Recent measurements of resonance widths for low-energy neutron scattering off heavy nuclei show large deviations from the Porter-Thomas distribution. We propose a “standard” width distribution based on the random matrix theory for a chaotic quantum system with a single open decay channel. Two methods of derivation lead to a single analytical expression that recovers, in the limit of very weak continuum coupling, the Porter-Thomas distribution. The parameter defining the result is the ratio of typical widths $\Gamma$ to the energy level spacing $D$. Compared to the Porter-Thomas distribution, the new distribution suppresses small widths and increases the probabilities of larger widths. We show also that it is necessary to take into account the $\gamma$ channels.

Gamow-Teller (GT) strength distributions have been investigated in a high-resolution (${}^3$He,$t$) charge-exchange experiment on the double-$\beta$ ($\beta \beta$ ) decaying nuclei ${}^{128}$Te and ${}^{130}$Te. The experiment was carried out at the Research Center for Nuclear Physics, Osaka, with a 420-MeV incident ${}^3$He beam and the Grand Raiden magnetic spectrometer. A final-state energy resolution of 35 keV was achieved. The extracted GT strength distributions at low excitation energies in the final nuclei ${}^{128}$I and ${}^{130}$I are presented and discussed in the context of the $\beta \beta$ decay matrix elements for the two tellurium nuclei. The additional neutron pair in ${}^{130}$Te seems to produce a moderate increase in the fragmentation of the low-energy GT distribution.

${}^{184}$Os has been excluded as a promising candidate for the search of neutrinoless double-electron capture. High-precision mass measurements with the Penning-trap mass spectrometer TRIGA-TRAP result in a marginal resonant enhancement with $\Delta =-8.89\left(58\right)$ keV excess energy to the 1322.152(22) keV $0^{+}$ excited state in ${}^{184}$W. State-of-the-art energy density functional calculations are applied for the evaluation of the nuclear matrix elements to the excited states predicting a strong suppression due to the large deformation of mother and daughter states. The half-life of the transition exceeds $T_{1/2}{(}^{184}\mathrm{Os})\ge 1.3\times {10}^{29}$ yr for an effective neutrino mass of 1 eV.

The nuclear Schiff moment creates a mechanism of transfer of the violation of parity and time-reversal invariance by weak interaction in nuclei into the atomic electric dipole moment. We point out an additional contribution to the Schiff moment generated by the mixing of single-particle states through the low-lying nuclear dipole resonances. An estimate shows that this contribution is by order of magnitude comparable to single-particle contributions and can be enhanced if the low-lying resonance has collective nature.

The role of proton shell effects in the structure of the $N=28$ isotones ${}^{45}$Cl and ${}^{44}$S has been studied via one-proton knockout from ${}^{45}$Cl. We compare measured $\gamma$-ray intensities, inclusive and partial knockout cross sections, and the inclusive momentum distribution of outgoing ${}^{44}$S particles with shell-model and reaction-theory predictions. The strong population in this reaction of the recently identified $4_1^{+}$ state in ${}^{44}$S, identified through its subsequent $\gamma$-ray decay energy, makes a compelling case for a $J^{\pi }=3/2^{+}$ ground state in ${}^{45}$Cl.

The high spin states of ${}^{106}$Pd have been investigated with in-beam $\gamma$-ray spectroscopic methods using the ${}^{100}$Mo(${}^{11}\text{B},1p4n$)${}^{106}$Pd reaction at a beam energy of 60 MeV. All earlier known bands were extended considerably and additional bands were identified. The configurations of these bands are discussed on the basis of the experimental aligned angular momenta and total Routhian surface calculations. Both two-quasineutron and two-quasiproton structures have been found in ${}^{106}$Pd. The nonyrast low-lying positive-parity band was interpreted as a $\gamma$-vibrational band.

We consider nucleon-nucleon interactions from chiral effective field theory applying the $N/D$ method. The case of coupled partial waves is treated, extending Albaladejo and Oller [Phys. Rev. C 84, 054009 (2011)], where the uncoupled case was studied. As a result, three $N/D$ elastic-like equations have to be solved for every set of three independent coupled partial waves. As in the previous reference the input for this method is the discontinuity along the left-hand cut of the nucleon-nucleon partial wave amplitudes. It can be calculated perturbatively in chiral perturbation theory because it involves only irreducible two-nucleon intermediate states. We apply our method to the leading-order result consisting of one-pion exchange as the source for the discontinuity along the left-hand cut. The linear integral equations for the $N/D$ method must be solved in the presence of $\ell -1$ constraints, with $\ell$ the orbital angular momentum, in order to satisfy the proper threshold behavior for $\ell ⩾2$. We dedicate special attention to satisfy the requirements of unitarity in coupled channels. We also focus on the specific issue of the deuteron pole position in ${}^3{S}_1{-}^3{D}_1$ scattering. Our final amplitudes are based on dispersion relations and chiral effective field theory, involving only convergent integrals. They are amenable to a systematic improvement order by order in the chiral expansion.

