We present a simple way to construct three-dimensional initial conditions for relativistic heavy-ion collisions based on the Glauber collision geometry. Local energy and momentum conservation conditions are imposed to set non-trivial constraints on our parametrizations of longitudinal profiles for the system's initial energy density and flow velocity. After calibrating parameters with charged hadron rapidity distributions in central $\mathrm{Au}+\mathrm{Au}$ collisions, we test model predictions for particle rapidity distributions in $d+\text{Au}$ and peripheral $\mathrm{Au}+\mathrm{Au}$ collisions in the Beam Energy Scan program at the Relativistic Heavy-Ion Collider. Simulations and comparisons with measurements are also made for $\mathrm{Pb}+\mathrm{Pb}$ collisions at Super Proton Synchrotron energies. We demonstrate that elliptic flow measurements in heavy-ion collisions at $\sqrt{s}\sim 10$ GeV can set strong constraints on the dependence of quark-gluon plasma shear viscosity on temperature and net baryon chemical potential.

We compute radiative corrections to nuclear reaction rates that determine the outcome of the big-bang nucleosynthesis (BBN). Any nuclear reaction producing a photon with an energy above $2m_e$ must be supplemented by the corresponding reaction where the final-state photon is replaced by an electron-positron pair. We find that pair production brings a typical $0.2\%$ enhancement to photon-emission rates, resulting in a similar size corrections to elemental abundances. The exception is ${}^4\mathrm{He}$ abundance, which is completely insensitive to the small changes in the nuclear reaction rates. We also investigate the effect of vacuum polarization on the Coulomb barrier, which brings a small extra correction when reaction rates are extrapolated from the measured energies to the BBN Gamow peak energies.

Silicon synthesis in high-temperature hydrogen burning environments presents one possible avenue for the study of abundance anomalies in globular clusters. This was suggested in a previous study, which found that the large uncertainties associated with the ${}^{30}\mathrm{Si}(p,\gamma ){}^{31}\mathrm{P}$ reaction rate preclude a firm understanding of the stellar conditions that give rise to the Mg-K anticorrelation observed in the globular cluster NGC 2419. In an effort to improve the reaction rate, we present new strength measurements of the $E_r^{\mathrm{lab}}=435$ keV and $E_r^{\mathrm{lab}}=501$ keV resonances in ${}^{30}\mathrm{Si}(p,\gamma ){}^{31}\mathrm{P}$. For the former, which was previously unobserved, we obtain a resonance strength of $\omega \gamma =(1.14\pm 0.25$) $\times {10}^{-4}$ eV. For the latter, we obtain a value of $\omega \gamma =(1.88\pm 0.14) \times {10}^{-1}$ eV, which has a smaller uncertainty compared to previously measured strengths. Based on these results, the thermonuclear reaction rate has been re-evaluated. The impact of the new measurements is to lower the reaction rate by a factor of $\approx 10$ at temperatures important to the study of NGC 2419. The rate uncertainty at these temperatures has also been reduced significantly.

Using the Wong formula, fusion cross sections of ${}^{18}\mathrm{O}+{}^{63}\mathrm{Cu},{}^{18}\mathrm{O}+{}^{194}\mathrm{Pt},{}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}$, and ${}^{12}\mathrm{C}+{}^{141}\mathrm{Pr}$ reactions are calculated with double-folding potentials (M3Y) and inclusion of the corrected temperature-dependent repulsive nuclear potential (M3Y $+$ rep). Two different values of repulsive diffuseness are selected in calculations and effect of nuclear temperature on the repulsive nuclear potential, the effective potential, and three parameters of the Wong formula are investigated. Our results show that the inclusion of temperature-dependent repulsive nuclear potential increases the effective potential in interior regions, noticeably. However, in the near-barrier region, little enhancement of the effective potential causes small variations in the barrier height, position, and frequency. Better agreement between theory and experiment is observed by including the repulsive nuclear potential.

The soft dipole $E1$ strength function is calculated for the transition from the ${}^6\mathrm{He}{0}^{+}$ ground state to the $1^{-}$ continuum ${}^4\mathrm{He}+n+n$. The calculations were performed within the hyperspherical harmonics formalism. The sensitivity of the results to the ${}^6\mathrm{He}$ ground-state structure and to final-state interactions, are analyzed. The large-basis calculations show the reliably converged results for soft dipole strength function and for momentum correlations of the ${}^6\mathrm{He}\to {}^4\mathrm{He}+n+n$ dissociation products. Transition mechanisms are analyzed based on the momentum correlations. The comparison with experimental data is provided.

