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PHOTON DETECTION AND LOCALIZATION WITH THE GAS ELECTRON MULTIPLIER (GEM). F. Sauli, T. Meinschad, L. Musa, L. Ropelewski CERN, GENEVA, SWITZERLAND. REFLECTIVE PHOTOCATHODE ON UPPER GEM SIDE: no photon feedback. MULTIGEM DETECTORS: VERY HIGH GAINS
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PHOTON DETECTION AND LOCALIZATION WITH THE GAS ELECTRON MULTIPLIER (GEM) F. Sauli, T. Meinschad, L. Musa, L. Ropelewski CERN, GENEVA, SWITZERLAND
REFLECTIVE PHOTOCATHODE ON UPPER GEM SIDE: no photon feedback MULTIGEM DETECTORS: VERY HIGH GAINS Single photoelectron detection with internal photocathode R. Bouclier et al, IEEE Trans. Nucl. Sci. NS44(1997)646 S. Bachmann et al, Nucl. Instr. Methods A 443(1999)464 D. Mörmann et al, Nucl. Instr. Methods 478(2002)364
EFFICIENCY AND RESOLUTION FOR UV PHOTON DETECTION Multi-GEM with Cesium Iodide coating on upper side of first GEM: Hydrogen UV lamp R HV C r ADCs T0 Collimator-attenuator Quartz window (inverted) drift field grid GEM1 CsI-coated GEM2 GEM3 Anode strip readout
SINGLE PHOTON DETECTION Pulse height spectra at decreasing UV source intensity: Single photoelectron spectra: Multiple photoelectron spectra: BEAM ATTENUATION
200 µm 160 µm FWHM Beam ~ 100 µm FWHM Intrinsic accuracy ~ 50 µm rms SINGLE PHOTOELECTRON POSITION ACCURACY: Two positions of collimated beam 200 µm apart T. Meinschad, L. Ropelewski and F. Sauli, Vienna Conference (Nucl. Instr. and Methods, in press)
GEM RICH: MULTIPLE PHOTONS Hexaboard closeup: 520 µm Ø pads Hexaboard readout: matrix of hexagonal pads interconnected along three projections at 120º U V W S. Bachmann et al Nucl. Instr. and Meth. A 478 (2002) 104
16 strips 16 strips 16 strips 8.3 mm HEXABOARD DETECTOR Standard assembly for 10x10 cm2 GEMs, 3x128 strips 3x16 strips readout: fast charge amplifier+ALTRO (FADC, 10 bit-25 MHz sampling) ALTRO: B. Mota et al, Nucl. Instr. and Methods, in press (2004)
SINGLE PHOTON EVENT: 16 strips 8.3 mm
SINGLE PHOTON CLUSTER WIDTH (rms) • ~ 0.5 pads (250 µm) Charge sharing (520 µm pad rows)
2.4 mm 1.1 mm 1.3 mm DOUBLE PHOTON EVENT:
CHARGE CORRELATION BETWEEN THE PROJECTIONS: SINGLE PHOTON CLUSTERS U-V W-U V-W
Scintillation DETECTION OF INTERNAL SCINTILLATION IN XENON CsI - Quad-GEM in pure Xenon X-ray Ionization G. Charpak, S. Majewski and F. Sauli, Nucl. Instr. and Meth. 126(1975)381 L. Periale, V. Peskov, P. Carlson, T. Francke, V. Pavlopulos, P. Picchi, F. Pietropaolo, Nucl. Instr. and Meth. 478(2002)377 (See also V. Peskov N25-3)
Primary scintillation PRIMARY SCINTILLATION IN XENON-CsI 22 keV from 109Cd
TIME DIFFERENCE PROMPT- MAIN PULSE LOW DRIFT FIELD: PRIMARY SCINTILLATION Efficiency 2% for 5.9 keV 10% for 22 keV
Secondary scintillation HIGH DRIFT FIELD: SECONDARY SCINTILLATION
TIME DIFFERENCE PROMPT- MAIN PULSE HIGH FIELD: SECONDARY SCINTILLATION 5.9 keV X-rays Efficiency for 5.9 keV 20% at 1.3 kV/cm 66% at 1.9 kV/cm 76% at 2.5 kV/cm
CONCLUSIONS MULTI-GEM DETECTORS WITH CsI PHOTOCATHODE: HIGH GAIN-EFFICIENT UV PHOTON DETECTION VERY GOOD POSITION ACCURACY ~ 50 µm rms WITH HEXABOARD READOUT: GOOD MULTI-HIT RESOLUTION ~ 2 mm GEM-CsI FOR DETECTION OF SCINTILLATION IN Xe EFFICIENCY FOR PRIMARY SCINTILLATION ~ 10% FOR 22 keV EFFICIENCY FOR SECONDARY SCINTILLATION ~ 80% FOR 5.9 keV TOWARDS A PARALLAX-FREE X-RAY DETECTOR?
SECONDARY SCINTILLATION IN XENON C.A.N. Conde et al, IEEE Trans. Nucl. Sci. NS-24 (1977) 221
Large size Hexaboard for MICE (Muon Ionization Cooling Experiment): Manufactured by CERN-EST workshops 31 cm V. Ableev et al, Nucl. Instr. and Meth. A518(2004)113
Gas Electron Multiplier (GEM) 70 µm 140 µm F. Sauli, Nucl. Instrum. Methods A386(1997)531
