Low- and medium-spin states of the odd-odd nucleus ${}^{130}\mathrm{La}$ were studied by in-beam and pulsed-beam $\gamma$-ray spectroscopy using the ${}^{121}\mathrm{Sb}({}^{12}\mathrm{C},3n)$ and ${}^{116}\mathrm{Sn}({}^{16}\mathrm{O},pn)$ fusion-evaporation reactions. The decay out of the $\pi h_{11/2}\otimes \nu h_{11/2}$ and $\pi h_{11/2}\otimes \nu g_{7/2}$ rotational structures to the ground state has been elucidated. Spin and parity values have been assigned to most of the newly observed states, as well as to the bandheads of the rotational bands. Two isomeric states were identified and placed in the level scheme, with the characteristics $J^{\pi }=5^{+},E_x=214.0$ keV, $T_{1/2}=0.76\left(9\right)$ $\mu$s and $J^{\pi }=6^{+},E_x=319.1$ keV, $T_{1/2}=33\left(1\right)$ ns. The magnetic and quadrupole interactions of the $6^{+}$ isomeric state have been investigated by the time-differential perturbed $\gamma$-ray angular distribution method. The $g$ factor value, $g\left(6^{+}\right)=+0.48\left(3\right)$, and the quadrupole coupling constant in polycrystalline metallic Sn lattice, ${\nu }_Q\left(6^{+}\right)=37\left(4\right)$ MHz, have been derived. The experimental data are compared with the predictions of two-quasiparticles plus rotor model calculations.

$\gamma$-ray transitions in ${}^{134}\text{Te}$, ${}^{135}\text{Te}$, and ${}^{136}\text{Te}$ were measured from ${}^9\text{Be}$-induced reactions with a radioactive ${}^{132}\text{Sn}$ beam at a sub-Coulomb barrier energy of 3 MeV per nucleon using particle-$\gamma$ coincidence spectroscopy. The transitions were selected by gating on alpha-like particles in a CsI detector following a combination of $({}^9\text{Be},\alpha 1n)$, $({}^9\text{Be},\alpha 2n)$, and $({}^9\text{Be},\alpha 3n)$ incomplete fusion-evaporation reactions. Distorted-wave Born approximation calculations suggest little to no contribution from the $({}^9\text{Be},{}^7\text{He})$, $({}^9\text{Be},{}^6\text{He})$, and $({}^9\text{Be},{}^5\text{He})$ direct reactions.$\gamma$-ray transitions from previously known $2^{+}\otimes \nu 2f_{7/2}$ and $4^{+}\otimes \nu 2f_{7/2}$ multiplet members in ${}^{135}\text{Te}$ are observed. A new $\gamma$ ray is observed, assigned to the third-excited state in ${}^{135}\text{Te}$, and new $2^{+}\otimes \nu 2f_{7/2}$ multiplet members are suggested. In addition, spin assignments are made by using recent one-neutron transfer data. The updated experimental data for ${}^{135}\text{Te}$ are compared to shell-model calculations for a relatively complete set of states up to the yrast ${15/2}^{-},4^{+}\otimes \nu 2f_{7/2}$ multiplet member at 1505 keV.

Evaporation proton yields were measured for the fusion of the radioactive proton-rich nucleus ${}^7\mathrm{Be}$ onto a ${}^{58}\mathrm{Ni}$ target at six near-barrier energies. Total fusion cross sections were deduced by using calculated proton multiplicities. The resulting fusion excitation function shows a considerable enhancement with respect to calculations for a bare potential, even for energies above the Coulomb barrier. Inelastic couplings can account for the enhancement at the highest energy. Total fusion channels nearly saturate the total reaction cross section in the measured energy region. Comparison with previous results scaled appropriately for ${}^7\mathrm{Be}+({}^{27}\mathrm{Al},{}^{238}\mathrm{U})$ shows good agreement.

We derive a system of moment-based dynamical equations that describe the $1+1d$ space-time evolution of a cylindrically symmetric massive gas undergoing boost-invariant longitudinal expansion. Extending previous work, we introduce an explicit degree of freedom associated with the bulk pressure of the system. The resulting form generalizes the ellipsoidal one-particle distribution function appropriate for massless particles to massive particles. Using this generalized form, we obtain a system of partial differential equations that can be solved numerically. In order to assess the performance of this scheme, we compare the resulting anisotropic hydrodynamics solutions with the exact solution of the $0+1d$ Boltzmann equation in the relaxation-time approximation. We find that the inclusion of the bulk degree of freedom improves the agreement between anisotropic hydrodynamics and the exact solution for a massive gas.

