0000000000007531
AUTHOR
K. Kruglov
Beta decay of neutron-rich cobalt and nickel isotopes
We report on the first β-γ spectroscopy measurements of the neutron-rich 68–70Co and 70–74Ni nuclei, produced in proton-induced fission of 238U and ionized in a laser ion guide coupled to an on-line mass separator. Several γ lines from the decay of these nuclei have been identified, half-lives determined and production cross sections deduced. The derived level schemes for the copper and nickel isotopes show that the occupation of the ν(1g9/2) state has a strong influence on the structure of these neutron-rich nuclei. This may have a clear impact on the predicted structure and decay properties of doubly-magic 78Ni.
On-line yields obtained with the ISOLDE RILIS
The ISOLDE resonance ionization laser ion source (RILIS) allows to ionize efficiently and selectively many metallic elements. In recent yield surveys and on-line experiments with the ISOLDE RILIS we observed 23–34 Mg, 26–34 Al, 98–132 Cd, 149 Tb, 155–177 Yb, 179–200 Tl, 183–215 Pb and 188–218 Bi. The obtained yields are presented together with measured release parameters which allow to extrapolate the release efficiency towards more exotic (short-lived) nuclides of the same elements. 2002 Elsevier Science B.V. All rights reserved.
Magicity of theN68iSemidouble-Closed-Shell Nucleus Probed by Gamow-Teller Decay of the Odd-ANeighbors
The particle-hole excitations through the $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}40$ subshell around ${}^{68}\mathrm{Ni}$ have been studied by the $\ensuremath{\beta}$ decay of ${}^{69}\mathrm{Co}$ and ${}^{69}\mathrm{Ni}$. The half-life of ${}^{69}\mathrm{Co}$ was measured to be 0.22(2) s, and a new $\ensuremath{\beta}$-decaying isomer with a half-life of 3.5(5) s was identified in ${}^{69}\mathrm{Ni}$. From the decay of the ${}^{69}\mathrm{Ni}$ isomer a 9(4)% mixing of the $\ensuremath{\pi}{p}_{3/2}^{+1}\ensuremath{\nu}{p}_{1/2}^{\ensuremath{-}2}\ensuremath{\nu}{g}_{9/2}^{+2}$ configuration into the ground state of ${}^{69}\mathrm{Cu}$ can be deduced. Significant polarizatio…
β decay of67Co
The \ensuremath{\beta}-decay properties of ${}^{67}\mathrm{Co}$ produced in proton-induced fission of ${}^{238}\mathrm{U}$ were measured by the detection of \ensuremath{\beta}-delayed \ensuremath{\gamma} rays emitted from an isotopically pure mass-separated source obtained by laser ionization. The measured half-life of 0.425(20) s is more accurate than previous values. New \ensuremath{\gamma} transitions were observed, and corresponding branching ratios and $\mathrm{log}\mathrm{ft}$ values were deduced. The ${}^{67}\mathrm{Co}$ decay scheme is discussed in terms of the single-particle shell model.
Beta Decay of68–74Niand Level Structure of Neutron-Rich Cu Isotopes
The isotopes ${}^{68--74}\mathrm{Ni}$, of interest both for nuclear physics and astrophysics, have been produced in proton-induced fission of ${}^{238}\mathrm{U}$ and ionized in a laser ion guide coupled to an on-line mass separator. Their $\ensuremath{\beta}$ decay was studied by means of $\ensuremath{\beta}$- $\ensuremath{\gamma}$ and $\ensuremath{\gamma}$- $\ensuremath{\gamma}$ spectroscopy. Half-lives have been determined and production cross sections extracted. A partial level scheme is presented for ${}^{73}\mathrm{Cu}$ and additional levels for ${}^{71}\mathrm{Cu}$, providing evidence for a sharply lowered position of the $\ensuremath{\pi}{1f}_{5/2}$ orbital as occupancy of the $\ens…
Beta decay of neutron-rich Co: Probing single-particle states at and above the N=40 subshell closure
Neutron-rich Co nuclei with A=66–70 were produced by the laser-ionization isotope-separation on-line method. The β decay from these nuclei has been studied. A case example is given by reporting on the observed decay scheme of 68Co. The half life of the ground-state decay of this nucleus was measured to be 0.21(3) seconds. In addition, a new β decaying isomer half life of 1.16(25) seconds was discovered. The level scheme of 68Ni has been significantly extended, and an interpretation of the observed levels is made by assuming that the N=40 gap has the characteristics of a shell closure.