Search

High-spin states in $^{71}\mathrm{As}$ were studied using the $^{54}\mathrm{Fe}$$({}^{23}$Na,$\ensuremath{\alpha}2p)$ reaction at 80 MeV. Prompt $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidences were measured using the Florida State University Compton-suppressed Ge array consisting of three clover detectors and seven single-crystal detectors. The existing high-spin level scheme has been verified, and 21 new transitions have been added based on an investigation of weak $\ensuremath{\gamma}$-ray coincidence relations and relative $\ensuremath{\gamma}$-ray intensities. Lifetimes of 16 excited states were measured using the Doppler-shift attenuation method applied to the experimental line shapes of decays in all of the known rotational bands. The $B(E2)$ strengths inferred from the lifetimes indicate that moderate to high collective behavior persists to the highest observed spins in the lowest positive- and negative-parity bands, in qualitative agreement with projected shell-model calculations. The band suggested to be based on the $\ensuremath{\pi}{f}_{7/2}$ orbital shows a similar degree of collectivity within the same spin range, with $B(E2)$ values in good agreement with those predicted by the projected shell model assuming a constant prolate deformation of ${\ensuremath{\epsilon}}_{2}=+0.27$. The experimental ${Q}_{t}$ values in this band are somewhat smaller than predicted by cranked Woods-Saxon calculations.

Low-spin states were studied in $^{30}\mathrm{Al}$ following the \ensuremath{\beta} decay of $^{30}\mathrm{Mg}$ produced in the fragmentation of 140-MeV/AMU $^{48}\mathrm{Ca}$. Analysis of the $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidences revealed a new ${1}^{+}$ state at 2413 keV, confirmation of the level scheme, and a more accurate half-life measurement of 315(6) ms for the $^{30}\mathrm{Mg}$ ground state. Higher-spin states were investigated in the reaction of $^{14}\mathrm{C}$ on $^{18}\mathrm{O}$ at 22 MeV. Protons and deuterons were detected in a segmented E-\ensuremath{\Delta}E Si telescope in coincidence with one or two \ensuremath{\gamma} rays in the FSU Ge detector array. A comparison of the resulting level and decay scheme with predictions of the $\mathit{sd}$ shell model shows good agreement with all but six of the states in both excitation energy and \ensuremath{\gamma}-decay branching ratios. The root-mean-square deviations in energy of these states using the older USD and newer USDA and USDB interactions were 265, 176, and 173 keV, respectively. The remaining six states are well described as ${4}^{\ensuremath{-}}$ to ${7}^{\ensuremath{-}}$ states, similar in relative energy to those in $^{28}\mathrm{Al}$ but shifted down by about 1200 keV. These states also agree well with the predictions of shell-model calculations using the WBP interaction. A comparison of the lowest ${4}^{\ensuremath{-}}$ states in even A Na, Al, and P isotopes shows a systematic decrease in energy with increasing N and with decreasing Z. The energies of the ${4}^{\ensuremath{-}}$ states are almost identical in nuclei with the same $N\text{\ensuremath{-}}Z$ values.

Electromagnetic transitions in {sup 22}F were investigated using the {sup 9}Be({sup 14}C, p) reaction at E{sub lab}=22 MeV. Proton-{gamma} and proton-{gamma}-{gamma} coincidences were measured using a segmented E-{delta}E Si telescope and the Florida State University {gamma} detector array. {gamma}-ray energies, intensities, and branching ratios were measured, and mean lifetimes were inferred using the Doppler-shift attenuation method. Several new states and many new {gamma}-decay branches were observed. The results are compared with sd shell model calculations using the USD, USDA, and USDB interactions. The excitation energies of the states below 2 MeV agree slightly better with the calculations using the USD interaction, while the levels between 2 and 4 MeV agree somewhat better with those using the newer USDA and USDB interactions.