Deformation of the N=Z nucleus 76Sr using beta-decay studies

A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of QRPA calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large Total Absorption gamma Spectrometer, "Lucrecia", newly installed at CERN-ISOLDE.Comment: Accepted in Phys. Rev. Letter

Shape study of the N = Z nucleus Kr-72 via beta decay

10 pags.; 11 figs.; 2 tabs.; PACS number(s): 23.40.Hc, 29.30.Kv, 27.50.+e, 21.10.Pc; Open Access funded by Creative Commons Atribution Licence 3.0The beta decay of the N = Z nucleus Kr-72 has been studied with the total absorption spectroscopy technique at ISOLDE (CERN). A total B(GT) = 0.79(4)g(A)(2)/4 pi has been found up to an excitation energy of 2.7 MeV. The B(GT) distribution obtained is compared with predictions from state-of-the-art theoretical calculations to learn about the ground state deformation of Kr-72. Although a dominant oblate deformation is suggested by direct comparison with quasiparticle random phase approximation (QRPA) calculations, beyond-mean-field and shell-model calculations favor a large oblate-prolate mixing in the ground state. Published by the American Physical SocietyJ.A.B. acknowledges the predoctoral grant BES-2008-009412 associated with the research project FPA2007-62170 funded by Ministerio de Ciencia e Innovacion (Spain). This work has ´ been partly supported by the Spanish Ministerio de Economía y Competitividad (MINECO) through projects FPA2012- 32443, FPA2011-24553, FPA2011-29854-C04-01, FPA2013- 41267-P, FPA2014-52823-C2-1-P and FIS2011-23565, by STFC-UK (Grant No. ST/F012012/1) and by the European Union by means of the European Commission within its Seventh Framework Programme (FP7) via ENSAR (Contract No. 262010)Peer Reviewe

Beta-decay in odd-A and even-even proton-rich Kr isotopes

Beta-decay properties of proton-rich odd-A and even-even Krypton isotopes are studied in the framework of a deformed selfconsistent Hartree-Fock calculation with density-dependent Skyrme forces, including pairing correlations between like nucleons in BCS approximation. Residual spin-isospin interactions are consistently included in the particle-hole and particle-particle channels and treated in Quasiparticle Random Phase Approximation. The similarities and differences in the treatment of even-even and odd-A nuclei are stressed. Comparison to available experimental information is done for Gamow-Teller strength distributions, summed strengths, and half-lives. The dependence of these observables on deformation is particularly emphasized in a search for signatures of the shape of the parent nucleus.Comment: 29 pages, 16 figure

The β+\beta^+-electron capture decay of 73^{73}Kr

The $\beta^+$ – electron capture decay of $^{73}$Kr, produced at the ISOLDE CERN facility, has been studied by $\beta$-delayed proton and gamma emission. The established decay scheme involves 15 up to now unreported gamma emitting levels in $^{73}$Br. The total proton branching ratio has been measured to be $0.0025 \pm 0.0003$. From this work, a spin and parity $3/2^-$ is assigned to the $^{73}$Kr ground state, on the basis of the allowed $\beta$ branch to the $^{73}$Br $J^{\pi}=1/2^-$ ground state and the feeding of the $5/2^+$ level located at 286 keV in $^{73}$Br

Beta Decay and Structure of Exotic Nuclei in the Mass Regions N=Z, A 70 and Near the N=20 Closed Shell

This paper describes two beta decay experiments performed at the CERN/ISOLDE mass separator. The structure of 74 Kr has been studied using a total absorption γ spectrometer (TAg

Search for proton radioactivity in <SUP>65</SUP>As, <SUP>69</SUP>Br and <SUP>77</SUP>Y

A search for proton radioactivity in 65As, 69Br and 77Y, produced as residues of fusion reactions, was carried out at the Orsay Tandem accelerator. The residues were collected at the image point of the spectrometer Soleno and implanted into the gaseous medium of an ionization chamber which was also used to detect the radioactivity protons. No such protons have been observed in the energy range of 250–600 keV and in the half-life interval of 10 μs-100 ms, within a production cross section sensitivity of 1 μb.Facultad de Ciencias Exacta

The N=Z nucleus Sr-76: Gamow-Teller strength and nuclear deformation

7 pages, 4 tables, 6 figures.--PACS nrs.: 21.10.Hw; 23.20.Lv; 23.40.Hc; 27.50.+e.Challenged by recent theoretical work, a, study of the β(+)-EC decay of the N = Z even-even nucleus Sr-76 has been undertaken in order to assign the parent ground-state deformation. lit this study 13 levels with J(π) = 1(+) have been located in Rb-76. The β-delayed proton emission has been observed for the first time in an N = Z even-even nucleus. The betap branching ratio has been determined to be (3.4 ± 0.8)x10(-5). The Sr-76 half-life has been remeasured and a more precise value of 7.89 ± 0.07 s has been obtained. On the basis of the comparison of measured Gamow-Teller strength with calculated strength distributions for both oblate and prolate deformation, it is concluded that the Sr-76 has strong prolate deformation in the ground state.This work was partially supported by the Spanish Agency CICYT under contract Nos. AEN96-1679 and AEN99-1046-C02-01, and by the French and Spanish Agreement IN2P3-CICYT.Peer reviewe