1. 1/27/2016Katsushi Arisaka 1 University of California, Los Angeles Department of Physics and Astronomy arisaka@physics.ucla.edu Katsushi Arisaka XAX 10 ton Noble-Liquid Double-Phase TPC for Rare Processes

2. XAX Detector (Option A) 1/27/2016Katsushi Arisaka 2 129/131 Xe (14 ton) 40 Ar (6 ton) Water Tank Veto 2 m 11 m 136 Xe (14 ton) 1.5 m 7m

3. XAX Detector (Option B) 1/27/2016Katsushi Arisaka 3 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: 136 Xe (14 ton) Year 4: 129/131 Xe (14 ton)

4. XAX Detector Design 1/27/2016Katsushi Arisaka 4 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 0 V 20 cm

5. Why Multiple Targets?  Systematic Study of Dark Matter Interaction  Target Mass dependence of Cross section Xenon vs. Argon  Spin dependence of cross section 129/131 Xe (Spin odd) vs. 136 Xe (Spin even)  Precise determination of Mass and Cross section  Neutrino-less Double Beda Decay (DBD)   > 10 28 years by 136 Xe (like EXO)  Solar Neutrino  1% measurement of pp chain flux by 129/131 Xe. 1/27/2016Katsushi Arisaka 5

6. QUPID (Quartz Photon Intensifying Detector) 1/27/2016Katsushi Arisaka 6 APD (0 V) Quartz Photo Cathode (-10 kV)

7. Simulation of Electron Trajectories 1/27/2016Katsushi Arisaka 7

8. 13 inch HAPD for T2K by Hamamatsu 1/27/2016Katsushi Arisaka 8

9. PE Distribution of 13 inch HAPD 1/27/2016Katsushi Arisaka 9 1 pe 2 pe 3 pe 4 pe 5 pe

10. Comparison UnitR8520R8778QUPIDQUPID/R8778 Size 1 inch2 inch3 inch Shape SquareRound Dimension Outer Size mm25.7 mm square57 mm diameter70 mm diameter Photo Cathode mm21.8 mm square45 mm diameter65 mm diameter Total Area cm 2 6.6025.5238.481.51 Photocathode Area cm 2 4.7515.9033.182.09 Filling factor %72.0%62.3%86.2%1.38 Price $$1,100$2,700$2,0000.74 Price per potocathode area $/cm 2 $231$170$600.36 Performance QE at 175 nm (Typical) %21%25%30%1.20 QE at 175 nm (Best) %25%35%38%1.09 Peak to Vally Ratio 1.32.552.00 ENF 1.31.110.91 DQE = QE/ENF (Typical) %16%23%30%1.32 Radioactivity Total (Typical) mBq10501.0000.020 Total (Best) mBq3100.1000.010 Per area (Typical) mBq/cm 2 3.03.10.0300.010 Per area (Best) mBq/cm 2 0.50.40.0030.008 1/27/2016Katsushi Arisaka 10

11. 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 1/27/2016Katsushi Arisaka 11

12. 1/27/2016Katsushi Arisaka 12 Super-LUX XENON10 LUX CDMSII 90% CL Sensitivity for WIMP XENON10 LUX- 100 CDMSII

13. Energy Resolution of XENON 10 1/27/2016Katsushi Arisaka 13 Xe-129 236 keV Xe-131 164 keV  = 0.9% at 2.5 MeV FWHM = 50 keV expected Xe-129 236 keV Xe-131 164 keV

14. Fraction of 2 neutrino Double Beta Decay Background vs. Energy resolution 1/27/2016Katsushi Arisaka 14

15. Energy Spectrum (Xe 136 enriched) Be7 Solar B8 Solar 2 DBD (10 22 yrs) pp Solar 0 DBD (10 27 yrs)

16. Be7 Solar B8 Solar 2 DBD (10 22 yrs) pp Solar 0 DBD (10 27 yrs) 0 cm shield 10 cm shield 20 cm shield 30 cm shield Expected Background from Gammas (1 mBq / QUPID)

17. Expected Background from Gammas (1 mBq / QUPID) 2 DBD (10 22 yrs) 0 DBD (10 27 yrs) 0 cm shield 10 cm shield 30 cm shield 20 cm shield B8 Solar  BG ~ 10 -7 dru FWHMM = 50 keV  4*10 -4 /FWHM*kg*year

18. Expected No. of DBD Signals and Backgrounds (10 ton-year of Liquid Xenon, Window = 2479 ± 25 keV) 1/27/2016Katsushi Arisaka 18 Self Shielding Cut (cm from wall)Life Time (Year) No. of Background EventsNo. of 0-Neutrino DBD Signals 14 ton6.6 ton2.4 ton9 ton4.2 ton

19. Summary of DBD Detection  All the gamma ray background can be effectively removed.  Low-radioactive QUPID is essential. 10 27 years 10 28 years  Extensive active shielding. 30 cm cut required (4 ton fiducial volume out of 14 ton.)  Multiple hit cut.  Ba 2+ 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 1/27/2016Katsushi Arisaka 19