I have used a recent parametrization of mirror energy differences to predict two-proton separation energies for ${}^{21-24}\mathrm{Si}$ and ${}^{24}\mathrm{S}$. Results are in good agreement with experimental values for ${}^{22,24}\mathrm{Si}$.

Background: Since the earliest days of fission, stochastic models have been used to describe and model the process. For a quarter century, numerical solutions of Langevin equations have been used to model fission of highly excited nuclei, where microscopic potential-energy effects have been neglected.

Purpose: In this paper I present a Langevin model for the fission of nuclei with low to medium excitation energies, for which microscopic effects in the potential energy cannot be ignored.

Method: I solve Langevin equations in a five-dimensional space of nuclear deformations. The macroscopic-microscopic potential energy from a global nuclear structure model well benchmarked to nuclear masses is tabulated on a mesh of approximately ${10}^7$ points in this deformation space. The potential is defined continuously inside the mesh boundaries by use of a moving five-dimensional cubic spline approximation. Because of reflection symmetry, the effective mesh is nearly twice this size. For the inertia, I use a (possibly scaled) approximation to the inertia tensor defined by irrotational flow. A phenomenological dissipation tensor related to one-body dissipation is used. A normal-mode analysis of the dynamical system at the saddle point and the assumption of quasiequilibrium provide distributions of initial conditions appropriate to low excitation energies, and are extended to model spontaneous fission. A dynamical model of postscission fragment motion including dynamical deformations and separation allows the calculation of final mass and kinetic-energy distributions, along with other interesting quantities.

Results: The model makes quantitative predictions for fragment mass and kinetic-energy yields, some of which are very close to measured ones. Varying the energy of the incident neutron for induced fission allows the prediction of energy dependencies of fragment yields and average kinetic energies. With a simple approximation for spontaneous fission starting conditions, quantitative predictions are made for some observables which are close to measurements.

Conclusions: This model is able to reproduce several mass and energy yield observables with a small number of physical parameters, some of which do not need to be varied after benchmarking to ${}^{235}\mathrm{U}(n,f)$ to predict results for other fissioning isotopes.

A search for new proton-rich isotopes using projectile fragmentation of a 345-MeV/nucleon ${}^{124}\mathrm{Xe}$ beam has been performed with the BigRIPS in-flight separator at the RIKEN Nishina Center RI Beam Factory. Projectile fragments were identified by measuring the time of flight, magnetic rigidity, and energy loss in the BigRIPS separator. Projectile fragments then were transported downstream of the BigRIPS separator and re-identified by measuring the time of flight and total kinetic energy. Through such particle re-identification, we have discovered four new isotopes ${}^{81,82}\mathrm{Mo}$ and ${}^{85,86}\mathrm{Ru}$ located near the proton drip line. The ${}^{76}\mathrm{Y}$ and ${}^{78}\mathrm{Zr}$ isotopes near the proton drip line also were identified, supporting the previous report on their discovery. Furthermore, we have obtained the first clear evidence for the particle instability of ${}^{103}\mathrm{Sb}$. Based on the systematics of measured production yields, the upper limit values were evaluated for the half-lives of the particle-unbound isotopes ${}^{81}\mathrm{Nb},{}^{85}\mathrm{Tc}$, and ${}^{103}\mathrm{Sb}$.

Using an effective Hamiltonian derived from the QCD multipole expansion, we calculate the cross sections of gluo-dissociation of heavy quarkonia in the quark-gluon plasma, by including both the chromo-electric dipole ($E_1$) and the chromo-magnetic dipole ($M_1$) transition mechanisms. While the former allows us to reproduce the results from operator-product-expansion calculations in the Coulomb approximation, the latter as a novel contribution is shown to be significant at low energies close to the threshold. Using thus obtained cross sections, we further carry out a full calculation of the gluo-dissociation rates for various charmonia and bottomonia within a nonrelativistic in-medium potential model. The $M_1$ contribution turns out to be most prominent for the $J/\psi$ and accounts for $\sim$10%–25% of the total ($E1+M1$) dissociation rate at temperatures close to the transition temperature.

