N. Kudomi

Spectroscopy of Double-Beta and Inverse-Beta Decays from 100 Mo for Neutrinos

Spectroscopic studies of two beta rays from 100Mo are shown to be of potential interest for investigating both the Majorana nu mass by neutrinoless double beta decay (0nubetabeta) and low energy solar nus by inverse beta decay. With a multiton 100Mo detector, coincidence studies of correlated betabeta from 0nubetabeta, together with the large Q value ( Q(betabeta)), permit identification of the nu-mass term with a sensitivity of approximately 0.03 eV. Correlation studies of the inverse beta decay and the successive beta decay of 100Tc, together with the large capture rates for low energy solar nus, make it possible to detect, in real time, individual low energy solar nu in the same detector.

Double Beta Decays of 116Cd

Double beta decays (ββ) from the 0 + ground state in 116 Cd to the 0 + ground state in 116 Sn were studied by means of ELEGANT V. A finite half-life for the two-neutrino ββ(2νββ) and an upper limit on the neutrinoless one (0νββ) were obtained as T 2ν 1/2 =2.6 +0.9 -0.5 ×10 19 y and T 0ν 1/2 >6.3×10 21 y (68% C.L.), respectively. The nuclear matrix element M 2ν ββ was deduced as 0.069±0.009 in units of ( m e c 2 ) -1 . This supports the universal quenching of the 2νββ rates in this mass region, which is consistent with that previously measured in 100 Mo.

Limits on neutrino-less double beta decay of 100Mo

Abstract Exclusive measurements of neutrino-less double beta decays (0νββ) of 100Mo were made by means of ELEGANT V. Most stringent lower limits on the half-lives for the ground-state transition were obtained for the 0νββ processes as T 1 2 0ν (m ν ) > 5.2 × 10 22 y , T 1 2 0ν (λ) > 3.9 × 10 22 y and T 1 2 0ν (η) > 5.1 × 10 22 y , for the mass term 〈mν〉, for the right-handed current terms of 〈λ〉 and 〈η〉, respectively, and as T 1 2 0νB > 5.4 × 10 21 y for the process (0νββB) followed by a Majoron (B). These limits lead to the upper limits of 〈mν〉

Limits on the annual modulation of WIMPs-nucleus scattering with large-volume NaI(Tl) scintillators

Abstract A search for cold dark matters has been carried out with the 662 kg NaI scintillator array of ELEGANT V at the Kamioka underground laboratory. The annual modulation of weakly interacting massive particles (WIMPs) energy spectra has been investigated. No significant modulations beyond statistical fluctuations were found. Stringent limits were obtained on masses and cross sections for both axial-vector coupled and vector coupled WIMPs.

Energy calibration of plastic scintillators for low energy electrons by using Compton scatterings of γ rays

An energy calibration of plastic scintillators for electrons in the energy region 0.5–3 MeV is shown to be made by means of Compton scatterings of γ-rays. The shape of the Compton spectrum was analytically derived and the availability of the shape function was tested by fitting the simulated spectrum. The method to derive the energy and energy resolution at the Compton edge of the γ-ray is described.

Supernova-neutrino studies with 100Mo

We show that supernova neutrinos can be studied by observing their charged-current interactions with 100 Mo, which has strong spin–isospin giant resonances. Information about both the effective temperature of the electron–neutrino sphere and the oscillation into electron neutrinos of other flavors can be extracted from the electron (inverse β) spectrum. We use measured hadronic charge-exchange spectra and the Quasiparticle Random Phase Approximation to calculate the chargedcurrent response of 100 Mo to electron neutrinos from supernovae, with and without the assumption of oscillations. A scaled up version of the MOON detector for ββ and solar-neutrino studies could potentially be useful for spectroscopic studies ofWe show that supernova neutrinos can be studied by observing their charged-current interactions with

Precise measurement of the cross section ofHe3(He3,2p)He4by usingHe3doubly charged beam

^{100}

Highly sensitive radon monitor and radon emanation rates for detector components

Mo, which has strong spin-isospin giant resonances. Information about both the effective temperature of the electron neutrino sphere and the oscillation into electron neutrinos of other flavors can be extracted from the electron (inverse

Search for WIMPs with the large NaI(Tl) scintillator of ELEGANT V

beta

Spin-isospin excitations in nuclei via (3He,t) reactions at 450 MeV

) spectrum. We use measured hadronic charge-exchange spectra and the Quasiparticle Random Phase Approximation to calculate the charged-current response of