Progress in Thick GEM- -like like Progress in Thick GEM (THGEM)- - PowerPoint PPT Presentation

Progress in Thick GEM- -like like Progress in Thick GEM (THGEM)- -based Detectors based Detectors (THGEM) R. Chechik, A. Breskin, C. Shalem, M. Cortesi & G. Guedes Weizmann institute of science, Rehovot, Israel V. Dangendorf Physikalisch Technische Bundesanstalt, Braunschweig, Germany D. Vartsky & D. Bar SOREQ NRC, Yavne, Israel MOTIVATION: MOTIVATION: Robust, economic, large-area radiation imaging detectors FAST, HIGH-RATE, MODERATE LOCALIZATION RESOLUTION R. Chechik et al. SNIC @ SLAC April 2006

Gaseous multiplication in holes Gaseous multiplication in holes • Avalanche confined within a small volume • Secondary effects confined/reduced -> high gains • True pixilated structures • Possibility to CASCADE multipliers -> further higher gains 1e - in � Breskin, Charpak NIM108(1973)427 Discharge in glass capillaries � Lum et al. IEEE NS27(1980)157, Avalanches & Del Guerra et al. NIMA257(1987)609 in holes � Sakurai et al. NIMA374(1996)341, Glass Capillary plates & Peskov et al. NIMA433(1999)492 � Sauli NIMA386(1997)531 GEM GEM � Ostling, Peskov et al, IEEE NS50(2003)809 G-10 10 3 -10 4 e - out “Capillary plates” � Chechik et al. NIMA535(2004)303 High electric field in & Physics/0502131 THGEM THGEM the holes R. Chechik et al. SNIC @ SLAC April 2006

Thick GEM- -like multipliers: THGEM like multipliers: THGEM Thick GEM R. Chechik et al. NIM A535 (2004) 303-308 & R. Chechik et al. NIM A553 (2005) 35-40 Manufactured by standard PCB techniques of precise drilling drilling in G-10 (+other materials) and Cu etching Cu etching. precise ECONOMIC & ROBUST ! ECONOMIC & ROBUST ! Hole diameter d= 0.3 - 1 mm Dist. Bet. holes a= 0.7- 4 mm Plate thickness t= 0.4 - 3 mm A small THGEM costs ~3$ /unit. With minimum order of 400$ � ~120 THGEMs. ~10 times cheaper than standard GEM. R. Chechik et al. SNIC @ SLAC April 2006

Standard GEM THGEM 10 3 gain in 10 5 gain in single GEM single-THGEM Important: 0.1mm G-10 rim. reduces discharges 1mm -> high gains! Cu ? GEM ? Is THGEM an “ “Expanded Expanded” ” GEM Is THGEM an expanded does not scale up •The dimensions •Electron diffusion & transport •Electric fields •Gain •Timing properties •Rate capability •Ions transport It is a new device that has to be studied. It is a new device that has to be studied. R. Chechik et al. SNIC @ SLAC April 2006

Operation mechanism (role of all fields) Operation mechanism (role of all fields) Semi- -transparent transparent Semi photocathode photocathode Reflective Reflective E drift photocathode photocathode E Hole E trans Garfield simulation of electron multiplication in Ar/CO 2 (70:30) Need to study the effect of all fields on: - and ion transport in/out holes e - and ion transport in/out holes e -> efficiency to single-electron events -> cascade THGEMs -> ion backflow to the conversion gap Electric fields at photocathode surface Electric fields at photocathode surface -> operation with solid photocathode Gain, signal rise-time, rate capability, localization, etc R. Chechik et al. SNIC @ SLAC April 2006

Example: Photon detector w reflective CsI PC Photon detector w reflective CsI PC Example: deposited on the THGEM top face deposited on the THGEM top face (e.g. RICH photon detectors) (e.g. RICH photon detectors) Electric field on photocathode surface Electric field on photocathode surface Electric field on photocathode surface created by the hole dipole field created by the hole dipole field Maxwell software calculation 0.4mm thick 40 0.3mm holes ∆ V GEM = 2200V ∆ V THGEM =2200V 0.7mm pitch ∆ V THGEM =2200V 30 ∆ V GEM = 1200V ∆ V THGEM =1200V ∆ V THGEM =1200V Ref PC ∆ V GEM = 800V ∆ V THGEM =800V E [kv/cm] ∆ V THGEM =800V e 20 10 >3kV/cm >3kV/cm 5 0 -0.08 -0.04 0.00 0.04 0.08 Distance from center [mm] Require: • High field on the PC surface (for high QE). • Good e - focusing into the holes (for high detection efficiency). • Low sensitivity for ionizing background radiation (e.g. RICH). R. Chechik et al. SNIC @ SLAC April 2006

Photon detector w reflective CsI CsI PC PC Photon detector w reflective deposited on the THGEM top face (2) (2) deposited on the THGEM top face Gain~10 3 100 e - transfer efficiency [%] 1 Atm. 80 2.0 Ar/CH 4 (95:5) E drift 60 1.5 Ref PC E Relative e E=0 40 1.0 E 20 0.5 0 0.0 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 Edrift [kv/cm] Focusing is done by hole dipole field. Focusing is done by hole dipole field. • Maximum efficiency at E drift =0. • • Slightly reversed E drift (50-100V/cm) good photoelectron collection low sensitivity to MIPS ! R. Chechik et al. SNIC @ SLAC April 2006

