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

SLIDE 1

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

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

SLIDE 2

Secondary effects in gaseous detectors Secondary effects in gaseous detectors

Gaseous Photo-Multiplier (GPM) Time Projection Chamber (TPC) Gaseous Photo Multiplier (GPM) Time Projection Chamber (TPC)

+ +

• nizing particle

GAS

h

incident photon

+

dynamic track

+ +

ioniz

E

drift

PC hν

+

secondary emission secondary emission

+

E

+ +

ions distortions

+

E

+ +

avalanche photons ions

d t l

E

+ +

avalanche

readout plane GAS

readout plane

Ions secondary e emission ion feedback pulses Ions

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

ion feedback pulses gain & performance limitations dynamic track distortions

SLIDE 3

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 MULTIPLIERS ti i DC d

• 2. NEW e- - MULTIPLIERS operation in DC mode

) OTHERS , MICROMEGAS…&: GEM*

• (cascaded

Challenge: BLOCK IONS WITHOUT AFFECTING Challenge: BLOCK IONS WITHOUT AFFECTING ELECTRON COLLECTION *GEM: Gas Electron Multiplier - Sauli, NIM A 386, (1997) 531.

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

SLIDE 4

Visible Visible-

• sensitive gaseous photomultipliers:

sensitive gaseous photomultipliers: Ion Ion-

• feedback development

feedback development

γeff : ion feedback coeff.

1 < ⋅ ⋅

+

G IBF

eff

γ

• stable operation of visible sensitive GPM

if

Ar/CH4 (95/5), γeff

+ ~0.03, Gain ~ 105 => IBF < 3.3*10-4

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs Visibile-sensitive gas photomultiplier review:

• M. Balcerzyk et al., IEEE Trans. Nucl. Sci. Vol. 50 no. 4 (2003) 847

4 (

), γ

+

,

SLIDE 5

IBF in cascaded GEM GPMs (high Edrift)

High Edrift (>0.5 kV/cm) needed to efficiently extract photoelectrons

B h l NIMA438(1999)376 5% @ 0 5kV/ G i 105 Bachman et al. NIMA438(1999)376 5% @ 0.5kV/cm, Gain ~105 Breskin et al. NIM A478(2002)225 2-5%@ 0.5kV/cm, Gain ~105 Bondar et al. NIM A496(2003)325 3% @ 0.5kV/cm, Gain ~ 105

N d th f t f 100!!!

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

Need another factor of 100!!!

SLIDE 6

The Microhole & Strip plate (MHSP)

30µm 70

Two multiplication stages on a single, double-sided, foil

R&D: Weizmann/Coimbra

30µm 100µm 70µm 140µm

R&D: Weizmann/Coimbra

photocathode

hv

100µm 210µm

V E drift VC-T VA-C E trans

C A

~80% of avalanche ions are trapped by cathode strips and plane

cathode mesh

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

Veloso et al. Rev. Sci. Inst. A 71 (2000) 237.

SLIDE 7

The benefit of MHSP in a cascade The benefit of MHSP in a cascade

3GEM MHSP 3GEMs+MHSP 4GEMs IBF: 20% @ Gain > 105 IBF: 3% @ Gain > 105 7 times lower than with cascaded GEMs

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

Maia et al. IEEE NS49 (2002) Maia et al. NIM A504(2003)364 Mörmann et al. NIM A516 (2004) 315

7 times lower than with cascaded GEMs

SLIDE 8

Reverse Reverse-

• biased MHSP (R

biased MHSP (R-

• MHSP) concept

MHSP) concept

Ions are trapped by negatively biased cathode strips

electrons

Flipped-R-MHSP R-MHSP

410V 70V A C

+++ ++

ions

C l f Can trap its own ions Can trap only ions from successive stages

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

Lyashenko et al., JINST (2006) 1 P10004 Lyashenko et al., JINST (2007) 2 P08004 Roth, NIM A535 (2004) 330 Breskin et al. NIM A553 (2005) 46 Veloso et al. NIM A548 (2005) 375

