Employing the quantal diffusion mechanism for multinucleon transfer, the double differential cross sections are calculated for production of primary projectile-like and target-like fragments in collisions of ${}^{136}\mathrm{Xe}+{}^{208}\mathrm{Pb}$ system at $E_{\text{c.m.}}=514$ MeV. Including de-excitation due to neutron emission, the cross section for production of ${}^{210}\mathrm{Po}, {}^{222}\mathrm{Rn}$, and ${}^{224}\mathrm{Ra}$ isotopes are estimated and compared with data.

Background: The mass region with $A\approx 100$ and $Z\approx 40$ is known to experience a sudden onset of deformation. The presence of the subshell closure $Z=40$ makes it feasible to create particle-hole excitations at a moderate excitation energy and, therefore, likely intruder states could be present in the low-lying spectrum. In other words, shape coexistence is expected to be a key ingredient to understand this mass region.

Purpose: The aim of this work is to describe excitation energies, transition rates, radii, and two-neutron separation energies for the even-even ${}^{94-110}\mathrm{Zr}$ nuclei and, moreover, to obtain information about wave functions and deformation.

Method: The interacting boson model with configuration mixing will be the framework to study the even-even Zr nuclei, considering only two types of configurations: 0particle-0hole and 2particle-2hole excitations. On one hand, the parameters appearing in the Hamiltonian and in the $E2$ transition operator are fixed trough a least-squares fit to the whole available experimental information. On the other hand, once the parameters have been fixed, the calculations allow to obtain a complete set of observables for the whole even-even Zr chain of isotopes.

Results: Spectra, transition rates, radii, ${\rho }^2\left(E0\right)$, and two-neutron separation energies have been calculated and a good agreement with the experimental information has been obtained. Moreover, a detailed study of the wave function has been conducted and mean-field energy surfaces and deformation have been computed too.

Conclusions: The importance of shape coexistence has been shown to correctly describe the $A\approx 100$ mass area for even-even Zr nuclei. This work confirmed the rather spherical nature of the ground state of ${}^{94-98}\mathrm{Zr}$ and its deformed nature for ${}^{100-110}\mathrm{Zr}$ isotopes. The sudden onset of deformation in ${}^{100}\mathrm{Zr}$ is owing to the rapid lowering of a deformed (intruder) configuration which is high-lying in lighter isotopes.

Excited states in the deformed nucleus ${}^{166}\mathrm{Er}$ have been studied with high-energy resolution in the ($p,t$) reaction, with the Munich Q3D spectrograph. 143 states have been observed up to 4 MeV excitation, and spin and parity has been proposed for about 100 states, based on a DWBA analysis of their angular distributions, out of which 11 are excited $0^{+}$ states, and 39 $2^{+}$ states. The excitation pattern of these states (especially the $0^{+}$ ones) in ${}^{166}\mathrm{Er}$ is compared to that in ${}^{168}\mathrm{Er}$. Calculations were carried out with the $spdf$-IBM model, which gives a reasonable agreement with the observed number of $0^{+}$ states in ${}^{166}\mathrm{Er}$ and their excitation in the ($p,t$) reaction. The $2n$-transfer intensity pattern for the $0^{+}$ states in the ${}^{166}\mathrm{Er}(t,p){}^{168}\mathrm{Er}$ reaction is also reasonably predicted. However, the $spdf$-IBM calculations do not explain the differences between ${}^{166}\mathrm{Er}$ and ${}^{168}\mathrm{Er}$, in the ($p,t$) transfer distribution of the $0^{+}$ states. The understanding of these differences, which appear to be related to a structure change at the $N=98$ deformed subshell closure, remains as an important issue of future, more elaborated model calculations.

