We have measured the angular distributions and production cross sections for the products of the reaction of 859-MeV ($E_{\text{c.m.}}=461.9\hspace{0.5em}\text{MeV}$) ${}^{160}\mathrm{Gd}$ with ${}^{186}\mathrm{W}$. We detected fragments that stopped in the 5.775 mg/cm${}^2$ target as well as fragments emerging at $9^{°}$–${17}^{°}$, ${17}^{°}$–${90}^{°}$, and ${90}^{°}$–${180}^{°}$. We also made a chemical separation of the Pb isotopes formed in this reaction. An unusually large yield of trans-target reaction products near $Z=79$ was observed. We compare these observations with the recent predictions of Zagrebaev and Greiner for this reaction.

The expressions for the differential cross section and polarization observables for the reaction $\mathrm{p̄}+p\to e^{+}+e^{-}$ are given in terms of the nucleon electromagnetic form factors in the laboratory system, assuming the one-photon exchange. Radiative corrections due to the emission of virtual and real soft photons from the leptons are also calculated. Unlike in the center-of-mass system, they depend on the scattering angle. Polarization effects are derived in the case when the antiproton beam, the target, and the electron in the final state are polarized. Numerical estimations have been done for all observables, using models for the nucleon electromagnetic form factors in the time-like region. The radiative corrections to the differential cross section are calculated as functions of the beam energy and electron angle.

We present calculations of asymptotic normalization coefficients (ANCs) for one-nucleon removals from nuclear states of mass numbers $3⩽A⩽9$. Our ANCs were computed from variational Monte Carlo solutions to the many-body Schrödinger equation with the combined Argonne $v_{18}$ two-nucleon and Urbana IX three-nucleon potentials. Instead of computing explicit overlap integrals, we applied a Green function method that is insensitive to the difficulties of constructing and Monte Carlo sampling the long-range tails of the variational wave functions. This method also allows computation of the ANC at the physical separation energy, even when it differs from the separation energy for the Hamiltonian. We compare our results, which for most nuclei are the first ab initio calculations of ANCs, with existing experimental and theoretical results and discuss further possible applications of the technique.

Perturbation theory is used systematically to investigate the symmetries of the Dirac Hamiltonian and their breaking in atomic nuclei. Using the perturbation corrections to the single-particle energies and wave functions, the link between the single-particle states in realistic nuclei and their counterparts in the symmetry limits is discussed. It is shown that the limit of $S-V=\text{const}$ and relativistic harmonic oscillator (RHO) potentials can be connected to the actual Dirac Hamiltonian by the perturbation method, while the limit of $S+V=\text{const}$ cannot, where $S$ and $V$ are the scalar and vector potentials, respectively. This indicates that the realistic system can be treated as a perturbation of spin-symmetric Hamiltonians, and the energy splitting of the pseudospin doublets can be regarded as a result of small perturbation around the Hamiltonian with RHO potentials, where the pseudospin doublets are quasidegenerate.

In this article, the lowest order constrained variational method is used to investigate the magnetic properties of spin-polarized neutron matter in the presence of strong magnetic field at zero temperature employing the ${\mathrm{AV}}_{18}$ potential. Our results indicate that a ferromagnetic phase transition is induced by a strong magnetic field with strength greater than ${10}^{18}$ G, leading to a partial spin polarization of the neutron matter. It is also shown that the equation of state of neutron matter in the presence of a magnetic field is stiffer than in the absence of a magnetic field.

A lifetime experiment, using the Doppler-shift attenuation method, has been performed at Gammasphere to measure the transition quadrupole moments $Q_t$ of strongly deformed bands in ${}^{171}\mathrm{Hf}$ and ${}^{172}\mathrm{Hf}$. The measured value of $Q_t$ $~$ 9.5 $e$ b for the band labeled ED in ${}^{171}\mathrm{Hf}$ strongly supports the recent suggestion that this sequence and several structures with similar properties in neighboring Hf isotopes are associated with a near-prolate shape with a deformation enhanced relative to that of normal deformed structures. The measured values of $Q_t$ $~$ 14 $e$ b for the bands labeled SD1 and SD3 in ${}^{172}\mathrm{Hf}$ confirm that these sequences are associated with a prolate superdeformed shape, a property inferred in earlier work from other measured characteristics of the bands. Similar bands in ${}^{173-175}\mathrm{Hf}$ are also likely to be associated with superdeformed shapes. The observations are in contrast to predictions of cranking calculations performed with the ultimate cranker code.

