The largest nuclear physics uncertainty in studies of gamma-ray emission from novae arises from the ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction rate that affects the abundance of ${}^{18}\mathrm{F}$. Direct measurements have been made of the ${}^{18}\mathrm{F}(p,p){}^{18}\mathrm{F}$ and ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction differential cross sections in the energy range $0.6⩽E_{\mathrm{c}.\mathrm{m}.}⩽1.6$ MeV. Several resonances have been observed in both measurements, with simultaneous $R$-matrix fits used to determine the properties of corresponding states in ${}^{19}\mathrm{Ne}$. A recently reported state at 7.420 MeV is not seen, while new states are seen including one of $J^{\pi }={\frac{3}{2}}^{+}$. A candidate for a recently predicted broad $J^{\pi }={\frac{1}{2}}^{+}$ state is seen, which would have significant impact on the low energy ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction rate, but its alpha width is significantly smaller than expected.

We study the equation of state for symmetric nuclear matter using a ring-diagram approach in which the particle-particle hole-hole (pphh) ring diagrams within a momentum model space of decimation scale Λ are summed to all orders. The calculation is carried out using the renormalized low-momentum nucleon-nucleon ($\mathit{NN}$) interaction $V_{\mathrm{low}\text{−}k}$, which is obtained from a bare $\mathit{NN}$ potential by integrating out the high-momentum components beyond Λ. The bare $\mathit{NN}$ potentials of CD-Bonn, Nijmegen, and Idaho have been employed. The choice of Λ and its influence on the single particle spectrum are discussed. Ring-diagram correlations at intermediate momenta ($k\simeq 2\hspace{0.5em}{\mathrm{fm}}^{-1}$) are found to be particularly important for nuclear saturation, suggesting the necessity of using a sufficiently large decimation scale so that the above momentum region is not integrated out. Using $V_{\mathrm{low}\text{−}k}$ with $\Lambda ~3\hspace{0.5em}{\mathrm{fm}}^{-1}$, we perform a ring-diagram computation with the above potentials, which all yield saturation energies $E/A$ and Fermi momenta $k_F^{(0)}$ considerably larger than the empirical values. On the other hand, similar computations with the medium-dependent Brown-Rho scaled $\mathit{NN}$ potentials give satisfactory results of $E/A\simeq -15$ MeV and $k_F^{(0)}\simeq 1.4\hspace{0.5em}{\mathrm{fm}}^{-1}$. The effect of this medium dependence is well reproduced by an empirical three-body force of the Skyrme type.

Theoretical studies of low-lying dipole strength in even-even spherical nuclei within the relativistic quasiparticle time blocking approximation (RQTBA) are presented. The RQTBA developed recently as an extension of the self-consistent relativistic quasiparticle random-phase approximation (RQRPA) enables one to investigate the effects of the coupling of two-quasiparticle excitations to collective vibrations within a fully consistent calculation scheme based on covariant energy density functional theory. Dipole spectra of even-even ${}^{130}\mathrm{Sn}\text{−}{}^{140}\mathrm{Sn}$ and ${}^{68}\mathrm{Ni}\text{−}{}^{78}\mathrm{Ni}$ isotopes calculated within both RQRPA and RQTBA show two well-separated collective structures: the higher lying giant dipole resonance and the lower lying pygmy dipole resonance, which can be identified by the different behavior of the transition densities of states in these regions.

Excited states in ${}^{209}\mathrm{Fr}$ have been studied using the ${}^{197}\mathrm{Au}({}^{16}\mathrm{O},4n){}^{209}\mathrm{Fr}$ reaction with pulsed beams and $\gamma$-ray and electron spectroscopy. A comprehensive scheme has been established up to an excitation energy of about 6 MeV and spins of about $49/2\hslash$. Several isomers have been identified including a $J^{\pi }=25/2^{+}$, $\tau =48(3)$ ns state at 2130 keV and a $606(26)$ ns, $45/2^{-}$ state at 4660 keV. The latter state decays via an enhanced $E3$ transition with a strength of 28.8(12) W.u. It can be identified with a similar isomer in the heavier odd isotopes ${}^{211}\mathrm{Fr}$ and ${}^{213}\mathrm{Fr}$, arising from the maximal coupling of the five valence protons in the $\pi h_{9/2}^3{i}_{13/2}^2$ configuration. The systematics of the yrast states in the odd-$A$ isotopes are discussed, including the presence of states arising from the main proton configurations coupled to the $p_{1/2}$, $f_{5/2}$, and $i_{13/2}$ neutron holes. Shell-model configurations are assigned to many of the observed states. The isotopic assignment differs from earlier work, which is shown to be erroneous.

