Efficient ion blocking in gaseous detectors Efficient ion blocking - PowerPoint PPT Presentation

Efficient ion blocking in gaseous detectors Efficient ion blocking in gaseous detectors and its application to and its application to and its application to and its application to visible visible- -sensitive gaseous photomultipliers sensitive gaseous photomultipliers A. Breskin, A. Lyashenko and R. Chechik Weizmann Institute of Science, Rehovot, Israel & J.M.F. dos Santos, F.D. Amaro and J.F.C.A. Veloso J.M.F. dos Santos, F.D. Amaro and J.F.C.A. Veloso University of Coimbra Portugal University of Coimbra, Portugal ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

Secondary effects in gaseous detectors Secondary effects in gaseous detectors Time Projection Chamber (TPC) Time Projection Chamber (TPC) Gaseous Photo-Multiplier (GPM) Gaseous Photo Multiplier (GPM) onizing particle GAS incident photon + + ioniz h ν h + + E PC + secondary secondary drift dynamic + emission emission track distortions ions + photons + + + E ions avalanche E E + + + + GAS avalanche readout plane readout plane d t l Ions � � secondary e emission Ions � � ion feedback pulses � ion feedback pulses � dynamic track distortions � gain & performance limitations ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

IBF: Ion Back-Flow Fraction IBF: The fraction of avalanche-generated ions back- flowing to the drift region or to the photocathode � Major efforts to limit ion backflow 1. GATING � operation in “gated-mode” � deadtime, trigger 2. NEW e - - MULTIPLIERS � operation in DC mode 2 NEW MULTIPLIERS � ti i DC d (cascaded - GEM* , MICROMEGAS…&: OTHERS ) � Challenge: BLOCK IONS WITHOUT AFFECTING � Challenge: BLOCK IONS WITHOUT AFFECTING ELECTRON COLLECTION *GEM: Gas Electron Multiplier - Sauli, NIM A 386, (1997) 531. ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

Visible Visible- -sensitive gaseous photomultipliers: sensitive gaseous photomultipliers: Ion Ion- -feedback development feedback development γ eff : ion feedback coeff. if - stable operation of visible sensitive GPM eff IBF G 1 γ ⋅ ⋅ < + + ~0.03, Gain ~ 10 5 => IBF < 3.3*10 -4 Ar/CH 4 (95/5), γ eff ), γ 4 ( , + Visibile-sensitive gas photomultiplier review: M. Balcerzyk et al., IEEE Trans. Nucl. Sci. Vol. 50 no. 4 (2003) 847 ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

IBF in cascaded GEM GPMs (high E drift ) High E drift (>0.5 kV/cm) needed to efficiently extract photoelectrons B Bachman et al. NIMA438(1999)376 5% h l NIMA438(1999)376 5% @ 0 5kV/ @ 0.5kV/cm, Gain ~10 5 G i 10 5 Breskin et al. NIM A478(2002)225 2-5%@ 0.5kV/cm, Gain ~10 5 Bondar et al. NIM A496(2003)325 3% @ 0.5kV/cm, Gain ~ 10 5 N Need another factor of 100!!! d th f t f 100!!! ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

The Microhole & Strip plate (MHSP) 30 µ m 30 µ m 70 µ m Two multiplication stages on a single, 70 double-sided, foil 100 µ m 140 µ m R&D: Weizmann/Coimbra R&D: Weizmann/Coimbra 100 µ m 210 µ m hv photocathode E drift V V A-C V C-T A C E trans cathode mesh ~80% of avalanche ions are trapped by cathode strips and plane Veloso et al. Rev. Sci. Inst. A 71 (2000) 237. ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

The benefit of MHSP in a cascade The benefit of MHSP in a cascade 3GEM 3GEMs+MHSP MHSP 4GEMs IBF: 20% @ Gain > 10 5 IBF: 3% @ Gain > 10 5 7 times lower than with cascaded GEMs 7 times lower than with cascaded GEMs Maia et al. IEEE NS49 (2002) Mörmann et al. NIM A516 (2004) 315 Maia et al. NIM A504(2003)364 ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

Reverse Reverse- -biased MHSP (R biased MHSP (R- -MHSP) concept MHSP) concept Ions are trapped by negatively biased cathode strips R-MHSP Flipped-R-MHSP electrons 410V 70V C A +++ ++ ions C Can trap only ions from l f Can trap its own ions successive stages Roth, NIM A535 (2004) 330 Lyashenko et al., JINST (2006) 1 P10004 Breskin et al. NIM A553 (2005) 46 Lyashenko et al., JINST (2007) 2 P08004 Veloso et al. NIM A548 (2005) 375 ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

BETTER ION BLOCKING: BETTER ION BLOCKING: “COMPOSITE” CASCADED MULTIPLIERS: “COMPOSITE” CASCADED MULTIPLIERS: COMPOSITE CASCADED MULTIPLIERS: COMPOSITE CASCADED MULTIPLIERS: 1st R-MHSP or F-R-MHSP: ion defocusing (no gain!) Mid Mid GEMs: GEMs: gain in Last MHSP: extra gain & ion blocking R-MHSP/GEM/MHSP F-R-MHSP/GEM/MHSP ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

