A search for Neutrinoless Double Beta Decay, AMoRE, and a New Underground Facility Young Soo Yoon Center for Underground Physics Institute for Basic Science T2HKK International Workshop Seoul National University, Nov. 21-22, 2016
Contents Introductions Neutrinoless Double Beta Decay Experimental Approach Advanced Molybdenum based Rare process Experiment CaMoO 4 Scintillation Crystal Detector Concept: Light and Heat Detectors Background Study using Simulation AMoRE-Pilot Experiment AMoRE Phase and Sensitivity Underground Laboratory YangYang Laboratory (Y2L) Site of Astroparticle Research Facility Location and Design of Underground Laboratory 2 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
Neutrinoless Double Beta Decay (0 νββ ) • Observed for 11 isotopes Energy • half-life > 10 18 yr (A, Z+1) • Standard model allowed Forbidden β transition (A, Z) Transition ββ 2 νββ Q ββ allowed (A, Z+2) Z 0 νββ Z Z+1 Z+2 (Z, A) → (Z+2, A) + 2e - + 2 ν e ( Δ L = 0, conserved) ¯ (Z, A) → (Z+2, A) + 2e - ( Δ L = 2, violated) • Not observed yet Q-value: the amount of energy released by reaction or decay • half-life > 10 25 yr • violation of lepton number T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS 3
Experimental Approach Sizable background case: AMoRE-II b = background index in cts/(keV kg y) 200kg zero Δ E = FWHM energy resolution at Q ββ in keV background M = mass of detector in kg, A = mass number of candidate material non-zero ε = detection efficiency at Q ββ background a = ββ isotope fraction (Enrichment) AMoRE-I T = measured time in years 5kg “Zero” background case: When background level, b , is so low, that M·T·b· Δ E ≲ 1, When all the experimental backgrounds were removed, we can measure a higher limit of half lifetime. 4 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
Experimental Aspects for 0 νββ Measurements 2 νββ current “zero background” Next generation 0 νββ “non-zero background” Good energy resolution Very low background Large mass detector High detection efficiency AMoRE • Detector technique: Cryogenic detectors (MMC+SQUID) • Background reduction: zero-background level • Isotope selection: CaMoO 4 ( 100 Mo) 5 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
A dvanced Mo lybdenum-based R are process E xperiment AMoRE Collaboration Russia Germany 11th AMoRE Collaboration meeting Ukraine Feb. 18-19, 2016 China Korea Pakistan Thailand Indonesia 10th AMoRE Collaboration meeting Aug. 27-28, 2015 8 countries, 18 Institutes, ~90 collaborators 6 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
Advanced Molybdenum-based Rare process Experiments Measurement at the underground laboratory Metallic Magnetic CaMoO 4 Crystal Calorimeter with low background MMC + SQUID • Energy resolution: ~10 keV • Fast rising time: ~1ms CaMoO 4 100 Mo • Q: 3.034MeV • N.A.: 9.824 % Background reduction • Cosmic-rays • muon … Pb Shield Cryogenic detector at low temperature (~10-20 mK) 7 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
Isotope Candidates Q-Value (keV) Abundance (%) 48 Ca 4272.3 0.187 76 Ge 2039.1 7.73 208 Tl → 208 Pb, 82 Se 2995.1 8.73 the highest γ -ray from 96 Zr 3350.4 2.80 natural radioactive 100 Mo 3034.3 9.82 116 Cd 2813.5 7.49 124 Sn 2287.0 5.76 128 Te 865.9 31.7 130 Te 2527.0 34.1 136 Xe 2457.8 8.86 150 Nd 3371.4 5.64 100 Mo has relatively high natural abundance and Q-value. 8 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
40 Ca 100 MoO 4 Crystals Enriched 100 Mo ✦ Natural abundance of 100 Mo: 9.6% ✦ Enriched 100 Mo: higher than 96% ✦ Depleted 48 Ca ✦ Natural abundance of 48 Ca: 0.157% in natural Ca ✦ Composition of 48 Ca is less than 0.001% ✦ ul- nals Emission Spectra Emission Spectra ( 137 Cs) low- to SB28 light Resolution : 30% (FWHM) Mean : 2.88 x 10 5 tals in S35 or Resolution : 16% (FWHM) icles Mean : 5.97 x 10 5 earch CMO-3 in Resolution : 16% (FWHM) elp Mean : 6.79 x 10 5 search ow the a m 14 J.H. So et al., IEEE Trans. Nucl. Sci. (2012) 9 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
Detector Concept Light , γ events β , alpha Phonon Source = detector Light/Heat measurement ➔ High detection efficiency ➔ α particle rejection ➔ High energy resolution 10 T2HKK workshop, SNU, Nov. 21-22, 2016 Young Soo Yoon, CUP, IBS
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