We present a fully relativistic model for polarized inclusive quasielastic proton-nucleus scattering that includes relativistic distorted waves for the projectile and ejectile (RDWIA), as well as the relativistic random-phase approximation (RPA) applied to the target nucleus. Using a standard relativistic impulse approximation treatment of quasielastic scattering and a two-body Scalar, Pseudoscalar, Vector, Axial vector, Tensor (SPVAT) form of the current operator, it is shown how the behavior of the projectile/ejectile and target can be decoupled. Distortion effects are included via a full partial-wave expansion of the relativistic wave functions. Target correlations are included via the relativistic RPA applied to mean-field theory in quantum hadrodynamics. A number of novel analytical and numerical techniques are employed to aid in this highly nontrivial calculation. A baseline plane-wave calculation is performed for the reaction ${}^{40}\mathrm{Ca}$$(\mathrm{p⃗},\mathrm{p⃗}\hspace{0.5em}{}^{\prime })$ at an energy of 500 MeV and an angle ${\theta }_{\mathrm{c}.\mathrm{m}.}={40}^{°}$. Here it is found that the effect of isoscalar correlations is a quenching of the cross section that is expected to become more pronounced at lower energies or for higher-density targets. A RDWIA calculation shows additional reduction and if isoscalar target correlations are included this effect is enhanced.

We develop a new approach to production of the spectator nucleons in the ultrarelativistic heavy ion collisions. The energy transfer to the spectator system is calculated using the Monte Carlo based on the updated version of our generator of configurations in colliding nuclei which includes a realistic account of short-range correlations in nuclei. The transferred energy distributions are calculated within the framework of the Glauber multiple-scattering theory, taking into account all individual inelastic and elastic collisions using an independent realistic calculation of the potential energy contribution of each of the nucleon-nucleon pairs to the total potential. We show that the dominant mechanism of the energy transfer is tearing apart pairs of nucleons with the major contribution coming from the short-range correlations. We calculate the momentum distribution of the directed flow of emitted nucleons which is strongly affected by short-range correlations, including its dependence on the azimuthal angle. In particular, we predict a strong angular asymmetry along the direction of the impact parameter $\text{b}$, providing a unique opportunity to determine the direction of $\text{b}$. Also, we predict a strong dependence of the shape of the nucleon momentum distribution on the centrality of the nucleus-nucleus collision.

The ${}^{18}\text{F}(p,\alpha ){}^{15}$O reaction rate is crucial for understanding the final abundance of ${}^{18}\mathrm{F}$ predicted by nova models. The $\gamma$-ray emission in the first few hours after a nova outburst is expected to be dominated by 511 keV annihilation photons from the decay of ${}^{18}\mathrm{F}$, and so understanding its production can provide important constraints on the conditions during the outburst when compared with observations. Results are presented from the lowest-energy direct measurement to date, performed at the Isotope Separator and Accelerator radioactive beam facility at the TRIUMF laboratory, Canada. Cross section measurements at center-of-mass energies of 250, 330, 453, and 673 keV are obtained and the results compared to previous data and $R$-matrix calculations. The implications for the overall reaction rate in the context of nova explosions have been discussed.

