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Present status and perspective of cryogenic liquid detectors. Satoshi SUZUKI Waseda University. 13/Mar./2006 Cryodet @ Gran Sasso. Recent Development of Cryogenic liquid detectors. ICARUS. Pioneer of LAr TPC. NuMI T2K LXe TPC. Technology of LAr TPC was established by ICARUS.

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Satoshi SUZUKI Waseda University

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Satoshi suzuki waseda university

Present status and perspective of cryogenic liquid detectors

Satoshi SUZUKI

Waseda University

13/Mar./2006

Cryodet @ Gran Sasso


Satoshi suzuki waseda university

Recent Development of Cryogenic liquid detectors

ICARUS

Pioneer of LAr TPC

NuMI

T2K

LXe TPC

Technology of LAr TPC was established by ICARUS.

Enlargement : 1kg---several steps---300ton(600ton)-〜10kton(final)

MEG

First big LXe detector form eg experiment

Energy resolution

Timing resolution

Position resolution

Demonstrate the potential of LXe detector

XMASS

Simple scintillation detector

Self Shielding

CLEAN(LNe)

The biggest LXe detector

for DM and pp 7Be solar n

DAMA(LXe)

ZEPLIN I

XMASS Ⅱ

ZEPLIN Ⅱ〜Ⅳ

XENON

WALP(LAr)

Double Phase Detector

DM search


Meg experiment

Signal

Eg = mm/2 = 52.8MeV

Ee = mm/2 = 52.8MeV

q = 180o

Time coincidence

g

m

e

MEG Experiment

Expected sensitivity 〜 order of 10-14

(present limit = 1.2x10-11)


Liquid xe scintillation

  • Large light output yield

    • Wph(1MeV e) = 22.4eV

  • Pile-up event rejection

    • Fast response and short decay time

  • Uniform

Liquid Xe scintillation


Meg xenon detector

MEG Xenon Detector

  • Active volume ~800l is surrounded PMTs on all faces

  • ~850PMTs in the liquid

  • No segmentation

  • Energy

    • All PMT outputs

  • Position

    • PMTs on the inner face

  • Timing

    • Averaging of signal arrival time of selected PMTs


Large prototype

Large Prototype

  • 70 liter active volume (120 liter LXe in use)

  • 238PMTs immersed in LXe

  • Large enough to contain 50MeV g event(17X0)

  • Performance test using

    • 10, 20, 40MeV Compton g beam

    • 60MeV Electron beam

    • g from p0 decay


Energy resolutions

Energy Resolutions

55 MeV

83 MeV to Xe

55 MeV to Xe

Exenon[nph]

83 MeV


Energy resolution vs energy

Energy Resolution vs Energy

PSI 2004

TERAS 2003

alpha

Right  is a nice function of gamma energy


Examples of reconstruction

Examples of Reconstruction

(40 MeV gamma beam w/ 1 mm collimator)


Absolute timing xe lyso analysis

Absolute timing, Xe-LYSO analysis

high gain

normal gain

103 psec

110 psec

55 MeV

Normal gain

High gain

A few cm in Z


Liquid phase circulation system

Liquid phase circulation system

Absorption length > 5m

in 10hours

1 m

2.5 m

5 m


Pmt development summary

PMT DevelopmentSummary


Self shielding for low energy events

Self-shielding for low energy events

Fiducial volume

liquid Xe

Volume for shielding

Fiducial volume

BG normalized by mass

PMTs

6 orders of magnitude reduction

for gamma rays below 500keV


Isotope separation

Isotope separation

Abundance of natural Xe

bb nucleon

124Xe 126Xe 128Xe 129Xe130Xe 131Xe132Xe 134Xe 136Xe

(0.10%) (0.09% ) (1.92%) (26.4%) (4.07%) (21.2%) (26.9%) (10.4%) (8.87%)

Even enriched

Odd enriched

Separate here

Dark Matter Ⅱ

Spin dependent

Dark Matter Ⅰ

2nbb/0nbb

Solar neutrino


Satoshi suzuki waseda university

10 ton detector

Strategy of the scale-up

800kg detector

100kg Prototype

~30cm

~80cm

R&D

~2.5m

Dark matter search

We are here

Multipurpose detector

(solar neutrino, bb …)


100 kg prototype detector

54 2-inch low BG PMTs

Hamamatsu R8778

16% photo-

coverage

Liq. Xe (31cm)3

MgF2 window

100 kg prototype detector

In the Kamioka Mine

(near the Super-K)

2,700 m.w.e.

