Search results for "electron capture"
showing 10 items of 90 documents
Direct measurement of the mass difference of As72−Ge72 rules out As72 as a promising β -decay candidate to determine the neutrino mass
2021
We report the first direct determination of the ground-state to ground-state electron-capture $Q$ value for the $^{72}\mathrm{As}$ to $^{72}\mathrm{Ge}$ decay by measuring their atomic mass difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The $Q$ value was measured to be 4343.596(75) keV, which is more than a fiftyfold improvement in precision compared to the value in the most recent Atomic Mass Evaluation 2020. Furthermore, the new $Q$ value was found to be 12.4(40) keV (3.1 $\ensuremath{\sigma}$) lower. With the significant reduction of the uncertainty of the ground-state to ground-state $Q$ value combined with the level scheme of $^{72}\mathrm{Ge}$ from $\ensurem…
Electron Capture Processes in Intermediate Mass stars
2015
Intermediate mass stars develop a degenerate core constituted of O, Ne and Mg during their evolution. As the density in the core increases electron capture sets in igniting Ne and O burning. Particularly important is electron capture on 20Ne that has been found recently to be dominated by a second forbidden transition from the 0+ ground state of 20Ne to the 2+ ground state of 20F. We have performed shell–model calculations to determine the transition strength and provide an updated value of the electron capture rate and the expected branching ratio to the corresponding β–decay process. peerReviewed
Octupolar-Excitation Penning-Trap Mass Spectrometry forQ-Value Measurement of Double-Electron Capture inEr164
2011
The theory of octupolar-excitation ion-cyclotron-resonance mass spectrometry is presented which predicts an increase of up to several orders of magnitude in resolving power under certain conditions. The new method has been applied for a direct Penning-trap mass-ratio determination of the $^{164}\mathrm{Er}\mathrm{\text{\ensuremath{-}}}^{164}\mathrm{Dy}$ mass doublet. $^{164}\mathrm{Er}$ is a candidate for the search for neutrinoless double-electron capture. However, the measured ${Q}_{ϵϵ}$ value of 25.07(12) keV results in a half-life of ${10}^{30}$ years for a 1 eV Majorana-neutrino mass.
Neutrino mass, neutrinoless double electron capture and rare beta decays
2010
We present results of our theoretical calculations on three nuclei of interest from the neutrino-physics point of view: Firstly, we present the second-forbidden decay branch of 115In with the ultra-low Q value and theoretical open questions related to such decays. Secondly, we have calculated estimates for the half-lives of the single-beta decay channels of 96Zr and concluded that the possible contamination from those to the geochemical measurements of 96Zr double-beta-decay half-life is rather small. Thirdly, we have taken a look at the neutrinoless resonance double-electron-capture decay of 112Sn in the light of recent JYFLTRAP Q value measurements and discovered that the badly fulfilled …
Double beta decay: an interface between nuclear, particle and atomic physics
2013
General properties of the nuclear matrix elements (NMEs) related to the various modes of neutrinoless double β decays are examined and analyzed. The decays include the electron-emitting double beta-minus decays β−β− and the various positron-emitting/electron capture decays. Special interest is devoted to the neutrinoless double electron capture decay with a resonance condition.
The Capabilities of monochromatic EC neutrino beams with the SPS upgrade
2007
The goal for future neutrino facilities is the determination of the U(e3) mixing and CP violation in neutrino oscillations. This will require precision experiments with a very intense neutrino source and energy control. With this objective in mind, the creation of monochromatic neutrino beams from the electron capture decay of boosted ions by the SPS of CERN has been proposed. We discuss the capabilities of such a facility as a function of the energy of the boost and the baseline for the detector. We conclude that the SPS upgrade to 1000 GeV is crucial to reach a better sensitivity to CP violation iff it is accompanied by a longer baseline. We compare the physics potential for two different…
Spin polarized electron transport and partial localization of photoelectrons in highly doped photocathodes
2011
The results of experimental and theoretical studies of spin polarized electron transport in semiconductor SL used for photoemitter application are presented. The experimental study is based on the time resolved measurements of electron emission from the cathode after its photoexcitation by fs laser pulse. The response and spin relaxation times have been determined by means of measured time dependent intensity and polarization of electron emission. We also performed theoretical calculations of photocathode pulse response and compared the obtained results with experimental data. Our analysis testifies the presence of partial electron localization in SL. Electron capture by localized states le…
Search for Electron-Capture Delayed Fission in the New Isotope Md244
2020
The electron-capture decay followed by a prompt fission process was searched for in the hitherto unknown most neutron-deficient Md isotope with mass number 244. Alpha decay with $\ensuremath{\alpha}$-particle energies of 8.73--8.86 MeV and with a half-life of ${0.30}_{\ensuremath{-}0.09}^{+0.19}\text{ }\text{ }\mathrm{s}$ was assigned to $^{244}\mathrm{Md}$. No fission event with a similar half-life potentially originating from spontaneous fissioning of the short-lived electron-capture decay daughter $^{244}\mathrm{Fm}$ was observed, which results in an upper limit of 0.14 for the electron-capture branching of $^{244}\mathrm{Md}$. Two groups of fission events with half-lives of ${0.9}_{\ens…
Neutrinoless double beta decays of 106Cd revisited
2011
Abstract Neutrinoless double beta ( 0 ν 2 β ) decays of 106 Cd are studied for the transitions to the ground state, 0 gs + , and 0 + excited states in 106 Pd by using realistic many-body wave functions calculated in the framework of the quasiparticle random-phase approximation and its extensions. Effective, G-matrix-based nuclear forces are used in large single-particle model spaces. Both the β + β + and β + EC channels of the 0 ν 2 β decay are discussed and half-lives are computed. Particular attention is devoted to the study of the detectability of the resonant neutrinoless double electron capture ( R 0 ν ECEC ) process in 106 Cd. The calculations of the present article constitute the thu…
Decay study of 246Fm at SHIP
2011
The decay chain of 246Fm has been investigated employing the SHIP separator at GSI Darmstadt. The 246Fm nuclei were produced via the 40Ar(208Pb, 2n)246Fm fusion-evaporation reaction. Improved values of the half-life, T 1/2 = 1.54(4) s, and of the spontaneous fission branching ratio, b SF = 0.068(6) , of 246Fm were obtained. The $ \beta^{+}_{}$ /electron capture branching ratio, b EC = 0.39(3) , of 242Cf was deduced. Possible structures of high-K states in 246Fm are discussed within the framework of a model calculation based on the Woods-Saxon potential.