Populating states in ${}^{22}\mathrm{Mg}$ via the $\left(p,t\right)$ reaction in inverse kinematics with a $55\text{−}\text{MeV}∕\text{nucleon}$ ${}^{24}\mathrm{Mg}$ beam, we have measured the proton-decay branching ratios of the levels at $5.96\text{MeV}$ and $6.05\text{MeV}$ and obtained an experimental upper limit on the branching ratio of the $5.71\text{−}\text{MeV}$ state. On the basis of the present and previous measurements, we assign spins and parities to the $5.96\text{−}\text{MeV}$ and $6.05\text{−}\text{MeV}$ states. We combine our branching ratios with independent measurements of the lifetimes of these states or their ${}^{22}\mathrm{Ne}$ analogs to compute the resonance strengths and thereby the astrophysical rate of the ${}^{21}\mathrm{Na}\left(p,\gamma \right){}^{22}\mathrm{Mg}$ reaction. We perform hydrodynamic calculations of nova outbursts with this new rate and analyze its impact on ${}^{22}\mathrm{Na}$ yields.

We calculate the neutrino mean free path and the equation of state of pure neutron matter at finite temperature within a self-consistent scheme based on the Brueckner-Hartree-Fock approximation. We employ the nucleon-nucleon part of the recent realistic baryon-baryon interaction (model NSC97e) constructed by the Nijmegen group. The temperatures considered range from 10 to $80\text{MeV}$. We report on the calculation of the mean field, the residual interaction, and the neutrino mean free path including short and long range correlations given by the Brueckner–Hartree–Fock plus random phase approximation (BHF+RPA) framework. This is the first fully consistent calculation in hot neutron matter dedicated to neutrino mean free path. We compare systematically our results to those obtained with the D1P Gogny effective interaction, which is independent of the temperature. The main differences between the present calculation and those with nuclear effective interactions come from the RPA corrections to BHF (a factor of about 8), while the temperature lack of consistency accounts for a factor of about 2.

A three-dimensional approach based on momentum vectors as variables for solving the three-nucleon Faddeev equation in first order is presented. The nucleon-deuteron breakup amplitude is evaluated in leading order in the nucleon-nucleon $\left(NN\right)T$ matrix, which is also generated directly in three dimensions avoiding a summation of partial wave contributions. A comparison of semiexclusive observables in the $d(p,n)pp$ reaction calculated in this scheme with those generated by a traditional partial wave expansion shows perfect agreement at lower energies. At about $200\text{MeV}$ nucleon laboratory energies deviations in the peak of the cross section appear, which may indicate that special care is required in a partial wave approach for energies at and higher than $200\text{MeV}$. The role of higher order rescattering processes beyond the leading order in the $NNT$ matrix is investigated with the result that at $200\text{MeV}$ rescattering still provides important contributions to the cross section and certain spin observables. The influence of a relativistic treatment of the kinematics is investigated. It is found that relativistic effects become important at projectile energies higher than $200\text{MeV}$.

The level scheme of ${}^{191}\mathrm{Au}$ was considerably extended to high spin using $\gamma$ spectroscopy with the Eurogam-II array and internal conversion measurements with the Orsay electron spectrometer. Several bands that appear as strongly coupled were associated with low-$\Omega$ configurations in ${}^{191}\mathrm{Au}$. Using total routhian surface and cranked shell model calculations it was shown that these bands have a rotation-aligned nature and are most likely generated by the nonaxiallity of the nucleus induced by the odd proton. The predictions for the presence of such bands in ${}^{191}\mathrm{Au}$ and in the oblate nuclei in the Pt-Au-Hg region found excellent agreement with the experimental data, as well as the predictions for their alignments and band-crossing frequencies in ${}^{191}\mathrm{Au}$.

A search for ${}^{19}\mathrm{Mg}$ was performed using projectile fragmentation of a $150\text{MeV}∕\text{nucleon}$ ${}^{36}\mathrm{Ar}$ beam. No events of ${}^{19}\mathrm{Mg}$ were observed. From the time of flight through the fragment separator an upper limit of $22\text{ns}$ for the half-life of ${}^{19}\mathrm{Mg}$ was established.

