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Beta-delayed proton emission from nuclides in the neighborhood of 100Sn was studied at the National Superconducting Cyclotron Laboratory. The nuclei were produced by fragmentation of a 120 MeV/nucleon 112Sn primary beam on a Be target. Beam purification was provided by the A1900 Fragment Separator and the Radio Frequency Fragment Separator. The fragments of interest were identified and their decay was studied with the NSCL Beta Counting System (BCS) in conjunction with the Segmented Germanium Array (SeGA). The nuclei 96Cd, 98Ing, 98Inm and 99In were identified as beta-delayed proton emitters, with branching ratios bp = 5.5(40)%, 5.5+3 -2%, 19(2)% and 0.9(4)%, respectively. The bp for 89Ru, 91,92Rh, 93Pd and 95Ag were deduced for the first time with bp = 3+1.9 -1.7%, 1.3(5)%, 1.9(1)%, 7.5(5)% and 2.5(3)%, respectively. The bp = 22(1)% for 101Sn was deduced with higher precision than previously reported. The impact of the newly measured bp values on the composition of the type-I X-ray burst ashes was studied.

Background: Nuclear structure plays a significant role on the rapid neutron capture process ($r$ process) since shapes evolve with the emergence of shells and subshells. There was some indication in neighboring nuclei that we might find examples of a new $N=56$ subshell, which may give rise to a doubly magic ${}_{34}^{90}$Se${}_{56}$ nucleus.Purpose: $\ensuremath{\beta}$-decay half-lives of nuclei around ${}^{90}$Se have been measured to determine if this nucleus has in fact a doubly magic character.Method: The fragmentation of a ${}^{136}$Xe beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the $A=90$ region.Results: We have measured the half-lives of 22 nuclei near the $r$-process path in the $A=90$ region. The half-lives of ${}^{88}\phantom{\rule{-0.16em}{0ex}}$As and ${}^{90}$Se have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a $N=56$ subshell, and its possible role in the emergence of a potential doubly magic ${}^{90}$Se. The impact of such hypothesis on the synthesis of heavy nuclei, particularly in the production of Sr, Y, and Zr elements was investigated with a weak $r$-process network.Conclusions: The new half-lives agree with results obtained from a standard global QRPA model used in $r$-process calculations, indicating that ${}^{90}$Se has a quadrupole shape incompatible with a closed $N=56$ subshell in this region. The impact of the measured ${}^{90}$Se half-life in comparison with a former theoretical predication associated with a spherical half-life on the weak $r$ process is shown to be strong.

A new picosecond lifetime measurement system developed at UNISOR was used to determine the half-life of the well-deformed [Formula: see text] levels in 188Hg and 186Hg. The half-life values were measured to be 204±45 ps in 188Hg and ≤52 ps in 186Hg. The corresponding values of ρ2(E0)×103, obtained from the partial half-lives, were [Formula: see text] and ≥32, respectively. Additionally, the half-lives of the [Formula: see text] levels were determined to be 141±31 ps in 188Hg and 48±27 ps in 186Hg.

The isomeric and $\ensuremath{\beta}$ decays of the $N=Z+2$ nucleus ${}^{96}\phantom{\rule{-0.16em}{0ex}}$Ag were investigated at the National Superconducting Cyclotron Laboratory. A cascade of $\ensuremath{\gamma}$-ray transitions originating from the deexcitation of a microsecond isomer was observed for the first time and was found in coincidence with two previously known transitions with energies of 470 and 667 keV. The isomeric half-life was determined as 1.45(7) $\ensuremath{\mu}$s, more precise than previously reported. The existence of a second, longer-lived microsecond isomer, associated with a 743-keV $\ensuremath{\gamma}$ transition, is also proposed here. Shell model results within the $({p}_{3/2}{p}_{1/2}{f}_{5/2}{g}_{9/2})$ model space, using the jj44b interaction, reproduced level energies and isomeric decay half-lives reasonably well.

Two new systems, to measure lifetimes of nuclear levels in the picosecond range that decay by E0 transitions, have been developed at the UNISOR on-line isotope separator facility. These systems make use, for the first time, of fast coincidences involving characteristic X-rays. The first of the two systems involves specifically the X-rays originating from the internal conversion process, while the second involves X-rays resulting from both the internal conversion and electron capture processes.

