Levels in ${}^{223}\mathrm{Th}$ populated by the $\alpha$ decay of ${}^{227}\mathrm{U}$ were investigated using $\alpha \text{−}\gamma$ decay spectroscopy. The ${}^{227}\mathrm{U}$ isotope was produced in the fusion-evaporation reaction ${}^{22}\mathrm{Ne}+{}^{208}\mathrm{Pb}$ at the velocity filter separator for heavy-ion reaction products at Gesellschaft für Schwerionenforschung in Darmstadt (Germany). Several new excited levels and $\gamma$ transitions were identified in ${}^{223}\mathrm{Th}$. An improved $\alpha$-decay scheme of ${}^{227}\mathrm{U}$ was suggested. The experimental $\alpha$-decay energy spectrum of ${}^{227}\mathrm{U}$ was compared with the Monte Carlo simulation performed using the toolkit geant4.

The spin dependent structure function, $g_2^{ww}$, is calculated in the valon model. A simple approach is given for the determination of the twist-3 part of $\overline{g_2}(x,Q^2)$ in Mellin space, thus enabling us to obtain the full transverse structure function $g_2(x,Q^2)$ for the proton, neutron, and deuteron. In light of the new data, we have further calculated the transversely polarized structure function of $g_2^{{}^3\mathrm{He}}(x,Q^2)$. Our results are checked against the experimental data and nice agreements are observed.

The theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The motion through the fission barrier is followed by a fast, nonadiabatic descent of the potential between the fragments. The latter stage is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained from the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the ${}^{258}\mathrm{Fm}$ nucleus are studied. The resulting fission fragment characteristics show good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle and quasiparticle picture is emphasized and qualitatively studied.

Arguments in favor of a light $\mathrm{\Xi }NN$ hypernucleus with $\left(I\right)J^P=(3/2)1/2^{+}$ are presented, within the uncertainties of our knowledge of the baryon-baryon strangeness $-2$ interactions. If bound, this $\mathrm{\Xi }NN$ state, being decoupled from the lowest $N\mathrm{\Lambda }\mathrm{\Lambda }$ system, would be stable. It will also benefit from additional binding due to the electromagnetic interaction what makes it worthwhile to look for. We show how the equivalent state with $J=3/2$ could never be bound in spite of the attractive interaction of the two-body subsystems. We illustrate our discussion with a full-fledged Faddeev calculation of the $\mathrm{\Xi }NN$ system using simple potentials that mimic more elaborate interactions. We also make contact with different recent phenomenological interactions from the literature, like the ESC08 Nijmegen potential or quark-model based potentials.

The rare $\beta$-decay channel of ${}^6\mathrm{He}$ into the $\alpha +d$ continuum was investigated at the REX-ISOLDE facility. Bunches of postaccelerated ${}^6\mathrm{He}$ ions were implanted into the optical time projection chamber (OTPC), where the decays with emission of charged particles were recorded. This novel technique allowed us to extend the low-energy end of the spectrum down to 150 keV in $\alpha +d$ center of mass, corresponding to a deuteron energy of 100 keV. The branching ratio for this process amounts to $[2.78\pm 0.07\left(\mathrm{stat}\right)\pm 0.17\left(\mathrm{sys}\right)]\times {10}^{-6}$. The shape of the spectrum is found to be in a good agreement with a three-body model, while the total intensity is about 20% larger than the predicted one.

The shell-model collective-pair truncation with negative-parity pairs is adopted to study the ${\left(h_{11/2}\right)}^2$ alignment in ${}^{132}\mathrm{Ba}$. The proton ${\left(h_{11/2}\right)}^2$-alignment state is predicted as an $E\sim 4.6$ MeV and $\tau \sim 0.5\mu \text{s}$ isomer with relatively strong $E3$ decay channels. The oblately deformed neutron ${\left(h_{11/2}\right)}^{-2}$ alignment in the yrast band and four negative-parity bands are confirmed, even though two of these negative-parity bands favor the prolate deformation, which directly manifests the $\gamma$ instability of ${}^{132}\mathrm{Ba}$.

