The search for an electric dipole moment (EDM) of the neutron is a crucial test for theoretical particle physics models with violation of time and spatial invariance. A new experiment recently has been carried out at the High-Flux Reactor at Institut Laue-Langevin, using the upgraded double-chamber magnetic resonance spectrometer developed at Petersburg Nuclear Physics Institute. The result is interpreted as an upper limit on the value of the neutron EDM, $|d_n|<5.5\times {10}^{-26}{e}_{}\mathrm{cm}$ (90% C.L.). This article provides a detailed description of the setup and experimental procedures, along with a discussion of possibilities for further improvement of the experimental accuracy.

Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient ${}^{196,198,200,202}\mathrm{Po}$ isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, ${}^{200,202}\mathrm{Po}$, the transitional and diagonal matrix elements of the $2_1^{+}$ state are determined. In ${}^{196,198}\mathrm{Po}$ multistep Coulomb excitation is observed, populating the $4_1^{+},0_2^{+}$, and $2_2^{+}$ states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from ${}^{196}\mathrm{Po}$ onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.

The effect of the production mechanism on the decay of a compound nucleus is investigated. The nucleus ${}^{90}\mathrm{Zr}$ was produced by three different reactions, namely ${}^{90}\mathrm{Zr}(p,p^{\prime }){}^{90}\mathrm{Zr}$, ${}^{91}\mathrm{Zr}(p,d){}^{90}\mathrm{Zr}$, and ${}^{92}\mathrm{Zr}(p,t){}^{90}\mathrm{Zr}$, which served as surrogate reactions for ${}^{89}\mathrm{Zr}(n,\gamma )$. The spin-parity $\left(J^{\pi }\right)$ distributions of the states populated by these reactions were studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as ${}^{89}\mathrm{Zr}$. Discrete $\gamma$ rays, associated with transitions in ${}^{90}\mathrm{Zr}$ and ${}^{89}\mathrm{Zr}$, were measured in coincidence with light ions for scattering angles of ${25}^{\circ }–{60}^{\circ }$ and ${}^{90}\mathrm{Zr}$ excitation energies extending above the neutron separation energy. The measured transition systematics were used to gain insights into the $J^{\pi }$ distributions of ${}^{90}\mathrm{Zr}$. The ${}^{90}\mathrm{Zr}(p,p^{\prime })$ reaction was found to produce fewer $\gamma$ rays associated with transitions involving high spin states $\left(J=6–8\hslash \right)$ than the other two reactions, suggesting that inelastic scattering preferentially populates states in ${}^{90}\mathrm{Zr}$ that have lower spins than those populated in the transfer reactions investigated. The $\gamma$-ray production was also observed to vary by factors of 2–3 with the angle at which the outgoing particle was detected. These findings are relevant to the application of the surrogate reaction approach.

The extension of the Majorana neutrino mass mechanism of the neutrinoless double-beta decay $\left(0\nu \beta \beta \right)$ with the inclusion of right-handed leptonic and hadronic currents is revisited. While only the exchange of light neutrinos is assumed, the $s_{1/2}$ and $p_{1/2}$ states of emitted electrons as well as recoil corrections to the nucleon currents are taken into account. Within the standard approximations the decay rate is factorized into a sum of products of kinematical phase-space factors, nuclear matrix elements, and the fundamental parameters that characterize the lepton number violation. Unlike in the previous treatments, the induced pseudoscalar term of hadron current is included, resulting in additional nuclear matrix elements. An improved numerical computation of the phase-space factors is presented, based on the exact Dirac wave functions of the $s_{1/2}$ and $p_{1/2}$ electrons with finite nuclear size and electron screening taken into account. The dependence of values of these phase-space factors on the different approximation schemes used in evaluation of electron wave functions is discussed. The upper limits for effective neutrino mass and the parameters $\langle \lambda \rangle$ and $\langle \eta \rangle$ characterizing the right-handed current mechanism are deduced from data on the $0\nu \beta \beta$ decay of ${}^{76}\text{Ge}$ and ${}^{136}\text{Xe}$ using nuclear matrix elements calculated within the nuclear shell model and quasiparticle random phase approximation. The differential decay rates, i.e., the angular correlations and the single electron energy distributions for various combinations of the total lepton number violating parameters that can help to disentangle the possible mechanism, are described and discussed.

