Scintillation and phonon measurement of 40 Ca 100

Scintillation and phonon measurement of 40 Ca 100 Mo. O crystal for the AMo. RE project 4 (AMo. RE project : searching a 0 n decay of 100 Mo) J. H. So on be half of AMo. RE collaboration ＳＣＩＮＴ ２０１５ 1

0 n double beta decay Energy 100 Tc 100 Mo Forbidden transition Transition bb allowed Qb b 100 Ru Z Z Z+1 Z+2 (Z, A) → (Z+2, A) + 2 e- + 2 anti-ne (DL = 0, conserved) (Z, A) → (Z+2, A) + 2 e(DL = 2, violated) • 0 n DBD is forbidden by Standard Model for lepton number violation. • If neutrino is a majorana particle, 0 n DBD is possible. • We will be able to define the neutrino type and absolute mass. ＳＣＩＮＴ ２０１５ 2

Why 100 Mo? Candidates Qbb(Me. V) N. A. (%) 48 Ca→ 48 Ti 4. 271 0. 187 76 Ge→ 76 Se 2. 040 7. 8 82 Se→ 82 Kr 2. 995 9. 2 96 Zr→ 96 Mo 3. 350 2. 8 100 Mo→ 100 Ru 3. 034 9. 6 110 Pd→ 110 Cd 2. 013 11. 8 116 Cd→ 116 Sn 2. 802 7. 5 124 Sn → 124 Te 2. 228 5. 64 130 Te→ 130 Xe 2. 533 34. 5 136 Xe→ 136 Ba 2. 479 8. 9 150 Nd→ 150 Sm 3. 367 5. 6 Phy. Rev. C, 53, 695 (1996) G. Pantis, F. Simkovic, J. D. Vergados, and Amand Faessler G : Phase space factor (~Qbb 5) M : Nuclear Matrix Element (large uncertainty) Barea et al. , Phy. Rev. Lett. 109, 042501 (2012) Ref. Werner Rodejohann, ar. Xiv: 1106. 1334 v 3. (2011). ＳＣＩＮＴ ２０１５ 3

40 Ca 100 Mo. O • 4 crystal Enrichment of 100 Mo (natural abundance : 9. 6%) - Gas-centrifuge method - Enrichment of 100 Mo is higher than 96%. • Depletion of 48 Ca (natural abundance : 0. 157%) in natural Ca - Electromagnetic separation - Composition of 48 Ca is less than 0. 001 %. ＳＣＩＮＴ ２０１５ 4

Scintillation at Room Temp. Presented at SCINT 2011 S 35 (256 g) SB 28 (196 g) SB 28 Resolution : 30% (FWHM) Mean : 2. 88 x 105 S 35 Resolution : 16% (FWHM) Mean : 5. 97 x 105 CMO-3 Resolution : 16% (FWHM) Mean : 6. 79 x 105 CMO-3 ＳＣＩＮＴ ２０１５ 5

Scintillation at Low Temp. Ref. Crystal research and Technology, 1 -6(2011) ? ? • The light output is increased as temperature decreasing. → The energy resolution will be improved for the higher light output. • The decay time is delayed as temperature decreasing. • What will happen at sub-K Temp? ＳＣＩＮＴ ２０１５ 6

Why we need to study it @ m. K? • For AMo. RE experiment - No! scintillation light at m. K is quite enough to searching at the Q of 100 Mo (3. 034 Me. V). - However, it can be used to searching a dark matter! • For Dark matter search - Yes! It will be more serious for dark matter search. Region of Interesting : less than 50 ke. V. Select a low energy nuclear recoil event. The quenched event emit very small amount of scintillation light with much longer decay. • For luminescence mechanism - It is quite interesting itself to understanding the luminescence mechanism of Ca. Mo. O 4 crystal. ＳＣＩＮＴ ２０１５ 7

Design concept for AMo. RE 4 (source = detector) + MMC (low temp. detector) Light 40 Ca 100 Mo. O b, g events alpha Phonon ＳＣＩＮＴ ２０１５ 8

Cryogenic light detector Wafer holder (Cu, heat bath) Phonon collector (Gold films) MMC chip SQUID sensor Light absorber (Ge wafer) Thermal links # Three gold patterns ~0. 2 ms of rise time at 30 m. K Temp. independent rise time - Thickness : 320 nm - Diameter : 5 mm # Ge wafer - Thickness : 500 mm - Diameter : 2 inch ＳＣＩＮＴ ２０１５ 9

Detector assembly SB 28 40 Ca 100 Mo. O crystal 4 ＳＣＩＮＴ ２０１５ 10

Particle discrimination (heat/light) ＳＣＩＮＴ ２０１５ 11

Phonon (pulse shape discrimination) ＳＣＩＮＴ ２０１５ 12

Event selection of light signal 210 Po 2 sigma width 5. 4 Me. V α The same width with α signals ＳＣＩＮＴ ２０１５ 2 sigma width 13

Comparison of signals from LD Contribution of scintillation decay time? ! Two different time components are shown on rising part. ＳＣＩＮＴ ２０１５ 14

Summary • Phonon and Photon of low radioactive 40 Ca 100 Mo. O 4 scintillation crystal has been measured at few tens m. K temp. for AMo. RE experiment, even study for dark matter search exp. • Pulse shape discrimination of phonon signal was possible that maybe caused by scintillation process. • In order to prove the correlation between phonon and photon in the scintillation crystal, further study is planning to understand the complete picture of luminescence mechanism of Ca. Mo. O 4. ＳＣＩＮＴ ２０１５ 15

Thank you for your attention! ＳＣＩＮＴ ２０１５ 16

Zero background experiment Sizable background case ; b = background index in cts/(ke. V kg y) DE = FWHM energy resolution at Qbb in ke. V M = mass of detector in kg, A = mass number of candidate material e = detection efficiency at Qbb, a = bb isotope fraction (Enrichment), T = measured time in years “Zero” background case ; DBU: counts/ (ke. V kg year) ＳＣＩＮＴ ２０１５ 17

Metallic Magnetic Calorimeter (Low temp. sensor) Magnetic material Au: Er(10~1000 ppm) • weakly-interacting paramagnetic system • metallic host: fast thermalization ( ~ 1 s) Field coil Pickup coil g = 6. 8 Junctions 5 m. T Δε = 1. 5 e. V 1 ke. V 109 spin flips Faster response time! Excellent energy resolution! Wide operating temperature! Neutrino and Dark Matter in Nuclear Physics 2015, Jyvaskyla, Finland