Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON-1

An ensemble of multi-layer scintillators is discussed as an option of the high-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic measurements of neutrino-less double beta decays. A prototype detector MOON-1, which consists of 6 layer plastic-scintillator plates, was built to study the sensitivity of the MOON-type detector. The scintillation photon collection and the energy resolution, which are key elements for the high-sensitivity experiments, are found to be 1835+/-30 photo-electrons for 976 keV electrons and sigma = 2.9+/-0.1% (dE/E = 6.8+/-0.3 % in FWHM) at the Qbb ~ 3 MeV region, respectively. The multi-layer plastic-scintillator structure with good energy resolution as well as good background suppression of beta-gamma rays is crucial for the MOON-type detector to achieve the inverted hierarchy neutrino mass sensitivity.Comment: 8 pages, 16 figures, submitted to Nucl.Instrum.Met

MOON for neutrino-less double beta decays

The MOON (Majorana/Mo Observatory Of Neutrinos) project aims at studies of the Majorana nature of the neutrino ($\nu$) and the $\nu$-mass spectrum by spectroscopic experiments of neutrino-less double beta decays ($0\nu \beta \beta$) with the $\nu$-mass sensitivity of $\langle m_{\nu}^m \rangle = 100$–30 meV. The solid scintillator option of the MOON detector is a super ensemble of multi-layer modules, each being composed by PL scintillator plates and position-sensitive detector planes with good overall energy resolution of $\sigma \approx 2\%$ at the $Q_{\beta \beta } \approx 3\,{\rm MeV}$. Thin $\beta \beta$ source films are interleaved between the detector planes. High localization of the two $\beta$ tracks enables one to select true signals and reject BG ones. The multi-layer structure of the detector makes it realistic to build a compact ton-scale detector. MOON with detector $\ne \beta \beta$ source is used for studying $0\nu \beta \beta$ decays from $^{100}{\rm Mo}$, 82Se and other $\beta \beta$ isotopes with large $Q_{\beta \beta }$. Real-time exclusive measurements of low energy solar neutrinos can be made by observing inverse $\beta$ rays from solar-ν captures of $^{100}{\rm Mo}$ in delayed coincidence with the subsequent β decay of 100Tc

MOON (Mo Observatory Of Neutrinos) for double beta decay

The MOON (Molybdenum Observatory Of Neutrinos) project aims at studies of double beta decays with a high sensitivity of < mν >∼0.03 eV and real-time studies of low-energy solar neutrinos. Two β rays from 100 Mo are measured in coincidence for the 0νββ studies. The inverse β rays from solar neutrino captures of 100 Mo are measured in delayed coincidence with the following β decay of 100 Tc. Measurements with good energy resolution and good position resolution enable one to select true signals. A prototype MOON detector (MOON 1) is now under development. The present report describes briefly the outline of the MOON project and the status of MOON 1