05/03/23 Katsushi Arisaka 1

University of California, Los Angeles

Department of Physics and Astronomy

arisaka@physics.ucla.edu

Katsushi Katsushi ArisakaArisaka

XAXXAX10 ton Noble-Liquid Double-10 ton Noble-Liquid Double-

Phase TPC for Rare ProcessesPhase TPC for Rare Processes

XAX Detector (Option A)

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129/131Xe(14 ton)

40Ar(6 ton)

Water Tank Veto 2 m

11 m

136Xe(14 ton)

1.5 m

7m

7 m

XAX Detector (Option B)

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Water Tank Veto

2 m

8 m

1.5 m

8 m

Xe(14 ton)

Year 1 : Natural Xe (14 ton)Year 2 : Argon (6 ton)Year 3: 136Xe (14 ton)Year 4: 129/131Xe (14 ton)

XAX Detector Design

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Liquid Xe (14 ton)

Gas Xe

3” QUPID(Total ~3600)

2 m

Fiducial Volume (7 ton)

1.5 m

-10.1 kV-10 kV

-18 kV

-180 kV-10 kV

-10

kV-10 kV

0 V

20 cm

Why Multiple Targets? Systematic Study of Dark Matter Interaction

Target Mass dependence of Cross section• Xenon vs. Argon

Spin dependence of cross section • 129/131Xe (Spin odd) vs. 136Xe (Spin even)

Precise determination of Mass and Cross section

Neutrino-less Double Beda Decay (DBD) > 1028 years by136Xe (like EXO)

Solar Neutrino 1% measurement of pp chain flux by 129/131Xe.

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QUPID(Quartz Photon Intensifying Detector)

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APD (0 V)

Quartz

Quartz

Quartz

Photo Cathode(-10 kV)

Simulation of Electron Trajectories

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13 inch HAPD for T2K by Hamamatsu

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PE Distribution of 13 inch HAPD

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1 pe2 pe

3 pe

4 pe

5 pe

Comparison  Unit R8520 R8778 QUPID QUPID/R8778

Size 1 inch 2 inch 3 inch Shape Square Round Round

Dimension Outer Size mm 25.7 mm square 57 mm diameter 70 mm diameter

Photo Cathode mm 21.8 mm square 45 mm diameter 65 mm diameter Total Area cm2 6.60 25.52 38.48 1.51

Photocathode Area cm2 4.75 15.90 33.18 2.09Filling factor % 72.0% 62.3% 86.2% 1.38

Price Price $ $1,100 $2,700 $2,000 0.74

Price per potocathode area $/cm2 $231 $170 $60 0.36Performance

QE at 175 nm (Typical) % 21% 25% 30% 1.20QE at 175 nm (Best) % 25% 35% 38% 1.09Peak to Vally Ratio 1.3 2.5 5 2.00

ENF 1.3 1.1 1 0.91DQE = QE/ENF (Typical) % 16% 23% 30% 1.32

Radioactivity Total (Typical) mBq 10 50 1.000 0.020

Total (Best) mBq 3 10 0.100 0.010Per area (Typical) mBq/cm2 3.0 3.1 0.030 0.010

Per area (Best) mBq/cm2 0.5 0.4 0.003 0.008

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Expected Performance of QUPID

Large diameter: 3 inch Existing largest PMT with low radioactivity is 2 inch (R8778)

Extremely low radioactivity: 1mBq (now) 0.1mBq (future) To be compared with

• R8778 (2 inch) 50 mBq• R8520 (1 inch) 10 mBq

True photon counting 1,2… 5 photo-electron peaks are clearly visible. Collection efficiency is ~100% Excess Noise Factor (ENF) = 1.0

Fast Timing: < 500 psec 500 psec Transit Time spread expected

Simple HV supply HV supply can be common for all HAPD

• No Tube to tube variation of gains Resister chain not necessary

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Super-LUX

XENON10

LUX

CDMSII

90% CL Sensitivity for WIMP

XENON10

LUX- 100

CDMSII

Energy Resolution of XENON 10

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Xe-129236 keV

Xe-131164 keV

= 0.9% at 2.5 MeV FWHM = 50 keV expected

Xe-129236 keV

Xe-131164 keV

Fraction of 2 neutrino Double Beta Decay Background vs. Energy resolution

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Energy Spectrum (Xe 136 enriched)

Be7 Solar

B8 Solar

2 DBD (1022 yrs)

pp Solar

0 DBD (1027 yrs)

Be7 Solar

B8 Solar

2 DBD (1022 yrs)

pp Solar

0 DBD (1027 yrs)

0 cm shield

10 cm shield

20 cm shield

30 cm shield

Expected Background from Gammas(1 mBq / QUPID)

Expected Background from Gammas(1 mBq / QUPID)

2 DBD (1022 yrs)

0 DBD (1027 yrs)

0 cm shield

10 cm shield

30 cm shield

20 cm shield

B8 Solar

BG ~ 10-7 druFWHMM = 50 keV 4*10-4 /FWHM*kg*year

Expected No. of DBD Signals and Backgrounds(10 ton-year of Liquid Xenon, Window = 2479 ± 25

keV)

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No. of Background Events No. of 0-Neutrino DBD Signals

14 ton 6.6 ton 2.4 ton9 ton 4.2 ton

Summary of DBD Detection All the gamma ray background can be

effectively removed. Low-radioactive QUPID is essential.

• < 1 mBq for > 1027 years• < 0.1 mBq for > 1028 years

Extensive active shielding. • 30 cm cut required (4 ton fiducial volume out of 14 ton.)

Multiple hit cut. Ba2+ tagging is not necessary, unlike EXO.

The tail from two neutrino double beta decays is negligible. based on XENON10, the energy resolution of the

double-phase Xenon should be superior to EXO. = 1.0% at 2.5 MeV (FWHM = 50 keV)• > 3 pe/keV is required

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