Since the first discovery in 1986 of a rotational band at high angular momentum with deformation parameters near β =0.6, a great deal of research has been devoted to the study of these superdeformed (SD) bands in nuclei leading to the identification of similar bands in numerous nuclei in the mass 130, 150, and 190 regions. While superdeformed shape isomers have been observed at low spin in the actinides via spontaneous fission and in a few cases via γ decay, below mass 200 the low-spin members of the SD bands have not been observed. Theoretical calculations are able to account for the relative stability of the superdeformed bands in the nuclei where they have been observed. These calculations suggest that in the HgPb region the SD shape should be stable at a rotational frequency of 0. Several experiments have been performed to search for the population and decay of the lower spin members of the SD bands in the mass 190 region and some are still in progress. To this date, none has provided conclusive observation of the 0 + bandhead of a superdeformed band. The experimental techniques utilized in several of these are described.

Angular distribution data for gamma radiation from separated116,116m,114Sb and116In oriented on-line at mK temperatures at the UNISOR Nuclear Orientation Facility, Oak Ridge, is reported. Mixing ratios of three 2+ states in116Sn are deduced. The magnetic moments of116mSb, (+)2.59(22) µN and114Sb, (+)1.72(8) µN, are extracted with full allowance for incomplete spin-lattice relaxation. Single particle descriptions of these states are briefly discussed.

Excited states in the N=30 neutron-rich isotope {sup 49}K have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target {gamma}-coincidence data from Gammasphere. The d{sub 3/2} proton-hole state is located 92 keV above the s{sub 1/2} ground state, and the proton-particle f{sub 7/2} state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2{sup +} of two neutrons above the N=28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure, which is found to be in satisfactory agreement with shell-model calculations.

The {beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {beta}-delayed neutron emission (P{sub n} values) for {sup 74}Co (18{+-}15%) and {sup 75-77}Ni (10{+-}2.8%, 14{+-}3.6%, and 30{+-}24%, respectively) for the first time, and remeasured the P{sub n} values of {sup 77-79}Cu, {sup 79,81}Zn, and {sup 82}Ga. For {sup 77-79}Cu and for {sup 81}Zn we obtain significantly larger P{sub n} values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of {sup 75}Co (30{+-}11 ms) and {sup 80}Cu (170{sub -50}{sup +110} ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is better able to reproduce the A=78-80 abundance pattern inferred from the solar abundances. The new data also influence r-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

The isomeric and $\beta$-decay properties of neutron-rich $^{53-57}$Sc and $^{53,54}$Ca nuclei near neutron number $N$=32 are reported, and the low-energy level schemes of $^{53,54,56}$Sc and $^{53-57}$Ti are presented. The low-energy level structures of the $_{21}$Sc isotopes are discussed in terms of the coupling of the valence $1f_{7/2}$ proton to states in the corresponding $_{20}$Ca cores. Implications with respect to the robustness of the $N$=32 subshell closure are discussed, as well as the repercussions for a possible $N$=34 subshell closure., Comment: 17 pages, 17 figures, accepted to Phys. Rev. C

The one-proton knockout reaction {sup 9}Be({sup 54}Ti,{sup 53}Sc+{gamma})X at 72 MeV/nucleon has been measured. The location of the first 3/2{sup -} state at 2110(3) keV was confirmed, and new {gamma}-ray transitions were observed at 1111(2), 1273(2), 1539(4), and 2495(5) keV. Large spectroscopic strength to excited states in {sup 53}Sc was found and attributed to the knockout of sd-shell protons.

The decay properties of rp‐process nuclei in the vicinity of 100Sn have been studied at the National Superconducting Cyclotron Laboratory (NSCL). The measured β‐decay half‐life for 100Sn is 0.55−0.31+0.70 s, in agreement with a previous measurement. In 98In, the β‐decay of the ground state plus that of a long lived isomer were observed with half‐lives of 47(13) ms and 0.66(40) s respectively. The half‐life of 96Cd, measured for the first time, is 1.03−0.21+0.24 s; however, the existence of a predicted isomeric state in this nucleus could not be confirmed. Additionally, a gamma cascade de‐exciting a μ‐isomer in the odd‐odd nucleus 96Ag was observed. The implications of the measured half‐life of 96Cd on the calculated rp‐process final abundances are discussed.

