0000000000697590
AUTHOR
P.o. Lipas
Unrestricted shapes of light nuclei in the local-density approximation: Comparison with jellium clusters
Abstract The shapes of light nuclei are studied within density-functional theory. The Kohn-Sham method and the local-density approximation are used. No symmetry restrictions are imposed. A parallel study is made of monovalent atomic clusters described on the jellium model. The shapes obtained for nuclei with Z = N = 2–22 show a striking similarity to those of atomic clusters of an equal number of valence electrons. Moments of inertia, when suitably normalized, are virtually identical. The calculated nuclear quadrupole moments are found insensitive to the effective interaction and in good agreement with experiment. Similar shape coexistence is established in both systems.
Measurement of the IAS resonance strength in 23Mg
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.
$\beta$ - decay of the M$_{T}$=-1 nucleus $^{58}$Zn studied by selective laser ionization
$\beta$ - decay of $^{58}$Zn has been studied for the first time. A new laser ion-source concept has been used to produce mass-separated sources for $\beta$ and $\gamma$ - spectroscopy. The half-life of $^{58}$Zn was determined to be 86(18) ms. Comparisons are made with previous data from charge-exchange reactions. Our Gamow-Teller strength to the 1$^{+}$ state at 1051 keV excitation in $^{58}$Cu agrees well with the value extracted from a recent ($^{3}$He, t) study. Extensive shell-model calculations are presented.
High-resolution studies of beta-delayed proton emitters at IGISOL facility
Beta-decays of23Al and41Ti have been studied by applying ion guide techniques, gamma detection and a gas-Si telescope for charged-particle detection. The experimental beta-decay strength of41Ti was found to be quenched by a factor ofq2 = 0.64 compared to our shell model calculations below 8 MeV excitation energy in41Sc. This result is in line with the generally accepted value ofq = 0.77. The isobaric analogue state of the41Ti ground state was measured to contain 10(8)% isospin impurity. This relatively high value could be well reproduced by the shell model calculation in thesdfp space. Gamma-decay of theT = 3/2 isobaric analogue state in23Mg was observed together with its decay by proton em…
Beta-decay strength and isospin mixing studies in the sd and fp-shells
We have studied beta decays of MT<0 nuclei in sd and fp shells. The decay of 41Ti shows a large, 10(8) %, isospin mixing of IAS and the Gamow-Teller strength is observed to be quenched by a factor of q2=0.64. These results can be reproduced qualitatively in our shell model calculations. We have observed for the first time proton and gamma decay of the isobaric analogue state in 23Mg. Our results on the isospin mixing of the isobaric analogue state agrees well with the shell model calculations. The obtained proton branch of the IAS is used to extract the transition strength for the reaction 22Na(p,γ)23Mg.
Shell-model and Hartree-Fock calculations for even-mass O, Ne, and Mg nuclei
Shell-model and deformed Hartree-Fock plus BCS calculations are reported for even-even nuclei [sup 18[minus]30]O, [sup 18[minus]36]Ne, and [sup 20[minus]42]Mg; shell-model calculations additionally included [sup 38,40]Ne and [sup 44,46,48]Mg. Ground-state binding energies and 2[sub 1][sup +] quadrupole moments are calculated by both models. Shell-model calculations, aided by a new truncation method, include 2[sub 1][sup +] excitation energies and magnetic moments. Hartree-Fock calculations with SkI6, RATP, Z[sub [sigma]][sup [asterisk]], and SkX Skyrme forces include ground-state deformations and rms radii; SkI6 gives the best overall agreement with experiment. The two models are compared w…
High-resolution study of the beta decay of 41Ti
Abstract An improved high-resolution study of the beta decay of 41 Ti, produced in the 40 Ca( 3 He, 2n) reaction at 40 MeV, has been performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The beta-delayed radiation was detected by a low-energy charged-particle detector and a large Ge detector for gamma rays. The experimental beta-decay strength and its distribution, extracted from delayed-proton data, are compared with results of shell-model calculations in the sdfp space. The lowest J π = 3 2 + , T = 3 2 state in 41 Sc, the isobaric analogue state of the 41 Ti ground state, is estimated to contain 10% isospin impurity.