Search results for "decay [meson]"
showing 10 items of 152 documents
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 …
Physics of nuclear processes triggered by the interplay of strong and weak interactions
2012
Neutrinoless double beta (0νββ) decay of nuclei is a process that requires the neutrino to be a massive Majorana particle and thus cannot proceed in the standard model of electro-weak interactions. Recent results of the neutrino-oscillation experiments have produced accurate information on the mixing of neutrinos and their squared mass differences. The 0νββ decay takes place in atomic nuclei where it can be observed, at least in principle, by underground neutrino experiments. The information about the weak-interaction observables, like the neutrino mass, has to be filtered from the data through the nuclear matrix elements (NMEs). In this article recent work of the Jyv¨askyl¨a group on the N…
Superallowed Gamow-Teller decay of the doubly magic nucleus $^{100}$Sn
2012
Expérience au GSI; The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During b1-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy fo…
αdecay studies of the nuclides195Rnand196Rn
2001
The new neutron deficient nuclide ${}^{195}\mathrm{Rn}$ and the nuclide ${}^{196}\mathrm{Rn}$ have been produced in fusion evaporation reactions using ${}^{56}\mathrm{Fe}$ ions on ${}^{142}\mathrm{Nd}$ targets. A gas-filled recoil separator was used to separate the fusion products from the scattered beam. The activities were implanted in a position sensitive silicon detector. The isotopes were identified using spatial and time correlations between implants and decays. Two $\ensuremath{\alpha}$ decaying isomeric states, with ${E}_{\ensuremath{\alpha}}=7536(11)\mathrm{keV}[{T}_{1/2}{=(6}_{\ensuremath{-}2}^{+3})\mathrm{ms}]$ for the ground state and ${E}_{\ensuremath{\alpha}}=7555(11)\mathrm{k…
Levels of118Sn populated in the decay of118In and118Sb isomers
1970
Gamma-rays in the disintegration of 5.0 s (1+), 8.5 s (7−, 8−), and 4.4 min (4+, 5+)118In isomers and of 3.5 min (1+) and 5.1 h (8−)118Sb isomers have been investigated using Ge(Li) detectors and Ge(Li)-NaI(Tl) coincidence spectrometers. The decay schemes of these isomers have been constructed incorporating 17 levels in the product nucleus,118Sn, at the following energies (in keV): 0 (0+), 1229.5 (2+), 1757.5 (0+), 2043.1 (2+), 2056.4 (0+), 2280.3 (4+), 2321.3 (5−), 2326.4 (1+, 2+), 2402.7 (4+), 2488.8 (4+), 2496.5 (0+), 2575.2 (7−), 2677.3, 2733.7 (2+), 2929.8, 2963.5 (4+), and 3137.1 (0+). The structure of118Sn is briefly discussed in view of results from recent quasiparticle-model calcul…
Beta decay of 108Mo and of neighbouring even Mo-isotopes
1995
Abstract A combination of the proton-induced fission of 238 U and the on-line mass separation based on the ion-guide technique has been applied in the study of neutron-rich Mo-isotopes. The decays of 106,108 Mo have been studied by using gamma-, beta-, X-ray and conversion-electron spectroscopy. The decay scheme of 106 Mo has been revised and a beta-decay half-life of 8.73(12) s has been measured for this nucleus. A beta-decay half-life of 1.09(2) s and a decay energy of 5120(40) keV have been measured for 108 Mo. The decay scheme of 108 Mo has been constructed and altogether 29 new transitions have been placed in the decay scheme. The beta-decay strengths of 102,104,106,108 Mo have been de…
Study of the neutron-rich nuclei with $N$ = 21, $^{35}$Si and $^{33}$Mg, by beta decay of $^{35}$Al and $^{33}$Na
2000
Abstract The first information on the level structure of the N =21 nuclei, 35 Si and 33 Mg, has been obtained by the beta decay study of 35 Al and 33 Na, produced by fragmentation of an UC target with 1.4 GeV protons at CERN/ISOLDE. The experimental technique involved β – γ , β – γ – γ , and β –n– γ coincidences, neutron spectra being obtained by time of flight measurements. Gamma detection was made either using large Ge counters or small BaF 2 scintillators (for lifetime measurements). In the case of the 35 Al decay, ( T 1/2 =41.6(2.2) ms), a simple structure has been found for the level scheme of 35 Si ( Z =14, N =21) which has been interpreted with the level sequence : 7/2 − , 3/2 − and …
Measurement of the IAS resonance strength in 23Mg
2000
Abstract Beta decay of 23 Al to excited states in 23 Mg has been studied using low-energy proton and high-energy gamma-ray detection combined with ion-guide-based on-line mass separation. For the first time, a T =3/2 isobaric analogue state, at 7801(2) keV, was observed to decay by both proton and gamma emission, with a proton branching of 0.17(8)%. The deduced resonance strength ωγ =2.2(10) meV is in agreement with upper limits reported from 22 Na(p, γ ) reaction studies. Shell-model calculations are incorporated.
Decay of aπh11/2⊗νh11/2microsecond isomer in61136Pm75
2008
An experiment has been performed to populate several extremely neutron-deficient nuclei around the mass-140 region of the nuclear chart, using a beam of {sup 54}Fe on a {sup 92}Mo target at an energy of 315 MeV. Analysis of these data using recoil-isomer tagging has established that the yrast {pi}h{sub 11/2} x {nu}h{sub 11/2},J{sup {pi}}=(8{sup +}), bandhead state in {sup 136}Pm is isomeric with a half-life of 1.5(1) {mu}s. This isomeric state decays via a 43-keV, probable-E1 transition to a J{sup {pi}}=(7{sup -}) state. Consideration of the theoretical Nilsson orbitals near the Fermi surface suggests that the J{sup {pi}}=(8{sup +}) state has a {nu}h{sub 11/2}[505](11/2){sup -} x {pi}h{sub …
Is the single-state dominance realized in double-β-decay transitions?
1998
In the single-state-dominance hypothesis (SSDH) the decay rate of the two-neutrino double-\ensuremath{\beta} decay to the final ground state is solely determined by virtual single-\ensuremath{\beta}-decay transitions via the ${1}^{+}$ ground state of the intermediate nucleus. A very important consequence the SSDH will be that some of nonaccelerator measurements of double-\ensuremath{\beta}-decay observables could be circumvented by single-\ensuremath{\beta}-decay measurements. To assess the validity of the SSDH, we have carried out a theoretical analysis of all double-\ensuremath{\beta}-decay transitions where the spin-parity of the ground-state of the intermediate nucleus is ${1}^{+}$. The…