108.07.11 RD51 mini week – Samuel Duval

01

Hybrid Multi Micro-Pattern Gaseous Photomultiplier for detection of liquid xenon

scintillationS. Duval,a L. Arazi,b A. Breskin,b R. Budnik,b W-T. Chen,a H. Carduner,a A.E.C. Coimbra,c M. Cortesi,b

R. Kaner,b J-P. Cussonneau,a J. Donnard,a J. Lamblin,a O. Lemaire,a P. Le Ray,a J. A. M. Lopes,c E. Morteau,a T. Oger,a J.M.F. dos Santos,c L. Scotto Lavina,a J-S. Stutzmann,a and D. Thers,a

a. Subatech, Ecole des Mines, CNRS/IN2P3 and Université de Nantes, 44307 Nantes, Franceb. Departement of Astrophysics and Particle Physics, Weizmann Institute of Science, 76100 Rehovot, Israel

c. Instrumentation Centre, University of Coimbra, 3004-516 Coimbra, Portugal

2NDIP 2011 – Samuel Duval

γ511keV

γ511keV

Scandium 44

Radioisotope : (β+, γ) emitter

Compton telescopeLiquid xenon

Context: 3γ imaging

C. Grignon et al., NIM A 571 (2007) 142

3NDIP 2011 – Samuel Duval

∆l = f(σE, σx, σy, σz)γ511keV

γ511keVE0 = 1,157 MeV

GPM

(E1, x1, y1, z1)

(E2, x2, y2, z2)

θΔ

Liquid xenon

Compton telescope

Context: 3γ imaging

Large Gaseous Photomultiplier

S. Duval et al., JINST 4 (2009) P12008

Cryo-GPM: of interest for Next Generation Dark Matter Experiments!

4NDIP 2011 – Samuel Duval

XEnon Medical Imaging System

Circulation & Purification circuit

Cryostat

Remote PTR

Biggest LXe facility in France!

5NDIP 2011 – Samuel Duval

Collection (THGEM) Eampl

Ecoll ~ 0

Etrans

Eind

Entrance window (MgF2 ou SiO2)

Liquid xenon

Cathode

Anode

Ne mixtures

Energy loss

UV photons

Transfer gap

Induction (MICROMEGAS)

Amplification (PIM)

Transfer gap

Eampl

Eampl

γ

Cryogenic GPM prototype principle

500 lpi

670 lpi

CERN grid

Photoelectric effect

THGEM

Reflective CsI photocathode QE (vacuum):

~30% @ 170nm

THGEM: Efficient photoelectron collection + low gainPIM/MICROMEGAS: ion blocking (less CsI damage) & gain

6NDIP 2011 – Samuel Duval

EAmpl

EDrift

Colas et al., NIM A 235 (2004) 226

Electric field lines

Ion

back

flow

EAmp/EDrift

J. Beucher, 2008

Ion blocking with micromeshes

Elementary mesh

125

µm

50-100 µm

3 mm

Parallel Ionization Multiplier

Zoom

500 lpi

670 lpi

Ion blocking

Avalanche-ions blocking reduced damage to CsI photocathode

Studies in Ne-mixtures in course

7NDIP 2011 – Samuel Duval

THGEM + supports

500 lpi grid*

670 lpi grid*

Kapton spacer (125 microns)

MICROMEGAS (50 microns)

Anode (ROGERS)

Base (stainless steel)

LXe GPM prototype (LXe side)

Vacuum sideGas

SHV

Cryogenic GPM prototype structure

*Precision EForming .LLC

THGEM/PIM/MICROMEGASInternal structure

Viewport (MgF2)

8NDIP 2011 – Samuel Duval

• Ne/CH4 (95:5):– Leading effect at LXe temp: backscattering due to 1.7 fold higher density– Water condensation on CsI suspected for further ~10% efficiency loss

• Pure CH4:– Nearly no backscattering (>90% above ~1 kV/cm)– Essentially no difference between LXeT and RT at same density (possibly

less water in this measurement)

CsI photoemission in cryogenic conditions

E

Ne-mixtures lower operation HV but lower efficiency (~60% of vacuum value)CH4 high operation HV, but high extraction efficiency (close to vacuum)Other gases investigated

Vacuum value

~60% of Vacuum value

9NDIP 2011 – Samuel Duval

THick Gaseous Electron Multiplier

Extraction efficiency

Gas

∆VTHGEM

Geometric characteristics:• Ø holes «d» = 300 µm • pitch «m» = 700 µm• thickness «e» = 400 µm• rims «c» = 50 µm

Eextr1 = 1kV/cm

32 mm

Cu(Au) ElectrodeG10

A. Breskin et al., NIM A 598 (2009) 107

Electric field (kV/cm)

0.5 1 1.5 2

0

x

High surface electric field good photoextraction

using Elmer software

(Ecoll = 0 kV/cm; ∆VTHGEM = 600V; Eextr1 = 1kV/cm)

10NDIP 2011 – Samuel Duval

GPM on cryostat

Liquid xenon

Vacuum

Cryogenic tests bench

Rate < 2 ln/h

∆Tin/out ~ 2K

PGPM = 1100 mbar, T = 171 K, PXe = 1200 mbar

Gas flow meters

Isolation vacuum

Pressure regulator

Gas outlet

valves

Pump

Pump Getter

55Fe

Pulse Tube Refrigerator

Cryostat

Ne

CF4

Liquid xenonGetter

Bypass

11NDIP 2011 – Samuel Duval

Gain measurements in pulse-mode with 55Fe source

THGEM

55Fe source

Eextr1

Eextr2

Ecoll

THGEM gain with extraction in Ne/CF4 (90:10) at 171K (Eextr1 = 1kV/cm)

5.9 keV x-ray

THGEM/PIMTHGEM/PIM/MICROMEGAS∆VTHGEM > 700V = E > 1kV/cm∆VTHGEM < 900V = Gtextr < 100

12NDIP 2011 – Samuel Duval

Gain measurements in pulse-mode with 55Fe source

Hybrid GPM : THGEM/PIM/MICROMEGAS

Polarization voltages:Ecoll = 0.25kV/cm∆VTHGEM = 900VEextr1 = 1kV/cm

∆VPIM = 490VEextr2 = 0.8kV/cm∆Vmicro = 330V High total gain!

With low THGEM gain

13NDIP 2011 – Samuel Duval

55Fe photoelectric peak

55Fe Hybrid GPM pulse

Fast 50Ω signal readout

25ns

GPM

u = Ri R

Readout

Almost like a PMT!

Oscilloscope snapshot : T = 173K; Ne/CF4 (90:10); Gain ~106

14NDIP 2011 – Samuel Duval

Conclusions

• High gains at LXe T ~106

• Efficient ion blocking expected also in Ne-mixtures

• CsI photocathode studies in progress

• Large-size prototype for Medical Imaging in designfor a LXe Compton Telescope (target: 20 inch diameter)

• GPM for LXe/LAr Dark Matter detectors: in course

Vacuum PMT pulse

Hybrid MPGD GPM: 238Pu scintillation pulse from LXe

Ne/CF4(90:10)T = 173KP = 1100mbar

S. Duval et al., JINST 6 (2011) P04007

GPM pulse

WIMPinteraction

LXe

e-

GPM Detector

Primaryscintillation

EG

EL

Secondaryscintillation GXe

UV-window

GPM Detector

UV-window

15NDIP 2011 – Samuel Duval

Thank you !