OFHC cubic chamber

Gamma ray shield


Satoshi suzuki waseda university

hole C

hole A

hole B

DATA

MC

Performance of the vertex reconstruction

Collimated g ray source run from 3 holes (137Cs, 662keV)

+

+

+

C

A

B

→ Vertex reconstruction works well


Satoshi suzuki waseda university

All volume

20cm FV

10cm FV

Performance of the energy reconstruction

Collimated g ray source run from center hole

137Cs, 662keV

[email protected]

(s/E ~ 10%)

Similar peak position in each fiducial.

No position bias

→ Energy reconstruction

works well


800kg detector

  • Total 840 hex PMTs

    immersed into liq. Xe

  • 70% photo-coverage

  • Radius to inner face ~43cm

800kg detector

  • A tentative design

    (not final one)

12 pentagons / pentakisdodecahedron

Eth = 5 keVee~25 p.e.

This geometry has been coded in a Geant 4 based simulator


Hamamatsu r8778mod hex

Hamamatsu R8778MOD(hex)

  • Hexagonal quartz window

  • Effective area: f50mm (min)

  • QE <~25 % (target)

  • Aiming for 1/10 lower

    background than R8778

5.8cm

(edge to edge)

0.3cm

(rim)

c.f. R8778

U 1.8±0.2x10-2 Bq

Th 6.9±1.3x10-3 Bq

40K 1.4±0.2x10-1 Bq

5.4cm

  • Prototype has been

    manufactured already

  • Now, being tested

12cm


Kr contamination

Kr contamination

  • 85Kr makes BG in low energy region

Target = Xe

102

cpd/kg/keV

Kr 0.1ppm

1

10-2

DM signal

(10-6 pb, 50GeV,

100 GeV)

10-4

10-6

  • Kr can easily mix with Xe

    because both Kr and Xe are rare gas

0

200

400

600

800

energy (keV)

  • Commercial Xe contains a few ppb Kr


Xe purification system

Xe purification system

  • Processing speed : 0.6 kg / hour

  • Design factor : 1/1000 Kr / 1 pass

  • Purified Xe : Off gas = 99:1

Lower

~3m

Raw Xe:

~3 ppb Kr

(178K)

Off gas Xe:

330±100 ppb Kr

(measured)

~1%

Purified Xe:

3.3±1.1 ppt Kr

(measured)

Higher

~99%

[email protected]

(180K)


Summary of bg measurement

Summary of BG measurement

Now (prototype detector) Goal (800kg detector)

  • g ray BG ~ 10-2 cpd/kg/keV

    → Increase volume for self shielding

    → Decrease radioactive impurities in PMTs (~1/10)

  • 238U = (33±7)×10-14 g/g

    → Remove by filter

  • 232Th < 23×10-14 g/g (90% C.L.)

    → Remove by filter (Only upper limit)

  • Kr = 3.3±1.1 ppt

    → Achieve by 2 purification pass

1/100

10-4 cpd/kg/keV

1/33

1×10-14 g/g

1/12

2×10-14 g/g

1/3

1 ppt

Very near to the target level!


W phase xe detector direct proportional scintillation

W- phase Xe Detector (Direct & proportional scintillation )

Gas

~1μsec

anode

S2

Drift Time

grid

e-

Liquid

~40 nsec

S1

cathode


Signal from double phase xe

Signal from Double Phase Xe

42000photon/MeV

Decay time 45nsec

direct

direct

direct

proportional

drift time

drift time

proportional


Recoil ray separation

Recoil /γ ray Separation

>99% γ ray rejection

Proportional scintillation(S2)

22 keV gamma ray

Recoil Xenon (neutron source)

Direct scintillation(S1)


Satoshi suzuki waseda university

Gas Xe

15 kg Double Phase Xe Detector

grid

Liquid Surface

anode

grid

Gas Xe

MgF2(cathode)

220mm

OFHC

Ed

Liq Xe

PTFE

(Field shaping ring)

165mm

PMT

(HAMAMATSU R8778 x 7)

MgF2(cathode)

160mm


Satoshi suzuki waseda university

15kg Chamber Construction

Anode - Grid Set

PTFE

Field Shaping Ring

PMT

MgF2 Window

(Cathode:gold coated mesh)


15 kg chamber construction

15 kg Chamber Construction

Shield


3d double phase xenon detector

3D-double phase xenon detector

If we have pure xenon which is free from radioactive impurities,

proportional scintillation is very useful.

