a. breskin , a. lyashenko, r. chechik weizmann institute of science, rehovot, israel
DESCRIPTION
High-gain Gaseous photomultipliers for the visible spectral range. A. Breskin , A. Lyashenko, R. Chechik Weizmann Institute of Science, Rehovot, Israel J.M.F. dos Santos, F.D. Amaro Univ. of Coimbra, Portugal J. F.C.A. Veloso Univ. of Aveiro, Portugal. - PowerPoint PPT PresentationTRANSCRIPT
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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 PMTsHyper-K: 200,000 PMTs !!! who can pay?
inducedring
Gaseous PM
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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-chamberTriple-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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
70μm50μm
GEM: Gas Electron MultiplierSauli, NIM A 386(1997)531
Balcerzyk, IEEE Trans. Nucl. Sci. Vol. 50 no. 4 (2003) 847
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
Tota
l gai
n
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?
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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-SbIon 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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
Reverse-biased MHSP (R-MHSP) conceptReverse-biased MHSP (R-MHSP) concept
410V 70VAC
+++++ions
electronsFlipped-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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
NEW! “COBRA”: GEM-LIKE PATTERNED ION-SUPPRESSING ELECTRODESNew 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 Gain IBF=3*10-6
Gain=105
IBF 1000 times lower than with GEMs; best results ever achievedBut: 20% photoelectron collection efficiency…TRYING TO IMPROVE!
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
Sealed detectorTest detector setup
Visible-sensitive GPMVisible-sensitive GPMUHV compatible materials
Bi-alkaliphotocathode
cascadedmultiplier
GEM/MHSP
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
• 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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
• 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, CH
4, 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_P
Cage
ing
Rela
tive
PC 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
Lyashenko et al, in preparation
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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%@375nm700 Torr Ar/CH4 (95/5)
K-Cs-Sb CsI (exp. fit)
F-R-MHSP/GEM/MHSP
Tota
l gai
nV
AC_MHSP, V
GEM [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 efficiencyFirst evidence of continuous high gain
operation of visible-sensitive GPM
K-Cs-Sb
CsI105
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
Visible-sensitive GPM featuresVisible-sensitive GPM features
Single photon sensitivityNo ion-feedback
Fast ns pulses
19 ns0 100 200 300 400 500
100
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
Coun
ts
Channel
100 photoelectrons
Lyashenko et al, JINST, in preparation
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
300 400 500 6000
5
10
15
20
file: 2
008-
05-2
5_FR
GM
_KCs
Sb_lo
ng_t
erm
_sta
b
700 Torr Ar/CH4 (95/5)
QE
in g
as [%
]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: 2
008-
02-0
4_PC
_sta
bility
_GAS
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
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
transmissionBack-scattering
h
GASPC
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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
Tran
smis
sion
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)
Tran
smis
sion
Electric 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
Lyashenko et al, in preparation
QEeff = QE x transmission (e- extraction efficiency into gas)
A. BreskinTIPP09 Tsukuba VISIBLE-SENSITIVE GAS-PMs
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!