DPF 2002, May 26 th Williamsburg, VA Triple GEM Tracking Detectors for COMPASS Klaus Dehmelt This...

DPF 2002, May 26th

Williamsburg, VA

Triple GEM Tracking Detectors for COMPASS

Klaus Dehmelt

DPF 2002 – K. Dehmelt – May, 26th

A COCOmmon MMuon and PProton AApparatus for SStructure and SSpectroscopy COMPASS

Measurement of Gluon polarization G/G due to cross-section differences (asymmetry) of open charm production(among other things)

ECAL1+2

-Wall 1+2

RICH

SM1+2

HCAL

TrackingPolarized

target

DC

MicroMegas

DPF 2002 – K. Dehmelt – May, 26th

A COCOmmon MMuon and PProton AApparatus for SStructure and SSpectroscopy COMPASS

Fixed Target Experiment

at SPS-CERN

ECAL1+2

-Wall 1+2

RICH

SM1+2

HCAL

TrackingPolarized

target

DC

MicroMegas

DPF 2002 – K. Dehmelt – May, 26th

ECAL1+2

-Wall 1+2

RICH

SM1+2

HCAL

TrackingPolarized

target

DC

MicroMegas

A COCOmmon MMuon and PProton AApparatus for SStructure and SSpectroscopy COMPASS

DPF 2002 – K. Dehmelt – May, 26th

Cover area up to ~20 cm around beam 7 stations with 14 detectors in 2001 10 stations with 20 detectors in 2002 Each station equipped with two Triple-GEM-detectors, rotated by 45º with respect to each other

Small Area Tracking (SAT) GEM (Gas Electron Multiplier)

DPF 2002 – K. Dehmelt – May, 26th

GEM - Basics

GEM structure: photolithography – etching(A. Gandi, R. de Oliveira)

DPF 2002 – K. Dehmelt – May, 26th

Applied potential difference U ~ 500V between electrodes

GEM - Basics

DPF 2002 – K. Dehmelt – May, 26th

COMPASS - GEMs

GEM: COMPASS design

Ar/CO2

(70/30)

DPF 2002 – K. Dehmelt – May, 26th

GEM: COMPASS design

COMPASS - GEMs

2-Dim Readout structure

DPF 2002 – K. Dehmelt – May, 26th

COMPASS - GEMs

GEM: COMPASS design

DPF 2002 – K. Dehmelt – May, 26th

Single cluster @ U0=4050 V

G ~ 8000

Triple-GEM properties

COMPASS - GEMs

DPF 2002 – K. Dehmelt – May, 26th

COMPASS - GEMs

Triple-GEM properties

DPF 2002 – K. Dehmelt – May, 26th

COMPASS - GEMs

Triple-GEM properties

Charge correlation ~ 1

Narrow correlation ~ 0.1

Resolve hit ambiguities

DPF 2002 – K. Dehmelt – May, 26th

COMPASS - GEMs

Triple-GEM properties

Absolute efficiency >98% @ G ~ 8000

DPF 2002 – K. Dehmelt – May, 26th

Triple-GEM properties

COMPASS - GEMs

Spatial resolution

< 50m

DPF 2002 – K. Dehmelt – May, 26th

Hit map: Positions of maximum clusters for each event (2.1 x 108

per spill)

COMPASS – GEMs Performance

DPF 2002 – K. Dehmelt – May, 26th

Hit map: Correlation

between two different

detectors, 0.5 m apart in beam

direction

(2.1 x 108 per spill)

COMPASS – GEMs Performance

DPF 2002 – K. Dehmelt – May, 26th

Summary

GEM detectors meet requirements for tracking devices in modern HEP experiments:

High rate capability

High spatial resolution

Large active area

Low material budget

No aging observed for COMPASS Triple GEM

GEM detectors will contribute to success of COMPASS

DPF 2002 – K. Dehmelt – May, 26th

The Group

B. Ketzer, M.C. Altunbas, K. Dehmelt,J. Ehlers, J. Friedrich, B. Grube,S. Kappler, I. Konorov, S. Paul,

A. Placci, L. Ropelewski, and F. Sauli