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تسجيل مستخدم جديدLow-energy Coulomb excitation of $^{62}$Fe and $^{62}$Mn following in-beam decay of $^{62}$Mn
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Sub-barrier Coulomb-excitation was performed on a mixed beam of $^{62}$Mn and $^{62}$Fe, following in-trap $beta^{-}$ decay of $^{62}$Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418~keV, which has been tentatively associated to a $(2^{+},3^{+})rightarrow1^{+}_{g.s.}$ transition. This fixes the relative positions of the $beta$-decaying $4^{+}$ and $1^{+}$ states in $^{62}$Mn for the first time. Population of the $2^{+}_{1}$ state was observed in $^{62}$Fe and the cross-section determined by normalisation to the $^{109}$Ag target excitation, confirming the $B(E2)$ value measured in recoil-distance lifetime experiments.
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Masses of the radioactive isotopes 62Ga, 62Zn and 62Cu have been measured at the JYFLTRAP facility with a relative precision of better than 18 ppb. A Q_EC value of (9181.07 +- 0.54) keV for the superallowed decay of 62Ga is obtained from the measured
cyclotron frequency ratios of 62Ga-62Zn, 62Ga-62Ni and 62Zn-62Ni ions. The resulting Ft-value supports the validity of the conserved vector current hypothesis (CVC). The mass excess values measured were (-51986.5 +-1.0) keV for 62Ga, (-61167.9 +- 0.9) keV for 62Zn and (-62787.2 +- 0.9) keV for 62Cu.
{bf Background:} Level sequences of rotational character have been observed in several nuclei in the $A=60$ mass region. The importance of the deformation-driving $pi f_{7/2}$ and $ u g_{9/2}$ orbitals on the onset of nuclear deformation is stressed.
{bf Purpose:} A measurement was performed in order to identify collective rotational structures in the relatively neutron-rich $^{62}$Ni isotope. {bf Method:} The $^{26}$Mg($^{48}$Ca,2$alpha$4$ngamma$)$^{62}$Ni complex reaction at beam energies between 275 and 320~MeV was utilized. Reaction products were identified in mass ($A$) and charge ($Z$) with the Fragment Mass Analyzer (FMA) and $gamma$ rays were detected with the Gammasphere array. {bf Results:} Two collective bands, built upon states of single-particle character, were identified and sizable deformation was assigned to both sequences based on the measured transitional quadrupole moments, herewith quantifying the deformation at high spin. {bf Conclusions:} Based on Cranked Nilsson-Strutinsky calculations and comparisons with deformed bands in the $A=60$ mass region, the two rotational bands are understood as being associated with configurations involving multiple $f_{7/2}$ protons and $g_{9/2}$ neutrons, driving the nucleus to sizable prolate deformation.
We report here the results of a study of the $beta$ decay of the proton-rich Ge isotopes, $^{60}$Ge and $^{62}$Ge, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of $^{62}$Ge (73.5(1) ms), $^{6
0}$Ge (25.0(3) ms) and its daughter nucleus, $^{60}$Ga (69.4(2) ms). We measured individual $beta$-delayed proton and $gamma$ emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total $beta$-delayed proton-emission branching ratio of 67(3)% has been obtained for $^{60}$Ge. New information has been obtained on the energy levels populated in $^{60}$Ga and on the 1/2$^-$ excited state in the $beta p$ daughter $^{59}$Zn. We extracted a ground state to ground state feeding of 85.3(3)% for the decay of $^{62}$Ge. Eight new $gamma$ lines have been added to the de-excitation of levels populated in the $^{62}$Ga daughter.
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