The momentum distribution of quark-gluon plasma at the early stage of a relativistic heavy-ion collision is anisotropic; consequently, the system, which is assumed to be weakly coupled, is unstable owing to chromomagnetic plasma modes. We consider a high-energy parton which flies across such an unstable plasma, and the energy transfer between the parton and the medium is studied as an initial value problem. In the case of equilibrium plasmas, the well-known formula of collisional energy loss is reproduced. The unstable plasma case is much more complex, and the parton can lose or gain energy depending on the initial conditions. The extremely prolate and extremely oblate systems are considered as examples of unstable plasmas, and two classes of initial conditions are discussed. When the initial chromodynamic field is uncorrelated with the color state of the parton, it typically looses energy, and the magnitude of the energy loss is comparable to that in an equilibrium plasma of the same density. When the initial chromodynamic field is induced by the parton, it can be either accelerated or decelerated depending on the relative phase factor. With a correlated initial condition, the energy transfer grows exponentially in time and its magnitude can much exceed the absolute value of energy loss in an equilibrium plasma. The energy transfer is also strongly directionally dependent. Consequences of our findings for the phenomenology of jet quenching in relativistic heavy-ion collisions are briefly discussed.

Alpha decays in the EXO-200 detector are used to measure the fraction of charged ${}^{218}\text{Po}$ and ${}^{214}\text{Bi}$ daughters created from $\alpha$ and $\beta$ decays, respectively. ${}^{222}\text{Rn} \alpha$ decays in liquid xenon (LXe) are found to produce ${}^{218}\text{Po}^{+}$ ions $50.3\pm 3.0\%$ of the time, while the remainder of the ${}^{218}\text{Po}$ atoms are neutral. The fraction of ${}^{214}\text{Bi}^{+}$ from ${}^{214}\text{Pb} \beta$ decays in LXe is found to be $76.4\pm 5.7\%$, inferred from the relative rates of ${}^{218}\text{Po}$ and ${}^{214}\text{Po} \alpha$ decays in the LXe. The average velocity of ${}^{218}\text{Po}$ ions is observed to decrease for longer drift times. Initially the ions have a mobility of $0.390\pm 0.006{\text{cm}}^2/\left(\text{kV}\text{s}\right)$, and at long drift times the mobility is $0.219\pm 0.004{\text{cm}}^2/\left(\text{kV}\text{s}\right)$. Time constants associated with the change in mobility during drift of the ${}^{218}\text{Po}^{+}$ ions are found to be proportional to the electron lifetime in the LXe.

The determination of absolute widths of two observed levels above the proton threshold in ${}^{15}\mathrm{N}$ has been improved by a combined analysis of our recent ${}^{15}\mathrm{N}(\gamma ,{\gamma }^{\prime }){}^{15}\mathrm{N}^{*}$ photon scattering data, resonance strengths $\omega \gamma$ of the ${}^{14}\mathrm{C}(p,\gamma ){}^{15}\mathrm{N}$ reaction, and $\gamma$-ray branchings $b_{\gamma ,i}$ in ${}^{15}\mathrm{N}$. The revised data are compared to the adopted values, and some inconsistencies in the adopted values are illustrated.

We use leading-order anisotropic hydrodynamics to study an azimuthally symmetric boost-invariant quark-gluon plasma. We impose a realistic lattice-based equation of state and perform self-consistent anisotropic freeze-out to hadronic degrees of freedom. We then compare our results for the full spatiotemporal evolution of the quark-gluon plasma and its subsequent freeze-out to results obtained using 1+1D Israel-Stewart second-order viscous hydrodynamics. We find that for small shear viscosities, $4\pi \eta /s\sim 1$, the two methods agree well for nucleus-nucleus collisions; however, for large-shear-viscosity-to-entropy-density ratios or proton-nucleus collisions we find important corrections to the Israel-Stewart results for the final particle spectra and the total number of charged particles. Finally, we demonstrate that the total number of charged particles produced is a monotonically increasing function of $4\pi \eta /s$ in Israel-Stewart viscous hydrodynamics, whereas in anisotropic hydrodynamics it has a maximum at $4\pi \eta /s\sim 10$. For all $4\pi \eta /s>0$, we find that for Pb-Pb collisions Israel-Stewart viscous hydrodynamics predicts more dissipative particle production than anisotropic hydrodynamics.

