Search results for "Beta Decay"
showing 10 items of 501 documents
Measurement of the double-βdecay half-life ofNd150and search for neutrinoless decay modes with the NEMO-3 detector
2009
The half-life for double-{beta} decay of {sup 150}Nd has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of {sup 150}Nd, we measured the half-life for 2{nu}{beta}{beta} decay to be T{sub 1/2}{sup 2{nu}}=(9.11{sub -0.22}{sup +0.25}(stat.){+-}0.63(syst.))x10{sup 18} yr. The observed limit on the half-life for neutrinoless double-{beta} decay is found to be T{sub 1/2}{sup 0{nu}}>1.8x10{sup 22} yr at 90% confidence level. This translates into a limit on the effective Majorana neutrino mass of <4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-hand…
The beta-decay of95Rb and97Rb
1983
Theβ-decay of 377 ms95Rb and 168ms97Rb has been thoroughly investigated by means ofγ-ray, conversion electron andβ-delayed neutron spectroscopy. More than 97% of theβ-decay to particle-bound states has been placed in level schemes of95Sr and97Sr. High-resolution neutron spectroscopic studies have allowed to extend the knowledge of the excitation spectra up to 9 MeV, respectively 10 MeV. The density of neutron-unbound levels in95Sr and97Sr has been derived from peak stripping analyses of the neutron spectra. Beta-strength functions (S β(E)) have been investigated in detail. They indicate that Gamow-Tellerβ-decay of both precursors is dominated by nuclear structure. The discovered pronounced …
Ordinary muon capture studies for the matrix elements in ββ decay
2018
Precise measurement of $\gamma$-rays following ordinary (non-radiative) capture of negative muons by natural Se, Kr, Cd and Sm, as well as isotopically enriched $^{48}$Ti, $^{76}$Se, $^{82}$Kr, $^{106}$Cd and $^{150}$Sm targets was performed by means of HPGe detectors. Energy and time distributions were investigated and total life time of negative muon in different isotopes was deduced. Detailed analysis of $\gamma$-lines intensity allows to extract relative yield of several daughter nuclei and partial rates of ($\mu$,$\nu$) capture to numerous excited levels of the $^{48}$Sc, $^{76}$As, $^{82}$Br, $^{106}$Ag and $^{150}$Tc isotopes which are considered to be virtual states of an intermedia…
Questioning model-independent estimates of 2 νββ decay rates
2000
Abstract In this work we discuss the validity of recently published results, by Rumyantsev and Urin, concerning nuclear matrix elements of the two-neutrino double-beta decay transitions. These authors claim that these matrix elements can be calculated in a model-independent way. We have re-analyzed their results and extended their formalism to account for proton-neutron correlations at the QRPA level of approximation. We have found that the formalism fails in describing the double beta decay observables.
Beta Decay of 111Tc to 111Ru
1998
The β-decay of the very neutron-rich 111Tc nucleus has been observed. A partial decay scheme of 111Ru is presented, complementing the high-spin levels earlier reported in spontaneous fission work.
Total absorption γ -ray spectroscopy of niobium isomers
2019
15 pags. 17 figs., 5 tabs.
Neutrino oscillations and new physics
2005
I discuss the theoretical background and the status of neutrino oscillation parameters from the current worlds' global data sample and latest flux calculations. I give their allowed ranges, best fit values and discuss the small parameters and sin2theta13, which characterize CP violation in neutrino oscillations. I mention the significance of neutrinoless double beta decay and current expectations in view of oscillation results.
Neutrinoless double beta decay in supersymmetry with bilinear R-parity breaking
1998
We reanalyze the contributions to neutrinoless double beta ($\znbb$) decay from supersymmetry with explicit breaking of R-parity. Although we keep both bilinear and trilinear terms, our emphasis is put on bilinear R-parity breaking terms, because these mimic more closely the models where the breaking of R-parity is spontaneous. Comparing the relevant Feynman diagrams we conclude that the usual mass mechanism of double beta decay is the dominant one. From the non-observation of $\znbb$ decay we set limits on the bilinear R-parity breaking parameters of typically a (few) 100 $keV$. Despite such stringent bounds, we stress that the magnitude of R-parity violating phenomena that can be expected…
New leptoquark mechanism of neutrinoless double beta decay
1996
A new mechanism for neutrinoless double beta ($\znbb$) decay based on leptoquark exchange is discussed. Due to the specific helicity structure of the effective four-fermion interaction this contribution is strongly enhanced compared to the well-known mass mechanism of $\znbb$ decay. As a result the corresponding leptoquark parameters are severely constrained from non-observation of $\znbb$-decay. These constraints are more stringent than those derived from other experiments.
Excess electronic recoil events in XENON1T
2020
We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 t-y and an unprecedentedly low background rate of $76\pm2$ events/(t y keV) between 1 and 30 keV, the data enables sensitive searches for solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV. The solar axion model has a 3.4$\sigma$ significance, and a 3D 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by $g_{ae}<3.8 \times 10^{-12}$,…