Within five different approaches to parton propagation and energy loss in dense matter, a phenomenological study of experimental data on suppression of large-$p_T$ single inclusive hadrons in heavy-ion collisions at both the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) was carried out. The evolution of bulk medium used in the study for parton propagation was given by 2 + 1 dimensional or 3 + 1 dimensional hydrodynamic models which are also constrained by experimental data on bulk hadron spectra. Values for the jet transport parameter $\widehat{q}$ at the center of the most central heavy-ion collisions are extracted or calculated within each model, with parameters for the medium properties that are constrained by experimental data on the hadron suppression factor $R_{AA}$. For a quark with initial energy of 10 GeV we find that $\widehat{q}\approx 1.2\pm 0.3$ GeV${}^2$/fm at an initial time ${\tau }_0=0.6$ fm/$c$ in Au + Au collisions at $\sqrt{s}=200$ GeV/n and $\widehat{q}\approx 1.9\pm 0.7$ GeV${}^2$/fm in Pb + Pb collisions at $\sqrt{s}=2.76$ TeV/n. Compared to earlier studies, these represent significant convergence on values of the extracted jet transport parameter due to new constraints provided by recent experiment data from the LHC.

This paper describes a precise measurement of electron scattering off the proton at momentum transfers of $0.003\lesssim Q^2\lesssim 1$ ${\mathrm{GeV}}^2$. The average point-to-point error of the cross sections in this experiment is $\sim 0.37\%$. These data are used for a coherent new analysis together with all world data of unpolarized and polarized electron scattering from the very smallest to the highest momentum transfers so far measured. The extracted electric and magnetic form factors provide new insight into their exact shape, deviating from the classical dipole form, and of structure on top of this gross shape. The data reaching very low $Q^2$ values are used for a new determination of the electric and magnetic radii. An empirical determination of the two-photon-exchange correction is presented. The implications of this correction on the radii and the question of a directly visible signal of the pion cloud are addressed.

M1 transitions between low-energy quadrupole excitations of the valence shell are often used as the signature for states of proton-neutron mixed-symmetry character. Starting from the Skyrme interaction $f_{-}$ together with the volume pairing interaction, we study the properties of the $2_{1,2}^{+}$ excitations of ${}^{132,134,136}\mathrm{Te}$. The coupling between one- and two-phonon terms in the wave functions of excited states is taken into account. Our calculations are performed within the finite-rank separable approximation, which enables one to perform quasiparticle random phase approximation calculations in very large two-quasiparticle configurational spaces. Using the same set of parameters we describe available experimental data and give the prediction for ${}^{136}\mathrm{Te}$, $B(M1;2_2^{+}\to 2_1^{+})=0.51{\mu }_N^2$ in comparison to $0.30{\mu }_N^2$ in the case of ${}^{132}\mathrm{Te}$.

A new level scheme of ${}^{80}\mathrm{Ga}$ has been determined. This nucleus was populated following the ${\beta }^{-}$ decay of ${}^{80}\mathrm{Zn}$ at ISOLDE, CERN. The proposed level scheme is significantly different compared to the previously reported one and contains 26 levels up to 3.4 MeV in excitation energy. The present study establishes that the previously identified 1.9-s ${\beta }^{-}$-decaying $6^{-}$ isomer is the ground state of ${}^{80}\mathrm{Ga}$ and the 1.3-s ${\beta }^{-}$-decaying 3${}^{-}$ isomer lies at an excitation energy of 22.4 keV. A new isomeric level was identified at 707.8 keV and its half-life was measured to be 18.3(5) ns, allowing the 685.4-keV transition de-exciting this state to be assigned an $M2$ multipolarity. The newly measured spectroscopic observables are compared with shell-model calculations using the jj44bpn and JUN45 interactions.