SLIDE 9

BETTER ION BLOCKING: BETTER ION BLOCKING: “COMPOSITE” CASCADED MULTIPLIERS: “COMPOSITE” CASCADED MULTIPLIERS: 1st R-MHSP or F-R-MHSP: ion defocusing (no gain!) Mid GEMs: in COMPOSITE CASCADED MULTIPLIERS: COMPOSITE CASCADED MULTIPLIERS: Mid GEMs: gain Last MHSP: extra gain & ion blocking

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

R-MHSP/GEM/MHSP F-R-MHSP/GEM/MHSP

SLIDE 10

IBF in “composite” micro-hole multipliers

IBF measured with 100% e-collection efficiency

10

• 1

E 0 2kV/

10

• 2

E =0 5kV/cm

TPC conditions (low drift field) Gas PMT conditions (high drift field)

10

• 3

10

• 2

E

drift=0.2kV/cm

BF

10

• 3

E

drift=0.5kV/cm

BF

10

• 4

10

F-R-M HSP/GEM /M HSP R-M HSP/GEM /M HSP A /CH (95/5) 760 T

IB

10

F-R-M HSP/GEM /M HSP R-M HSP/GEM /M HSP Ar/CH

4 (95/5), 760 Torr

IB

10

2

10

3

10

4

10

• 5

Ar/CH

4 (95/5), 760 Torr

Total gain

10

3

10

4

10

5 2x10 5

10

• 4

Ar/CH

4 (95/5), 760 Torr

Total gain

IBF=1 5*10-4 @ Gain=104 IBF=3*10-4 @ Gain=105 IBF=1.5 10 @ Gain=10 IBF=3 10 @ Gain=10 IBF is 100 times lower than with 3GEMs

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

Lyashenko et al., JINST (2007) 2 P08004

IBF is 100 times lower than with 3GEMs

SLIDE 11

R&D in course @ WEIZMANN/COIMBRA )

New ideas for ion blocking

30µm 100µm 70µm 140µm

• 100µm

210µm

NEW! “COBRA”: GEM-LIKE PATTERNED

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs NEW! COBRA : GEM LIKE PATTERNED ION-SUPPRESSING ELECTRODES (R. d’Oliveira, CERN)

SLIDE 12

IBF suppression with “Cobra” IBF suppression with “Cobra”

10

Flipped-Cobra/2GEM

3

10

• 2

10

• 1

F

IBF=2.7*10-5 Gain=104 IBF 3*10-6

5

10

• 4

10

• 3

GPM TPC

IBF

IBF=3*10-6 Gain=105

10

3

10

4

10

5

10

6

10

• 6

10

• 5

700 Torr Ar/CH4 (95/5) Edrift=0.5kV/cm

Total Gain Total Gain

IBF 1000 times lower than with GEMs, best results ever achieved

Though presently at the expense of electron collection ( 20%)

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs Though, presently at the expense of electron collection (~20%)

SLIDE 13

IBF reduction summary IBF reduction summary

TPC (Edrift=0.1-0.2kV/cm, GPM (Edrift=0.5kV/cm, TPC (Edrift 0.

• 0. kV/cm,

Gain=104) GPM (Edrift 0.5kV/cm, Gain=105) Detector type IBF Collection ffi i IBF Collection ffi i type efficiency efficiency 3GEM 0.5% 100% 5% (20%)* 100% 4GEM 100% 2% (0.01%)** 100% R MHSP/ 0 08% 100% 0 1% 100% R-MHSP/ GEM/MHSP 0.08% 100% 0.1% 100% F-R-MHSP/ 0.015% 100% 0.03% 100% GEM/MHSP “Cobra”/ 2GEM 0.0027% 20% 0.0003% 20%

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

2GEM

* Reflective PC **Gated mode

SLIDE 14

Test detector setup

Visible Visible-

• sensitive GPM

sensitive GPM

Sealed detector p

UHV compatible materials

Sealed detector

Bi-alkali PC

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

Base plate made in Novosibirsk

SLIDE 15

Visible Visible-

• sensitive GPM: Gain Divergence

sensitive GPM: Gain Divergence

3

10

4

Edrift=0.5kV/cm K-Cs-Sb QE=22%@375nm

10

2

10

3

al gain

@

Gmeas

10

1

700 Torr Ar/CH4 (95/5)

Tota

G

200 220 240 260 280 300 320 340 10

VGEM [V]