Transient-field $g$-factor measurements in inverse kinematics were performed for the first-excited states of the stable, even isotopes of Ge and Se. The $g$ factors of ${}^{74}\mathrm{Ge}$ and ${}^{74}\mathrm{Se}$ were measured simultaneously using a cocktail beam, which eliminates most possible sources of systematic error in a relative $g$-factor measurement. The results are $g\left({}^{74}\mathrm{Se}\right)/g\left({}^{74}\mathrm{Ge}\right)=1.34\left(7\right), g\left({}^{70}\mathrm{Ge}\right)/g\left({}^{74}\mathrm{Ge}\right)=1.16\left(15\right), g\left({}^{72}\mathrm{Ge}\right)/g\left({}^{74}\mathrm{Ge}\right)=0.92\left(13\right), g\left({}^{76}\mathrm{Ge}\right)/g\left({}^{74}\mathrm{Ge}\right)=0.88\left(5\right), g\left({}^{76}\mathrm{Se}\right)/g\left({}^{74}\mathrm{Se}\right)=0.96\left(7\right), g\left({}^{78}\mathrm{Se}\right)/g\left({}^{74}\mathrm{Se}\right)=0.82\left(5\right), g\left({}^{80}\mathrm{Se}\right)/g\left({}^{74}\mathrm{Se}\right)=0.99\left(7\right)$, and $g\left({}^{82}\mathrm{Se}\right)/g\left({}^{74}\mathrm{Se}\right)=1.19\left(6\right)$. The measured $g$-factor ratios are in agreement with ratios from previous measurements, despite considerable variation in previous reported absolute values. The absolute values of the $g$ factors remain uncertain, however, the Rutgers parametrization was used to set the transient-field strength and then compare the experimental $g$ factors with shell-model calculations based on the JUN45 and jj44b interactions. Modest agreement was found between experiment and theory for both interactions. The shell-model calculations indicate that the $g\left(2_1^{+}\right)$ values and trends are determined largely by the balance of the spin carried by orbital motion of the protons.

Evaporation residue cross sections are measured for the reaction ${}^{48}\mathrm{Ti}+{}^{138}\mathrm{Ba}$ which forms the compound nucleus ${}^{186}{\mathrm{Pt}}^{*}$. The cross sections are measured at beam energies in the range of 189.3–234.4 MeV. The experimental evaporation residue cross sections are compared with the dynamical model which employs one-dimensional Langevin dynamical calculations. The dissipation strength of the Langevin equation is calculated using both chaos weighted wall formula and a constant reduced dissipation function. The measured ER cross sections are found to be much less than the theoretical predictions. Further, the measured ER cross sections for the system ${}^{48}\mathrm{Ti}+{}^{138}\mathrm{Ba}$ are compared with those of ${}^{32}\mathrm{S}+{}^{154}\mathrm{Sm}$ forming the same compound nucleus. The suppression in the evaporation residue cross sections of the former reaction may be attributed to the increasing competition from quasifission. The quasifission reaction is found to have superseded any effect of neutron shell closure $\left(N=82\right)$ of the target in the present study.

We study neutron-proton equilibration in dynamically deformed nuclear systems by investigating the correlations between the three largest fragments produced in collisions of ${}^{70}\mathrm{Zn}+{}^{70}\mathrm{Zn}$ at 35 MeV per nucleon. The rotation angle is interpreted as a measure of the duration of contact between the regions of the excited projectile-like fragment as it decays. In this work we address questions of whether there is a simultaneous or a double rupture scenario, sizing of the fragments, and alignment of the configuration.

Background: In the late stages of stellar core collapse just prior to core bounce, electron captures on medium-heavy nuclei drive deleptonization. Therefore, simulations require the use of accurate reaction rates. Nuclei with neutron number near $N=50$ above atomic number $Z=28$ play an important role. Rates presently used in astrophysical simulations rely primarily on a relatively simple single-state approximation. In order to improve the accuracy of the astrophysical simulations, experimental data are needed to test the electron-capture rates and to guide the development of better theoretical models and astrophysical simulations.

Purpose: The purpose of the present work was to measure the Gamow-Teller transition strength from ${}^{86}\mathrm{Kr}$ to ${}^{86}\mathrm{Br}$, to derive the stellar electron-capture rates based on the extracted strengths, and to compare the derived rates with rates based on shell-model and quasiparticle random-phase approximation (QRPA) Gamow-Teller strengths calculations, as well as the single-state approximation. An additional purpose was to test the impact of using improved electron-capture rates on the late evolution of core-collapse supernovae.