Very strong magnetic fields can arise in noncentral heavy-ion collisions at ultrarelativistic energies, and may not decay quickly in a conducting plasma. We carry out relativistic magnetohydrodynamics (RMHD) simulations to study the effects of this magnetic field on the evolution of the plasma and on resulting flow fluctuations in the ideal RMHD limit. Our results show that the magnetic field leads to enhancement in elliptic flow for small impact parameters while it suppresses it for large impact parameters (which may provide a signal for the initial stage magnetic field). Interestingly, we find that magnetic field in localized regions can temporarily increase in time as evolving plasma energy density fluctuations lead to reorganization of magnetic flux. This can have important effects on the chiral magnetic effect. The magnetic field has nontrivial effects on the power spectrum of flow fluctuations. For the very strong magnetic field case, one sees a pattern of even-odd difference in the power spectrum of flow coefficients arising from reflection symmetry about the magnetic field direction if initial state fluctuations are not dominant. We discuss the situation of nontrivial magnetic field configurations arising from collision of deformed nuclei and show that it can lead to anomalous elliptic flow. Special (crossed body-body) configurations of deformed nuclei collisions can lead to the presence of a quadrupolar magnetic field, which can have very important effects on the rapidity dependence of transverse expansion (similar to beam focusing from quadrupole fields in accelerators).

We studied the $N^{*}\left(1875\right)(3/2^{-})$ resonance with a multichannel unitary scheme, considering the $\mathrm{\Delta }\pi$ and ${\mathrm{\Sigma }}^{*}K$, with their interaction extracted from chiral Lagrangians, and then added two more channels, the $N^{*}\left(1535\right)\pi$ and $N\sigma$, which proceed via triangle diagrams involving the ${\mathrm{\Sigma }}^{*}K$ and $\mathrm{\Delta }\pi$ respectively in the intermediate states. The triangle diagram in the $N^{*}\left(1535\right)\pi$ case develops a singularity at the same energy as the resonance mass. We determined the couplings of the resonance to the different channels and the partial decay widths. We found a very large decay width to ${\mathrm{\Sigma }}^{*}K$, and also observed that, due to interference with other terms, the $N\sigma$ channel has an important role in the $\pi \pi$ mass distributions at low invariant masses, leading to an apparently large $N\sigma$ decay width. We discuss justifying the convenience of an experimental reanalysis of this resonance, in light of the findings of the paper, using multichannel unitary schemes.

Thermal states of neutron stars in soft x-ray transients (SXRTs) are thought to be determined by “deep crustal heating” in the accreted matter that drives the quiescent luminosity and cooling via emission of photons and neutrinos from the interior. In this study, we assume a global thermal steady state of the transient system and calculate the heating curves (quiescent surface luminosity as a function of mean accretion rate) predicted from theoretical models, taking into account variations in the equations of state, superfluidity gaps, thickness of the light element layer, and a phenomenological description of the direct Urca threshold. We further provide a statistical analysis on the uncertainties in these parameters, and compare the overall results with observations of several SXRTs, in particular the two sources containing the coldest (SAX J1808.4-3658) and the hottest (Aql X-1) neutron stars. Interpretation of the observational data indicates that the direct Urca process is required for the most massive stars and also suggests small superfluid gaps.

Background: Although SU(2) isospin symmetry is generally assumed in the basic theory of the strong interaction, a number of significant violations have been observed in scattering and bound states of nucleons. Many of these violations can be attributed to the electromagnetic interaction but the question of how much of the violation is due to it remains open.

Purpose: To establish the connection between diquark clustering in the two-nucleon system and isospin breaking from the Coulomb interaction between the members of diquark pairs.

Method: A schematic model based on clustering of quarks in the interior of the confinement region of the two-nucleon system is introduced and evaluated. In this model the Coulomb interaction is the source of all isospin breaking. It draws on a picture of the quark density based on the diquark-quark model of hadron structure which has been investigated by a number of groups.

Results: The model produces three isospin breaking potentials connecting the unbroken value of the low-energy scattering amplitude to those of the $pp$, $nn$, and $np$ singlet channels. A simple test of the potentials in the three-nucleon energy difference problem yields results in agreement with the known binding energy difference.

Conclusion: The illustrative model suggests that the breaking seen in the low-energy nucleon-nucleon (NN) interaction may be understood in terms of the Coulomb force between members of diquark clusters. It allows the prediction of the charge symmetry breaking interaction and the $nn$ scattering length from the well measured $np$ singlet scattering length. Values of the $nn$ scattering length around $-18$ fm are favored. Since the model is based on the quark picture, it can be easily extended, in the SU(3) limit, to calculate isospin breaking in the strange sector in the corresponding channels. A natural consequence of isospin breaking from diquark clustering is that the breaking in the strange sector, as measured by the separation energy difference between ${}_{\mathrm{\Lambda }}{}^4\mathrm{H}$ and ${}_{\mathrm{\Lambda }}{}^4\mathrm{He}$, is several times larger than that seen in the comparison of three-nucleon mirror nuclei as observed experimentally.