The baryon-strangeness correlation in the hadronization of quark matter is studied within the quark combination mechanism. We calculate the correlation coefficient $C_{BS}=-3\left(\langle BS\rangle -\langle B\rangle \langle S\rangle \right)/\left(\langle S^2\rangle -{\langle S\rangle }^2\right)$ of initial hadrons produced from the deconfined free quark system with $C_{BS}^{\left(q\right)}=1$. The competition of the production of baryons against that of mesons is the key dynamics that is most relevant to the change of baryon-strangeness correlation during system hadronization. Results of quark combination under the Poisson statistics agree with the statistical model predictions for a hadron resonance gas at vanishing chemical potential but differ from those at relatively large chemical potentials. Results beyond Poisson statistics are also obtained and are compared with calculations of lattice QCD in the quark-hadron phase boundary. We predict the dependence of the $C_{BS}$ of the hadron system on the baryon chemical potential and strangeness. These predictions are expected to be tested by future lattice QCD calculations at nonzero chemical potentials and/or by the Beam Energy Scan experiment of the STAR Collaboration at RHIC.

Background: Identification of proton-neutron mixed-symmetric one-quadrupole phonon excitations (the $2_{\text{ms}}^{+}$ states) of atomic nuclei provides information on the isovector part of the residual nucleon-nucleon interaction. It was predicted that the $2_{\text{ms}}^{+}$ state of particular nuclei close to the U(5) limit of the interacting boson model, in particular ${}^{140}\mathrm{Ba}$, should be considerably populated by $\alpha$-transfer reactions [C. E. Alonso et al., Phys. Rev. C 78, 017301 (2008)].

Purpose: We aim at the identification of the $2_{\text{ms}}^{+}$ mixed-symmetry state (MSS) of radioactive ${}^{140}\mathrm{Ba}$ and investigate its population by the $\alpha$-transfer reaction as a suitable tool to selectively populate MSSs and as a potential new signature for its mixed-symmetric character.

Method: A $\gamma$-ray spectroscopy experiment was performed in inverse kinematics in order to populate the $2_{\text{ms}}^{+}$ state of ${}^{140}\mathrm{Ba}$ by $\alpha$-transfer from a ${}^{nat}\mathrm{C}$ target on ${}^{136}\mathrm{Xe}$ beam ions. The population of the candidate for the $2_{\text{ms}}^{+}$ state of ${}^{140}\mathrm{Ba}$ was measured relative to the population of the $2_1^{+}$ state.

Results: The candidate for the $2_{\text{ms}}^{+}$ state of ${}^{140}\mathrm{Ba}$ was populated by $\alpha$ transfer three times weaker than predicted. Another $2^{+}$ state that can be ruled out as the MSS was in turn as strongly populated by the $\alpha$ transfer as predicted for the MSS.

Conclusions: The relative population of $2^{+}$ states by $\alpha$-transfer cannot serve as a new signature for MSSs, since other $2^{+}$ states are also strongly populated. Nevertheless, the substantial population of the MSS candidate of ${}^{140}\mathrm{Ba}$ by $\alpha$ transfer qualifies this type of reaction as suitable tool to excite MSSs and study their electromagnetic decay properties.