The heavy shell model (HSM) [Y. Sun and C.-L. Wu, Phys. Rev. C 68, 024315 (2003)] was proposed to take the advantages of two existing models, the projected shell model (PSM) and the fermion dynamical symmetry model (FDSM). To construct the HSM, one extends the PSM by adding collective $D$ pairs into the intrinsic basis. The HSM is expected to describe simultaneously low-lying collective and quasiparticle excitations in deformed nuclei, and still keeps the model space tractable even for the heaviest systems. As the first numerical realization of the HSM, we study systematically the band structures for some deformed actinide nuclei, with a model space including up to 4-quasiparticle and 1-$D$-pair configurations. The calculated energy levels for the ground-state bands, the collective bands such as $\beta$ and $\gamma$ bands, and some quasiparticle bands agree well with known experimental data. Some low-lying quasiparticle bands are predicted, awaiting experimental confirmation.

Background: Significant enhancement of sub-barrier fusion cross sections owing to neutron rearrangement with positive $Q$ values were found for many combinations of colliding nuclei. However, several experimental results on fusion reactions were reported recently in which such enhancement has not been observed in spite of a possibility for neutron rearrangement with positive $Q$ values.

Purpose: We aim to clarify much better the mechanism of neutron rearrangement in sub-barrier fusion reactions to find the other requirements (beside positive $Q$ values) which favor (or prevent) sub-barrier fusion enhancement.

Methods: A channel coupling approach along with the semiclassical model for neutron transfer has been used for analysis of available experimental data on sub-barrier fusion of heavy ions.

Results: The role and interplay of different factors determining the enhancement of sub-barrier fusion (such as $Q$ values for neutron rearrangement, properties of collective excitations, and neutron binding energies) have been studied and clarified.

Conclusions: (1) Only $1n$ and $2n$ transfers with positive $Q$ values have a noticeable impact on sub-barrier fusion. A positive $Q$ value for neutron rearrangement is a necessary but not sufficient requirement for additional sub-barrier fusion enhancement to take place. (2) The “rigidity” of colliding nuclei with respect to collective excitations is important for sub-barrier fusion enhancement due to neutron rearrangement with positive $Q$ values to be clearly visible. (3) The neutron binding energy of the “donor” nucleus has a strong impact only in the case of fusion of light weakly bound nuclei.

Background: The repulsive Coulomb force poses severe challenges when solving the three-body problem for ($d,p$) reactions on intermediate mass and heavy nuclei. Recently, a new approach based on the Coulomb-distorted basis in momentum space was proposed.

Purpose: In this work, we demonstrate the feasibility of using the Coulomb-distorted basis in momentum space for calculating matrix elements expected in a wide range of nuclear reactions.

Method: We discuss the analytic forms of the Coulomb wave function in momentum space. We analyze the singularities in the Coulomb-distorted form factors and the required regularization techniques. Employing a separable interaction derived from a realistic nucleon-nucleus optical potential, we compute and study the Coulomb-distorted form factors for a wide range of cases, including charge, angular momentum, and energy dependence. We also investigate in detail the precision of our calculations.

Results: The Coulomb-distorted form factors differ significantly from the nuclear form factors except for the very highest momenta. Typically, the structure of the form factor is shifted away from zero momentum due to the Coulomb interaction. Unlike the Yamaguchi forms typically used in three-body methods, our realistic form factors have a short high-momentum tail, which allows for a safe and efficient truncation of the momentum grid.

Conclusions: Our results show that the Coulomb-distorted basis can be effectively implemented.

Background: Pulsar glitches—the sudden spin-up in the rotational frequency of a neutron star—suggest the existence of an angular-momentum reservoir confined to the inner crust of the neutron star. Large and regular glitches observed in the Vela pulsar have originally constrained the fraction of the stellar moment of inertia that must reside in the solid crust to about 1.4%. However, crustal entrainment—which until very recently has been ignored—suggests that in order to account for the Vela glitches, the fraction of the moment of inertia residing in the crust must increase significantly; to about 7–9 %. This indicates that the required angular momentum reservoir may exceed that which is available in the crust.

Purpose: We explore the possibility that uncertainties in the equation of state provide enough flexibility for the construction of models that predict a large crustal thickness and consequently a large crustal moment of inertia.

Methods: Moments of inertia—both total and crustal—are computed in the slow-rotation approximation using a relativistic mean-field formalism to generate the equation of state of neutron-star matter.