Light clusters (mass number $A\le 4$) in nuclear matter at subsaturation densities are described using a quantum statistical approach to calculate the quasiparticle properties and abundances of light elements. I review the formalism and approximations used and extend it with respect to the treatment of continuum correlations. Virial coefficients are derived from continuum contributions to the partial densities which depend on temperature, densities, and total momentum. The Pauli blocking is modified taking correlations in the medium into account. Both effects of continuum correlations lead to an enhancement of cluster abundances in nuclear matter at higher densities. Based on calculations for $A=2$, estimates for the contributions with $A=3,4$ are given. The properties of light clusters and continuum correlations in dense matter are of interest for nuclear structure calculations, heavy-ion collisions, and astrophysical applications such as the formation of neutron stars in core-collapse supernovae.

Elastic scattering angular distributions for the weakly bound nucleus ${}^7\mathrm{Li}$ on ${}^{64}\mathrm{Zn}$ have been measured in a wide angular range at energies around the Coulomb barrier. The present experimental data and our previously measured elastic scattering data for the system ${}^6\mathrm{Li}+{}^{64}\mathrm{Zn}$ have been analyzed within the continuum-discretized coupled-channels method, where the resonant and nonresonant states of the projectile are taken into account. In this theoretical framework, we have also analyzed our previously measured excitation functions of elastic scattering at backward angles and the corresponding barrier distributions for the same systems. A good agreement between the experimental data and the calculations has been observed. The obtained results, besides confirming the importance of the coupling to the breakup channels in collisions with weakly bound nuclei, show that, in the case of ${}^6\mathrm{Li}$, the inclusion of the resonant states of the projectile produces non-negligible effects.

We present final results on the photon electroproduction $\left(\vec{e}p\to ep\gamma \right)$ cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region from Jefferson Lab experiment E00-110. Results from an analysis of a subset of these data were published before, but the analysis has been improved, which is described here at length, together with details on the experimental setup. Furthermore, additional data have been analyzed, resulting in photon electroproduction cross sections at new kinematic settings for a total of 588 experimental bins. Results of the $Q^2$ and $x_B$ dependencies of both the helicity-dependent and the helicity-independent cross sections are discussed. The $Q^2$ dependence illustrates the dominance of the twist-2 handbag amplitude in the kinematics of the experiment, as previously noted. Thanks to the excellent accuracy of this high-luminosity experiment, it becomes clear that the unpolarized cross section shows a significant deviation from the Bethe-Heitler process in our kinematics, compatible with a large contribution from the leading twist-2 ${\mathrm{DVCS}}^2$ term to the photon electroproduction cross section. The necessity to include higher-twist corrections to fully reproduce the shape of the data is also discussed. The DVCS cross sections in this paper represent the final set of experimental results from E00-110, superseding the previous publication.

The rigorous treatment of proton localization phenomenon in asymmetric nuclear matter is presented. The solution of proton wave function and neutron background distribution is found by the use of the extended Thomas-Fermi approach. The minimum of energy is obtained in the Wigner-Seitz approximation of a spherically symmetric cell. The analysis of four different nuclear models suggests that the proton localization is likely to take place in the interior of a neutron star.

Cross sections for the production of shell-stabilized evaporation residues in the ${}^{50}\mathrm{Ti}+{}^{160}\text{Gd}, {}^{159}\mathrm{Tb}, {}^{162}\mathrm{Dy}$, and ${}^{54}\mathrm{Cr}+{}^{162}\text{Dy}$ reactions are reported. The compound nucleus excitation energy range considered principally covers the $4n$ evaporation channel with segments of the $3n$ and $5n$ channels also measured. The resultant production cross sections are for nuclides with $Z=86-90$. From an analysis based on a statistical model, it is concluded that a larger fission probability than that predicted by the Bohr-Wheeler transition-state theory is needed to describe the data. This outcome is attributed to the influence of collective nuclear excitations. Subsequently, the expected stability enhancement against fission due to the influence of the magic $N=126$ shell is not evident. The $xn$ excitation functions measured in previous experiments in the reactions ${}^{48}\mathrm{Ca}+{}^{154}\text{Gd}, {}^{159}\mathrm{Tb},{}^{162}\text{Dy}$, and ${}^{165}\mathrm{Ho}$ are combined with the present data for $Z>20$ projectiles to illustrate systematic behavior of measured cross sections as a function of the difference in fission barrier and neutron separation energy.

We present the final results for the deuteron spin structure functions obtained from the full data set collected in 2000–2001 with Jefferson Lab's continuous electron beam accelerator facility (CEBAF) using the CEBAF large acceptance spectrometer (CLAS). Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.8 GeV were scattered from deuteron (${}^{15}{\mathrm{ND}}_3$) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double-spin asymmetry, the virtual photon absorption asymmetry $A_1^d$ and the polarized structure function $g_1^d$ were extracted over a wide kinematic range ($0.05{\mathrm{GeV}}^2<Q^2<5{\mathrm{GeV}}^2$ and $0.9\text{GeV}<W<3\text{GeV}$). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions $A_1^n$ and $g_1^n$ of the (bound) neutron, which are so far unknown in the resonance region, $W<2$ GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations, as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large $x$, a better understanding of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the operator product expansion.