On-line nuclear orientation was performed on70As. Anisotropy data have been obtained at 8.7mK for 29 gamma transitions. Multipole mixing ratios have been extracted for 17 transitions. Our results are in good agreement with existing data for the ten previously measured transitions. Our first time data for the 1496 keV, 2+→2+ γ-ray suggest the 2536 keV level is a good candidate for a mixed symmetry level.

A more complete level scheme is presented here for the decay of187Pt, incorporating many new lines and levels up to 2.4 MeV. Emphasis has been placed on the extraction of multipole mixing ratios from nuclear orientation data. Analysis of that data, however, required a more complete understanding of the level structure (including, in particular, branching ratios, conversion coefficients, and level feedings), prompting the collection of new spectroscopy data. The low-lying, positive-parity levels are described in terms of (odd-proton) single-particle Nilsson states coupled to a triaxial core. Multipole mixing ratios are compared to those calculated in the Particle-Plus-Triaxial-Rotor Model.

The184Au→184Pt decay, studied on-line with the UNISOR facility at HHIRF, is discussed. Gamma-ray and conversion-electron spectroscopy of184Pt as well as on-line nuclear orientation measurements of184Au were done. A new low-lying level scheme of184Pt is proposed. Two coexisting bands with different deformations and their respective γ-vibrational bands are established. Internal conversion coefficients for interband transitions between states with the same spin are extracted from the spectroscopy measurements. The relative E0 contents of the transitions are determined by combining internal conversion coefficients with E2/M1 mixing ratios deduced from gamma-ray anisotropies measured from oriented nuclei.

The magnetic dipole moment of114Sb has been measured using on-line nuclear orientation (OLNO) at the UNISOR Nuclear Orientation Facility (UNISOR/NOF). The value was determined to be 1.72 (8) nuclear magnetons. The observed anisotropy of the 1299 keV transition was fitted as a function of temperature making allowance for incomplete thermalization of the114Sb nuclei prior to decay. The relaxation constant, Ck, is discussed, as is the ground state structure of114Sb. © 1992 J.C. Baltzer A.G., Scientific Publishing Company.

A symmetrical four-detector Compton polarimeter was used to measure the linear polarization of gamma-rays emitted from nuclei oriented by the hyperfine interaction at low temperature. Its polarization detection efficiency was determined in the range 0.3–1.4 MeV and compared with some other polarimeters.

A symmetrical four Ge detector Compton polarimeter was used to measure the linear polarization of γ-rays emitted from nuclei oriented by the hyperfine interaction at low temperature by using the UNISOR/NOF 3He4He dilution refrigerator. Its polarization detection efficiency was determined over the energy range 0.3–1.4 MeV, and is higher than those of other known polarimeters. It was used to measure the polarization of γ-rays in 186Hg observed in-beam.

Gamma rays from {sup 52}Ti have been studied with Gammasphere and the Fragment Mass Analyzer using reactions induced by a {sup 48}Ca beam on a {sup 9}Be target. The data have been used in combination with information from deep-inelastic reactions of {sup 48}Ca beams on a thick {sup 238}U target at an energy about 25% above the Coulomb barrier. The {sup 52}Ti level scheme was expanded considerably, and the lifetimes of some of the identified states were determined for the first time. The excitation of two protons and two neutrons outside the {sup 48}Ca core provide new tests of effective interactions in the full pf-shell model space. The positive-parity states in {sup 52}Ti were compared to theoretical predictions obtained with the GXPF1A, FPD6, and KB3G effective interactions. The comparisons favor, to a degree, the results computed with the GXPF1A interaction.

The yrast structure of the neutron-rich nucleus $^{97}\mathrm{Zr}$ has been studied using fission of targetlike products in the reaction of a $^{48}\mathrm{Ca}$ beam on a thick $^{238}\mathrm{U}$ target. The level scheme, known from previous studies up to an excitation energy and spin-parity of approximately 4619 keV and $23/{2}^{\ensuremath{-}}$, has been extended by about 3 MeV and a few units of angular momentum. Two states fed in the $\ensuremath{\beta}$ decay of the $27/{2}^{\ensuremath{-}}$ high-spin isomer in $^{97}\mathrm{Y}$ were identified at 5570 and 5606 keV. The located level structure can be discussed in terms of shell-model configurations.