Multi-purpose detector

WIMPs

136Xe double b decay

pp 7Be solar n


3d w phase test chamber

3D W-phase test chamber

Recirculation purification

Circulation

pump

Getter

  • PMT: Hamamatsu R5900-06MOD

    • 1inch square type

    • QE=5%

    • Work in LXe

Gas Xe

Liquid Xe


Satoshi suzuki waseda university

Position resolution(x,y)

  • Simulation

  • (for 100 keV electron)

  • Distance between PMT and anode: 3 cm

  • proportional scintillation

  • :1 mm Gaussian

  • Collection of electrons :80%

  • PMT Coverage : 20%

  • QE : 5%

1ph/e

1000ph/e

103

104

105

106

107

  • σxy < 1 mm will be possible by good adjustment of PMTs

  • Use multi -anode PMTs for double b decay experiment


Satoshi suzuki waseda university

Proportional scintillation

Energy spectrum for low energy g rays

Low energy threshold for pp 7Be solarn

< few keV

5.9 keV g ray from 55Fe

22 keV g ray from 107Cd

  • Independent of detector size


Satoshi suzuki waseda university

g ray rejection for 0nbb decay experiment

S1 one signal

S2 more than two

Compton scattering events

ΔZ ~ few 100 mm


Low energy detection by 3d double phase detector in underground

Low energy detection by 3D-double phase detector in Underground

Shielding

Detector

Low background environments

WIMPs

0nbb decay

pp, 7Be solar n

low Eth <10 keV

large mass

particle ID

energy resolution

γ/βID

low Eth

huge mass 〜10 ton

real time

self-shielding

particle ID (WIMPs, neutrons,)


What is the most important in the future

What is the most important in the future?

How to collect photon effectively?

Small detector

Maybe yes

Improve photon detector, PMT …

Big detector

No

The best is to find a wave length shifter.


Satoshi suzuki waseda university

Attenuation length vs Wavelength(l)

T. Ypsilantis et al.(‘95)

Rayleigh scattering ∝ 1/l4


Light collection efficiency

Light collection efficiency

λ= 175 nm

15 kg W-phase detector

Reflectance for PTFE:0.90

Absorption length of LXe:1 m

Scattering length:40 cm

15.3 %

1.75 pe/keV

(QE:25%)

λ= 350 nm

Reflectance for PTFE:〜 0.99

Absorption length of LXe:〜 20 m

Scattering length:〜 3m

〜 80 %

〜 8 pe/keV

MgF2:1.45

Refractancequartz:1.56

LXe : 1.60


Tea doped rare gas experiment

TEA doped rare gas experiment

Emission from TEA

Ar* + Ar + Ar → Ar2* + Ar

Ar2* → Ar + Ar + hn(VUV)

Competitive process

hn(VUV) + TEA → TEA*

Ar2* + TEA → Ar + Ar + TEA*

hn(VUV) + TEA → TEA+ + e

Ar2* + TEA → Ar + Ar + TEA+ + e

M.SUZUKI et al. (1987)


Satoshi suzuki waseda university

Is it possible to apply to liquid?

LAr

Photo ionization effect was

observed for both liquid.

hn(VUV) + TEA → TEA+ + e

(Ar2* + TEA → Ar + Ar + TEA+ + e)

QE = 0.23

LXe

hn(VUV) + TEA → TEA+ + e

(Xe2* + TEA → Xe + Xe + TEA+ + e)

QE 〜 1

Nobody check visible(UV) light!

Excitation process should be occurred.

Especially to LAr because of small QE.


Satoshi suzuki waseda university

The end


Rn assay with prototype detector

Rn assay with prototype detector

  • 238U series

    • 222Rn(t1/2 = 3.8d, 3.3MeV beta), …

  • 232Th series

    • 220Rn(55s, 2.3MeV beta[64%]), …

214Bi214Po210Pb

b (Emax=3.3MeV)a (7.7MeV)

t1/2 =164msec

Observed coincident events

212Bi212Po208Pb

b (Emax=2.3MeV)a (8.8MeV)

t1/2 =299nsec

(BR=64%)

No candidate found


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