A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs A. Breskin, A. Lyashenko, R. Chechik Weizmann Institute of Science, Rehovot, Israel J.M.F. dos Santos,

A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs

A. Breskin, A. Lyashenko, R. ChechikWeizmann Institute of Science, Rehovot, Israel

J.M.F. dos Santos, F.D. AmaroUniv. of Coimbra, Portugal

J. F.C.A. VelosoUniv. of Aveiro, Portugal

High-gain Gaseous High-gain Gaseous photomultipliers photomultipliers

for the for the visible spectral rangevisible spectral range

Talk dedicated to my friend Georges CharpakCelebrating 85 in March 2009


SK 500mm Vacuum PMT

Photomultipliers should go flatPhotomultipliers should go flat!!

Flat,Low cost

Bulky,High cost~11,000 PMTs

~10mm

h

photocathode

Gaseous electron multiplier

readout

Super Kamiokande

NEXT:UNO: 56,650 PMTs

Hyper-K: 200,000 PMTs !!! who can pay?

inducedring

Gaseous PM


UV-GPMs used in UV-GPMs used in experiments:experiments:ALICE, HADES, COMPASS, J-LAB, PHENIX

UV - Gaseous Photomultipliers UV - Gaseous Photomultipliers (GPM)(GPM)

GPM Rev: Chechik & Breskin, NIM A595(2008)116

CERN-ALICE

PHENIX

Wire-chamber

Triple-GEM

400 x 600 mm2

250 x 250 mm2

CRYO: Bondar, 2008 JINST 3 P07001

UV photon

e-

readout electrode

CsI photocathode

THGEM

Double-THGEM

NEW! Thick-GEMTalk by Chechik


Secondary effects in GPMs Secondary effects in GPMs “open geometry” GPM

PCh

readout plane

+++ avalanche

photonsions

incident photon

+secondaryemission

secondaryemission

GAS

Main problem: Ions & photons secondary e emission Ion & photon feedback pulses gain & performance limitations

PC masked by electrode• Much lower photon feedback• Lower ion-feedback• better performance

Hole-multiplier

GEM

+++

V

1e in

>1000e out

Ehole

Edrift

Eind

PCh


Motivation for R&D: • large areas• flat geometry (1bar gas)• operation in magnetic fields• sensitivity to single photons• fast (ns)• high localization accuracy (sub-mm)• low cost (dream: few-$/cm2)

Visible-sensitive GPMsVisible-sensitive GPMs

Rev: Chechik & Breskin NIM A 595 (2008) 116

Sealed Triple-GEM with K-Cs-SbPrevious status:• bialkali stable under avalanche• gas detectors with coated bialkali• Sealed triple-GEM with bialkali• high gain only in pulsed-gate mode• low aging under avalanche• MAIN DIFFICULTY: ION FEEDBACK

70μm

50μm

GEM: Gas Electron MultiplierSauli, NIM A 386(1997)531

Balcerzyk, IEEE Trans. Nucl. Sci. Vol. 50 no. 4 (2003) 847


Visible-sensitive GPM: Ion-feedback developmentVisible-sensitive GPM: Ion-feedback development

1 GIBFeff stable operation of visible sensitive GPMif

200 220 240 260 280 300 320 340100

101

102

103

104

700 Torr Ar/CH4 (95/5)

Edrift

=0.5kV/cm

Tot

al g

ain

VGEM

[V]

K-Cs-Sb QE=22%@375nm

CsI

K-Cs-Sb

K-Cs-Sb, Na-K-Sb, Cs-Sb : Current deviates from

exponential Max Gain ~ few 100, IBF~10%

G~105, γ+eff ?, IBF?


IBF depends on IBF depends on effective ion-induced electron emission effective ion-induced electron emission

from PCsfrom PCs

PC K-Cs-Sb Na-K-Sb

Ion CH4+ CH4

+

γ+eff (experimental) 0.03±0.01 0.02±0.006

γ+eff (theory) 0.027 0. 029

PC

extreff

Ar/CH4 (95/5), γeff+ ~0.03, Gain ~ 105 IBF < 3.3*10-4

1 GIBFeff stable operation of visible sensitive GPMif

Lyashenko et al, in preparation

backscattering on gas moleculesFunction of Ee- (~7eV)

Function of:Eion & PC material(Eion~13eV for CH4

+) extr ~ 7% in Ar/5%CH4


Cascaded-GEM GPMs: Cascaded-GEM GPMs: high gain but also high high gain but also high ion back-flowion back-flow

SemitransparentGPM

ReflectiveGPM

107

105

103


IBF: Ion Back-Flow FractionIBF: Ion Back-Flow Fraction IBF: The fraction of avalanche-generated ions back-flowing to the photocathode

Challenge: BLOCK IONS WITHOUT AFFECTING

ELECTRON COLLECTION

Bachman, NIM A438(1999)376 IBF= 5%Breskin, NIM A478(2002)225 IBF= 2-5%Bondar, NIM A496(2003)325 IBF= 3%

@ Edrift 0.5kV/cm, Gain ~105 :

IBF~5 10-2 Need another factor of 100!!!