The excitation spectra in the deformed nucleus ${}^{158}\mathrm{Gd}$ have been studied with high energy resolution for the extended spin and parity range by means of the $(p, t)$ reaction using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for more than 200 excited states seen in the triton spectra up to 4.3 MeV. Spins and parities of states were assigned by comparison of experimental angular distributions with the calculated ones with the help of the chuck3 code. Differential cross-section calculations for multistep processes were required in order to make spin assignments for spins greater than zero and so that different pathways were inferred for different states. In addition to the previously studied multiple $0^{+}$ excitations, in this study, the assignments for levels with higher spins are the following: 95 for $2^{+}$ states, 64 for $4^{+}$ states, 14 for $6^{+}$ states, and about 20 for negative parity states. Selected sequences of states with energies following $I(I+1)$ systematics and suitable cross section variations are treated as rotational bands. An analysis of the moments of inertia defined for these bands is carried out. This high number of excited states in a deformed nucleus, close to a complete level scheme, constitutes a very good ground to check models of nuclear structure. The large ensembles of states with the same spin-parity offer unique opportunities for statistical analysis. Such an analysis for the $0^{+}$ and $2^{+}$ states sequences, for all $K$ values and for well-determined projections $K$ of the angular momentum is performed. The obtained data may indicate on a $K$ symmetry breaking. Experimental data are compared with interacting boson model (IBM) calculations using the $spdf$ version of the model. The energies of the low-lying levels, the transition probabilities in the first bands, and the distribution in transfer intensity of the $0^{+}$ states are calculated and compared with experiment.

I have computed expected energies and widths of excited $0^{+}$ states in ${}^{14}\mathrm{O}$, using experimental information from ${}^{14}\mathrm{C}$ and a variety of wave functions. Agreement for the $0_2$ state is fair, but my calculations do not support a recent suggestion that a previously unknown state unresolved from the second $2^{+}$ state might be the $0_3$ state.

The 30.8 keV ${(1/2)}^{-}$ isomeric state in ${}_{41}{}^{93}\mathrm{Nb}$ decays by an $M4$ transition to the ${(9/2)}^{+}$ ground state. We have measured the $K$-shell internal conversion coefficient ${\alpha }_K$ for this transition in order to test the validity of current methods of calculation for a case with relatively low atomic number, low transition energy, and a high value of ${\alpha }_K$. Taking the fluorescence yield of niobium to be 0.751(4), we obtain ${\alpha }_K=2.56\left(9\right)\times {10}^4$, a result that agrees with the Dirac-Fock calculations that take into account the presence of a $K$ vacancy in the final state, and disagrees by 1.7 standard deviations with calculations that ignore the vacancy. We also determine the energy of the isomeric state to be 30.760(5) keV, a fourfold improvement in precision over the currently accepted value.

Experimental signatures of moderately enhanced octupole correlations at high spin in ${}^{136}\mathrm{Nd}$ are indicated for the first time. The extracted dipole moments of two negative-parity bands are only two times smaller than those of the lanthanide nuclei with $N\approx 90$ which present well-established octupole correlations. Calculations using the cranked quasiparticle random phase approximation and a model of quadrupole-octupole rotations with octupole vibrations reveal the structure of the bands and the enhanced octupole correlations at high spin in ${}^{136}\mathrm{Nd}$.

Isospin characters of nuclear excitations in ${}^{26}\mathrm{Mg}$ and ${}^{10}\mathrm{Be}$ are investigated via proton ($p$) and alpha ($\alpha$) inelastic scattering. A structure model of antisymmetrized molecular dynamics (AMD) is applied to calculate the ground and excited states of ${}^{26}\mathrm{Mg}$ and ${}^{10}\mathrm{Be}$. The calculation describes the isoscalar feature of the ground-band $2_1^{+}(K^{\pi }=0_1^{+}$) excitation and predicts the neutron dominance of the side-band $2_2^{+}(K^{\pi }=2^{+}$) excitation in ${}^{26}\mathrm{Mg}$ and ${}^{10}\mathrm{Be}$. The $p$ and $\alpha$ inelastic scattering off ${}^{26}\mathrm{Mg}$ and ${}^{10}\mathrm{Be}$ is calculated by microscopic coupled-channel (MCC) calculations with a $g$-matrix folding approach by using the matter and transition densities of the target nuclei calculated with AMD. The calculation reasonably reproduces the observed $0_1^{+},2_1^{+}$, and $2_2^{+}$ cross sections of ${}^{26}\mathrm{Mg}+p$ scattering at incident energies $E_p=24$ and 40 MeV and of ${}^{26}\mathrm{Mg}+\alpha$ scattering at $E_{\alpha }=104$ and 120 MeV. For ${}^{10}\mathrm{Be}+p$ and ${}^{10}\mathrm{Be}+\alpha$ scattering, inelastic cross sections to the excited states in the $K^{\pi }=0_1^{+}$ ground, $K^{\pi }=2^{+}$ side, $K^{\pi }=0_2^{+}$ cluster, and $K^{\pi }=1^{-}$ cluster bands are investigated. The isospin characters of excitations are investigated via inelastic scattering processes by comparison of the production rates in the ${}^{10}\mathrm{Be}+p,{}^{10}\mathrm{Be}+\alpha$, and ${}^{10}\mathrm{C}+p$ reactions. The result predicts that the $2_2^{+}$ state is selectively produced by the ${}^{10}\mathrm{Be}+p$ reaction because of the neutron dominance in the $2_2^{+}$ excitation as in the case of the ${}^{26}\mathrm{Mg}+p$ scattering to the $2_2^{+}$ state, whereas its production is significantly suppressed in the ${}^{10}\mathrm{C}+p$ reaction.