Background: Alpha emission from a nucleus is a fundamental decay process in which the alpha particle formed inside the nucleus tunnels out through the potential barrier.

Purpose: We describe alpha decay of ${}^{212}$Po and ${}^{104}$Te by means of the configuration interaction approach.

Method: To compute the preformation factor and penetrability, we use the complex-energy shell model with a separable $T=1$ interaction. The single-particle space is expanded in a Woods-Saxon basis that consists of bound and unbound resonant states. Special attention is paid to the treatment of the norm kernel appearing in the definition of the formation amplitude that guarantees the normalization of the channel function.

Results: Without explicitly considering the alpha-cluster component in the wave function of the parent nucleus, we reproduce the experimental alpha-decay width of ${}^{212}$Po and predict an upper limit of $T_{1/2}=5.5\times {10}^{-7}$ sec for the half-life of ${}^{104}$Te.

Conclusions: The complex-energy shell model in a large valence configuration space is capable of providing a microscopic description of the alpha decay of heavy nuclei having two valence protons and two valence neutrons outside the doubly magic core. The inclusion of proton-neutron interaction between the valence nucleons is likely to shorten the predicted half-live of ${}^{104}$Te.

The level scheme of the neutron-deficient nucleus ${}^{95}$Pd has been studied with the ${}^{58}$Ni + ${}^{40}$Ca fusion-evaporation reaction at 135 MeV with the GASP $\gamma$-ray array, the ISIS silicon ball, and the N-ring neutron detector. Excited levels with spins at least up to $\frac{45}{2}\hslash$ are reported for both parities. The observed experimental data are compared to large-scale shell-model calculations.

The activation method has been used to measure the cross sections for radiative capture of neutrons by all isotopes of stable Ce (mass numbers 136, 138, 140, and 142). Both the thermal cross sections and the resonance integrals have been determined from separate irradiations with thermal and epithermal neutrons, wherever possible cross-checking results from different irradiation facilities with different flux distributions. Because determination of precise cross sections by activation requires equally precise values of the decay half-lives, we have remeasured decay half-lives of ${}^{137}$Ce${}^g$, ${}^{137}$Ce${}^m$, ${}^{139}$Ce${}^m$, ${}^{141}$Ce, and ${}^{143}$Ce. Improved values for the energies and intensities of the γ rays in the decays of ${}^{137}$Ce${}^g$ and ${}^{137}$Ce${}^m$ have also been determined, along with corresponding values for the β-decay feedings and energies of excited states in ${}^{137}$La.

We study the evolution of the equation of state of a strongly interacting quark system as a function of the diquark interaction strength. We show that for the system to avoid collapsing into a pressureless boson gas at sufficiently strong diquark coupling strength, the diquark-diquark repulsion has to be self-consistently taken into account. In particular, we find that the tendency at zero temperature of the strongly interacting diquark gas to condense into the system ground state is compensated by the repulsion between diquarks if the diquark-diquark coupling constant is higher than a critical value ${\lambda }_C=7.65$. Considering such diquark-diquark repulsion, a positive pressure with no significant variation along the whole strongly interacting region is obtained. A consequence of the diquark-diquark repulsion is that the system maintains its BCS character in the whole strongly interacting region.

The interplay between the collective dynamics of the quadrupole and octupole deformation degree of freedom is discussed in a series of Sm and Gd isotopes both at the mean-field level and beyond, including parity symmetry restoration and configuration mixing. Physical properties such as negative-parity excitation energies and $E1$ and $E3$ transition probabilities are discussed and compared to experimental data. Other relevant intrinsic quantities such as dipole moments, ground-state quadrupole moments or correlation energies associated with symmetry restoration and configuration mixing are discussed. For the considered isotopes, the quadrupole-octupole coupling is found to be weak and most of the properties of negative-parity states can be described in terms of the octupole degree of freedom alone.

The excited levels of ${}^{115}$Ag have been studied via the beta decay of ${}^{115}$Pd and ${}^{115}$Pd${}^m$. The beta-decay schemes for both states have been considerably extended, especially the scheme following the decay of ${}^{115}$Pd${}^m$ which was practically unknown before this work. Transition intensities and ${\log }_{10}ft$ values are reported, which have been missing in the literature. A set of levels around 2 MeV has been found to be strongly populated by the beta decay of the ground state of ${}^{115}$Pd and is suggested to have a three-quasiparticle nature. The properties of excited levels have been compared with the level systematics of lighter neutron-rich silver isotopes, and new spin assignments as well as identification of Nilsson states in ${}^{115}$Ag have been made.