Results: We compute the fractional moment of inertia of neutron stars of various masses using a representative set of relativistic mean-field models. Given that analytic results suggest that the crustal moment of inertia is sensitive to the transition pressure at the crust-core interface, we tune the parameters of the model to maximize the transition pressure, while still providing an excellent description of nuclear observables. In this manner we are able to obtain fractional moments of inertia as large as 7% for neutron stars with masses below 1.6 solar masses.

Conclusions: We find that uncertainties in the equation of state of neutron-rich matter are large enough to accommodate theoretical models that predict large crustal moments of inertia. In particular, we find that if the neutron-skin thickness of ${}^{208}\mathrm{Pb}$ falls within the (0.20–0.26) fm range, large enough transition pressures can be generated to explain the large Vela glitches—without invoking an additional angular-momentum reservoir beyond that confined to the solid crust. Our results suggest that the crust may be enough.

We extend the study of hadron yield correlation in quark-combination models in a recent publication to baryon-antibaryon flavor correlations in heavy-ion collisions. We show that the universal behaviors of the antibaryon-to-baryon yield ratios as functions of that of $K^{-}$ to $K^{+}$ are naturally explained. We study also the “mixed ratios” and propose other measurements that might be sensitive to the hadronization mechanism.

We have performed measurements of the $0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+}$ excitations in the neutron-rich isotopes ${}^{48,50}\mathrm{Ca}$ via inelastic proton scattering on a liquid hydrogen target, using the GRETINA $\gamma$-ray tracking array. A comparison of the present results with those from previous measurements of the lifetimes of the $2_1^{+}$ states provides the ratio of the neutron and proton matrix elements for the $0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+}$ transitions. These results allow the determination of the ratio of the proton and neutron effective charges to be used in shell model calculations of neutron-rich isotopes in the vicinity of ${}^{48}\mathrm{Ca}$.

The cross sections for the photodisintegration of ${}^6\mathrm{Li}$ have been measured for all the available reaction channels that have neutrons in the final state, except the ${}^6\mathrm{Li}(\gamma ,p_0){}^5\mathrm{He}\text{(g.s.)}$ channel. The cross sections were measured at the photon energies, 8, 9, 10, 11, 12, 13, 15, and 15.6 MeV using linearly polarized photons, and 20, 25, 30, and 35 MeV using circularly polarized photons. Associated Legendre function coefficients are extracted for the ${}^6\mathrm{Li}(\gamma ,n_0){}^5\mathrm{Li}\text{(g.s.)}$ and ${}^6\mathrm{Li}(\gamma ,n_1){}^5\mathrm{Li}\mathrm{(1.49)}$ channels. For all observed reaction channels Legendre function parametrizations are used to determine total cross sections. Comparisons with recent theoretical calculations of the total photodisintegration cross section using various nucleon-nucleon interactions are inconclusive because of the large uncertainty in the cross sections for reactions channels that are not measured. We hope that the precision of our results for specific reaction channels will prompt calculations for those reaction channels.

Azimuthal anisotropies of reconstructed jets [$v_n^{\mathrm{jet}}(n=2,3)$] have been investigated in Pb + Pb collisions at the center of mass energy $\sqrt{s_{NN}}=2.76$ TeV within a framework of a multiphase transport (AMPT) model. The $v_2^{\mathrm{jet}}$ is in good agreement with the recent ATLAS data. However, the $v_3^{\mathrm{jet}}$ shows a smaller magnitude than $v_2^{\mathrm{jet}}$, and approaches zero at a larger transverse momentum. It is attributed to the path-length dependence in which the jet energy loss fraction depends on the azimuthal angles with respect to different orders of event planes. The ratio $v_n^{\mathrm{jet}}/{\varepsilon }_n$ increases from peripheral to noncentral collisions, and $v_n^{\mathrm{jet}}$ increases with the initial spatial asymmetry $\left({\varepsilon }_n\right)$ for a given centrality bin. These behaviors indicate that the $v_n^{\mathrm{jet}}$ is produced by the strong interactions between jet and the partonic medium with different initial geometry shapes. Therefore, azimuthal anisotropies of reconstructed jet are proposed as a good probe to study the initial spatial fluctuations, which are expected to provide constraints on the path-length dependence of jet quenching models.