The Lagrange-mesh $R$-matrix method is generalized to inhomogeneous equations. This method is numerically stable and efficient. It can be directly used for transfer reactions with the formalism discussed by Ascuitto and Glendenning [Phys. Rev. 181, 1396 (1969)] and for inclusive breakup reactions modeled by Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985)]. We first present a simple example to assess the method. Then the application to the ${}^{93}\mathrm{Nb}(d,pX)$ nonelastic breakup is discussed.

A phenomenological model of two-body current (2p2h) contribution to neutrino cross section is introduced. Predictions of the Valencia model for 2p2h [J. Nieves et al., Phys. Rev. C 83, 045501 (2011)] are modified using recent $\mathrm{CC}0\pi$ measurements from T2K and MINERvA experiments. Our results suggest a significant increase of the 2p2h cross section at neutrino energies bigger than 1 GeV and also a redistribution of 2p2h events as function of energy and momentum transfer. This may have a big impact on neutrino energy reconstruction in neutrino oscillation parameters.

The $\mathrm{SNO}+$ experiment collected data as a low-threshold water Cherenkov detector from September 2017 to July 2019. Measurements of the 2.2-MeV $\gamma$'s produced by neutron capture on hydrogen were made using an Am-Be calibration source, for which a large fraction of emitted neutrons are produced simultaneously with a 4.4-MeV $\gamma$. Analysis of the delayed coincidence between the 4.4-MeV $\gamma$ and the 2.2-MeV capture $\gamma$ revealed a neutron detection efficiency that is centered around 50% and varies at the level of 1% across the inner region of the detector, which to our knowledge is the highest efficiency achieved among pure water Cherenkov detectors. In addition, the neutron capture time constant was measured and converted to a thermal neutron-proton capture cross section of $336.3_{-1.5}^{+1.2}\mathrm{mb}$.

Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized $\vec{n}p$ scattering performed in the energy region of the $d^{*}\left(2380\right)$ dibaryon resonance covering the range of beam energies $T_n=0.98-1.29$ GeV ($\sqrt{s}=2.32-2.44$ GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process $dp\to np+p_{\mathrm{spectator}}$. In this way the $np$ differential cross section $\sigma \left(\mathrm{\Theta }\right)$ was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power $A_{\mathrm{y}}\left(\mathrm{\Theta }\right)$ measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled ${}^{3}D_3\text{−}{}^{3}G_3$ waves.

Scientists often try to incorporate prior knowledge into their regression algorithms, such as a particular analytic behavior or a known value at a kinematic endpoint. Unfortunately, there is often no unique way to make use of this prior knowledge, and thus, different analytic choices can lead to very different regression results from the same set of data. To illustrate this point in the context of the proton electromagnetic form factors, we use the Mainz elastic data with its 1422 cross section points and 31 normalization parameters. Starting with a complex unbound nonlinear regression, we will show how the addition of a single theory-motivated constraint removes an oscillation from the magnetic form factor and shifts the extracted proton charge radius. We then repeat both regressions using the same algorithm, but with a rebinned version of the Mainz dataset. These examples illustrate how analytic choices, such as the function that is being used or even the binning of the data, can dramatically affect the results of a complex regression. These results also demonstrate why it is critical when using regression algorithms to have either a physical model in mind or a firm mathematical basis.

The odd-$Z {}^{251}\mathrm{Md}$ nucleus was studied using combined $\gamma$-ray and conversion-electron in-beam spectroscopy. Besides the previously observed rotational band based on the $\left[521\right]1/2^{-}$ configuration, another rotational structure has been identified using $\gamma -\gamma$ coincidences. The use of electron spectroscopy allowed the rotational bands to be observed over a larger rotational frequency range. Using the transition intensities that depend on the gyromagnetic factor, a $\left[514\right]7/2^{-}$ single-particle configuration has been inferred for this band, i.e., the ground-state band. A physical background that dominates the electron spectrum with an intensity of $\simeq 60\%$ was well reproduced by simulating a set of unresolved excited bands. Moreover, a detailed analysis of the intensity profile as a function of the angular momentum provided a method for deriving the orbital gyromagnetic factor, namely $g_K=0.{69}_{-0.16}^{+0.19}$ for the ground-state band. The odd-$Z {}^{249}\mathrm{Md}$ was studied using $\gamma$-ray in-beam spectroscopy. Evidence for octupole correlations resulting from the mixing of the $\mathrm{\Delta }l=\mathrm{\Delta }j=3 \left[521\right]3/2^{-}$ and $\left[633\right]7/2^{+}$ Nilsson orbitals were found in both ${}^{249,251}\mathrm{Md}$. A surprising similarity of the ${}^{251}\mathrm{Md}$ ground-state band transition energies with those of the excited band of ${}^{255}\mathrm{Lr}$ has been discussed in terms of identical bands. Skyrme-Hartree-Fock-Bogoliubov calculations were performed to investigate the origin of the similarities between these bands.