The nuclear magnetic moment of the ground state of $^{55}\mathrm{Ni}$ (${I}^{\ensuremath{\pi}}=3/{2}^{\ensuremath{-}}$, ${T}_{1/2}=204$ ms) has been deduced to be $|\ensuremath{\mu}(^{55}\mathrm{Ni})|=(0.976\ifmmode\pm\else\textpm\fi{}0.026) {\ensuremath{\mu}}_{N}$ using the $\ensuremath{\beta}$-ray detecting nuclear magnetic resonance technique. Results of a shell model calculation in the full $\mathit{fp}$ shell model space with the GXPF1 interaction reproduce the experimental value. Together with the known magnetic moment of the mirror partner $^{55}\mathrm{Co}$, the isoscalar spin expectation value was extracted as $\ensuremath{\langle}\ensuremath{\sum}{\ensuremath{\sigma}}_{z}\ensuremath{\rangle}=0.91\ifmmode\pm\else\textpm\fi{}0.07$. The $\ensuremath{\langle}\ensuremath{\sum}{\ensuremath{\sigma}}_{z}\ensuremath{\rangle}$ shows a trend similar to that established in the $\mathit{sd}$ shell. The present theoretical interpretations of both $\ensuremath{\mu}(^{55}\mathrm{Ni})$ and $\ensuremath{\langle}\ensuremath{\sum}{\ensuremath{\sigma}}_{z}\ensuremath{\rangle}$ for the $T=1/2$, $A=55$ mirror partners support the softness of the $^{56}\mathrm{Ni}$ core.

$\ensuremath{\beta}$ decay of the $^{61}\mathrm{Cr}{}_{37}$ ground state has been studied. A new half-life of $233\ifmmode\pm\else\textpm\fi{}11$ ms has been deduced, and seven delayed $\ensuremath{\gamma}$ rays have been assigned to the daughter $^{61}\mathrm{Mn}{}_{36}$. The low-energy level structure of $^{61}\mathrm{Mn}{}_{36}$ is similar to that of the less neutron-rich $^{57,59}\mathrm{Mn}$ nuclei. The odd-${A}_{25}$Mn isotopes follow the systematic trend in the yrast states of the even-even, $Z+1$ ${}_{26}$Fe isotopes, and not that of the $Z\ensuremath{-}1$ ${}_{24}$Cr isotopes, where a possible onset of collectivity has been suggested to occur already at $N=36$.

Measurements of $\ensuremath{\beta}$-decay properties of $A\ensuremath{\lesssim}110$ r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory at Michigan State University. $\ensuremath{\beta}$-decay half-lives for $^{105}\mathrm{Y}$, $^{106,107}\mathrm{Zr}$, and $^{111}\mathrm{Mo}$, along with $\ensuremath{\beta}$-delayed neutron emission probabilities of $^{104}\mathrm{Y}$, $^{109,110}\mathrm{Mo}$ and upper limits for $^{105}\mathrm{Y}$, $^{103\ensuremath{-}107}\mathrm{Zr}$, and $^{108,111}\mathrm{Mo}$ have been measured for the first time. Studies on the basis of the quasi-random-phase approximation are used to analyze the ground-state deformation of these nuclei.

Excited states in the neutron-rich 121, 123, 125Ag were studied via the fragmentation of a 136Xe beam at 120MeV/nucleon in a thick 9Be target. The levels in 121Ag were populated in the $ \beta$ decay of 121Pd while those assigned to 123, 125Ag were identified via isomer spectroscopy. The transitions identified in 121Ag are consistent with the $ \gamma$ -rays reported in 117, 119Ag . The newly observed transitions were placed in the level schemes of 123, 125Ag based on the analysis of $ \gamma$ - $ \gamma$ coincidences and the systematics. We attribute the onset of isomerism in the 123, 125Ag isotopes to the drop in energy of the negative-parity levels similar to the 5- state in the even-even Cd cores. The proposed level scheme for 125Ag is well described by the NuShellX shell model calculations.

The transient-field technique has been used to measure the $g$ factor of the ${2}_{1}^{+}$ state in $^{56}\mathrm{Fe}$ relative to the independently determined $g$ factor of the first $5/{2}^{\ensuremath{-}}$ state in $^{57}\mathrm{Fe}$. The new result for $^{56}\mathrm{Fe}$ agrees with previous measurements but is more precise. Implications for calibrating the transient field and $g$-factor measurements in the $\mathit{fp}$ region are discussed.