Within the Skyrme-Hartree-Fock (SHF) approach, we show that for a fixed mass number $A$, both the symmetry energy coefficient $a_{\mathrm{sym}}(A)$ in the semiempirical mass formula and the nuclear matter symmetry energy $E_{\mathrm{sym}}({\rho }_A)$ at a subsaturation reference density ${\rho }_A$ can be determined essentially by the symmetry energy $E_{\mathrm{sym}}({\rho }_0)$ and its density slope $L$ at saturation density ${\rho }_0$. Meanwhile, we find the dependence of $a_{\mathrm{sym}}(A)$ on $E_{\mathrm{sym}}({\rho }_0)$ or $L$ is approximately linear and very similar to the corresponding linear dependence displayed by $E_{\mathrm{sym}}({\rho }_A)$, providing an explanation for the relation $E_{\mathrm{sym}}({\rho }_A)\approx a_{\mathrm{sym}}(A)$. Our results indicate that a value of $E_{\mathrm{sym}}({\rho }_A)$ leads to a linear correlation between $E_{\mathrm{sym}}({\rho }_0)$ and $L$ and thus can put important constraints on $E_{\mathrm{sym}}({\rho }_0)$ and $L$. Particularly, the values of $E_{\mathrm{sym}}({\rho }_0)=30.5\pm 3$ MeV and $L=$ $52.5\pm 20$ MeV are simultaneously obtained by combining the constraints from recently extracted $E_{\mathrm{sym}}({\rho }_A=0.1$ fm${}^{-3})$ with those from recent analyses of neutron skin thickness of Sn isotopes in the same SHF approach.

A spectroscopic investigation of the $\gamma$ decays from excited states in ${}^{160}\mathrm{Er}$ has been performed in order to study the changing structural properties exhibited from low spin up toward ultrahigh spin ($I~60\hslash$). The nucleus ${}^{160}\mathrm{Er}$ was populated by the reaction ${}^{116}\mathrm{Cd}$(${}^{48}\mathrm{Ca}$,4$n$$\gamma$) at a beam energy of 215 MeV, and resulting $\gamma$ decays were studied using the Gammasphere spectrometer. New rotational structures and extensions to existing bands were observed, revealing a diverse range of quasiparticle configurations, which are discussed in terms of the cranked shell model. At spins around 50$\hslash$ there is evidence for oblate states close to the yrast line. Three rotational bands that have the characteristics of strongly deformed triaxial structures are observed, marking a return to collectivity at even higher spin. The high-spin data are interpreted within the framework of cranked Nilsson-Strutinsky calculations.

Experimental studies of meson production through two-photon fusion in inelastic electron-nucleus scattering are now under way. A high-energy photon radiated by the incident electron is fused with a soft photon radiated by the nucleus to create the meson. The process takes place in the small-angle Coulomb region of nuclear scattering. We expound the theory for this production process as well as its interference with coherent-radiative-meson production. In particular, we investigate the distortion of the electron wave function due to multiple-Coulomb scattering.

Angular correlations arising from particle-particle (pp) propagation in symmetric nuclear matter are investigated. Their account follows a detailed treatment of the angular dependence of the energy denominator of the propagator in the Brueckner-Bethe-Goldstone (BBG) equation, in conjunction with the Pauli exclusion principle for intermediate states. As a result, taking a monopole approximation for the propagator, a correlation form factor emerges from the Cauchy principal-value integral of the pp propagator, while the imaginary part becomes structurally different from those in Lippmann-Schwinger-type equations. These features are investigated within the continuous choice of the single-particle potential considering the Argonne $v_{18}$ and Paris two-nucleon potentials. We find that the behavior of the mass operator is affected, deepening slightly the saturation point of symmetric nuclear matter relative to those based on angle-averaged energy denominators. Implications of these angular correlations were also investigated in the context of proton-nucleus scattering, showing clear effects on scattering observables below 100 MeV.

The isotopic evolution of the ground-state nuclear shapes and the systematics of one-quasiproton configurations are studied in neutron-rich odd-$A$ yttrium and niobium isotopes. We use a self-consistent Hartree-Fock-Bogoliubov formalism based on the Gogny energy density functional with two parametrizations, D1S and D1M. The equal-filling approximation is used to describe odd-$A$ nuclei preserving both axial and time-reversal symmetries. Shape-transition signatures are identified in the $N=60$ isotopes in both the charge radii and spin parities of the ground states. These signatures are a common characteristic for nuclei in the whole mass region. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasiproton states. Finally, a global picture of the neutron-rich $A~100$ mass region from krypton up to molybdenum isotopes is illustrated with the systematics of the nuclear charge radii isotopic shifts.