The ground-state configuration of ${}^{35}\mathrm{Al}$ has been studied via Coulomb dissociation (CD) using the LAND-FRS setup (GSI, Darmstadt) at a relativistic energy of $\sim 403$ MeV/nucleon. The measured inclusive differential CD cross section for ${}^{35}\mathrm{Al}$, integrated up to 5.0 MeV relative energy between the ${}^{34}\mathrm{Al}$ core and the neutron using a Pb target, is 78(13) mb. The exclusive measured CD cross section that populates various excited states of ${}^{34}\mathrm{Al}$ is 29(7) mb. The differential CD cross section of ${}^{35}\mathrm{Al}\to {}^{34}\mathrm{Al}+n$ has been interpreted in the light of a direct breakup model, and it suggests that the possible ground-state spin and parity of ${}^{35}\mathrm{Al}$ could be, tentatively, $1/2^{+}$ or $3/2^{+}$ or $5/2^{+}$. The valence neutrons, in the ground state of ${}^{35}\mathrm{Al}$, may occupy a combination of either $l=3,0$ or $l=1,2$ orbitals coupled with the ${}^{34}\mathrm{Al}$ core in the ground and isomeric state(s), respectively. This hints of a particle-hole configuration of the neutron across the magic shell gaps at $N=20,28$ which suggests narrowing the magic shell gap. If the $5/2^{+}$ is the ground-state spin-parity of ${}^{35}\mathrm{Al}$ as suggested in the literature, then the major ground-state configuration of ${}^{35}\mathrm{Al}$ is a combination of ${}^{34}\mathrm{Al}(\text{g.s.};4^{-})\otimes {\nu }_{p_{3/2}}$ and ${}^{34}\mathrm{Al}(\text{isomer};1^{+})\otimes {\nu }_{d_{3/2}}$ states. The result from this experiment has been compared with that from a previous knockout measurement and a calculation using the SDPF-M interaction.

Two generic methods based on frequentism and Bayesianism are presented in this work aiming to adequately estimate decay lifetimes from measured data, while accounting for restricted observation times in the measurements. All the experimental scenarios that can possibly arise from the observation constraints are treated systematically and formulas are derived. The methods are then tested against the decay data of bare isomeric ${}^{94m}\mathrm{Ru}^{44+}$, which were measured using isochronous mass spectrometry with a timing detector at the CSRe in Lanzhou, China. Applying both methods in three distinct scenarios yields six different but consistent lifetime estimates. The deduced values are all in good agreement with a prediction based on the neutral-atom value modified to take the absence of internal conversion into account. Potential applications of such methods are discussed.

We introduce a simplified effective-range function for charged nuclei, related to the modified $K$ matrix but differing from it in several respects. Negative-energy zeros of this function correspond to bound states. Positive-energy zeros correspond to resonances and “echo poles” appearing in elastic-scattering phase-shifts, while its poles correspond to multiple-of-$\pi$ phase shifts. Padé expansions of this function allow one to parametrize phase shifts on large energy ranges and to calculate resonance and bound-state properties in a very simple way, independently of any potential model. The method is first tested on a $d$-wave ${}^{12}\mathrm{C}+\alpha$ potential model. It is shown to lead to a correct estimate of the subthreshold-bound-state asymptotic normalization constant (ANC) starting from the elastic-scattering phase shifts only. Next, the ${}^{12}\mathrm{C}+\alpha$ experimental $p$-wave and $d$-wave phase shifts are analyzed. For the $d$ wave, the relatively large error bars on the phase shifts do not allow one to improve the ANC estimate with respect to existing methods. For the $p$ wave, a value agreeing with the ${}^{12}\mathrm{C}({}^6\mathrm{Li},d){}^{16}\mathrm{O}$ transfer-reaction measurement and with the recent remeasurement of the ${}^{16}\mathrm{N}\beta$-delayed $\alpha$ decay is obtained, with improved accuracy. However, the method displays two difficulties: the results are sensitive to the Padé-expansion order and the simplest fits correspond to an imaginary ANC, i.e., to a negative-energy “echo pole,” the physical meaning of which is still debatable.