Differential and total cross sections for the quasifree reactions $\gamma p\to \eta p$ and $\gamma n\to \eta n$ have been determined at the MAMI-C electron accelerator by using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes $\eta \to 2\gamma$ and $\eta \to 3{\pi }^0\to 6\gamma$ and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The $\eta$-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree-proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the $S_{11}$(1535) resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy $W=(1670\pm 5)$ MeV with an intrinsic width of $\Gamma \approx 30$ MeV.

A method is introduced that establishes relations between properties of collective excitations in finite nuclei and the phase transition density $n_t$ and pressure $P_t$ at the inner edge separating the liquid core and the solid crust of a neutron star. A theoretical framework that includes the thermodynamic method, relativistic nuclear energy density functionals, and the quasiparticle random-phase approximation is employed in a self-consistent calculation of $(n_t,P_t)$ and collective excitations in nuclei. Covariance analysis shows that properties of charge-exchange dipole transitions, isovector giant dipole and quadrupole resonances, and pygmy dipole transitions are correlated with the core-crust transition density and pressure. A set of relativistic nuclear energy density functionals, characterized by systematic variation of the density dependence of the symmetry energy of nuclear matter, is used to constrain possible values for $(n_t,P_t)$. By comparing the calculated excitation energies of giant resonances, energy-weighted pygmy dipole strength, and dipole polarizability with available data, we obtain the weighted average values: $n_t=0.0955\pm 0.0007$ ${\mathrm{fm}}^{-3}$ and $P_t=0.59\pm 0.05$ MeV ${\mathrm{fm}}^{-3}$. This approach crucially depends on experimental results for collective excitations in nuclei and, therefore, accurate measurements are necessary to further constrain the structure of the crust of neutron stars.

The ground states of ${}^{48}\mathrm{Cr},{}^{88}\mathrm{Ru}$, and ${}^{92}\mathrm{Pd}$ are studied in the $1f_{7/2}$ or $1g_{9/2}$ shell model with effective interactions from the literature. They are found to be composed, quite independently of the shell and the interaction, roughly of 75% of $(s,t)=(0,0)$ and 25% of $(s,t)=(4,0)$, where $s$ is the seniority and $t$ the reduced isospin. Other irreps of the symplectic group $\mathrm{Sp}(2j+1)$, where $j$ is the single-nucleon angular momentum, make only very small contributions. The state $\chi$ obtained by antisymmetrization and normalization of the ground state in the stretch scheme of Danos and Gillet [ and , Phys. Rev. 161, 1034 (1967)] has a very different structure where the $\mathrm{Sp}(2j+1)$ irreps other than $(s,t)=(0,0)$ and $(4,0)$ contribute 20% and 41% for $j=7/2$ and $9/2$, respectively. The contributions of $\chi$ and the $s=0$ state to the calculated states are about equal for ${}^{48}\mathrm{Cr}$. For ${}^{88}\mathrm{Ru}$ and ${}^{92}\mathrm{Pd}$ the $s=0$ state is unambigously a better approximation to the calculated states than $\chi$. A state ${\chi }^{\prime }$ obtained by antisymmetrization and normalization of the product of two stretch-scheme ground states of the system with two valence nucleons or nucleon holes of each type has much larger overlaps with the calculated ground states than $\chi$ but a deviating $\mathrm{Sp}(2j+1)$ decomposition.

The high excitation energy region, $E_x>15$ MeV, of ${}^{12}\mathrm{C}$ was probed using the ${}^{12}\mathrm{C}$$({}^3\mathrm{He},{}^3\mathrm{He})$$3\alpha$ reaction. The ${}^3\mathrm{He}$ nucleus was detected using a particle identification telescope and was used to reconstruct the excitation energy of ${}^{12}\mathrm{C}$. The $3\alpha$ decay of ${}^{12}\mathrm{C}$ was observed via the detection of two of the three final-state $\alpha$ particles in an array of two double-sided silicon strip detectors. The present analysis selected decays via ${}^8\mathrm{Be}$${}_{\mathrm{gs}}+\alpha$. Evidence is found for a series of states at 16.3(0.2), 17.2(0.2), 18.4(0.2), 19.7(0.2), 22.2(0.3), and 25.1(0.3) MeV.