Slide1: F. Sauli, T. Meinschad, L. Musa, L. Ropelewski CERN, GENEVA, SWITZERLAND PHOTON DETECTION AND LOCALIZATION WITH THE GAS ELECTRON MULTIPLIER (GEM)


Slide2: REFLECTIVE PHOTOCATHODE ON UPPER GEM SIDE: no photon feedback MULTIGEM DETECTORS: VERY HIGH GAINS Single photoelectron detection with internal photocathode S. Bachmann et al, Nucl. Instr. Methods A 443(1999)464 R. Bouclier et al, IEEE Trans. Nucl. Sci. NS44(1997)646 D. Mörmann et al, Nucl. Instr. Methods 478(2002)364


Slide3: Quartz window (inverted) drift field grid GEM1 CsI-coated GEM2 GEM3 Anode strip readout Collimator-attenuator T0


Slide4: SINGLE PHOTON DETECTION Pulse height spectra at decreasing UV source intensity: Single photoelectron spectra: Multiple photoelectron spectra: BEAM ATTENUATION


Slide5: 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)


Slide6: Hexaboard readout: matrix of hexagonal pads interconnected along three projections at 120º U V W GEM RICH: MULTIPLE PHOTONS Hexaboard closeup: 520 µm Ø pads S. Bachmann et al Nucl. Instr. and Meth. A 478 (2002) 104


Slide7: HEXABOARD DETECTOR Standard assembly for 10x10 cm2 GEMs, 3x128 strips 3x16 strips readout: fast charge amplifier+ALTRO (FADC, 10 bit-25 MHz sampling) B. Mota et al, Nucl. Instr. and Methods, in press (2004) ALTRO:


Slide8: SINGLE PHOTON EVENT: 16 strips 8.3 mm


Slide9: SINGLE PHOTON CLUSTER WIDTH (rms) ~ 0.5 pads (250 µm) Charge sharing (520 µm pad rows)


Slide10: DOUBLE PHOTON EVENT:


Slide11: CHARGE CORRELATION BETWEEN THE PROJECTIONS: SINGLE PHOTON CLUSTERS U-V W-U V-W


Slide12: 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)


Slide13: 22 keV from 109Cd PRIMARY SCINTILLATION IN XENON-CsI


Slide14: LOW DRIFT FIELD: PRIMARY SCINTILLATION TIME DIFFERENCE PROMPT- MAIN PULSE Efficiency 2% for 5.9 keV 10% for 22 keV


Slide15: HIGH DRIFT FIELD: SECONDARY SCINTILLATION


Slide16: 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


Slide17: 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?


Slide18: SECONDARY SCINTILLATION IN XENON C.A.N. Conde et al, IEEE Trans. Nucl. Sci. NS-24 (1977) 221


Slide19: Manufactured by CERN-EST workshops 31 cm Large size Hexaboard for MICE (Muon Ionization Cooling Experiment): V. Ableev et al, Nucl. Instr. and Meth. A518(2004)113


Slide20: Gas Electron Multiplier (GEM) F. Sauli, Nucl. Instrum. Methods A386(1997)531 70 µm 140 µm


Slide21: 5 MeV a TRACKS AT LOW FIELD


Slide22: (PURE) XENON DRIFT VELOCITY (ONE BAR)


Slide23: ELECTRON DIFFUSION IN XENON