Search results for "Double beta"
showing 10 items of 320 documents
R-matrix analysis of theβdecays ofN12andB12
2010
The β decays of 12N and 12B have been studied at KVI and JYFL to resolve the composition of the broad and interfering 0+ and 2+ strengths in the triple-α continuum. For the first time a complete treatment of 3α decay is presented including all major breakup channels. A multilevel, many-channel R-matrix formalism has been developed for the complete description of the breakup in combination with the recently published separate analysis of angular correlations. We find that, in addition to the Hoyle state at 7.65 MeV, more than one 0+ and 2+ state is needed to reproduce the spectra. Broad 03+ and 22+ states are found between 10.5 and 12 MeV in this work. The presence of β strength up to the 12…
High-precision mass measurement ofS31with the double Penning trap JYFLTRAP improves the mass value forCl32
2010
Mean-field effects on neutrinoless double beta decay
1998
Abstract Mean-field effects on the nuclear matrix elements involved in the neutrinoless double beta (0νββ) decay of several double-electron and double-positron emitters have been studied within the framework of the relativistic quark-confinement model and the quasiparticle random-phase approximation. The single-particle energies of the model space have been generated both by using the standard Woods-Saxon parametrization of the mean field and adjusting the quasiparticle spectra with the data from neutron- and proton-odd nuclei. The 0νββ rates are found to be much less affected by the energies of the mean-field orbitals than the rates of the two-neutrino double beta decay. The present study …
Neutrinoless double beta decay to excited collective 0+ states
2000
Abstract The many recently performed experiments to study the two-neutrino double beta (2 νββ ) decay to the first excited 0 + final state encourage similar experiments to be done for the neutrinoless double beta (0 νββ ) decay. Based on the accumulated theoretical and experimental information on the 2 νββ decays one could hope that the 0 νββ decay to the excited 0 + state would be very efficient in restricting the parameter space of modern particle-physics theories. In this article the 0 νββ decays of 76 Ge and 82 Se to excited collective 0 + states are studied within a realistic nuclear model. It is found that the lower limits for the half-lives of these decays are of the order of 10 27 y…
On the double-beta decays of 70Zn, 86Kr, 94Zr, 104Ru, 110Pd and 124Sn
2011
Abstract Double-beta decays of 70Zn, 86Kr, 94Zr, 104Ru, 110Pd and 124Sn to the final ground states and the decays of 110Pd and 124Sn to the excited states in 110Cd and 124Te are studied in the framework of the proton–neutron quasiparticle random-phase approximation (pnQRPA) combined with the multiple-commutator model (MCM) for description of decays to the excited final states. Reasonably large single-particle model spaces and G-matrix-based effective nuclear forces are used to compute the relevant nuclear matrix elements and decay half-lives. The present study is among the very few that have been dedicated to double-beta decays of these nuclei, although the associated double-beta Q values e…
Theory of double beta decay
2005
Basic features of the two-neutrino double beta ( 2 ν β β ) decay and neutrinoless double beta ( 0 ν β β ) decay are discussed. A short review of the most important nuclear models, used to describe the ββ decay, is given. A deeper survey of the nuclear matrix elements, related to the above-mentioned decay modes, is performed using the proton-neutron quasiparticle random-phase approximation (pnQRPA). In particular, the extraction of a proper value of the proton-neutron particle-particle interaction parameter in this theory is addressed. The relevance of different multipoles in the multipole decomposition of the 0 ν β β matrix element is also discussed in the pnQRPA framework.
β-decay studies of r-process nuclei at NSCL
2008
Abstract Observed neutron-capture elemental abundances in metal-poor stars, along with ongoing analysis of the extremely metal-poor Eu-enriched sub-class provide new guidance for astrophysical models aimed at finding the r-process sites. The present paper emphasizes the importance of nuclear physics parameters entering in these models, particularly β -decay properties of neutron-rich nuclei. In this context, several r-process motivated β -decay experiments performed at the National Superconducting Cyclotron Laboratory (NSCL) are presented, including a summary of results and impact on model calculations.
β-decay half-lives andβ-delayed neutron emission probabilities of nuclei in the regionA≲110, relevant for the r process
2009
Measurements of $\ensuremath{\beta}$-decay properties of $A\ensuremath{\lesssim}110$ r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory at Michigan State University. $\ensuremath{\beta}$-decay half-lives for $^{105}\mathrm{Y}$, $^{106,107}\mathrm{Zr}$, and $^{111}\mathrm{Mo}$, along with $\ensuremath{\beta}$-delayed neutron emission probabilities of $^{104}\mathrm{Y}$, $^{109,110}\mathrm{Mo}$ and upper limits for $^{105}\mathrm{Y}$, $^{103\ensuremath{-}107}\mathrm{Zr}$, and $^{108,111}\mathrm{Mo}$ have been measured for the first time. Studies on the basis of the quasi-random-phase approximation are used to analyze the ground-state deformation of these…
Total absorption study of theβdecay of102,104,105Tc
2013
The $\ensuremath{\beta}$-feeding probabilities for three important contributors to the decay heat in nuclear reactors, namely ${}^{102,104,105}$Tc, have been measured using the total absorption spectroscopy technique. For the measurements, sources of very high isobaric purity have been obtained using a Penning trap (JYFLTRAP). A detailed description of the data analysis is given and the results are compared with high-resolution measurements and theoretical calculations.
Half-life measurements for neutron-rich Tc, Ru, Rh, and Pd isotopes. Identification of the new isotopesTc111,Ru113, andRh113
1988
The decays of three new neutron-rich nuclides $^{111}\mathrm{Tc}$, $^{113}\mathrm{Ru}$, and $^{113}\mathrm{Rh}$ have been observed at an on-line isotope separator facility. In addition, the beta decays of several other n-rich isotopes with Ag100 have been studied for the first time. The new half-lives reported in this work include: $^{111}\mathrm{Tc}$ [${T}_{1/2}$=0.30(3) s], $^{111}\mathrm{Ru}$ [2.12(7) s], $^{112}\mathrm{Ru}$ [1.75(7) s], $^{113}\mathrm{Ru}$ [0.80(10) s], $^{113}\mathrm{Rh}$ [2.72(22) s], and $^{118}\mathrm{Pd}$ [2.24(17) s]. In general, these results support the microscopic theoretical half-life predictions below Z=50.