High spin states in ${}^{140}\mathrm{Eu}$ were populated following the reaction ${}^{92}\mathrm{Mo}\left({}^{51}\mathrm{V},2pn\right)$ at a beam energy of $205\text{MeV}$ by the ESTU accelerator at the Wright Nuclear Structure Laboratory, Yale University. A total of 5 bands and 69 transitions were assigned to ${}^{140}\mathrm{Eu}$. The assignments were based on $K_{\alpha }$ x-ray coincidences and on excitation function measurements. $\gamma \text{−}\gamma$ and $\gamma \text{−}\gamma \text{−}\gamma$ coincidence matrices were created. Directional correlation of oriented states analysis, angular distributions, and Compton asymmetry measurements were performed and $B\left(M1\right)∕B\left(E2\right)$ branching ratios were extracted. The band assignments and structures are discussed in terms of the rotational model and interpreted following a series of cranked shell model and total Routhian surface calculations. In particular, two pairs of bands, one pair based on the $\pi h_{11∕2}\otimes \nu h_{11∕2}$ configuration, the other based on the $\pi (g_{7∕2},d_{5∕2})\otimes \nu h_{11∕2}$ configuration, are identified. These bands show some features expected of either chiral partners or shape coexistence, based on triaxial shapes with $\gamma \sim \pm 25°$. Further measurements are required to distinguish between these two possibilities.

The $\alpha$ decay of ${}^{188,192}\mathrm{Po}$ has been reexamined in order to probe the $0^{+}$ states in the daughter nuclei ${}^{184,188}\mathrm{Pb}$ that can be associated with coexisting spherical, oblate, and∕or prolate configurations. Improved values were measured for the excitation energy and the feeding $\alpha$-decay intensity of the $0_2^{+}$ state in ${}^{184,188}\mathrm{Pb}$ and conflicting results on the $0_3^{+}$ state in ${}^{188}\mathrm{Pb}$ were clarified. All known cases of fine structure in the $\alpha$ decay of the even-even Po nuclei are reviewed. The reduced $\alpha$-decay width systematics combined with potential-energy-surface calculations confirm the onset of deformation in the ground state of the polonium nuclei around the neutron midshell. An isomeric state with a half-life of $580\left(100\right)\text{ns}$ has been identified in ${}^{192}\mathrm{Po}$.

An improved prescription for choosing a transformed harmonic-oscillator (THO) basis for use in configuration-space Hartree-Fock-Bogoliubov (HFB) calculations is presented. The new $\text{HFB}+\text{THO}$ framework that follows accurately reproduces the results of coordinate-space HFB calculations for spherical nuclei, including those that are weakly bound. Furthermore, it is fully automated, facilitating its use in systematic investigations of large sets of nuclei throughout the periodic table. As a first application, we have carried out calculations using the Skyrme force SLy4 and volume pairing, with exact particle-number projection following application of the Lipkin-Nogami prescription. Calculations were performed for all even-even nuclei from the proton drip line to the neutron drip line having proton numbers $Z=2,4,\dots ,108$ and neutron numbers $N=2,4,\dots ,188$. We focus on nuclei near the neutron drip line and find that there exist numerous particle-bound even-even nuclei (i.e., nuclei with negative Fermi energies) that have at the same time negative two-neutron separation energies. This phenomenon, which was earlier noted for light nuclei, is attributed to bound shape isomers beyond the drip line.

High-spin states in the odd-odd ${}^{172}\mathrm{Re}$ have been investigated via the ${}^{149}\mathrm{Sm}({}^{27}\mathrm{Al},4n\gamma ){}^{172}\mathrm{Re}$ reaction through excitation functions, $x\text{−}\gamma$ and $\gamma \text{−}\gamma$ coincidence measurements. A level scheme consisting of three rotational bands has been identified for the first time extending the high-spin studies of $A\sim 160$ odd-odd nuclei to the currently lightest rhenium isotope. The three bands have been assigned to be built on the $\pi h_{11∕2}\otimes \nu i_{13∕2}$, $\pi h_{9∕2}\otimes \nu i_{13∕2}$, and $\pi 1∕2^{-}\left[541\right]\otimes \nu 1∕2^{-}\left[521\right]$ configurations according to their rotational properties in quasiparticle alignments, signature splitting, in-band $B\left(M1\right)∕B\left(E2\right)$ ratios, level spacing systematics, band crossing frequencies, as well as the existing knowledge in neighboring nuclei. Low-spin signature inversion has been confirmed in the first two bands due to the observation of signature crossing at high-spin states. The general features of inversion phenomenon in the semidecoupled bands are presented and discussed with reference to theoretical calculations of two quasiparticle plus rotor model including $p\text{−}n$ interactions.