K-Cs-Sb, Na-K-Sb, Cs-Sb : Current deviates from exponential Max Gain ~ few 100, IBF~10%

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

• D. Mörmann et al.,NIM A 504 (2003) 93

SLIDE 16

Gated operation of visible Gated operation of visible-

• sensitive GPM

sensitive GPM

Ion gating electrode

G in 106 Gain~106

GATED MULTI GEM GATED MULTI-GEM

GAIN: ~100 in DC mode (ion feedback limit),IBF~10% ~106 in ion gating mode; IBF~10-4

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

A.Breskin et al. NIM A553 (2005) 46-52

~106 in ion-gating mode; IBF~10 4

SLIDE 17

DC operation of visible DC operation of visible-

• sensitive GPM

sensitive GPM

6

Flipped Cobra + 2GEMs

10

5

10

6

Flipped-Cobra/2GEM Edrift=0.5kV/cm 700 Torr Ar/CH4 (95/5) UV-LED 375nm

in

K-Cs-Sb Flipped Cobra GEMs

10

3

10

4

• tal Gai

Gain~105

CsI

50

K-Cs-Sb PC

K C Sb

200 250 300 350 10

1

10

2

K-Cs-Sb (QE~40%) CsI Exponential fit of Exponential fit of

To

20 30 40

QE [%]

K-Cs-Sb

200 250 300 350

VGEM [V]

DC Gain limit~100 in cascaded GEMs

Gain >105 in DC mode single photon sensitivity

300 400 500 600 10

Wavelength [nm]

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

But: e- collection efficiency ~ 20%

SLIDE 18

DC operation of F DC operation of F-

• R

R-

• MHSP/GEM/MHSP

MHSP/GEM/MHSP with K with K-

• Cs

Cs-

• Sb photocathode

Sb photocathode p

10

6

F-R-MHSP/GEM/MHSP E =0 5kV/cm

10

5

Edrift=0.5kV/cm 700 Torr Ar/CH4 (95/5) UV-LED 375nm

ain

10

4

K-Cs-Sb (QE~27%@375nm) CsI Exponential fit of

Ga

200 220 240 260 280 10

3

Exponential fit of Exponential fit of

VAC2 [V]

Gain ~105 at full photoelectron collection efficiency

Fi t id f DC hi h i ti f i ibl iti GPM

AC2 [ ]

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

First evidence of DC high gain operation of visible-sensitive GPM

SLIDE 19

Summary Summary

Cascaded Patterned Hole Multipliers (PHM) significant improvement in ion blocking in gaseous detectors significant improvement in ion blocking in gaseous detectors

• f importance in:

Tracking detectors (TPC) & Gaseous Photomultipliers with MHSP/GEM-based CASCADED MULTIPLIERS

• 100 times lower IBF than with cascaded GEMs

with full efficiency for collecting primary electrons! y g p y

• Gain >105 reached with visible-sensitive K-Cs-Sb PC

with Cobra/GEM-based CASCADED MULTIPLIERS

• 1000 times lower IBF than with cascaded GEMs

1000 times lower IBF than with cascaded GEMs

• with so-far low e- collection efficiency

– Gain >105 reached with visible-sensitive K-Cs-Sb PC

First evidence of high gain DC operation of visible sensitive GPM First evidence of high-gain DC operation of visible-sensitive GPM Further work:

• Optimization of COBRA

D bl id d tt d h l lti li

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs

• Double-sided patterned hole-multipliers

SLIDE 20

K-

• Cs

Cs-

• Sb stability in gas

Sb stability in gas

20

K-Cs-Sb PC 700 Torr Ar/CH (95/5)

15

[%]

700 Torr Ar/CH4 (95/5)

10

QE [

5

312nm 365nm 405nm 436nm 546nm

10 20 30

Time [days]

• A. Breskin

RD51 Amsterdam 4/08

ION BLOCKING & visible-sensitive gas-PMs