High-spin states in ${}^{70}\mathrm{As}$ were studied using the ${}^{55}\mathrm{Mn}({}^{18}\mathrm{O},3n)$ fusion-evaporation reaction at a beam energy of 50 MeV. Prompt $\gamma \text{−}\gamma$ coincidences were measured using the Florida State University Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. A reinvestigation of the known level scheme resulted in the addition of 32 new transitions and the rearrangement of 10 others. The high-spin decay pattern of yrast negative-parity states was modified and enhanced extensively. Spins were assigned based on directional correlation of oriented nuclei ratios. Lifetimes of seven excited states were measured using the Doppler-shift attenuation method. The $B\left(E2\right)$ rates inferred from the lifetimes of states in the yrast positive-parity band imply substantial collectivity, in agreement with the results of previous studies. Substantial signature splitting and large alternations in the $B\left(M1\right)$ strengths were observed in this band as well, supporting the interpretation of an aligned $\pi g_{9/2}\otimes \nu g_{9/2}$ intrinsic configuration for this structure beginning at the lowest $9^{+}$ state. Large-scale shell-model calculations performed for ${}^{70}\mathrm{As}$ reproduce the relative energy differences between adjacent levels and the $B\left(M1\right)$ rates in the yrast positive-parity band rather well, but underestimate the $B\left(E2\right)$ strengths. The $g_{9/2}$ orbital occupancies for the lowest $9^{+}$ state predicted by the shell-model calculations provide additional evidence of a stretched $\pi g_{9/2}\otimes \nu g_{9/2}$ configuration for this state.

The low-lying structures of ${}_{\mathrm{\Lambda }}{}^{10}\mathrm{Be}$ and ${}_{\mathrm{\Lambda }}{}^{11}\mathrm{Be}$ are investigated within the framework of the antisymmetrized molecular dynamics. We focus on the modifications of the excitation spectra and dynamical changes of the $2\alpha$ cluster structure caused by a $\mathrm{\Lambda }$ particle as an impurity in these hypernuclei. It is found that the excitation energies of well-pronounced cluster states are largely shifted up by the addition of a $\mathrm{\Lambda }$ particle. Furthermore, we also find that the $2\alpha$ cluster structure is significantly changed in the excited states, whereas it is almost unchanged in the ground states.

A high-spin isomer with $\tau >700$ ns has been found in ${}^{204}\mathrm{Hg}$, populated in reactions of 1360-MeV ${}^{208}\mathrm{Pb}$ and 330-MeV ${}^{48}\mathrm{Ca}$ beams with a thick ${}^{238}\mathrm{U}$ target and a 1450-MeV ${}^{208}\mathrm{Pb}$ beam on a thick ${}^{208}\mathrm{Pb}$ target. The observed $\gamma$-ray decay of the isomer has established the yrast states below it, including another isomer with $\tau =33\left(3\right)$ ns. The experimental results are compared with shell-model calculations that include four holes in the configuration space between ${}^{132}\mathrm{Sn}$ and ${}^{208}\mathrm{Pb}$. The available spectroscopic information, including transition strengths, total conversion, and angular correlation coefficients, together with the observed agreement with the calculations, allows spin, parity, and configuration assignments to be proposed for the experimental states. The $\tau >700$ ns isomer is the ${22}^{+}$ state of maximum spin available from the alignment of the four valence holes with the configuration $\pi h_{11/2}^{-2}\nu i_{13/2}^{-2}$.

The reaction $\gamma p\to K^{+}{\mathrm{\Sigma }}^0$ has been investigated using a tree-level effective Lagrangian model similar to that employed previously by the author to study the electromagnetic production of $\mathrm{\Lambda }$'s from protons. In addition to the Born terms, the model incorporates a number of baryon resonances with spins up to $\frac{5}{2}$ and the two kaon resonances, $K^{☆}\left(892\right)$ and $K1\left(1270\right)$. Momentum- and energy-dependent widths for the nucleon and $\mathrm{\Delta }$ resonances are included by means of a dynamical model that makes use of empirical on-shell branching ratios. The model parameters, consisting of products of the coupling strengths at the electromagnetic and strong interaction vertices in the resonance contributions, are fit to a large pool of photoproduction data from the CLAS and GRAAL Collaborations. Results are presented for the unpolarized differential cross section, the photon beam asymmetry $\mathrm{\Sigma }$, the hyperon recoil asymmetry $P$, and the double-polarization observables $C_x$ and $C_z$ in a variety of kinematical situations and compared with the data.