Analysis shows that directed neutrino beams could be generated by using electron-capture β-decay sources, and the requirements for the magnetic field and temperature are discussed. The recoil forces produced by ${}^{119}$Sb and ${}^{57}$Co sources are estimated, and it is shown that the neutrino emissions from a ${}^{119}$Sb source could be detected using an atomic force microscope.

In this work the roles of the nucleon resonances in the $\Lambda$(1520) photoproduction off a proton target are investigated within the effective Lagrangian method. Besides the Born terms, including the contact term and $s$, $u$, and $K$ exchanged $t$ channels, the vector meson $K^{*}$ exchanged $t$ channel is considered in our investigation, which is negligible at low energy and important at high energy. The important nucleon resonances predicted by the constituent quark model (CQM) are considered and the results are found to be well comparable with the experimental data. Besides the dominant $D_{13}\left(2080\right)$, the resonance ${\left[{\frac{5}{2}}^{-}\right]}_2\left(2080\right)$ predicted by the CQM is found to be important for reproducing the experimental data. Other nucleon resonances are found to give small contributions in the channel considered in this work. With all important nucleon resonances predicted by the CQM, the prediction of the differential cross section at an energy up to $5.5$ GeV is presented also; this can be checked by future CLAS experimental data.

We investigate projectile breakup effects on ${}^6\mathrm{Li}+{}^{209}\mathrm{Bi}$ elastic scattering near the Coulomb barrier with the four-body version of the continuum-discretized coupled-channels method (four-body CDCC). The elastic scattering is well described by the $p$ $+$ $n$ $+$ ${}^4$He $+$ ${}^{209}$Bi four-body model. Furthermore, we propose a reasonable $d$ $+$ ${}^4$He $+$ ${}^{209}$Bi three-body model for describing the four-body scattering, clarifying four-body dynamics of the elastic scattering.

Starting from the adiabatic time-dependent Hartree-Fock approximation (ATDHF), we propose an efficient method to calculate the Thouless-Valatin moments of inertia for the nuclear system. The method is based on the rapid convergence of the expansion of the inertia matrix. The accuracy of the proposed method is verified in the rotational case by comparing the results with the exact Thouless-Valatin moments of inertia calculated using the self-consistent cranking model. The proposed method is computationally much more efficient than the full ATDHF calculation, yet it retains a high accuracy of the order of $1\%$.

A theoretical approach based on a deformed quasiparticle random phase approximation built on a Skyrme self-consistent mean field is used to describe the recent measurements of the Gamow-Teller GT${}^{-}$ strength distribution extracted from the charge-exchange reaction ${}^{76}$Ge(${}^3$He${,t)}^{76}$As with high energy resolution. The same analysis is made to describe the Gamow-Teller GT${}^{+}$ strength distribution measured in the ${}^{76}$Se$(d{,}^2$He)${}^{76}$As reaction. Combining these two branches, the nuclear matrix element for the two-neutrino double-$\beta$ decay process is evaluated and compared to experiment. The role of the nuclear deformation on those processes is emphasized and analyzed.

The decay of the hot and rotating compound nucleus ${}^{241}$Pu${}^{*}$ formed in the reaction ${}^9$Be + ${}^{232}$Th around the Coulomb barrier ($\approx$42.16 MeV), at energies ranging from 37 to 48 MeV, is studied using the dynamical cluster-decay model (DCM) with the effects of static and dynamic deformations included. With the inclusion of dynamical deformations both the preformation probability $P_0$ and the tunneling probability $P$, and hence the cross sections, change considerably. The only parameter of the model, namely, the neck-length parameter, varies smoothly with excitation energy or temperature of the system both at above- and below-barrier energies, whose value depends strongly on the limiting angular momentum, which in turn depends on the sticking and nonsticking moments of inertia. The relative effect of static and dynamic deformations on the neck-length parameter $\Delta R$ is also studied which indicates the reaction time scale for both static and dynamic choices of deformation. In addition, the exclusive role of angular momentum and “barrier modification” effects at sub-barrier energies are also addressed. Although calculated anisotropies are consistent with the results of Appannababu et al. [Phys. Rev. C 83, 067601 (2011)], no significant contribution of a noncompound nucleus in the form of incomplete fusion is seen on the basis of DCM calculations.

Employing the quantum diffusion approach, the behaviors of the capture cross section, mean square angular momentum, astrophysical $S$ factor, logarithmic slope of the excitation function, and barrier distribution have been determined for the recently measured reactions ${}^{58}$Ni + ${}^{54}$Fe and ${}^{40}$Ca + ${}^{40}$Ca at deep subbarrier energies. The calculated results for the reactions ${}^{58}$Ni + ${}^{54}$Fe, ${}^{58}$Ni + ${}^{58,60,64}$Ni, ${}^{40}$Ca + ${}^{40}$Ca, ${}^{60}$Ni + ${}^{89}$Y, and ${}^{32,36}$S, and ${}^{40,48}$Ca + ${}^{90,96}$Zr are in a good agreement with the existing experimental data.