IBF


operated with ion gating operated with ion gating Gaseous detectors with Visible-PCGaseous detectors with Visible-PC

Ion gating

NO FEEDBACK!

GATED MULTI-GEM

DC: IBF~10-1 → gain limited to 102

Ion gating: IBF~10-4 → gain ~106

Moerman, PhD Thesis, 2005 JINST TH004Breskin, NIM A553 (2005) 46

106

But: gating dead-time; needs trigger


The Microhole & Strip plate (MHSP)Two multiplication stages on a single, double-sided, foil

R&D: Weizmann/Coimbra/Aveiro

30m

100m

100m

70m

140m

210m

MHSP: Veloso, Rev. Sci. Inst. A 71 (2000) 237Maia, NIM A A523(2004)334-344

IBF ~ 10-2

Strips: multiply charges


Reverse-biased MHSP (R-MHSP) conceptReverse-biased MHSP (R-MHSP) concept

410V 70V

AC

+++++ions

electrons

Flipped-Reversed-MHSP(F-R-MHSP)

Reversed-MHSP(R-MHSP)

Can trap its own ions

Ions are trapped by negatively biased cathode strips

Lyashenko JINST (2006) 1 P10004 Lyashenko JINST (2007) 2 P08004

Roth, NIM A535 (2004) 330Breskin NIM A553 (2005) 46Veloso NIM A548 (2005) 375

Can trap only ions from successive stages

Strips: collect ions


103 104 105 2x10510-4

10-3

10-2

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

Edrift

=0.5kV/cm

Ar/CH4 (95/5), 760 Torr

IBF

Total gain

Lyashenko 2007 JINST 2 P08004

IBF measured with 100% e-collection efficiency

IBF=3*10-4 @ Gain=105 100 times lower than 3GEMs

1st R-MHSP or F-R-MHSP: ion defocusing (no gain!)Mid GEMs: gainLast MHSP: extra gain & ion blocking

BEST ION BLOCKING:BEST ION BLOCKING:““COMPOSITE” CASCADED MULTIPLIERSCOMPOSITE” CASCADED MULTIPLIERS::

IBF=3*10-

4


NEW! “COBRA”: GEM-LIKE PATTERNED ION-SUPPRESSING ELECTRODES

New ideas for ion blockingNew ideas for ion blocking

103 104 105 10610-6

10-5

10-4

10-3

10-2

10-1

100

GPM

TPC

700 Torr Ar/CH4 (95/5)

Flipped-Cobra/2GEM

Edrift

=0.5kV/cm

IBF

Total GainIBF=3*10-6

Gain=105

IBF 1000 times lower than with GEMs; best results ever achievedBut: 20% photoelectron collection efficiency…TRYING TO IMPROVE!


Sealed detector

Test detector setup

Visible-sensitive GPMVisible-sensitive GPMUHV compatible materials

Bi-alkaliphotocathode

cascadedmultiplier

GEM/MHSP


• Multi-alkali photocathode production (QE 20-40% @ 360-420nm in vacuum for semi-transparent PC)

• Hot Indium sealing to package @130-150ºC

UHV setup for photocathode/detector investigationsUHV setup for photocathode/detector investigations

M. Balcerzyk et al., IEEE TNS Vol. 50 no. 4 (2003) 847D. Moerman, PhD Thesis 2005 JINST TH 004


• 20% QE drop @ 2 μC/mm2 ion charge on photocathode: • only ~ 4 x faster drop compared to thin ST CsI (~8 μC/mm2)

K-Sb-Cs PC ageing in avalanche modeK-Sb-Cs PC ageing in avalanche mode

Real conditions: gain=105; IBF=3*10-4. • 20% QE drop 46 years @ 5kHz/mm2 ph.• same conditions with a MWPC (IBF=1) 3000 times shorter lifetime: ~5 days!

Breskin NIM A553 (2005) 460 2 4 6 8 10 12 14 16

0,0

0,2

0,4

0,6

0,8

1,0

1,2

CsI(300A) QE~7%(180nm)

50Torr, CH4, G~103

K-Cs-Sb

PC1 QE~17% (375nm), 100Torr, G~103

PC2 QE~25% (375nm), 100Torr, G~20

PC3 QE~11% (375nm), 700Torr, G~103

Ar/CH4 (95:5)

0408

16_S

b-K

-Cs_

PC

agei

ng

Rel

ativ

e P

C c

urre

nt

PC accumulated charge [C/mm2]

Typical QE of bi-alkali PC produced in our labTypical QE of bi-alkali PC produced in our lab