Background: The ${}^{15}\mathrm{N}\left(n,\gamma \right){}^{16}\mathrm{N}$ reaction plays an important role in red giant stars and also in inhomogeneous big bang nucleosynthesis. However, there are controversies regarding spectroscopic factors of the four low-lying states of ${}^{16}\mathrm{N}$, which have direct bearing on the total direct capture cross section and also on the reaction rate. Direct measurements of the capture cross section at low energies are scarce and available only at three energies below 500 keV.

Purpose: The aim of this paper is to calculate the ${}^{15}\mathrm{N}\left(n,\gamma \right){}^{16}\mathrm{N}$ radiative capture cross section and its subsequent reaction rate by an indirect method and in that process investigate the effects of spectroscopic factors of different levels of ${}^{16}\mathrm{N}$ to the cross section.

Method: A fully quantum mechanical Coulomb breakup theory under the aegis of post-form distorted wave Born approximation is used to calculate the Coulomb breakup of ${}^{16}\mathrm{N}$ on Pb at 100 MeV/$u$. This is then related to the photodisintegration cross section of ${}^{16}\mathrm{N}\left(\gamma ,n\right){}^{15}\mathrm{N}$ and subsequently invoking the principle of detailed balance, the ${}^{15}\mathrm{N}\left(n,\gamma \right){}^{16}\mathrm{N}$ capture cross section is calculated.

Results: The nonresonant capture cross section is calculated with spectroscopic factors from the shell model and those extracted (including uncertainties) from two recent experiments. The data seem to favor a more single particle nature for the low-lying states of ${}^{16}\mathrm{N}$. The total neutron capture rate is also calculated by summing up nonresonant and resonant (significant only at temperatures greater than 1 GK) contributions and comparison is made with other charged particle capture rates. In the typical temperature range of $0.1–1.2$ GK, almost all the contributions to the reaction rate come from capture cross sections below 0.25 MeV.

Conclusion: We have attempted to resolve the discrepancy in the spectroscopic factors of low-lying ${}^{16}\mathrm{N}$ levels and conclude that it would certainly be useful to perform a Coulomb dissociation experiment to find the low energy capture cross section for the reaction, especially below 0.25 MeV.

Isoscalar giant resonances in ${}^{90,92,94}\text{Zr}$ have been studied with inelastic scattering of 240 MeV $\alpha$ particles at small angles including $0^{\circ }$. A significant fraction of the energy-weighted sum rule (EWSR) was found for isoscalar $E0$ (106%,103%,106%), $E1$ (64%,53%,96%), $E2$ (92%,93%,67%) and high energy octupole $E3$ (59%,69%,58%) resonances in ${}^{90,92,94}\text{Zr}$ respectively. Hartree-Fock random phase approximation (RPA) calculations were made for each multipole using the KDE0v1 Skyrme-type effective nucleon-nucleon interaction and the results are compared to the experimental distributions.

Background: The high-momentum distribution of atoms in two spin-state ultracold atomic gases with strong short-range interactions between atoms with different spins, which can be described by using Tan's contact, are dominated by short-range pairs of different fermions and decreases as $k^{-4}$. In atomic nuclei the momentum distribution of nucleons above the Fermi momentum ($k>k_F\approx 250$ MeV/$c$) is also dominated by short-range-correlated different-fermion (neutron-proton) pairs.

Purpose: Compare high-momentum unlike-fermion momentum distributions in atomic and nuclear systems.

Methods: We show that, for $k>k_F$ MeV/$c$, nuclear momentum distributions are proportional to that of the deuteron. We then examine the deuteron momentum distributions derived from a wide variety of modern nucleon-nucleon potentials that are consistent with $NN$-scattering data.

Results: The high-momentum tail of the deuteron momentum distribution, and hence of the nuclear momentum distributions, appears to decrease as $k^{-4}$. This behavior is shown to arise from the effects of the tensor part of the nucleon-nucleon potential. In addition, when the dimensionless interaction strength for the atomic system is chosen to be similar to that of atomic nuclei, the probability for finding a short-range different-fermion pair in both systems is the same.