We present a qualitative analysis of the effects of the Coulomb force on the edge scattering produced in elastic nuclear collisions occurring under strong absorption conditions. This analysis is illustrated with several examples of nucleus-nucleus and antiproton-nucleus elastic scattering.

The $R$-matrix approach has proved to be very useful in extrapolating the astrophysical factor down to astrophysically relevant energies, since the majority of measurements are not available in this region. However, such an approach has to be critically considered when no complete knowledge of the reaction model is available. To get reliable results in such cases one has to use all the available information from independent sources and, accordingly, fix or constrain variations of the parameters. In this paper we present a thorough $R$-matrix analysis of the ${}^{15}\mathrm{N}(p,\gamma ){}^{16}\mathrm{O}$ reaction, which provides a path from the CN cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor for this reaction is dominated by resonant capture through two strong $J^{\pi }=1^{-}$ resonances at $E_R=312$ and $962$ keV and direct capture to the ground state. Recently, a new measurement of the astrophysical factor for the ${}^{15}\mathrm{N}(p,\gamma ){}^{16}\mathrm{O}$ reaction has been published [P. J. LeBlanc et al., Phys. Rev. C 82, 055804 (2010)]. The analysis has been done using the $R$-matrix approach with unconstrained variation of all parameters including the asymptotic normalization coefficient (ANC). The best fit has been obtained for the square of the ANC $C^2=539.2$ fm${}^{-1}$, which exceeds the previously measured value by a factor of $\approx 3$. Here we present a new $R$-matrix analysis of the Notre Dame–LUNA data with the fixed within the experimental uncertainties square of the ANC $C^2=200.34$ fm${}^{-1}$. Rather than varying the ANC we add the contribution from a background resonance that effectively takes into account contributions from higher levels. Altogether we present ten fits, seven unconstrained and three constrained. For the unconstrained fit with the boundary condition $B_c=S_c(E_2)$, where $E_2$ is the energy of the second level, we get $S(0)=39.0\pm 1.1$ keVb and normalized ${\mathrm{\chi ̃}}^2=1.84$, i.e., the result which is similar to LeBlanc et al. From all our fits we get the range $33.1⩽S(0)⩽40.1$ keVb which overlaps with the result of LeBlanc et al. We address also the physical interpretation of the fitting parameters.

We use a density-dependent relativistic mean field model to study the properties of nuclear systems at finite temperature. The liquid-gas phase transition of symmetric and asymmetric nuclear matter is discussed. A limiting pressure $p_{\lim }$ for hot asymmetric nuclear matter has been found because of the density dependence of the nucleon–nucleon–$\rho$ meson coupling. It is found that the liquid-gas phase transition cannot take place if $p>p_{\lim }$. The binodal surface for this model is addressed. In addition, we calculated the asymmetry parameter dependence of the critical temperature.

In the present work we study the hadron-quark phase transition with boson condensation in asymmetric matter by investigating the binodal surface and extending it to finite temperature to mimic the QCD phase diagram. We consider a system with two conserved charges (isospin and baryon densities) using the Gibbs’ criteria for phase equilibrium. To obtain these conditions we use two different models for the two possible phases, namely, the nonlinear Walecka model (NLWM) for the hadron matter (also including hyperons) and the MIT bag model for the quark phase. It is shown that the phase transition is very sensitive to the density dependence of the equation of state and the symmetry energy. For an isospin asymmetry of 0.2 and a mixed phase with a fraction of $20\%$ of quarks, a transition density in the interval $2{\rho }_0<{\rho }_t<4{\rho }_0$ was obtained for temperatures $30<T<65$ MeV.

The planned rhenium $\beta$-decay experiment, called the “Microcalorimeter Arrays for a Rhenium Experiment” (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which will take commissioning data in 2011 and will proceed for 5 years. We present the energy distribution of emitted electrons for the first unique forbidden $\beta$ decay of ${}^{187}\mathrm{Re}$. It is found that the $p$-wave emission of electron dominates over the $s$ wave. By assuming mixing of three neutrinos, the Kurie function for the rhenium $\beta$ decay is derived. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed $\beta$ decay of ${}^3\mathrm{H}$.