Photon detector w reflective CsI CsI PC PC Photon detector w reflective deposited on the THGEM top face (2) (2) deposited on the THGEM top face Gain~10 3 100 e - transfer efficiency [%] 1 Atm. 80 2.0 Ar/CH 4 (95:5) E drift 60 1.5 Ref PC E Relative e E=0 40 1.0 E 20 0.5 0 0.0 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 Edrift [kv/cm] Focusing is done by hole dipole field. Focusing is done by hole dipole field. • Maximum efficiency at E drift =0. • • Slightly reversed E drift (50-100V/cm) good photoelectron collection low sensitivity to MIPS ! R. Chechik et al. SNIC @ SLAC April 2006

- transport into holes. Single- -THGEM: e THGEM: e - transport into holes. Single Role of E E hole Role of hole CH 4 Ar/CH 4 Ar/CO 2 CF 4 Electron transfer efficiency 1.4 gain 30 gain 20 gain 6 gain 3 Ref. PC 1.2 1.0 0.8 0.6 0.4 0.2 E drift =0 0.0 0 400 800 1200 1600 2000 2400 ∆ V THGEM [v] Full electron transfer efficiency into the holes, already at low gain. gain. Full electron transfer efficiency into the holes, already at low -> good single-electron detection efficiency -> good energy resolution with highly ionizing radiation R. Chechik et al. SNIC @ SLAC April 2006

Single- -THGEM: e THGEM: e- - transport into holes. transport into holes. Single Role of E E hole (2) Role of (2) hole gain 100 gain 10 1.2 1.2 Transfer efficiency ST PC Ar/CO 2 (70:30) 1.0 1.0 Pulse counting mode Pure CH 4 0.8 0.8 0.6 0.6 0.4 0.4 Current mode With ST PC require: 0.2 0.2 E drift =1kv/cm E drift ~1kV/cm 0.0 0.0 0 0 400 400 800 800 1200 1200 1600 1600 2000 2000 2400 2400 2800 2800 ∆ V TGEM (v) ∆ V THGEM (V) Full electron transfer efficiency into the holes, already at low gain. gain. Full electron transfer efficiency into the holes, already at low -> good single-electron detection efficiency -> good energy resolution with highly ionizing radiation R. Chechik et al. SNIC @ SLAC April 2006

Single- -THGEM: gain THGEM: gain Single Example: THGEM photon detector with reflective CsI photocathode. R. Chechik et al. NIMA553 (2005) 35-40 6 Ar/CH 4 (5%) 6 6 10 10 10 Ar/CO 2 (30%) 10 5 Atm. Pressure CH 4 5 5 5 5 10 10 10 10 4 4 4 CF 4 10 10 10 Effective Gain 3 Ref. PC 3 3 3 10 10 10 10 2 2 2 10 10 10 1 1 1 1 10 10 10 10 0 0 0 10 10 10 -1 -1 -1 -1 Single THGEM 10 10 10 10 -2 -2 -2 10 t=0.4, d=0.3, a=0.7 [mm] 10 10 -3 -3 -3 -3 10 10 10 10 0 0 500 500 1000 1500 2000 2500 3000 1000 1500 2000 2500 3000 ∆ V THGEM [v] • Gain up to 10 4 -10 5 with single electrons (sparks) Similar gain w ST PC. R. Chechik et al. SNIC @ SLAC April 2006

Single- -THGEM: counting rate THGEM: counting rate Single 5 10 4 Effective gain 10 Ref. PC 3 10 2 10 5 6 7 8 8 10 10 10 10 10 Rate [electrons / mm 2 sec] •Signal rise time < 10ns •Rate capability: ~10MHz/mm 2 (space charge) R. Chechik et al. SNIC @ SLAC April 2006

Double- -THGEM: Cascaded operation THGEM: Cascaded operation Double role of E trans role of E trans C. Shalem et al. NIM A558 (2006) 475-489 e - E hole > E trans e - focused into hole E hole < E trans e - collected on GEM top Require: Large E trans for good extraction from THGEM 1 Small E trans for good focus sing into THGEM 2 → Optimization R. Chechik et al. SNIC @ SLAC April 2006

Double- -THGEM: cascaded operation THGEM: cascaded operation Double Role of E E trans (2) Role of (2) trans Ar/CO 2 (70:30) 760torr 1.4 1.4 1.4 Pulse counting mode Both 1.2 1.2 1.2 Transfer efficiency 0.4mm thick 1.0 1.0 1.0 0.3mm holes 0.7mm pitch 0.8 0.8 0.8 0.6 0.6 0.6 0.4 0.4 0.4 ∆ V TGEM =1800V (Gain~10 4 ) ∆ V TGEM =1700V (Gain~10 3 ) ∆ V TGEM =1300V ( Gain~10 ) 0.2 0.2 0.2 0.0 0.0 0.0 0 0 0 1 2 2 2 3 4 4 4 5 6 6 6 7 8 8 8 9 E trans E Drift (kv/cm) efficient transfer to the 2 nd THGEM: efficient transfer to the 2 nd THGEM: •up to high E trans (e.g. 3kV/cm). •at relatively low THGEM gains. R. Chechik et al. SNIC @ SLAC April 2006