The recently proposed effective shell-model interaction, the pairing-plus-multipole Hamiltonian with the monopole interaction obtained by empirical fits starting from the monopole-based universal force (PMMU), is systematically applied to nuclei of the $p{f}_{5/2}{g}_{9/2}$ shell region. It is demonstrated that the calculation describes reasonably well a wide range of experimental data, including not only the low-lying and high-excitation spectra, $E2$ transitions, quadrupole moments, and magnetic moments, but also the binding energies, for Ni, Cu, Zn, Ga, Ge, As, and Se isotopes with $A=64–80$. In particular, a structure of the neutron-rich Ge and Se isotopes is discussed in detail.

The interaction between nuclei and a strong zeptosecond laser pulse with coherent MeV photons is investigated theoretically. We provide a first semiquantitative study of the quasi-adiabatic regime where the photon absorption rate is comparable to the nuclear equilibration rate. In that regime, multiple photon absorption leads to the formation of a compound nucleus in the so-far unexplored regime of excitation energies several hundred MeV above the yrast line. The temporal dynamics of the process is investigated by means of a set of master equations that account for dipole absorption, stimulated dipole emission, neutron decay, and induced fission in a chain of nuclei. That set is solved numerically by means of state-of-the-art matrix exponential methods also used in nuclear fuel burn-up and radioactivity transport calculations. Our quantitative estimates predict the excitation path and range of nuclei reached by neutron decay and provide relevant information for the layout of future experiments.

The ATLAS Collaboration measures the inclusive production of $Z$ bosons via their decays into electron and muon pairs in $p+\mathrm{Pb}$ collisions at $\sqrt{s_{\mathit{NN}}}=5.02\mathrm{TeV}$ at the Large Hadron Collider. The measurements are made using data corresponding to integrated luminosities of 29.4 and 28.1 ${\mathrm{nb}}^{-1}$ for $Z\to ee$ and $Z\to \mu \mu$, respectively. The results from the two channels are consistent and combined to obtain a cross section times the $Z\to \ell \ell$ branching ratio, integrated over the rapidity region $|y_Z^{*}|<3.5$, of $139.8\pm 4.8\left(\mathrm{statistical}\right)\pm 6.2\left(\mathrm{systematic}\right)\pm 3.8$ (luminosity) nb. Differential cross sections are presented as functions of the $Z$ boson rapidity and transverse momentum and compared with models based on parton distributions both with and without nuclear corrections. The centrality dependence of $Z$ boson production in $p+\mathrm{Pb}$ collisions is measured and analyzed within the framework of a standard Glauber model and the model's extension for fluctuations of the underlying nucleon-nucleon scattering cross section.

The neutron capture cross section of the $s$-process branch nucleus ${}^{63}\mathrm{Ni}$ affects the abundances of other nuclei in its region, especially ${}^{63}\mathrm{Cu}$ and ${}^{64}\mathrm{Zn}$. In order to determine the energy-dependent neutron capture cross section in the astrophysical energy region, an experiment at the Los Alamos National Laboratory has been performed using the calorimetric $4\pi {\mathrm{BaF}}_2$ array DANCE. The ($n,\gamma$) cross section of ${}^{63}\mathrm{Ni}$ has been determined relative to the well-known ${}^{197}\mathrm{Au}$ standard with uncertainties below 15%. Various ${}^{63}\mathrm{Ni}$ resonances have been identified based on the $Q$ value. Furthermore, the $s$-process sensitivity of the new values was analyzed with the new network calculation tool NETZ.

An unexpected breakdown of the isobaric multiplet mass equation in the $A=20,T=2$ quintet was recently reported, presenting a challenge to modern theories of nuclear structure. In the present work, the excitation energy of the lowest $T=2$ state in ${}^{20}\mathrm{Na}$ has been measured to be $6498.4\pm 0.2_{\text{stat}}\pm 0.4_{\text{syst}}$ keV by using the superallowed $0^{+}\to 0^{+}$ beta decay of ${}^{20}\mathrm{Mg}$ to access it and an array of high-purity germanium detectors to detect its $\gamma$-ray deexcitation. This value differs by 27 keV (1.9 standard deviations) from the recommended value of $6525\pm 14$ keV and is a factor of 28 more precise. The isobaric multiplet mass equation is shown to be revalidated when the new value is adopted.