Numerical semiclassical calculations are carried out to study the angular distribution of deuterons from the p,d pickup reaction of 25 MeV protons incident on the nucleus ${}^{156}\mathrm{Gd}$ and also its proton elastic scattering. It is found that, due to the rapid fall of the real optical potential in the vicinity of the target nucleus, the classical trajectories are very sensitive to the proton impact parameters. A selection of 276,983 trajectories is used for protons with impact parameters $b_{\mathrm{p}}$ satisfying $7.23018\mathrm{fm}\le b_{\mathrm{p}}\le 10\mathrm{fm}$ with steps of ${10}^{-5}\mathrm{fm}$. Using the imaginary part of the optical potential for protons, a simple quantum approach is constructed to evaluate the probability of a surviving proton throughout its path. In addition, a simple three-body quantum approach is developed to calculate the probability of a neutron transfer by a surviving proton at closest approach. The formed deuteron is then allowed to start its trajectory while keeping its identity until detected. Throughout this journey, the deuteron trajectory is under the influence of its Coulomb and real optical potential, while its absorption is determined by the imaginary optical potential component. Within estimated uncertainties, the resulting theoretical angular distribution achieves a comparable fit with experimental results for the angular momentum transfer $\mathrm{L}=0$ compared to other theoretical models, and concludes that the strong p,d cross sections are due to the dominant ${\mathrm{s}}_{1/2}$ component of the Nilsson ${\frac{1}{2}}^{+}\left[400\right]$ level in ${}^{155}\mathrm{Gd}$.

$\varphi$-meson–nucleus bound state energies and absorption widths are calculated for seven selected nuclei by solving the Klein-Gordon equation with complex optical potentials. Essential input for the calculations, namely the medium-modified $K$ and $\overline{K}$ meson masses, as well as the density distributions in nuclei, are obtained from the quark-meson coupling model. The attractive potential for the $\varphi$ meson in the nuclear medium originates from the in-medium enhanced $K\overline{K}$ loop in the $\varphi$-meson self-energy. The results suggest that the $\varphi$ meson should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths.

Background: The ${}^{31}\mathrm{S}(p,\gamma ){}^{32}\mathrm{Cl}$ reaction becomes important for sulfur production in novae if the ${}^{31}\mathrm{P}(p,\alpha ){}^{28}\mathrm{Si}$ reaction rate is somewhat greater than currently accepted. The rate of the ${}^{31}\mathrm{S}(p,\gamma ){}^{32}\mathrm{Cl}$ reaction is uncertain, primarily due to the properties of resonances at $E_{\mathrm{c}.\mathrm{m}.}=156$ and 549 keV.

Purpose: We precisely determined the excitation energies of states in ${}^{32}\mathrm{Cl}$ through high-resolution $\gamma$ spectroscopy including the two states most important for the ${}^{31}\mathrm{S}(p,\gamma ){}^{32}\mathrm{Cl}$ reaction at nova temperatures.

Method: Excited states in ${}^{32}\mathrm{Cl}$ were populated using the ${}^{10}\mathrm{B}({}^{24}\mathrm{Mg},2n){}^{32}\mathrm{Cl}$ reaction with a ${}^{24}\mathrm{Mg}$ beam from the ATLAS facility at Argonne National Laboratory. The reaction channel of interest was selected using recoils in the Fragment Mass Analyzer, and precise level energies were determined by detecting $\gamma$ rays with Gammasphere.

Results: We observed $\gamma$ rays from the decay of six excited states in ${}^{32}\mathrm{Cl}$. The excitation energies for two unbound levels at $E_x=1738.1$ (6) keV and 2130.5 (10) keV were determined and found to be in agreement with a previous high-precision measurement of the ${}^{32}\mathrm{S}({}^3\mathrm{He},t){}^{32}\mathrm{Cl}$ reaction [1].

Conclusions: An updated ${}^{31}\mathrm{S}(p,\gamma ){}^{32}\mathrm{Cl}$ reaction rate is presented. With the excitation energies of important levels firmly established, the dominant uncertainty in the reaction rate at nova temperatures is due to the strength of the resonance corresponding to the 2131-keV state in ${}^{32}\mathrm{Cl}$.

We report on the mass measurements of ${}^{31,32}\mathrm{Na}$ and ${}^{29,34,35}\mathrm{Al}$, performed with the TITAN Penning trap mass spectrometer at TRIUMF. The mass excesses were found to be $12246\left(14\right)$ and $18638\left(37\right)$ keV for ${}^{31,32}\mathrm{Na}$ and $-18207.77\left(37\right),-3000.5\left(29\right)$, and $-223.7\left(73\right)$ keV for ${}^{29,34,35}\mathrm{Al}$, respectively. Our measurements confirm the observation of a crossover in the two-neutron separation energies of ${}^{33}\mathrm{Mg}$ and ${}^{34}\mathrm{Al}$. We did not observe the recently reported, long-lived, isomeric state of ${}^{34}\mathrm{Al}$, but, based on the previously measured half-lives, the mass value of the ground state was determined.