300 350 400 450 500 5500

10

20

30

40

QE [%

]

Wavelength [nm]

K-Cs-Sb PC

300 350 400 450 500 5500

10

20

30

40

QE

[%]

Wavelength [nm]

Na-K-Sb PC

vacuum vacuum

K-Cs-Sb Na-K-Sb



200 220 240 260 280 300100

101

102

103

104

105

106

107

K-Cs-Sb CsI (exp. fit)

Double-GEM

Edrift

=0.5 kV/cm, QE~27%@375nm

700 Torr Ar/CH4 (95/5)

K-Cs-Sb CsI (exp. fit)

F-R-MHSP/GEM/MHSP

Tot

al g

ain

VAC_MHSP

, VGEM

[V]

Continuous operation of F-R-MHSP/GEM/MHSPContinuous operation of F-R-MHSP/GEM/MHSP with K-Cs-Sb photocathodewith K-Cs-Sb photocathode

Gain ~105 at full photoelectron collection efficiency

First evidence of continuous high gain operation of

visible-sensitive GPM

K-Cs-Sb

CsI

105


Visible-sensitive GPM featuresVisible-sensitive GPM features

Single photon sensitivityNo ion-feedback

Fast ns pulses

19 ns

0 100 200 300 400 500100

101

102

103

104

105

Gain ~ 105

Gain ~ 2*105

Gain ~ 3*105

700 Torr Ar/CH4 (95/5)

K-Cs-Sb (QE~26%@375nm)F-R-MHSP/GEM/MHSP

Cou

nts

Channel

100 photoelectrons

Lyashenko et al, JINST, in preparation


300 400 500 6000

5

10

15

20

file:

200

8-05

-25_

FR

GM

_KC

sSb_

long

_ter

m_s

tab

700 Torr Ar/CH4 (95/5)

QE in

gas

[%]

Wavelength [nm]

K-Cs-Sb

fresh PC

after 14 hoursof operation

photocathode stability photocathode stability inside UHV preparation chamberinside UHV preparation chamber

Rate: 12kHz/mm2 photonsGain: 105

Total anode charge ~125μC

0 10 20 300

5

10

15

20

file:

200

8-02

-04_

PC

_sta

bilit

y_G

AS

312nm 365nm 405nm 436nm 546nm

QE

[%]

Time [days]

K-Cs-Sb PC700 Torr Ar/CH

4 (95/5)

PC is stable in gas in the large vacuum chamber

Expected even better stability for sealed devicesKapton glass? Ceramic? Other?

gas

gas

Lyashenko et al, JINST, in preparation


BACKSCATTERING IN GAS: EFFECTIVE QEBACKSCATTERING IN GAS: EFFECTIVE QE

Coelho, NIMA 581(2007)190Breskin, NIM A483 (2002) 670

Dashed-lines are simulation

Noble gases

Divergence due to scintillationCsI

CsI

QEeff = QE x transmission (e- extraction efficiency into gas)

TRANSMISSION

TRANSMISSION

transmission

Back-scattering

h

GASPC


0,0 0,5 1,0 1,5 2,0 2,50,0

0,2

0,4

0,6

0,8

1,0

312 nm 365 nm 405 nm 436 nm 546 nm

K-Cs-Sb 700 Torr pure CH4

Tra

nsm

issi

on

Electric field [kV/cm]0,0 0,5 1,0 1,5 2,0 2,5

0,0

0,2

0,4

0,6

0,8

1,0

312 nm 365 nm 405 nm 436 nm 546 nm

K-Cs-Sb 700 Torr Ar/CH4 (95/5)

Tra

nsm

issi

onElectric field [kV/cm]

Photoelectron transmission from Photoelectron transmission from K-Cs-K-Cs-SbSb

as a function of E-field & photon wavelengths

700 Torr Methane 700 Torr Ar/CH4 (95/5)

Higher effective QE at longer WL’s

NEW


QEeff = QE x transmission (e- extraction efficiency into gas)


SummarySummary Cascaded Patterned Hole Multipliers (MHSP/GEM) • RECORD in ion blocking in gaseous detectors, crucial in GPMs• IBF~3 10-4 with full photoelectron collection efficiency! • Further improvements in progress (other patterned electrodes)• NEW: Stable visible-sensitive GPM DC-mode operation at 105

Photocathodes• “Reasonable” effective QE in 1 bar gas (18% @ 400nm); can be

improved (gas/geometry)•

Potential applications • Atmospheric-pressure large-area photon detectors!• Potential applications in Particle Physics, Astroparticle, Medical,

NDT, etc• Suitable for cryogenic operation (UV GPMs OK)

SCIENTIFICALLY FEASABLE BUT: INDUSTRIAL PROJECT!

Documents

A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs A. Breskin, A. Lyashenko, R. Chechik Weizmann Institute of Science, Rehovot, Israel J.M.F. dos Santos,