Influence of the target and projectile deformation changes within the overlapping region of the fusion configuration is studied. A deformed two-center shell model for ellipsoidal nuclei partners is presented. The model produces the level scheme of the two partially superposed deformed nuclei all along the fusion path towards the synthesized element. Shell corrections are calculated in fusion reactions as functions of target or projectile deformation changes and also for different mass asymmetries. It is shown that lower shell correction values are obtained when the initial deformation of a partner nucleus is modified within the overlapping region. Studies are performed for light and superheavy nuclei synthesis reactions.

A modified quark meson coupling (MQMC) model is extended to include $\Lambda$ hyperons and $\Xi$ hyperons. The extended model is then used to study the equation of state (EOS) for strange hadronic matter. A weak $\Lambda \text{−}\Lambda$ interaction deduced from recent observation of ${}_{\Lambda \Lambda }{}^6\mathrm{He}$ double hypernucleus is adopted in the calculation. The resultant EOS is compared with that deduced from a strong $\Lambda \text{−}\Lambda$ interaction. It is found that while the system with the strong $\Lambda \text{−}\Lambda$ interaction is more deeply bound than ordinary nuclear matter due to the opening of new degrees of freedom, the system with the weak $\Lambda \text{−}\Lambda$ interaction is rather loosely bound compared to the latter. It is necessary to introduce the strange mesons ${\sigma }^{*}$ and $\varphi$ in the MQMC model to properly describe the interaction between the hyperons in either strong or weak $\Lambda \text{−}\Lambda$ interaction cases.

This is the third part of a series of work that we have done in the context of the meson cloud model. In the first two parts [F. Zamani, Phys. Rev. C 58, 3641 (1998); F. Zamani and D. Saranchak, Phys. Rev. C 63, 065202 (2001)] we used pseudoscalar mesons to calculate unpolarized and polarized quark distribution functions along with the nucleon’s $F_2$ and $g_1$ structure functions. Now we have added the vector mesons to the meson cloud to calculate the polarized quark distribution functions and $g_1$ structure function. The calculation is performed in the light-cone frame. The dressed nucleon is assumed to be a superposition of the bare nucleon plus virtual light-cone Fock states of baryon-meson pairs. For bare nucleon we consider both the case of diquark-quark clustering and the case where there is no quark clustering inside the nucleon. The initial distributions are evolved. The final results are compared with experimental results and other theoretical predictions.

Neutrino interactions on a ${}^{208}\mathrm{Pb}$ target nucleus are widely regarded as an excellent tool for the study of a galactic supernova explosion in a terrestrial detector. To serve this goal an accurate knowledge of the neutrino cross section on ${}^{208}\mathrm{Pb}$ is needed. We examine the influence of the supernova-neutrino energy spectrum on the response in a detector. In view of the results of recent calculations for supernova-neutrino spectra, we discuss the importance of the distribution’s average energy and width and comment on the influence of uncertainties in the parametrization of the spectrum. We show that changes in the energy distributions parameters can have a disproportionately large influence on the folded cross section. Our calculations point out that implementing the new supernova-neutrino spectra causes a reduction of the folded supernova-neutrino cross sections. We note a remarkably large sensitivity of the folded cross sections to the high-energy tail of the spectrum. The discussion focuses on neutral-current reactions in a terrestrial detector considering one- and two-neutron knockout.

