9-June-2003NDM2003 M. Nomachi M. Nomachi OSAKA University and MOON collaboration MOON (Mo Observatory Of Neutrinos) for double beta decay Photo by

9-June-2003NDM2003 M. Nomachi MOON Objectives Double beta ( ββ ) decays with m ν ~0.03 eV. Low energy pp, 7 Be solar ν e by inverse β followed by successive β Spectroscopy of two β rays from 1ton of 100 Mo

9-June-2003NDM2003 M. Nomachi T(0  ) = S N [ 2 ] S N = G |M  | 2 (G ~ Q  5 ) 100 Mo Low threshold (0.17MeV) for inverse beta decay Large nuclear matrix element High natural abundance (9.6%) Large Q value (3.03MeV)

9-June-2003NDM2003 M. Nomachi Neutrino mass and ββ decay

9-June-2003NDM2003 M. Nomachi

9-June-2003NDM2003 M. Nomachi Double beta decays 100 Ru 100 Mo 100 Tc β1β1 β2β2 0MeV 1MeV 2MeV -1MeV -2MeV -3MeV Measure two beta rays at the same time at the same position. ΣE β = Q ββ (3.034MeV)

9-June-2003NDM2003 M. Nomachi Major BG at the 0  window Radio Activities in Detector/Source –0.1ppt of U-Th: mBq/t. Cosmogenic Radio Activities –Negligible at underground lab. 2νββ –T 1/2 ~ y Good energy resolution

9-June-2003NDM2003 M. Nomachi 100 Ru 100 Mo 100 Tc 0MeV 1MeV 2MeV -1MeV -2MeV -3MeV β delayed β prompt Solar ν Solar neutrino Measure two beta rays in the time window (~15sec) at the same position. E β2 = Q ββ (3.2MeV)

9-June-2003NDM2003 M. Nomachi Major BG at the solar neutrino Accidental coincidence of 2ν  and radio activities in detector/source –2νββ T 1/2 ~ y –Radio Activities 0.1ppt of U-Th: mBq/t. Define coincidence volume as small as possible. Good position resolution

9-June-2003NDM2003 M. Nomachi MOON 100 Mo loaded liquid scintillator –Photon detection on the surface –WLS readout 100 Mo foil and SciFi+Plastic scintillator Purified materials WLS Observe Extracted photon Photo sensor Observation on the surface SciFi

9-June-2003NDM2003 M. Nomachi Liquid Scintillator Photon detector array on all surfaces 1.No structure and less kind of material near source. 2.Good photon collection 3.No energy loss in the source MOON 100 Mo loaded Liquid Scintillator

9-June-2003NDM2003 M. Nomachi Position resolution (RMS) : 1.4 mm Position measurement Photon distribution on the surface Please come to the poster “A position sensitive scintillating detector with photon distribution measurement”

9-June-2003NDM2003 M. Nomachi Position resolution Distance (Pixel) Position resolution (r.m.s. in Pixel) 100 p.e. 300 p.e p.e. 5cm PMT 1m 2 cm r.m.s. is expected Not enough position resolution for solar neutrino Small amount of 100 Mo loading

9-June-2003NDM2003 M. Nomachi MOON Plastic/fiber scintillator/Mo Ensemble

9-June-2003NDM2003 M. Nomachi Double Beta Decay 100 Mo Plastic Scintillator β1β1 β2β2 Decay Position SciFi (X axis) SciFi (Y axis) Plastic Scintillator 6mm 0.4mm 0.8mm θ

9-June-2003NDM2003 M. Nomachi pp neutrino 100 Mo Plastic Scintillator β1β1 β2β2 Reaction Position SciFi (X axis) SciFi (Y axis) Plastic Scintillator 6mm 0.4mm 0.8mm 3.2MeV 0.25 MeV MAX

9-June-2003NDM2003 M. Nomachi PL + SciFi Energy loss of Mo-foil and SciFi is not included 12 mm GEANT Simulation for  Mo = 6.6 mg/cm 2 ~ 0.05 eV  ×2·10 6

9-June-2003NDM2003 M. Nomachi PL + SciFi 12 mm Mo = 6.6 mg/cm 2 ~ 0.05 eV 2  back to back  2   GEANT Simulation for   ×2·10 6

9-June-2003NDM2003 M. Nomachi Energy loss of Mo-foil and SciFi is taken into account  Mo = 20 mg/cm 2 PL + SciFi 12 mm  Mo = 6.6 mg/cm 2 ~ 0.05 eV GEANT Simulation for 

9-June-2003NDM2003 M. Nomachi MOON-I Objectives MOON MOON is step-by-step project. MOON-1 is the first step with ~1kg of 100 Mo. MOON-1 (2003: design, 2004/2005: construction) MOON-2 consists of 10~30 units and has total 1t of 100 Mo. One unit has 30~100kg of 100 MoMOON-1 We will explore neutrino mass region of eV. MOON-1 will detect more higher sensitivity than ELEGANTS-V (Upper limit ~ 2 eV), which is in Ohto Lab. We will measure fundamental data for the future detector which detects double beta decay (MOON-2, 0.03eV sensitivity). “MOON-1” is first important step for “MOON-2”.

9-June-2003NDM2003 M. Nomachi MOON-I design Size ; Plastic Scintillator ~ 50cm X 50cm 100 Mo foil ~ 30cm X 30cm 100 Mo Plastic Scintillator SciFi (X axis) SciFi (Y axis) Plastic Scintillator 6mm 0.4mm 0.8mm Light Guide NaI active shield 4 ~ 10 layers

9-June-2003NDM2003 M. Nomachi MOON-I design Plastic Scintillator 50cm 100 Mo 2”PMT MA-PMT SciFi flax (X axis) SciFi flax (Y axis) SciFi (X axis) SciFi (Y axis) 50cm Light guide Please come to the poster “A status of MOON-1 detector development”

9-June-2003NDM2003 M. Nomachi R&D items Purification –Assembling Glue fibers Handling of 100 Mo foil Energy resolution –Photon collection Photo-sensor Light guide Mirror Position resolution –Efficiency Photon collection –Cost Photo-sensor Readout system Please come to the poster “Development of a multi-channel readout system for the double beta decay experiment”

9-June-2003NDM2003 M. Nomachi Summary of ＭＯＯＮ 100 Mo with the large responses for  ν and solar- ν are used for ν studies. MOON(Mo Observatory Of Neutrinos) : real-time spectroscopy of –Majorana ν with sensitivity of m ν ~0.03 eV by 0nbb. –Low E solar/ supernova ν ’s by inverse  tagged by successive . High position resolution and adequate time window for two b rays reduce correlated and accidental BG. “MOON-1” is first important step for “MOON-2”.

9-June-2003NDM2003 M. Nomachi Photo by