Conclusions: Although nuclei do not satisfy all of the conditions for Tan's contact, the observed similarity of the magnitude and $k^{-4}$ shape of nuclear and atomic momentum distributions is remarkable because these systems differ by about 20 orders of magnitude in density. This similarity may lead to a greater understanding of nuclei and the density dependence of nuclear systems.

High-energy Li-Be-B nuclei in cosmic rays are being measured with unprecedented accuracy by the AMS experiment. These data bring valuable information to the cosmic ray propagation physics. In particular, combined measurements of B/C and Be/B ratios may allow to break the parameter degeneracy between the cosmic-ray diffusion coefficient and the size of the propagation region, which is crucial for dark matter searches. The parameter determination relies on the calculation of the Be and B production from collisions of heavier nuclei with the gas. Using the available cross-section data, I present for the first time an evaluation of the nuclear uncertainties and their impact in constraining the propagation models. I found that the AMS experiment can provide tight constraints on the transport parameters allowing to resolutely break the degeneracy, while nuclear uncertainties in the models are found to be a major limiting factor. Once these uncertainties are accounted for, the degeneracy remains poorly resolved. In particular, the Be/B ratio at $\sim 1–10 \mathrm{GeV}/n$ is found not to bring valuable information for the parameter extraction. On the other hand, precise Be/B data at higher energy may be useful to test the nuclear physics inputs of the models.

We use quantum Monte Carlo (QMC) techniques to calculate the static structure function $S\left(q\right)$ of a one-component ion lattice and use it to calculate the thermal conductivity $\kappa$ of high-density solid matter expected in the neutron star crust. By making detailed comparisons with the results for the thermal conductivity obtained using standard techniques based on the one-phonon approximation (OPA) valid at low temperatures and the multiphonon harmonic approximation expected to be valid over a wide range of temperatures, we assess the temperature regime where $S\left(q\right)$ from the QMC can be used directly to calculate $\kappa$. We also compare the QMC results to those obtained using the classical Monte Carlo to quantitatively assess the magnitude of the quantum corrections. We found that quantum effects became relevant for the calculation of $\kappa$ at a temperature of $T\lesssim 0.3{\mathrm{\Omega }}_{\mathrm{P}}$, where ${\mathrm{\Omega }}_{\mathrm{P}}$ is the ion plasma frequency. At $T\simeq 0.1{\mathrm{\Omega }}_{\mathrm{P}}$ the quantum effects suppress $\kappa$ by about 30%. The comparison with the results of the OPA indicates that dynamical information beyond the static structure is needed when $T\lesssim 0.1{\mathrm{\Omega }}_{\mathrm{P}}$. These quantitative comparisons help to establish QMC as a viable technique to calculate $\kappa$ at moderate temperatures in the range of $T=0.1–1{\mathrm{\Omega }}_{\mathrm{P}}$ of relevance to the study of accreting neutron stars. This finding is especially important because QMC is the only viable technique so far for calculating $\kappa$ in multicomponent systems at low temperatures.

The previously accepted spin values of the 991 and 1599 keV levels in ${}^{140}\mathrm{Sm}$ have been revised and established as $2{}^{+}$ and $0{}^{(+)}$, respectively. The $\gamma \text{−}\gamma$ angular correlation method was used to determine the new spin values. The excited low-spin levels in ${}^{140}\mathrm{Sm}$ were populated in the ${}^{140}\mathrm{Eu}{\to }^{140}\mathrm{Sm}$ and ${}^{140}\mathrm{Gd}\to {}^{140}\mathrm{Eu}{\to }^{140}\mathrm{Sm}$ decays. The ${}^{140}\mathrm{Gd}$ and ${}^{140}\mathrm{Eu}$ nuclei were produced in the ${}^{112}\mathrm{Cd}+{}^{32}\mathrm{S}$ reaction at a beam energy of 155 MeV.