Using an optical model potential including an inelastic scattering potential as well as a conventional short-range nuclear potential, we investigate the ratio $P_{\mathrm{inel}}$ of the inelastic scattering cross section to the Rutherford cross section for the ${}^{11}\mathrm{Be}+{}^{197}\mathrm{Au}$ system. As a result, we find that the contribution of the inelastic scattering to the first excited state of the ${}^{11}\mathrm{Be}$ projectile cannot be ignored at backward angles in unresolved elastic $+$ inelastic scattering data and the $P_{\mathrm{inel}}$ relevant to the contribution of inelastic scattering depends on the incident energy $E_{\mathrm{c}.\mathrm{m}.}$ and excitation energy $\varepsilon$.

Background: The coupling of the last nucleon with configurations in the ground state of the even-even core is known to augment the single quasiparticle fragmentation pattern. In a recent experimental study by Yordanov et al. the values of the magnetic dipole and electric quadrupole moments of the $11/2^{-}$ state in a long chain of Cd isotopes were found to follow a simple trend which we try to explain by means of incorporating long-range correlations in the ground state.

Purpose: Our purpose is to study the influence of ground-state correlations (GSCs) on the magnetic moments and compare our results with the data for the odd-$A$ Cd isotopes.

Method: In order to evaluate if the additional correlations have bearing on the magnetic moments we employ an extension to the quasiparticle-phonon model (QPM) which takes into account $\mathrm{quasiparticle}\otimes \mathrm{phonon}$ configurations in the ground state of the even-even core affecting the structure of the odd-$A$ nucleus wave function.

Results: It is shown that the values for the magnetic moments which the applied QPM extension yields deviate further from the Schmidt values. The latter is in agreement with the measured values for the Cd isotopes.

Conclusions: The GSCs exert significant influence on the magnetic dipole moments and reveal a potential for reproducing the experimental values for the studied cadmium isotopes.

Absolute $\gamma$-ray emission probabilities in the ${\beta }^{-}$ decay of ${}^{67}\mathrm{Cu}$ were measured by means of $\gamma$-ray and ${\beta }^{-}$-decay singles and ${\beta }^{-}\text{−}\gamma$ coincidences. The new results, together with the known decay scheme of ${}^{67}\mathrm{Cu}$, were used to determine absolute ${\beta }^{-}$-decay branching intensities. The present data differ significantly from previously published values. In addition, the half-life of the $I^{\pi }={\frac{1}{2}}^{-}$ isomer in ${}^{67}\mathrm{Zn}$ was measured as $T_{1/2}=9.37\left(4\right) \mu \mathrm{s}$, in a good agreement with earlier measurements. From the analysis of the Fermi–Kurie plots, $Q_{{\beta }^{-}}\left(\text{g.s.}\right)=560.3\left(10\right)$ keV was deduced, which differs from the previously measured value of 577(8) keV but is in good agreement with $Q_{{\beta }^{-}}\left(\text{g.s.}\right)=561.3(15)$ keV recommended in the latest Atomic Mass Evaluation.

The problem of the calculation of inclusive breakup cross sections in nuclear reactions is reexamined. For that purpose, the post-form theory proposed by Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985)] is revisited, and an alternative derivation of the nonelastic breakup part of the inclusive breakup is presented, making use of the coupled-channels optical theorem. Using the distorted-wave Born approximation (DWBA) version of this model, several applications to deuteron and ${}^6\mathrm{Li}$ reactions are presented and compared with available data. The validity of the zero-range approximation of the DWBA formula is also investigated by comparing zero-range with full finite-range calculations.

Using a random-matrix approach and Monte Carlo simulations, we generate scattering matrices and cross sections for compound-nucleus reactions. In the absence of direct reactions we compare the average cross sections with the analytic solution given by the Gaussian orthogonal ensemble (GOE) triple integral, and with predictions of statistical approaches such as the ones from Moldauer; Hofmann, Richert, Tepel, and Weidenmüller; and Kawai, Kerman, and McVoy. We find perfect agreement with the GOE triple integral and display the limits of validity of the latter approaches. We establish a criterion for the width of the energy-averaging interval such that the relative difference between the ensemble-averaged and the energy-averaged scattering matrices lies below a given bound. Direct reactions are simulated in terms of an energy-independent background matrix. In that case, cross sections averaged over the ensemble of Monte Carlo simulations fully agree with results from the Engelbrecht-Weidenmüller transformation. The limits of other approximate approaches are displayed.