Isoscalar giant resonances in ${}^{92,96,98,100}\mathrm{Mo}$ 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 was found for isoscalar $E0(107\%,105\%,103\%,\mathrm{and}110\%),E1(71\%,71\%,70\%,\mathrm{and}55\%),E2(73\%,69\%,85\%,\mathrm{and}79\%)$, and high-energy octupole $E3(52\%,65\%,61\%,\mathrm{and}53\%)$ resonances in ${}^{92,96,98,100}\mathrm{Mo}$, respectively. Spherical Hartree-Fock-based random-phase approximation calculations were performed for each multipole using the KDE0v1 Skyrme-type effective interaction, and the results are compared to the experimental distributions.

Background: A signature of many dynamical models of dark energy is that they admit variation in the fine structure constant $\alpha$ over cosmological time scales.

Purpose: We reconsider the analysis of the sensitivity of neutron resonance energies $E_i$ to changes in $\alpha$ with a view to resolving uncertainties that plague earlier treatments.

Methods: We point out that with more appropriate choices of nuclear parameters, the standard estimate (from Damour and Dyson) of the sensitivity for resonances in $\mathrm{Sm}$ is increased by a factor of 2.5. We go on to identify and compute excitation, Coulomb, and deformation corrections. To this end, we use deformed Fermi density distributions fitted to the output of Hartree-Fock (HF) + BCS calculations (with both the SLy4 and ${\mathrm{SkM}}^{*}$ Skyrme functionals), the energetics of the surface diffuseness of nuclei, and thermal properties of their deformation. We also invoke the eigenstate thermalization hypothesis, performing the requisite microcanonical averages with two phenomenological level densities which, via the leptodermous expansion of the level density parameter, include the effect of increased surface diffuseness. Theoretical uncertainties are assessed with the inter-model prescription of Dobaczewski et al. [J. Phys. G: Nucl. Part. Phys. 41, 074001 (2014)].

Results: The corrections diminish the revised $\mathrm{Sm}$ sensitivity but not by more than 25%. Subject to a weak and testable restriction on the change in $m_q/\mathrm{\Lambda }$ (relative to the change in $\alpha )$ since the time when the Oklo reactors were active $(m_q$ is the average of the $\text{u}$ and $\text{d}$ current quark masses, and $\mathrm{\Lambda }$ is the mass scale of quantum chromodynamics), we deduce that $|{\alpha }_{\text{Oklo}}-{\alpha }_{\text{now}}|<1.1\times {10}^{-8}{\alpha }_{\text{now}}$ (95% confidence level). The corresponding bound on the present-day time variation of $\alpha$ is tighter than the best limit to date from atomic clock experiments.

Conclusions: The order of magnitude of our Oklo bound on changes in $\alpha$ is reliable. It is one order of magnitude lower than the Oklo-based bound most commonly adopted in earlier attempts to identify phenomenologically successful models of $\alpha$ variation.

In an experiment at the A1900 spectrometer of the National Superconducting Cyclotron Laboratory at Michigan State University the new isotope ${}^{59}\mathrm{Ge}$ was identified and the cross section for production of the most neutron-deficient ${}^{59-62}\mathrm{Ge}$ isotopes in the fragmentation of a ${}^{78}\mathrm{Kr}$ beam at 150 MeV/nucleon measured. This experimental information is relevant for the hunt of new two-proton emitters in the region above the doubly-magic ${}^{48}\mathrm{Ni}$.