The g factors of the 2{sub 1}{sup +} states in {sup 54}Fe and {sup 58}Fe have been measured relative to the 2{sub 1}{sup +} state g factor of {sup 56}Fe using the transient-field technique in inverse kinematics. The results are in satisfactory agreement with recent shell model calculations in the fp model space. For {sup 56}Fe and {sup 58}Fe the g factors approach Z/A and are therefore also consistent with collective interpretations of these 2{sup +} states.

A half-life of 2.2 \ifmmode\pm\else\textpm\fi{} 0.2 s has been deduced for the ground-state $\ensuremath{\beta}$ decay of $^{84}\mathrm{Mo}$, more than $1\ensuremath{\sigma}$ shorter than the previously adopted value. $^{84}\mathrm{Mo}$ is an even-even $N=Z$ nucleus lying on the proton dripline, created during explosive hydrogen burning in type I x-ray bursts in the rapid proton capture ($\mathit{rp}$) process. The effect of the measured half-life on $\mathit{rp}$-process reaction flow is explored. Implications on theoretical treatments of nuclear deformation in $^{84}\mathrm{Mo}$ are also discussed.

The {beta}{sup {minus}} decay of {sup 136}I isomers to levels in {sup 136}Xe was studied using sources isolated at the on-line mass separator TRISTAN. Conversion-electron and gamma-ray singles data have been collected. Evidence for excited O{sup +} states at 2582.4 and 4320 keV has been obtained. A shell-model study elucidating the salient features related to the first excited O{sup +} state in the {ital N}=82 nuclei has been carried out. Comparing two-particle, four-particle exact shell-model and two-quasiparticle shell-model calculations using both a Gaussian and surface-delta interaction in the latter case, an explanation could be given for the {ital Z} dependence in the {ital E}{sub {ital x}}(O{sub 2}{sup +}) excitation energy. We also calculate the {ital E}0 reduced matrix elements for {sup 134}Te.

The {beta}-decay properties of the N=Z nuclei {sup 96}Cd, {sup 98}In, and {sup 100}Sn have been studied. These nuclei were produced at the National Superconducting Cyclotron Laboratory by fragmenting a 120 MeV/nucleon {sup 112}Sn primary beam on a Be target. The resulting radioactive beam was filtered in the A1900 and the newly commissioned Radio Frequency Fragment Separator to achieve a purity level suitable for decay studies. The observed production cross sections of these nuclei are lower than predicted by factors of 10-30. The half-life of {sup 96}Cd, which was the last experimentally unknown waiting point half-life of the astrophysical rp process, is 1.03{sub -0.21}{sup +0.24} s. The implications of the experimental T{sub 1/2} value of {sup 96}Cd on the abundances predicted by rp process calculations and the origin of A=96 isobars such as {sup 96}Ru are explored.

The $\ensuremath{\beta}$ decay of $^{33}\mathrm{Mg}$ ($N=21$) presented in this Letter reveals intruder configurations in both the parent and the daughter nucleus. The lowest excited states in the $N=20$ daughter nucleus, $^{33}\mathrm{Al}$, are found to have nearly $2p\ensuremath{-}2h$ intruder configuration, thus extending the ``island of inversion'' beyond Mg. The allowed direct $\ensuremath{\beta}$-decay branch to the $5/{2}^{+}$ ground state of the daughter nucleus $^{33}\mathrm{Al}$ implies positive parity for the ground state of the parent $^{33}\mathrm{Mg}$, contrary to an earlier suggestion of negative parity from a $g$-factor measurement. An admixture of $1p\mathrm{\text{\ensuremath{-}}}1h$ and $3p\mathrm{\text{\ensuremath{-}}}3h$ configurations is proposed for the ground state of $^{33}\mathrm{Mg}$ to explain all of the experimental observables.