Inclusive $\left(p,\alpha x\right)$ reactions from 42 to 300 MeV are investigated to quantitatively understand the roles of direct pickup and knockout processes. These two processes as well as indirect pickup are incorporated into the intranuclear cascade model. Calculations followed by the evaporation model successfully explain the double-differential cross-section spectra in terms of both shape and magnitude. Direct pickup occupies the low excitation energies of the spectra, and knockout appears between the direct pickup and evaporation regions. The contribution of knockout is negligible below 100 MeV, increases to be comparable with that of direct pickup at 160 MeV, and is dominant above 200 MeV. Indirect pickup shows an important contribution at 300 MeV. The direct pickup and knockout processes show decreasing trends of incident-energy dependence, common to targets ranging from ${}^{12}\mathrm{C}$ to ${}^{209}\mathrm{Bi}$. However, the decrease of direct pickup is much faster than that for knockout.

The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber to study the fission process by reconstructing full three-dimensional tracks of fission fragments and other ionizing radiation. The amount of linear momentum imparted to the fissioning nucleus by the incident neutron can be inferred by measuring the opening angle between the fission fragments. Using this measured linear momentum, fission fragment angular distributions can be converted to the center-of-mass frame for anisotropy measurements. Angular anisotropy is an important experimental observable for understanding the quantum mechanical state of the fissioning nucleus and vital to determining detection efficiency for cross section measurements. Neutron linear momentum transfer to fissioning ${}^{235}\mathrm{U}, {}^{238}\mathrm{U}$, and ${}^{239}\mathrm{Pu}$ and fission fragment angular anisotropy of ${}^{235}\mathrm{U}$ and ${}^{238}\mathrm{U}$ as a function of neutron energies in the range 130 keV–250 MeV are presented.

First-principle calculations within the density-functional theory framework are used to study the effect of high electronegativity atoms on decay rate of the ${}^7\mathrm{Be}$ nucleus. In this study, the electron-capture decay rate of the ${}^7\mathrm{Be}$ nucleus is investigated in $\mathrm{Be}{\left(\mathrm{OH}\right)}_2, \mathrm{Be}{\mathrm{F}}_2, \mathrm{Be}{\mathrm{F}}_3, \mathrm{Be}{\mathrm{F}}_4, \mathrm{Be}{\mathrm{Cl}}_2, \mathrm{Be}{\mathrm{Cl}}_3, \mathrm{Be}{\mathrm{Cl}}_4, {\mathrm{C}}_{36}$, and ${\mathrm{C}}_{60}$ species. It was found that the more decrease of the ${}^7\mathrm{Be}$ decay rate was estimated in the $\mathrm{Be}{\mathrm{F}}_4$ (2.04%) and $\mathrm{Be}{\mathrm{Cl}}_4$ (1.99%) relative to the Be metal. Furthermore, the half-life of ${}^7\mathrm{Be}$ is different in various positions within ${\mathrm{C}}_{36}$ and ${\mathrm{C}}_{60}$. The ${}^7\mathrm{Be}$ half-life in ${}^7\mathrm{Be}$@${\mathrm{C}}_{36}$ is greater than that in other fullerene compounds investigated, while the ${}^7\mathrm{Be}$ half-life inside ${\mathrm{C}}_{60}$ is smaller.

The detailed knowledge of the inner crust properties of neutron stars might be important to explain different phenomena such as pulsar glitches or the possibility of an $r$-process site in neutron star mergers. It has been shown in the literature that quantal effects like shell correction or pairing may play a relevant role to determine the composition of the inner crust of the neutron star. In this paper we construct the equation of state of the inner crust using the finite-range Gogny interactions, where the mean field and the pairing field are calculated with same interaction. We have used the semiclassical variational Wigner-Kirkwood method along with shell and pairing corrections calculated with the Strutinsky integral method and the BCS approximation, respectively. Our results are compared with those of some popular models from the literature. We report a unified equation of state of the inner crust and core computed with the D1M* Gogny force, which was specifically fabricated for astrophysical calculations.