IBF in “composite” micro-hole multipliers IBF measured with 100% e-collection efficiency Gas PMT conditions (high drift field) TPC conditions (low drift field) -2 -1 10 10 E E =0 5kV/cm drift =0.5kV/cm E E drift =0.2kV/cm 0 2kV/ -2 10 BF BF -3 IB -3 IB 10 10 10 10 F-R-M HSP/GEM /M HSP -4 10 F-R-M HSP/GEM /M HSP R-M HSP/GEM /M HSP R-M HSP/GEM /M HSP Ar/CH Ar/CH 4 (95/5), 760 Torr 4 (95/5), 760 Torr Ar/CH A /CH (95/5) 760 T 4 (95/5), 760 Torr -4 10 -5 10 5 2x10 3 4 5 10 10 10 2 3 4 10 10 10 Total gain Total gain IBF=1 5*10 -4 @ Gain=10 4 IBF=1.5 10 @ Gain=10 IBF=3*10 -4 @ Gain=10 5 IBF=3 10 @ Gain=10 IBF is 100 times lower than with 3GEMs IBF is 100 times lower than with 3GEMs Lyashenko et al., JINST (2007) 2 P08004 ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

New ideas for ion blocking R&D in course @ WEIZMANN/COIMBRA ) 30 µ m 70 µ m 100 µ m 140 µ m 100 µ m 210 µ m � NEW! “COBRA”: GEM-LIKE PATTERNED NEW! COBRA : GEM LIKE PATTERNED ION-SUPPRESSING ELECTRODES (R. d’Oliveira, CERN) ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

IBF suppression with “Cobra” IBF suppression with “Cobra” 0 10 Flipped-Cobra/2GEM -1 10 IBF= 2.7*10 -5 -2 10 Gain=10 4 IBF 3*10 -6 IBF= 3*10 -6 F IBF -3 3 TPC 10 Gain=10 5 -4 10 GPM -5 5 10 E drift =0.5kV/cm 700 Torr Ar/CH 4 (95/5) -6 10 3 4 5 6 10 10 10 10 Total Gain Total Gain IBF 1000 times lower than with GEMs, best results ever achieved Though Though, presently at the expense of electron collection (~20%) presently at the expense of electron collection ( 20%) ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

IBF reduction summary IBF reduction summary TPC (E drift =0.1-0.2kV/cm, TPC (E drift 0. 0. kV/cm, GPM (E drift =0.5kV/cm, GPM (E drift 0.5kV/cm, Gain=10 4 ) Gain=10 5 ) Detector IBF Collection IBF Collection type type efficiency ffi i efficiency ffi i 3GEM 0.5% 100% 5% (20%) * 100% 4GEM 100% 2% 100% (0.01%) ** R MHSP/ R-MHSP/ 0 08% 0.08% 100% 100% 0 1% 0.1% 100% 100% GEM/MHSP F-R-MHSP/ 0.015% 100% 0.03% 100% GEM/MHSP “Cobra”/ 0.0027% 20% 0.0003% 20% 2GEM 2GEM * Reflective PC **Gated mode ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

Visible Visible- -sensitive GPM sensitive GPM Test detector setup p UHV compatible materials Sealed detector Sealed detector Bi-alkali PC Base plate made in Novosibirsk ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

Visible Visible- -sensitive GPM: Gain Divergence sensitive GPM: Gain Divergence 4 10 E drift =0.5kV/cm K-Cs-Sb QE=22%@375nm @ 3 3 10 al gain G meas 2 10 Tota G 1 10 700 Torr Ar/CH 4 (95/5) 0 10 200 220 240 260 280 300 320 340 V GEM [V] K-Cs-Sb, Na-K-Sb, Cs-Sb : Current deviates from exponential Max Gain ~ few 100, IBF~10% D. Mörmann et al.,NIM A 504 (2003) 93 ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

Gated operation of visible Gated operation of visible- -sensitive GPM sensitive GPM Ion gating electrode G in 10 6 Gain~10 6 GATED MULTI GEM GATED MULTI-GEM GAIN: ~ 100 in DC mode (ion feedback limit), IBF~10% ~10 6 in ion gating mode; IBF~10 -4 ~10 6 in ion-gating mode; IBF~10 4 A.Breskin et al. NIM A553 (2005) 46-52 ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin

DC operation of visible DC operation of visible- -sensitive GPM sensitive GPM Flipped Cobra Flipped Cobra + 2GEMs GEMs 6 6 10 Flipped-Cobra/2GEM K-Cs-Sb E drift =0.5kV/cm 5 10 700 Torr Ar/CH4 (95/5) in UV-LED 375nm otal Gai Gain~10 5 4 10 CsI 3 10 To K-Cs-Sb (QE~40%) 2 CsI 10 Exponential fit of Exponential fit of 50 1 10 0 K-Cs-Sb PC K-Cs-Sb K C Sb 200 200 250 250 300 300 350 350 40 V GEM [V] DC Gain limit~100 QE [%] 30 in cascaded GEMs 20 10 Gain >10 5 in DC mode � 0 300 400 500 600 single photon sensitivity Wavelength [nm] But: e - collection efficiency ~ 20% ION BLOCKING & visible-sensitive gas-PMs RD51 Amsterdam 4/08 A. Breskin