Heavy ion collisions at the BNL Relativistic Heavy Ion Collider produce direct photons at low transverse momentum $p_T$ from 1–3 $\mathrm{GeV}/c$, in excess of the $p+p$ spectra scaled by the nuclear overlap factor $T_{AA}$. These low-$p_T$ photons have a large azimuthal anisotropy $v_2$. Theoretical models, including hydrodynamic models, struggle to quantitatively reproduce the large low-$p_T$ direct photon excess and $v_2$ in a self-consistent manner. This paper presents a description of the low-$p_T$ photon flow as the result of increased photon production from soft-gluon-mediated $q-\overline{q}$ interactions as the system becomes color neutral. This production mechanism will generate photons that follow constituent quark number, $n_q$, scaling of $v_2$ with an $n_q$ value of 2 for direct photons. ${\chi }^2$ comparisons of the published PHENIX direct photon and identified particle $v_2$ measurements finds that $n_q$ scaling applied to the direct photon $v_2$ data prefers the value $n_q=1.8$ and agrees with $n_q=2$ within errors in most cases. The 0–20% and 20–40% Au+Au direct photon data are compared to a coalescence-like Monte Carlo simulation that calculates the direct photon $v_2$ while describing the shape of the direct photon $p_T$ spectra in a consistent manner. The simulation, while systematically low compared to the data, is in agreement with the Au+Au measurement at $p_T$ less than 3 $\mathrm{GeV}/c$ in both centrality bins. Furthermore, this production mechanism predicts that higher order flow harmonics $v_n$ in direct photons will follow the modified $n_q$-scaling laws seen in identified hadron $v_n$ with an $n_q$ value of 2.

In this work I develop a new framework for anisotropic hydrodynamics that generalizes the leading order of the hydrodynamic expansion to the full (3 + 1)-dimensional anisotropic massive case. Following previous works, my considerations are based on the Boltzmann kinetic equation with the collisional term treated in the relaxation time approximation. The momentum anisotropy is included explicitly in the leading term, allowing for a large difference between the longitudinal and transverse pressures as well as for nontrivial transverse dynamics. Energy and momentum conservation is expressed by the first moment of the Boltzmann equation. The system of equations is closed by using the zeroth and second moments of the Boltzmann equation. The close-to-equilibrium matching with second-order viscous hydrodynamics is demonstrated. In particular, I show that the coupling between shear and bulk pressure corrections, recently proved to be important for an accurate description of momentum anisotropy and bulk viscous dynamics, does not vanish in the close-to-equilibrium limit.

Background: Fifty percent of the heavy element abundances are produced via slow neutron capture reactions in different stellar scenarios. The underlying nucleosynthesis models need the input of neutron capture cross sections.

Purpose: One of the fundamental signatures for active nucleosynthesis in our galaxy is the observation of long-lived radioactive isotopes, such as ${}^{60}\mathrm{Fe}$ with a half-life of $2.60\times {10}^6$ yr. To reproduce this $\gamma$ activity in the universe, the nucleosynthesis of ${}^{60}\mathrm{Fe}$ has to be understood reliably.

Methods: An ${}^{60}\mathrm{Fe}$ sample produced at the Paul Scherrer Institut (Villigen, Switzerland) was activated with thermal and epithermal neutrons at the research reactor at the Johannes Gutenberg-Universität Mainz (Mainz, Germany).

Results: The thermal neutron capture cross section has been measured for the first time to ${\sigma }_{\text{th}}=0.226{(}_{-0.049}^{+0.044})\text{b}$. An upper limit of ${\sigma }_{\text{RI}}<0.50\text{b}$ could be determined for the resonance integral.

Conclusions: An extrapolation towards the astrophysically interesting energy regime between $kT=10$ and 100 keV illustrates that the $s$-wave part of the direct capture component can be neglected.

Elastic electromagnetic form factors for the ${\rho }^{+}$ meson are calculated in a Nambu–Jona-Lasinio model which incorporates quark confinement through the use of the proper-time regularization scheme. A comparison is made with recent lattice QCD results and previous quark model calculations for static quantities and the Sachs form factors. The results are qualitatively in good agreement with the lattice QCD calculations, with the exception of the quadrupole moment and corresponding form factor, which may be related to a lack of spherical symmetry on the lattice.

Background: Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering $NN\nu \overline{\nu }$ ($nn\nu \overline{\nu },pp\nu \overline{\nu }$, and $np\nu \overline{\nu }$) have recently attracted attention in studies of neutrino emission in neutron stars, because of the implications for the neutron star cooling. The calculated $NN\nu \overline{\nu }$ emissivities within the neutron star environment are relatively insensitive to the two-nucleon dynamical model used in the calculations, but differ significantly from those obtained using an one-pion-exchange (OPE) model.