As a continuation of a systematic study of reactions relevant to the astrophysical $p$ process, the cross sections of the ${}^{74,76}\mathrm{Se}\left(p,\gamma \right){}^{75,77}\mathrm{Br}$ and ${}^{82}\mathrm{Se}\left(p,n\right){}^{82}\mathrm{Br}$ reactions have been measured at energies from 1.3 to $3.6\text{MeV}$ using an activation technique. The results are compared to the predictions of Hauser-Feshbach statistical model calculations using the NON-SMOKER and MOST codes. The sensitivity of the calculations to variations in the optical proton potential and the nuclear level density was studied. Good agreement between theoretical and experimental reaction rates was found for the reactions ${}^{74}\mathrm{Se}\left(p,\gamma \right){}^{75}\mathrm{Br}$ and ${}^{82}\mathrm{Se}\left(p,n\right){}^{82}\mathrm{Br}$.

We study the effects of the finite size of baryons on the equation of state of homogeneous hadronic matter. The finite extension of hadrons is introduced in order to improve the performance of field theoretical models at very high densities. We simulate the in-medium averaged baryon-baryon strong repulsion at very short distances by introducing a van der Waals–like normalization of the fields. This is done in the framework of the quark meson coupling model that allows to take care of the quark structure of baryons. Since within this model the confinement volume evolves with the fields configuration, the treatment is not equivalent to a simple hard-core potential. We investigate the phase transition to quark matter and the structure of neutron stars. We have found significant corrections at high densities.

We show that, contrary to a recent paper, the new, analytic, critical point symmetry $\mathrm{X}\left(5\right)$, which is parameter-free (except for scale), reproduces the data in ${}^{152}\mathrm{Sm}$ and ${}^{150}\mathrm{Nd}$ quite well, and better than multiparameter models based on bandmixing of pure rotor states.

High-spin states of ${}^{187}\mathrm{Ir}$ have been populated in the ${}^{176}\mathrm{Yb}\left({}^{15}\mathrm{N},4n\right)$ reaction and measured with the YRAST Ball spectrometer. The $\pi h_{9∕2}$ rotational band has been extended beyond the first alignment crossing, which was found at rotational frequency $\hslash {\omega }_c\approx 0.39\text{MeV}$. Two different scenarios for describing this crossing are considered: the alignment of an $h_{9∕2}$ proton or $i_{13∕2}$ neutron pair and it is concluded that a proton band crossing is more likely. A systematic study of the rotational alignment crossings in the $\pi h_{9∕2}$ bands in the $N=104,106,108$ isotopes of ${}_{73}\mathrm{Ta},{}_{75}\mathrm{Re},{}_{77}\mathrm{Ir},$ and ${}_{79}\mathrm{Au}$ is presented.

The ${}^{233}\mathrm{Pa}(n,f)$ cross section, a key ingredient for fast reactors and accelerators driven systems, was measured recently with relatively good accuracy [F. Tovesson et al., Phys. Rev. Lett. 88, 062502 (2002)]. The results are at strong variance with accepted evaluations and an existing indirect experiment. This circumstance led us to perform a quite detailed and complete evaluation of the ${}^{233}\mathrm{Pa}(n,f)$ cross section between 1.0 and $3.0\text{MeV}$, where use of our newly developed routines for the parametrization of the nuclear surface and the calculation of deformation parameters and level densities (including low-energy discrete levels) were made. The results show good quantitative and excellent qualitative agreement with the experimental direct data obtained by Tovesson et al. [F. Tovesson et al., Phys. Rev. Lett. 88, 062502 (2002)]. Additionally, our methodology opens new possibilities for the analysis of subthreshold fission and above threshold second-chance fission for both ${}^{233}\mathrm{Pa}$ and its decay product ${}^{233}\mathrm{U}$, as well as other strategically important fissionable nuclides.

In a previous work, the full Glauber series of the elastic scattering between two cluster nuclei has been evaluated in an approximate way. The present paper introduces a more elaborate technique to calculate such series rigorously. The deuteron-carbon elastic angular distribution is calculated by the two approaches and the results showed that the inaccuracy of the previous approach is significant at large angles. Impressive fit is observed to the experimental data when the phase variation is included in the present analysis.

The region from $6<E_x<11\text{MeV}$ in ${}^{40}\mathrm{Ca}$ has been studied with inelastic scattering of $240\text{MeV}$ $\alpha$ particles at small angles including $0°$. Strength corresponding to $3.2\pm 1.0\%$ of the isoscalar $E0$ sum rule was identified with a centroid of $8.7\pm 0.30\text{MeV}$.