Method: The Gamow-Teller strengths from ${}^{86}\mathrm{Kr}$ were extracted from the ${}^{86}\mathrm{Kr}(t,{}^3\mathrm{He}+\gamma$) charge-exchange reaction at $115\mathrm{MeV}/u$. The electron-capture rates were calculated as a function of stellar density and temperature. Besides the case of ${}^{86}\mathrm{Kr}$, the electron-capture rates based on the QRPA calculations were calculated for 78 additional isotopes near $N=50$ above $Z=28$. The impact of using these rates instead of those based on the single-state approximation is studied in a spherically symmetrical simulation of core collapse just prior to bounce.

Results: The derived electron-capture rates on ${}^{86}\mathrm{Kr}$ from the experimental Gamow-Teller strength distribution are much smaller than the rates estimated based on the single-state approximation. Rates based on Gamow-Teller strengths estimated in shell-model and QRPA calculations are more accurate. The core-collapse supernova simulation with electron-capture rates based on the QRPA calculations indicate a significant reduction in the deleptonization during the collapse phase.

Conclusions: It is important to utilize microscopic theoretical models that are tested by experimental data to constrain and estimate Gamow-Teller strengths and derived electron-capture rates for nuclei near $N=50$ that are inputs for astrophysical simulations of core-collapse supernovae and their multimessenger signals, such as the emission of neutrinos and gravitational waves.

We consider deuterium-tritium fusion as a generic example for general fusion reactions. For initial kinetic energies in the keV regime, the reaction rate is exponentially suppressed due to the Coulomb barrier between the nuclei, which is overcome by tunneling. Here, we study whether the tunneling probability could be enhanced by an additional electromagnetic field, such as an x-ray free electron laser (XFEL). We find that the XFEL frequencies and field strengths required for this dynamical assistance mechanism should come within reach of present-day or near-future technology.

Unitary transformations of a Hamiltonian generally induce interaction terms beyond the particle rank present in the untransformed Hamiltonian that have to be captured and included in a many-body calculation. In systems with strangeness such as hypernuclei, the three-body terms induced by the hyperon-nucleon interaction are strong, so their inclusion is crucial. We present in detail a procedure for computing hyperon-nucleon-nucleon interaction terms that are induced during a similarity renormalization group (SRG) flow. The SRG is carried out in a basis spanned by antisymmetric harmonic-oscillator states with respect to three-body Jacobi coordinates. We discuss basis construction, antisymmetrization, numerical evaluation of the flow equations, and separation of the genuine three-body terms. We then use the hypernuclear no-core shell model with SRG-evolved Hamiltonians, addressing the sensitivity of hypernuclear states and hyperon separation energies to changes in the nucleonic Hamiltonian by example of ${}_{\mathrm{\Lambda }}{}^7\mathrm{Li},{}_{\mathrm{\Lambda }}{}^9\mathrm{Be},{}_{\mathrm{\Lambda }}{}^{11}\mathrm{B},{}_{\mathrm{\Lambda }}{}^{13}\mathrm{C}$, and the hyper-helium chain. We also present a survey of the hyper-hydrogen chain, exploring the structure of hypernuclei with extreme neutron-proton asymmetries.

The lowest order constrained variational method is reformulated to find the equation of state of hypernuclear matter. For the nucleon-nucleon interaction we employed the well-known Argonne V18 (AV18) interaction. The equation of state is calculated using two-body central potentials for $\mathrm{\Lambda }N$ and $\mathrm{\Lambda }\mathrm{\Lambda }$ interactions that are determined in order to reproduce the experimental data on single- and double-$\mathrm{\Lambda }$ hypernuclei. For the odd-state part of the $\mathrm{\Lambda }\mathrm{\Lambda }$ interaction, which is not known due to the lack of experimental data, a proposed repulsive and attractive potential is employed to calculate the equation of state. It is shown that the presence of $\mathrm{\Lambda }$ in the hypernuclear matter produces a strong softening of the equation of state. The results are compared with similar calculations with another variational method. The state-dependent energy as well as central and tensor correlation functions are studied up to $J=2$ for each JLSTMT channel where related to total (J), orbital (L) and spin (S) angular momentum and isospin (T) and the third component of isospin (MT) respectively for $\mathrm{\Lambda }N$ and $\mathrm{\Lambda }\mathrm{\Lambda }$ interactions. Furthermore, the effect of baryon density and hyperon density as well as the type of hyperon-hyperon interaction on the two-body correlation functions are investigated.