Purpose: We investigate the free $NN\nu \overline{\nu }$ cross sections using a realistic nucleon-nucleon scattering amplitude, comparing the relative sizes of the cross sections for the three processes $nn\nu \overline{\nu },pp\nu \overline{\nu }$, and $np\nu \overline{\nu }$.

Method: We employ a realistic one-boson-exchange (ROBE) model for $NN$ scattering and combine those strong scattering amplitudes with the well-known nucleon weak interaction vertices to construct weak bremsstrahlung amplitudes. Using the resulting $NN\nu \overline{\nu }$ amplitudes we investigate the relative importance of the vector $\left({\mathrm{\Gamma }}_V^{\mu }\right)$, axial vector $\left({\mathrm{\Gamma }}_A^{\mu }\right)$, and tensor $\left({\mathrm{\Gamma }}_T^{\mu }\right)$ terms. The ROBE model bremsstrahlung amplitudes are also used as a two-nucleon dynamical model with which we calculate the cross sections $\frac{d\sigma }{d\omega }$ for $nn\nu \overline{\nu },pp\nu \overline{\nu }$, and $np\nu \overline{\nu }$.

Results: The three free $NN\nu \overline{\nu }$ cross sections $\frac{d\sigma }{d\omega }$ are of similar order of magnitude. Each increases with increasing neutrino-pair energy $\omega$. For the neutrino-pair energy of $\omega =1\mathrm{MeV}$ our $nn\nu \overline{\nu }$ results are in quantitative agreement with those previously reported by Timmermans et al. [Phys. Rev. C 65, 064007 (2002)], who used the leading-order term of the soft-neutrino-pair bremsstrahlung amplitude to calculate the cross sections. Differences between the $nn\nu \overline{\nu }$ and $pp\nu \overline{\nu }$ cross section are not discernible over the nucleon-nucleon incident energy region considered, due to the complete dominance of the axial vector component of the weak interaction nucleon vertex function ${\mathrm{\Gamma }}^{\mu }$ as demonstrated analytically in Appendix A. The $np\nu \overline{\nu }$ cross section is smaller than either the $nn\nu \overline{\nu }$ or the $pp\nu \overline{\nu }$ cross section for low to moderate values of $\omega$; this characteristic only changes at larger neutrino-pair energies around $\omega \sim 50\mathrm{MeV}$, which is above the low energy region characterized in Appendix B.

Conclusions: The free $NN\nu \overline{\nu }$ cross sections, calculated using a realistic nucleon-nucleon amplitude model, are new except for the $nn\nu \overline{\nu }$ cross section at $\omega =1\mathrm{MeV}$ that was first reported by Timmermans et al., and at $\omega =0.5,1,2\mathrm{MeV}$ by Li et al. [Phys. Rev. C 80, 035505 (2009)]. The $nn\nu \overline{\nu }$ and $pp\nu \overline{\nu }$ cross sections are virtually identical in magnitude. All three $NN\nu \overline{\nu }$ processes are dominated by the axial vector component of the vertex function ${\mathrm{\Gamma }}^{\mu }$, with only slight deviations from this behavior being seen in the $np\nu \overline{\nu }$ process at large neutrino-pair energies.

Background: The stable nucleus ${}^{15}\mathrm{N}$ is the mirror of ${}^{15}\mathrm{O}$, the bottleneck in the hydrogen burning CNO cycle. Most of the ${}^{15}\mathrm{N}$ level widths below the proton emission threshold are known from just one nuclear resonance fluorescence (NRF) measurement, with limited precision in some cases. A recent experiment with the AGATA demonstrator array determined level lifetimes using the Doppler shift attenuation method in ${}^{15}\mathrm{O}$. As a reference and for testing the method, level lifetimes in ${}^{15}\mathrm{N}$ have also been determined in the same experiment.