Investigations on the internal one-particle density matrix in the case of Bose-Einstein condensates with a finite number ($N$) of particles in a harmonic potential are performed. We solve the eigenvalue problem of the Pethick-Pitaevskii-type internal density matrix and find a fragmented condensate. On the contrary the condensate Jacobi-type internal density matrix gives complete condensation into a single state. The internal one-particle density matrix is, therefore, shown to be different in general for different choices of the internal coordinate system. We propose two physically motivated criteria for the choice of the adequate coordinate systems that give us a unique answer for the internal one-particle density matrix. One criterion is that in the infinite particle number limit ($N=\infty$) the internal one-particle density matrix should have the same eigenvalues and eigenfunctions as those of the corresponding ideal Bose-Einstein condensate in the laboratory frame. The other criterion is that the coordinate of the internal one-particle density matrix should be orthogonal to the remaining $(N-2)$ internal coordinates, though the $(N-2)$ coordinates, in general, do not need to be mutually orthogonal. This second criterion is shown to imply the first criterion. It is shown that the internal Jacobi coordinate system satisfies these two criteria while the internal coordinate system adopted by Pethick and Pitaevskii for the construction of the internal one-particle density matrix does not. It is demonstrated that these two criteria uniquely determine the internal one-particle density matrix that is identical to that calculated with the Jacobi coordinates. The relevance of this work concerning $\alpha$-particle condensates in nuclei, as well as bosonic atoms in traps, is pointed out.

New angular distributions for the ${}^7\mathrm{Li}({}^{10}\mathrm{B},{}^9\mathrm{Be}){}^8\mathrm{Be}$ reaction at an energy of $E_{\mathrm{lab}}({}^{10}\mathrm{B})=51$ MeV for the ground and excited states of ${}^8\mathrm{Be}$ were analyzed within the coupled-reaction-channels method. The reactions are dominated by single proton transfer at forward angles except for that to the ${}^8\mathrm{Be}$ 11.35-MeV state, which requires multistep routes for its population. The ${}^8\mathrm{Be}+{}^9\mathrm{Be}$ potential parameters for ground and excited states of ${}^8\mathrm{Be}$ were deduced by fitting ${}^7\mathrm{Li}({}^{10}\mathrm{B},{}^9\mathrm{Be}){}^8\mathrm{Be}$ and ${}^{10}\mathrm{B}({}^7\mathrm{Li},{}^9\mathrm{Be}){}^8\mathrm{Be}$ reaction data and are compared with a previously determined ${}^7\mathrm{Be}+{}^9\mathrm{Be}$ potential. The ${}^8\mathrm{Be}+{}^9\mathrm{Be}$ real potential is very similar to that for ${}^7\mathrm{Be}+{}^9\mathrm{Be}$, whereas the imaginary one for ${}^8\mathrm{Be}+{}^9\mathrm{Be}$ has a much greater spatial extent than that for ${}^7\mathrm{Be}+{}^9\mathrm{Be}$.

The ${}^{18}\mathrm{Ne}(\alpha ,p){}^{21}\mathrm{Na}$ reaction plays a crucial role in the $(\alpha ,p)$ process, which leads to the rapid proton capture process in x-ray bursts. The reaction rate depends upon properties of ${}^{22}\mathrm{Mg}$ levels above the $\alpha$ threshold at 8.14 MeV. Despite recent studies of these levels, only the excitation energies are known for most with no constraints on the spins. We have studied the ${}^{24}\mathrm{Mg}(p,t){}^{22}\mathrm{Mg}$ reaction at the Oak Ridge National Laboratory (ORNL) Holifield Radioactive Ion Beam Facility (HRIBF), and by measuring the angular distributions of outgoing tritons, we provide some of the first experimental constraints on the spins of astrophysically important ${}^{18}\mathrm{Ne}(\alpha ,p){}^{21}\mathrm{Na}$ resonances.

α-particle (quartet) condensation in homogeneous spin-isospin symmetric nuclear matter is investigated. The usual Thouless criterion for the critical temperature is extended to the quartet case. The in-medium four-body problem is strongly simplified by the use of a momentum-projected mean-field ansatz for the quartet. The self-consistent single-particle wave functions are shown and discussed for various values of the density at the critical temperature. Excellent agreement of the critical temperature with a numerical solution of the Faddeev-Yakubovsky equation is obtained.

