1. Fabio Sauli-CERN 1 IEEE-NSS Rome 04 F. Sauli, T. Meinschad, L. Musa, L. Ropelewski CERN, GENEVA, SWITZERLAND PHOTON DETECTION AND LOCALIZATION WITH THE GAS ELECTRON MULTIPLIER (GEM)

2. Fabio Sauli-CERN 2 IEEE-NSS Rome 04 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

3. Fabio Sauli-CERN 3 IEEE-NSS Rome 04 Quartz window (inverted) drift field grid GEM1 CsI-coated GEM2 GEM3 Anode strip readout Collimator-attenuator T0T0 EFFICIENCY AND RESOLUTION FOR UV PHOTON DETECTION Multi-GEM with Cesium Iodide coating on upper side of first GEM: Hydrogen UV lamp R C HV r ADCs

4. Fabio Sauli-CERN 4 IEEE-NSS Rome 04 SINGLE PHOTON DETECTION Pulse height spectra at decreasing UV source intensity: Single photoelectron spectra: Multiple photoelectron spectra: BEAM ATTENUATION

5. Fabio Sauli-CERN 5 IEEE-NSS Rome 04 SINGLE PHOTOELECTRON POSITION ACCURACY: Two positions of collimated beam 200 µm apart 200 µm 160 µm FWHM Beam ~ 100 µm FWHM Intrinsic accuracy ~ 50 µm rms T. Meinschad, L. Ropelewski and F. Sauli, Vienna Conference (Nucl. Instr. and Methods, in press)

6. Fabio Sauli-CERN 6 IEEE-NSS Rome 04 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

7. Fabio Sauli-CERN 7 IEEE-NSS Rome 04 HEXABOARD DETECTOR Standard assembly for 10x10 cm 2 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) 16 strips 8.3 mm 16 strips ALTRO:

8. Fabio Sauli-CERN 8 IEEE-NSS Rome 04 SINGLE PHOTON EVENT: 16 strips 8.3 mm

9. Fabio Sauli-CERN 9 IEEE-NSS Rome 04 SINGLE PHOTON CLUSTER WIDTH (rms)  ~ 0.5 pads (250 µm) Charge sharing (520 µm pad rows)

10. Fabio Sauli-CERN 10 IEEE-NSS Rome 04 DOUBLE PHOTON EVENT: 1.1 mm 2.4 mm 1.3 mm

11. Fabio Sauli-CERN 11 IEEE-NSS Rome 04 CHARGE CORRELATION BETWEEN THE PROJECTIONS: SINGLE PHOTON CLUSTERS U-V W-U V-W

12. Fabio Sauli-CERN 12 IEEE-NSS Rome 04 DETECTION OF INTERNAL SCINTILLATION IN XENON CsI - Quad-GEM in pure Xenon X-ray Scintillation 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)

13. Fabio Sauli-CERN 13 IEEE-NSS Rome 04 22 keV from 109 Cd Primary scintillation PRIMARY SCINTILLATION IN XENON-CsI

14. Fabio Sauli-CERN 14 IEEE-NSS Rome 04 LOW DRIFT FIELD: PRIMARY SCINTILLATION TIME DIFFERENCE PROMPT- MAIN PULSE Efficiency 2% for 5.9 keV 10% for 22 keV

15. Fabio Sauli-CERN 15 IEEE-NSS Rome 04 Secondary scintillation HIGH DRIFT FIELD: SECONDARY SCINTILLATION

16. Fabio Sauli-CERN 16 IEEE-NSS Rome 04 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

17. Fabio Sauli-CERN 17 IEEE-NSS Rome 04 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?

18. Fabio Sauli-CERN 18 IEEE-NSS Rome 04 SECONDARY SCINTILLATION IN XENON C.A.N. Conde et al, IEEE Trans. Nucl. Sci. NS-24 (1977) 221

19. Fabio Sauli-CERN 19 IEEE-NSS Rome 04 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

20. Fabio Sauli-CERN 20 IEEE-NSS Rome 04 Gas Electron Multiplier (GEM) F. Sauli, Nucl. Instrum. Methods A386(1997)531 70 µm140 µm

21. Fabio Sauli-CERN 21 IEEE-NSS Rome 04 5 MeV  TRACKS AT LOW FIELD

22. Fabio Sauli-CERN 22 IEEE-NSS Rome 04 (PURE) XENON DRIFT VELOCITY (ONE BAR)

23. Fabio Sauli-CERN 23 IEEE-NSS Rome 04 ELECTRON DIFFUSION IN XENON