Electromagnetic transitions from isobaric analogue states to study nuclear matrix elements for double beta decays and astro-neutrino inverse beta decays

Experimental studies for nuclear matrix elements (NMEs) for neutrinoless double beta decays (DBDs) and astro-neutrino inverse beta decays (IBDs) are crucial for neutrino studies beyond the standard model and the astro neutrino reactions since theoretical model calculations for the NMEs are hard due to the high sensitivities of the NMEs to the models. The NMEs associated with DBDs and IBDs are found for the first time to be studied experimentally by measuring electro-magnetic (gamma) transitions from isobalic analogue states (IASs) of the DBD and IBD nuclei. They are used to help the theoretical model calculations for them. The IAS gamma cross sections and the event rates are estimated to show the feasibility of the experiments.Comment: 5 pages, 4 figure

Resonant photonuclear isotope detection using medium-energy photon beam

Resonant photonuclear isotope detection (RPID) is a nondestructive detection/assay of nuclear isotopes by measuring gamma rays following photonuclear reaction products. Medium-energy wideband photons of 12-16 MeV are used for the photonuclear reactions and gamma rays characteristic of the reaction products are measured by means of high-sensitivity Ge detectors. Impurities of stable and radioactive isotopes of the orders of micro-nano gr and ppm-ppb are investigated. RPID is used to study nuclear isotopes of astronuclear and particle physics interests and those of geological and historical interests. It is used to identify radioactive isotopes of fission products as well.Comment: 6 pages, 3 figure

Nuclear Matrix Elements for β and ββ Decays and Quenching of the Weak Coupling gA in QRPA

Nuclear matrix elements (NMEs) for double beta decays (DBDs) are crucial for studying neutrino mass and neutrino properties of particle physics interest. The major components of the DBD NMEs are axial-vector NMEs associated with spin isospin transition operators. In this work it is discussed how absolute values for the NMEs are reduced (quenched) with respect to those for the model NMEs. The reduction is discussed in terms of the renormalized (quenched) axial-vector coupling gAeff in unit of gA for free nucleon. Recent experimental studies at RCNP on single and double β NMEs relevant to DBDs are briefly discussed. The axial-vector single β NMEs are shown to be reduced by the renormalization (quenching factor) factor gAeff/gA≈ 0.5–0.6 with respect to the QRPA (Quasi particle Random Phase Approximation) model NMEs due to non-nucleonic and nuclear medium effects which are not explicitly included in the model. Two-neutrino axial-vector DBD NMEs are reduced much with respect to the QP (Quasi Particle) NMEs, and are reproduced by the FSQP (Fermi Surface Quasi Particle) model NMEs. Impact of the reduction of the axial-vector NMEs on the DBD NMEs and the DBD experiments is briefly discussed

Ordinary muon capture for double beta decay and anti-neutrino nuclear responses

This is a brief review on ordinary muon capture (OMC) experiments at Research Center for Nuclear Physics (RCNP) Osaka University relevant for the study of double beta decays (DBDs) and astro anti-neutrinos (neutrino) nuclear responses. OMC usually leaves the nucleus in highly excited unbound state. OMC is a charge exchange reaction via the charged weak boson as given by (μ,vμ) reactions with μ and vμ being the muon and muon neutrino. Subjects discussed include 1) unique features of OMC for studying DBDs and astro anti-neutrino (neutrino) nuclear responses, 2) experiments of OMCs on 100Mo and natMo to study neutrino nuclear responses for DBDs and astro anti-neutrinos, 3) impact of the OMC results on neutrino nuclear responses for DBDs and astro anti-neutrinos. Remarks and perspectives on OMC experiments for neutrino nuclear responses are briefly described

Editorial: Neutrino Nuclear Responses for Astro-Particle Physics by Nuclear Reactions and Nuclear Decays

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High purity NaI(Tl) scintillator to search for dark matter

A high purity and large volume NaI(Tl) scintillator was developed to search for cosmic dark matter. The required densities of radioactive impurities (RIs) such as U-chain, Th-chain are less than a few ppt to establish high sensitivity to dark matter. The impurity of RIs were effectively reduced by selecting raw materials of crucible and by performing chemical reduction of lead ion in NaI raw powder. The impurity of $^{226}$Ra was reduced less than 100 $\mu$Bq/kg in NaI(Tl) crystal. It should be remarked that the impurity of $^{210}$Pb, which is difficult to reduce, is effectively reduced by chemical processing of NaI raw powder down to less than 30 $\mu$Bq/kg. The expected sensitivity to cosmic dark matter by using 250 kg of the high purity and large volume NaI(Tl) scintillator (PICO-LON; Pure Inorganic Crystal Observatory for LOw-background Neutr(al)ino) is 7$\times$10$^{-45}$ cm$^{2}$ for 50 GeV$/c^{2}$ WIMPs.Comment: 6 pages, 2 Figures, Proceedings of International Symposium on Radiation Detectors and Their Uses (ISRD2016). Talk given on 19th Jan. 2016 by K.Fushimi. To be published in Proceedings will be published as JPS conference proceedings (2016