The saturation properties of neutron-rich matter are investigated in a relativistic mean-field formalism using two accurately calibrated models: NL3 and FSUGold. The saturation properties—density, binding energy per nucleon, and incompressibility coefficient—are calculated as a function of the neutron-proton asymmetry $\alpha \equiv (N-Z)/A$ to all orders in $\alpha$. Good agreement (at the 10% level or better) is found between these numerical calculations and analytic expansions that are given in terms of a handful of bulk parameters determined at saturation density. Using insights developed from the analytic approach and a general expression for the incompressibility coefficient of infinite neutron-rich matter, i.e., $K_0(\alpha )=K_0+K_{\tau }{\alpha }^2+\dots$, we construct a hybrid model with values for $K_0$ and $K_{\tau }$ as suggested by recent experimental findings. Whereas the hybrid model provides a better description of the measured distribution of isoscalar monopole strength in the Sn isotopes relative to both NL3 and FSUGold, it significantly underestimates the distribution of strength in ${}^{208}\mathrm{Pb}$. Thus, we conclude that the incompressibility coefficient of neutron-rich matter remains an important open problem.

Using the experimental evaporation residue cross sections in the ${}^{48}\mathrm{Ca}$-induced complete fusion reactions and the complete fusion cross sections calculated within the dinuclear system model, the survival probabilities of superheavy nuclei with charge numbers $Z=112\text{−}116$ and 118 in the $\mathit{xn}$-evaporation channels are extracted. The effects of angular momentum and deformations of colliding nuclei are taken into account. The obtained dependence of the survival probability on $Z$ indicates the next doubly magic nucleus beyond ${}^{208}\mathrm{Pb}$ at $Z⩾120$.

We present results for the evolution of the momentum distribution of a hard parton traversing a brick of quark-gluon plasma, considering both bremsstrahlung and collisional energy loss. The complete leading order transition rates are included. We find a significant modification of the evolving momentum distribution compared to results obtained by employing an approximate implementation of the collisional energy loss that uses the mean energy loss, together with momentum diffusion.

Recent global analyses of ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ have incorporated both elastic-scattering and $\beta$-decay data in addition to direct measurements. In that context, it has been shown that an improvement in the available elastic-scattering data could help determine the contribution of the two subthreshold states, $6.92(2^{+})$ and $7.12(1^{-})$ MeV, and with excellent statistics could restrict resonance parameters above the threshold. To this end angular distributions of ${}^{12}\mathrm{C}(\alpha ,\alpha ){}^{12}\mathrm{C}$ in the $\alpha$-energy range of 2.6–8.2 MeV, at angles from 24${}^{\circ }$ to 166${}^{\circ }$ have been measured at the University of Notre Dame using an array of 32 silicon detectors. Details of the experiment are reported. In the present analysis, the phase shifts have been determined from our previously reported $R$-matrix fit to these data. The uncertainties in the $R$-matrix phase shifts ($\ell =0\dots 6)$ are derived by a new Monte Carlo analysis technique as described in the article. We provide these phase shifts here for general use, in particular for the improved analysis and extrapolation of the $\alpha$ radiative capture to low energies.

It is pointed out that so far all theoretical estimates of coherent pion production off nuclei induced by neutrinos rely on the “local approximation” well known in photonuclear physics. The effects of dropping this approximation are discussed. It is found that in a plane wave approximation for the pion, the local approximation overestimates the coherent neutrino-induced pion production on nuclei.

The nuclear cosmochronometer suggested by Hayakawa et al. [Phys. Rev. C 77, 065802 (2008)] based on the ${}^{138}\mathrm{La}\text{−}{}^{138}\mathrm{Ce}\text{−}{}^{136}\mathrm{Ce}$ abundance ratio in presolar grains would be affected by the existence of a hitherto unknown low-energy $1^{+}$ state in ${}^{138}\mathrm{La}$. Results of a recent high-resolution study of the ${}^{138}\mathrm{Ba}({}^3\mathrm{He},t)$ reaction under kinematics selectively populating $1^{+}$ states in ${}^{138}\mathrm{La}$ through Gamow-Teller transitions provides strong evidence against the existence of such a hypothetical state.