XIA LLC has developed a 16-channel digital gamma-ray spectrometer (DGF Pixie-16) and associated electronics for instrumenting segmented germanium detector systems with large numbers of channels. The Pixie-16 is a CompactPCI/PXI-based data acquisition module equipped with 100 MHz 12-bit digitizers, signal processing field programmable gate arrays and a digital signal processor. Housed in a custom 6U PXI chassis, its operation can be extended to multiple chassis by using modules which distribute clock and triggers between chassis in LVDS format to achieve high speed and low distortion transmission. XIA LLC has collaborated with the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University in the construction of a fully Digital Data Acquisition System (DDAS) for instrumenting the 594-channel Segmented Germanium Array (SeGA) at NSCL. Using its gamma-ray tracking capability and consequently improved precision in determining gamma-ray interaction positions in the SeGA detectors, the DDAS will significantly improve their ability to determine gamma-ray emission angles and thus achieve better Doppler corrections. In this paper, we demonstrate the capability to achieve sub-nanosecond timing resolution when capturing waveforms in modules across multiple chassis in response to common global triggers. We then discuss the NSCL DDAS firmware solution, especially considering its capability for data acquisition with near zero dead times.

The beta decay of 33Mg (N=21) presented in this Letter reveals intruder configurations in both the parent and the daughter nucleus. The lowest excited states in the N=20 daughter nucleus, 33Al, are found to have nearly 2p-2h intruder configuration, thus extending the "island of inversion" beyond Mg. The allowed direct beta-decay branch to the 5/2{+} ground state of the daughter nucleus 33Al implies positive parity for the ground state of the parent 33Mg, contrary to an earlier suggestion of negative parity from a g-factor measurement. An admixture of 1p-1h and 3p-3h configurations is proposed for the ground state of 33Mg to explain all of the experimental observables.

The low energy level structure of N=20 {sup 32}Mg obtained via {beta}-delayed {gamma} spectroscopy is reported. The level structure of {sup 32}Mg is found to be completely dominated by intruders. An inversion between the 1p-1h and 3p-3h states is observed for the negative parity states, similar to the 0p-0h and 2p-2h inversion for the positive parity states in these N{approx}20 nuclei. The intruder excited states, both positive and negative parity, are reasonably explained by Monte Carlo shell model calculations, which suggest a shrinking N=20 shell gap with decreasing Z.

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.

On-line {beta}-NMR measurements on nuclei oriented at low temperatures of the magnetic dipole moment of {sup 71}Cu(N=42) are reported, with the result {mu}({sup 71}Cu)=+2.28(1) nuclear magneton (n.m.). The value shows a significant difference from {mu}({sup 67}Cu)=+2.54(2) n.m., revealing asymmetry with respect to N=40. This effect presents a challenge to theoretical interpretation.

\ensuremath{\beta}-decay properties of neutron-rich Ca isotopes have been obtained. Half-life values were determined for the first time for $^{54}\mathrm{Ca}$ ($86\ifmmode\pm\else\textpm\fi{}7$ ms), $^{55}\mathrm{Ca}$ ($22\ifmmode\pm\else\textpm\fi{}2$ ms), and $^{56}\mathrm{Ca}$ ($11\ifmmode\pm\else\textpm\fi{}2$ ms). The half-life of $230\ifmmode\pm\else\textpm\fi{}60$ ms deduced for $^{53}\mathrm{Ca}$ is significantly longer than reported previously, where the decay chain $^{53}\mathrm{K}$ \ensuremath{\rightarrow} $^{53}\mathrm{Ca}$ \ensuremath{\rightarrow} $^{53}\mathrm{Sc}$ was considered. A delayed \ensuremath{\gamma} ray with an energy of 247 keV was identified following \ensuremath{\beta} decay of $^{54}\mathrm{Ca}$ and is proposed to depopulate the ${1}_{1}^{+}$ level in $^{54}\mathrm{Sc}$. The \ensuremath{\beta}-decay properties compare favorably with the results of shell-model calculations completed in the full $\mathit{pf}$ space with the GXPF1 interaction. The half-lives of the neutron-rich Ca isotopes are also compared with gross \ensuremath{\beta}-decay theory. The systematic trend of the neutron-rich Ca half-lives is consistent with the presence of a subshell gap at $N=32$.

The low-lying yrast states in the {sup 51}Ca and {sup 52}Sc nuclei were investigated to obtain information on the evolution of the p{sub 1/2} and f{sub 5/2} neutron single-particle orbitals in neutron-rich nuclei near proton number Z=20. Level structures associated with neutron excitations into these two orbitals and with proton excitations across the Z=20 shell gap were identified. Shell-model calculations with the recently proposed GXPF1A interaction account reasonably well for the fp-shell states. The energy separation between the {nu}p{sub 1/2} and {nu}f{sub 5/2} orbitals in the Ca isotopes appears to be overestimated by the GXPF1A Hamiltonian.