Variational calculations of ground-state properties of ${}^4\mathrm{He},{}^{16}\mathrm{O}$, and ${}^{40}\mathrm{Ca}$ are carried out employing realistic phenomenological two- and three-nucleon potentials. The trial wave function includes two- and three-body correlations acting on a product of single-particle determinants. Expectation values are evaluated with a cluster expansion for the spin-isospin dependent correlations considering up to five-body cluster terms. The optimal wave function is obtained by minimizing the energy expectation value over a set of up to 20 parameters by means of a nonlinear optimization library. We present results for the binding energy, charge radius, one- and two-body densities, single-nucleon momentum distribution, charge form factor, and Coulomb sum rule. We find that the employed three-nucleon interaction becomes repulsive for $A\ge 16$. In ${}^{16}\mathrm{O}$ the inclusion of such a force provides a better description of the properties of the nucleus. In ${}^{40}\mathrm{Ca}$ instead, the repulsive behavior of the three-body interaction fails to reproduce experimental data for the charge radius and the charge form factor. We find that the high-momentum region of the momentum distributions, determined by the short-range terms of nuclear correlations, exhibits a universal behavior independent of the particular nucleus. The comparison of the Coulomb sum rules for ${}^4\mathrm{He},{}^{16}\mathrm{O}$, and ${}^{40}\mathrm{Ca}$ reported in this work will help elucidate in-medium modifications of the nucleon form factors.

The cross section for neutron capture in the continuum region has been difficult to calculate accurately. Previous results for ${}^{238}\mathrm{U}$ show that including an $M1$ scissors-mode contribution to the photon strength function resulted in very good agreement between calculation and measurement. This paper extends that analysis to ${}^{234,236}\mathrm{U}$ by using $\gamma$-ray spectra measured with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center to constrain the photon strength function used to calculate the capture cross section. Calculations using a strong scissors-mode contribution reproduced the measured $\gamma$-ray spectra and were in excellent agreement with the reported cross sections for all three isotopes.

We have studied the dynamical fluctuation of net charge of hadrons produced in Au+Au collisions at energies that in near future will be available at the Facility for Antiproton and Ion Research (FAIR). Data simulated by a microscopic transport model based on ultrarelativistic quantum molecular dynamics are analyzed for this purpose. The centrality and pseudorapidity dependence of the net-charge fluctuation of hadrons are examined. Our simulated results are compared with the results available for nucleus-nucleus collision experiments held at similar energies. The gross features of our simulated results on net-charge fluctuations are found to be consistent with the experiment. At incident beam energy $E_{\mathrm{lab}}=10A$ GeV, the magnitude of net-charge fluctuation is very large, and in comparison with the rest its centrality dependence appears to be a little unusual. The effect of global charge conservation is expected to be very crucial at FAIR energies. The charge fluctuations measured with varying pesudorapidity window size depend on the collision centrality. The dependence is, however, exactly opposite in nature to that observed in the Pb+Pb collision at $\sqrt{s_{{}_{NN}}}=2.76$ TeV.

Anisotropic flow of hadronic matter is considered a sensitive tool to detect the early-stage dynamics of high-energy heavy-ion collisions. Taking the event-by-event fluctuations of the collision geometry into account, the elliptic flow parameter and the triangular flow parameter derived from the azimuthal distribution of produced hadrons are investigated within the framework of a multiphase transport (AMPT) model, at a collision energy that in near future will typically be available at the Facility for Antiproton and Ion Research. The dependence of elliptic and triangular flow parameters on initial fluctuations, on parton scattering cross sections and their mass ordering on different hadron species, and on the constituent quark number scaling are examined. The AMPT simulation cannot exactly match the elliptic flow results on Pb+Pb collision at $40A$ GeV of the NA49 experiment. The simulation results presented in this work are expected to provide us with an insight to study flow properties at high baryonic density and at moderate temperature, and with an opportunity to compare similar results available from Relativistic Heavy Ion Collider and Large Hadron Collider experiments.

The ${}^{24}\mathrm{Mg}(p,\alpha ){}^{21}\mathrm{Na}$ reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study the spectroscopy of the radionuclide ${}^{21}\mathrm{Na}$. A 31-MeV proton beam from the 25 MV tandem accelerator bombarded isotopically enriched ${}^{24}\mathrm{Mg}$ targets. Recoiling ${}^4\mathrm{He}$ particles were identified by an annular silicon strip detector array. Two energy levels at $E_x=6.594$ and 7.132 MeV were observed for the first time. By comparing the experimentally obtained angular distributions and distorted wave Born approximation calculations, the spins and parities of ${}^{21}\mathrm{Na}$ energy levels were constrained. The astrophysically-important ${}^{17}\mathrm{F}(\alpha ,p){}^{20}\mathrm{Ne}$ reaction rate was also calculated for the first time using resonance parameters for 12 energy levels.