Complete fusion excitation function for the ${}^6\mathrm{Li}+{}^{144}\mathrm{Sm}$ reaction has been measured at near barrier energies by the activation technique. Coupled-channel calculations show an enhancement in fusion cross section at energies below the barrier compared to the one-dimensional barrier penetration model calculation, but they overpredict it in the entire energy range compared to the experimental data. Reduced fusion cross sections for the present system at energies normalized to the Coulomb barrier were also found to be systematically lower than those with strongly bound projectiles forming a similar compound nucleus. These two observations conclusively show that the complete fusion cross section, at above barrier energies, is suppressed by $~32\%$ in the ${}^6\mathrm{Li}+{}^{144}\mathrm{Sm}$ reaction. Reanalyses of existing fusion data for ${}^7\mathrm{Li}+{}^{165}\mathrm{Ho}$ and ${}^7\mathrm{Li}+{}^{159}\mathrm{Tb}$ also show a suppression compared to those with strongly bound projectiles, which contradicts earlier conclusions. The fusion suppression factor seems to exhibit a systematic behavior with respect to the breakup threshold of the projectile and the atomic number of the target nucleus.

Thermal properties of low-density neutron matter are investigated by determinantal quantum Monte Carlo lattice calculations on 3+1 dimensional cubic lattices. Nuclear effective field theory (EFT) is applied using the pionless single- and two-parameter neutron-neutron interactions, determined from the ${}^1{S}_0$ scattering length and effective range. The determination of the interactions and the calculations of neutron matter are carried out consistently by applying EFT power counting rules. The thermodynamic limit is taken by the method of finite-size scaling, and the continuum limit is examined in the vanishing lattice filling limit. The ${}^1{S}_0$ pairing gap at $T\approx 0$ is computed directly from the off-diagonal long-range order of the spin pair-pair correlation function and is found to be approximately 30% smaller than BCS calculations with the conventional nucleon-nucleon potentials. The critical temperature $T_c$ of the normal-to-superfluid phase transition and the pairing temperature scale $T^{*}$ are determined, and the temperature-density phase diagram is constructed. The physics of low-density neutron matter is clearly identified as being a BCS-Bose-Einstein condensation crossover.

Various quantities of an attractively interacting fermion system at the unitary limit are determined by extrapolating Monte Carlo results of low-density neutron matter. Smooth extrapolation in terms of $1/(k_F{a}_0)$ ($k_F$ is the Fermi momentum, and $a_0$ is the ${}^1{S}_0$ scattering length) is found with the quantities examined: the ground-state energy, the pairing gap at $T\approx 0$, and the critical temperature of the normal-to-superfluid phase transition. We emphasize proximity of the physics of low-density neutron matter to that at the unitary limit. The extrapolated quantities are in a reasonable agreement with those in the literature.

Using the ${\mathrm{U}}_{\nu }(6/12)\otimes {\mathrm{U}}_{\pi }(6/4)$ extended supersymmetry, we constructed the energy spectrum and electromagnetic transition properties of the supermultiplet member ${}^{198}\mathrm{Hg}$ with two proton fermions coupled to a neutron boson core. Consistency between the supersymmetric interacting boson fermion fermion approximation (IBFFA) description and the F-spin symmetric interacting boson approximation (IBA-2) description is shown for this two-fermion–$N$-boson multiplet member. The data of a $\gamma \gamma$ angular correlation experiment using the HORUS cube $\gamma$-ray spectrometer—determining new multipole mixing ratios, level spins, $\gamma$ transitions, and energy states—shows quite a good agreement, also for the low-energy part of the spectrum, when comparing theoretical predictions and experimental data. This is contrary to the usual assumption that a two-fermion–$N$-boson constellation should describe just the excited two-quasiparticle states.

A new analysis method to investigate halos in finite many-fermion systems is designed, as existing characterization methods are proven to be incomplete/inaccurate. A decomposition of the internal wave-function of the $N$-body system in terms of overlap functions allows a model-independent analysis of medium-range and asymptotic properties of the internal one-body density. The existence of a spatially decorrelated region in the density profile is related to the existence of three typical energy scales in the excitation spectrum of the $(N-1)$-body system. A series of model-independent measures, taking the internal density as the only input, are introduced. The new measures allow a quantification of the potential halo in terms of the average number of fermions participating to it and of its impact on the system extension. Those new “halo factors” are validated through simulations and applied to results obtained through energy density functional calculations of medium-mass nuclei. Performing spherical Hartree-Fock-Bogoliubov calculations with state-of-the-art Skyrme plus pairing functionals, a collective halo is predicted in drip-line Cr isotopes, whereas no such effect is seen in Sn isotopes.