “Self-Stretched - Sans Spacer”

GEM tensioningGEM foil in inner frame assembly

GEM foil with inner & outer frame

Inside of readout board with O-ring sealChamber closed byreadout board with

Panasonic connectorsfor frontend electronics

compact HV divider

Vias for strips sealed w/ kapton

HV noisefilters

-sector with 384 radial

readout strips (12.4 cm long)

base pcb with drift electrode

2012

No spacers in active volume


GEM active areas: 990 mm (220-445) mm Single-mask technology 1D radial strip read-out with 3 8 128 = 3,072 channels HV sectors: 35 3/1/2/1 mm gap sizes Gas mixtures:

Ar/CO2 (70:30; 90:10)Ar/CO2/CF4 (45:15:40; 60:20:20)

Gas flow: ≈ 5 l/h

The new self-stretching technique has been applied to the full-size CMS GEMsProduction of 5 prototypes launched in May 2012

CMS Full-size GE1/1 Detector Prototype


Prototype Production: Status & Plans

4 chambers completed at CERN • 2 in SPS test beam in summer; 3rd being prepared for fall TB• Some issue with dust particles from fiberglass frame getting

into active GEM area in first two prototypes• micro sand blasting & polyurethane coating of frames

→ change to different material (PEEK) for inner frame that holds GEMs

• 1st chamber to be assembled and commissioned outside CERN this fall (at Florida Tech)

Frame after machining

After sand blast

After PU coating


Rui De Oliveira

As a lot of dust was released during the screw insertions into FR4 frames, CERN has replaced FR4 by PEEK for inner frames.

PEEK is one of the best polymers in terms of:-radiation tolerance-mechanical properties-outgassing-chemical resistance

Next Prototype: No Gluing & PEEK frames

Use O-ring to seal outer frames to drift plane

Panasonic readout connector

Readout PCB

GEM foilsOuter frame

Inner frameDrift Board

On-foil protection resistors


We are now below 2 hours for the GE1/1 assembly with the self-stretching technique (after gluing outer frames to drift)

•Three 30cm 30cm detectors have been produced•Up to now ok

•Four 1.2m 0.45m detectors have been produced•2 tested OK but gain uniformity still to be improved

•2 others currently being tested

•Four new ones will be produced with all the improvements

to reach final specifications (< 30% gain non-uniformity)

•Preparing a new laboratory for CMS GEM assembly and quality control at CERN (spring 2013)

Rui De Oliveira

Summary of GEM production & Plans


COMMISSIONING OF FULL-SIZE GEM PROTOTYPES


CMS GEM Summer Test Beam Effort at SPS

See Poster N14-137


3rd GE1/1 Prototype: Commissioning Results

Preliminary

Preliminary

Preliminary 2012 test results (bench tests & beam test at SPS H4)

Fe55 spectrum

Rate plateauGain uniformity

Long-term Aging Test at CERN GIF

lead

shi

eld

The CMS full-size prototype has been installed in the CERN Gamma Irradiation Facility over the summerThe detector performance is being monitored along with environmental/gas variables

Ensure long-term operation in CMS Understand the effects of the radiation on the materials Understand aging origin (if any) and propose solutions

Motivations

GEM settings:

Drift: 3kV/cm, Others: 3,5 kV/cm Induction: 5 kV/cm

Gain: 8 x 103 – 104

Gas Mix: Ar/CO2/CF4 (45:15:40)

CMS high-η

maximum integrated

charge Gain of 2x104 50 MHz/cm2 X-rays,

10 days = > 20 C/cm2 integrated (LHCb)

CMS prototype

Armaingnaud/Merlin/Rohee/Furic/Buhours

See Poster N14-138


Continuing R&D: Zigzag strips to reduce readout channel count while maintaining high spatial resolution

CA

D D

esig

n by C

. Pa

ncake

, Sto

ny B

roo

k

2 mm 2 mm

Preliminary Results

Beam Test 2012

Zigzag Resolution: /2 = 73 µm

With 2mm strip pitch


PLANS FOR INSTALLATION IN CMS


GE1/1

GE1/1

ME1/1

ME1/1

GE2/1ME2/1

YOKE

GEM Installation in LHC Long Shutdown 1

P5 CAVERN UXC

Prop

osed

to C

MS

Upg

rade

Man

agem

ent

4 GEM chambers in LS1

CMS Integration and Installation of 2 GE1/1 superchambers = 4 GE1/1 chambers (and possibly 1 super-chamber GE2/1)

Measure in situ:•Rates, Background/Noise, Stability, Uniformity, Efficiency•Spatial resolution

– In the actual high-η environment – In actual magnetic field

• Split signal to CSC and participate in CMS muon trigger and reconstruction• Install new pre-production TMB prototypes on chambers that overlap with GEMs• Prove that the electronics design is working and demonstrate in situ that we can operate

CSC TMB with GEM input in various operating regimes• Reduce CSC X-Y ambiguity and ghosts• Once we go into beam operations, we will demonstrate the above again, this time

measuring muon trigger rates and efficiency with and without GEMs.

Participate in CRAFT 2014


GEM DAQ Prototype System for LS1

P. Aspell

DAQ also with link to newCSC Trigger Mother Board

Gigabit Link Interface Boards


Summary & OutlookLong Shutdown 1 (LS1) • 4 full-size GE1/1 detectors successfully constructed using simplified

self-stretch & sans spacer technique; being validated• GEM electronics and DAQ prototype underway • Installation, services, and integration with CSC’s underway• Zero additional cost to CMS upgrade projects• GEMs to participate in CRAFT 2014

Long Shutdown 2 (LS2)• A GE1/1 station can be completed and installed in LS2 • Capacity in CERN Workshop to produce all (72 validated) detectors in

2 years; final electronics ready for 2015• Cost 2-3 MCHF


Thank you for your time!We would like to explicitly acknowledge here the strong technical support received from the RD51 Collaboration for this project!

marcus hohlmann (florida institute of technology) with c. armaingaud, s. colafranceschi, r. de...

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