Purpose: The latest compilation of ${}^{15}\mathrm{N}$ level properties dates back to 1991. The limited precision in some cases in the compilation calls for a new measurement to enable a comparison to the AGATA demonstrator data. The widths of several ${}^{15}\mathrm{N}$ levels have been studied with the NRF method.

Method: The solid nitrogen compounds enriched in ${}^{15}\mathrm{N}$ have been irradiated with bremsstrahlung. The $\gamma$ rays following the deexcitation of the excited nuclear levels were detected with four high-purity germanium detectors.

Results: Integrated photon-scattering cross sections of 10 levels below the proton emission threshold have been measured. Partial $\gamma$-ray widths of ground-state transitions were deduced and compared to the literature. The photon-scattering cross sections of two levels above the proton emission threshold, but still below other particle emission energies have also been measured, and proton resonance strengths and proton widths were deduced.

Conclusions: Gamma and proton widths consistent with the literature values were obtained, but with greatly improved precision.

A systematic study on $\alpha$-decay fine structure is presented for even-even nuclei in the range $78\le Z\le 102$. The penetration probability is obtained from the WKB approximation in combination with the Bohr-Sommerfeld quantization condition. The potential barrier is numerically constructed in the well-established double-folding model for both Coulomb and nuclear potentials. A realistic M3Y interaction, based on the $G$-matrix elements of the Paris $NN$ potential, has been used in the folding calculation. The local approximation for the nondiagonal one-body density matrix in the calculation of the exchange potential was included by using the harmonic oscillator representation of the nondiagonal density matrix of the $\alpha$ particle. The computed partial half-lives and branching ratios are compared with the recent experimental data and they are in good agreement.

${}^{240}\mathrm{Pu}$ has recently been pointed out by a sensitivity study of the Organization for Economic Cooperation and Development (OECD) Nuclear Energy Agency (NEA) to be one of the isotopes whose fission cross section lacks accuracy to meet the upcoming needs for the future generation of nuclear power plants (GEN-IV). In the High Priority Request List (HPRL) of the OECD, it is suggested that the knowledge of the ${}^{240}\mathrm{Pu}(n,f)$ cross section should be improved to an accuracy within 1–3 %, compared to the present 5%. A measurement of the ${}^{240}\mathrm{Pu}$ cross section has been performed at the Van de Graaff accelerator of the Joint Research Center (JRC) Institute for Reference Materials and Measurements (IRMM) using quasi-monoenergetic neutrons in the energy range from 0.5 MeV to 3 MeV. A twin Frisch-grid ionization chamber (TFGIC) has been used in a back-to-back configuration as fission fragment detector. The ${}^{240}\mathrm{Pu}(n,f)$ cross section has been normalized to three different isotopes: ${}^{237}\mathrm{Np}(n,f)$, ${}^{235}\mathrm{U}(n,f)$, and ${}^{238}\mathrm{U}(n,f)$. Additionally, the secondary standard reactions were benchmarked through measurements against the primary standard reaction ${}^{235}\mathrm{U}(n,f)$ in the same geometry. A comprehensive study of the corrections applied to the data and the associated uncertainties is given. The results obtained are in agreement with previous experimental data at the threshold region. For neutron energies higher than 1 MeV, the results of this experiment are slightly lower than the ENDF/B-VII.1 evaluation, but in agreement with the experiments of Laptev et al. (2004) as well as Staples and Morley (1998).

The coherent $\eta$-meson energy $E_{\eta }$ distribution spectra in proton nucleus reactions have been calculated to investigate the ${\pi }^0–\eta$ mesons' interference, in addition to the study of resonance $N^{*}$ dynamics in the nucleus. The elementary reaction occurring in the nucleus is assumed to proceed as $pN\to p{N}^{*}$; $N^{*}\to N\eta$. Born terms in the intermediate state are also considered. In a scalar-isovector nucleus, this reaction occurs because of ${\pi }^0$- and $\eta$-meson exchange interactions for the forward going proton and the $\eta$ meson; other meson exchange potentials do not contribute to this process. The sensitivity of the cross section to the hadron nucleus interactions and the beam energy dependence of the cross section are studied for this reaction.