1 / 20

Operation of MHSP electron multipliers at atmospheric-to-high pressures

Operation of MHSP electron multipliers at atmospheric-to-high pressures. J. F. C. A. Veloso a,b , F. Amaro a , J. M. Maia a,c , A. Breskin d , R. Chechik d , J. M. F. dos Santos a a Physics Dept., University of Coimbra, 3004-516 Coimbra, Portugal

ugo
Download Presentation

Operation of MHSP electron multipliers at atmospheric-to-high pressures

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Operation of MHSP electron multipliers at atmospheric-to-high pressures J. F. C. A. Velosoa,b, F. Amaroa, J. M. Maiaa,c, A. Breskind, R. Chechikd, J. M. F. dos Santosa aPhysics Dept., University of Coimbra, 3004-516 Coimbra, Portugal bPhysics Dept., University of Aveiro, 3810-193 Aveiro, Portugal cPhysics Dept., University of Beira Interior, 6200-001 Covilhã, Portugal dDept. of Particle Physics, The Weizmann Institute of Science, 76100 Rehovot, Israel 2004 VCI - Vienna

  2. The Micro-Hole & Strip Plate gas detector operation • A MSGC and GEM combination in a single plate • hole / strip pitch ~ 200 µm • 2 multiplication stages • High gain • 2D capability • 2 sided patterns on MHSP • Patterned cathode plane e.g., Veloso et al, RSI, 71(2000)2371 Veloso et al, RSI, 73(2002)488 Maia et al., NIM A 504 (2003)364 VCI - 2004

  3. Motivation • Atmospheric pressure: • High gain multipliers in standard and noble-gas mixtures (simple to purify - no gas ageing) • X-ray & UV-Photon detectors • High pressures: • Noble gas mixtures • Dual-phase (liq/gas) detectors: Dark-matter, PET, etc • X-ray & n detectors, etc VCI - 2004

  4. 200μm MHSP production • Attempts to overcome this limitations are in progress: • Kapton/Cu etching improvement • Ceramic and others… Top Bottom • Production limitations • Low production yields • Photolithographic defects • Low voltage limit VCI - 2004

  5. General Features • This device provides: • High gain • Fast charge collection • High energy resolution • Low ion back-flow to conversion region • Low UV photon feedback • 2-D intrinsic capability • Large field of applications VCI - 2004

  6. Gas Gain • Gain > 5x104 @ 1 bar • Hole gain ≈ 103 • MS gain ≈ 30-50 Ar/5%Xe Veloso et al., NIMA 2004, in press. VCI - 2004

  7. Pulse shape – rise time Ar-30%CO2 5.9 keV x-rays Fast Charge Collection • GEM+MHSP - rise time < 10 ns (charge collected at MHSP anode) • Double GEM - rise time < 20 ns (charge collected on the 2º GEM bottom) Maia et al., NIM A 504 (2003)364 VCI - 2004

  8. Energy Resolution • Very good energy resolution: 13.7 %FWHM @ 5.9 keV • Low background Ar – 5%Xe , 1bar VCI - 2004

  9. GEM MHSP Ion back-flow • Back-flow of avalanche-ions “dangerous” particularly in photon detectors • Induces ion-feedback! • Damage to photocathode • Reduction of 80 % ion back flow. • Compares favourably with single-GEM, where all ions flow back! Maia et al., NIM A 2004, in press. VCI - 2004

  10. hv Monte Carlo Simulation photocathode Oleg Bouianov (LNS/MIT) simulations agree with the experiment cathode mesh VCI - 2004

  11. The multi-GEM & MHSP photomultiplier Maia et al., NIM A 2004, in press. • High gain and low ion back flow: 2-3% • Important also in TPCs! Mörmann, NIM A, in press: 20 % for 4-GEM VCI - 2004

  12. Gas Gain for Ar/Xe Variables: pressure; Xe-concentration VCI - 2004

  13. Gain limited by imperfections Gas Gain for Ar/ 50mb Xe VCI - 2004

  14. Comparative Spectra for 1 and 6 bar VCI - 2004

  15. Pure Xenon Preliminary Results dE/E ~ 7% FWHM Bondar et al. NIM A481(2002)200: gain 104 @ 1 bar for 3-GEM VCI - 2004

  16. Ar/Xe + He:detection possibility of thermal-n Veloso et al., IEEE-TNS 2003, submitted VCI - 2004

  17. Conclusions • Significant ion back flow reduction in GEM cascades • Very important in photosensor or TPC applications. • The operation in noble gases at high pressures was demonstrated. • Gains > 103 for Ar/50 mbar Xe up 7 bar. • Gains ~ 103 for pure xenon at 1 and 2 bar. • Future work: • More systematic studies for different gases and higher pressures. • Improved technology will result in improved performance. VCI - 2004

  18. 3 mm 1.5 mm 1.5 mm 0.5 mm 1.5 mm 0.4 mm X-ray imaging 2-GEM + MHSP Ar/5% CH4, 1 bar x- FWHM ~250 μm y- FWHM ~200 μm • Wedge &Strip readout • Ar/5%CH4, 1 bar • G~105 at anode-strips • Ge-layer signal transmission ~15% • -> W&S signal amplitude ~7 x lower Maia et al. to be submitted to NIMA VCI - 2004

  19. MHSP+CsI as a photosensor of a GPSC Preliminary Results • 6 Photoelectrons from CsI per primary per primary electron.  photoelectron collection efficiency ~ 13 % (43%/EQ). • The RE = 16 % obtained is still far from the 8 % obtained for a standard GPSC. VCI - 2004

  20. VCI - 2004

More Related