The prompt fission $\gamma$-ray energy spectrum for cold-neutron-induced fission of ${}^{235}\mathrm{U}$ was measured in the energy range $E_{\gamma }=0.8–20\mathrm{MeV}$, by gaining a factor of about ${10}^5$ in statistics compared to the measurements performed so far. The spectrum exhibits local bump structures at $E_{\gamma }\approx 4\mathrm{MeV}$ and $\approx 6\mathrm{MeV}$, and also a broad one at $\approx 15\mathrm{MeV}$. In order to understand the origins of these bumps, the $\gamma \text{−}\mathrm{ray}$ spectra were calculated using a statistical Hauser-Feshbach model, taking into account the deexcitation of all the possible primary fission fragments. It is shown that the bump at $\approx 4\mathrm{MeV}$ is created by the transitions between the discrete levels in the fragments around ${}^{132}\mathrm{Sn}$, and the bump at $\approx 6\mathrm{MeV}$ mostly comes from the complementary light fragments. It is also indicated that a limited number of nuclides, which have high-spin states at low excitation energies, can contribute to the bump structure around $E_{\gamma }\approx 15\mathrm{MeV}$, induced by the transition feeding into the low-lying high-spin states.

We have applied the extended factorization scheme to investigate the electroweak pion production on nuclei. The ANL-Osaka model, which was obtained by analyzing the data of $\pi N, \gamma N, N(e,e^{\prime }\pi )$, and $N(\nu ,\mu \pi )$ reactions up to invariant mass $W=2\mathrm{GeV}$, is used to generate the matrix elements of current operators relevant to pion production off the nucleon. Medium effects on the $\mathrm{\Delta }$ (1232) component of the meson-exchange current are included by using a $\mathrm{\Delta }$-nucleus potential determined from the previous $\mathrm{\Delta }$-hole model studies of pion-nucleus reactions. Nuclear correlations in the initial target state and in the spectator system(s) are modeled using realistic hole spectral functions. As a first step, we show that the data of ${}^{12}\mathrm{C}(e,e^{\prime })$ up to the $\mathrm{\Delta }$ (1232) region can be described reasonably well. The interplay between the pion production and two-body meson-exchange mechanisms is shown to be essential in improving the agreement with the data in the “dip” region, between the quasielastic and the $\mathrm{\Delta }$ (1232) peaks. Predictions for ${}^{12}\mathrm{C}(\nu ,\mu \pi )$ have also been made. They can be used to estimate pion-emission rates in neutrino-nucleus cross section, which constitutes an important systematic uncertainty to the reconstructed neutrino energy. With further improvements of the Metropolis Monte Carlo techniques to account for final states comprised of more than two particles, our approach can be employed up to $W=2$ GeV, where two-pion production and higher mass nucleon resonances must be included for analyzing the data from accelerator-based neutrino-oscillation experiments.

Excited states of the neutron-rich isotopes ${}^{42,44}\mathrm{S}$ and ${}^{41,43}\mathrm{P}$ have been studied via inverse-kinematics proton scattering from a liquid hydrogen target, using the GRETINA $\gamma$-ray tracking array to extract inelastic-scattering cross sections. Deformation lengths of the $2_1^{+}$ excitations in ${}^{42,44}\mathrm{S}$ have been determined and, when combined with deformation lengths determined with electromagnetic probes, yield the ratio of neutron-to-proton matrix elements $M_n/M_p$ for the $2_1^{+}$ excitations in these nuclei. The present results for ${}^{41,43}\mathrm{P}(p,p^{\prime })$ are used to compare two shell-model interactions, SDPF-U and SDPF-MU. As in a recent study of ${}^{42}\mathrm{Si}$, the present results on ${}^{41,43}\mathrm{P}$ favor the SDPF-MU interaction.

The cross section for one-proton knockout from ${}^{16}\mathrm{C}$ with a large neutron-proton separation energy asymmetry on a carbon target has been measured at an intermediate beam energy of around 240 MeV/nucleon. The measured cross section is compared to the predictions based on the eikonal reaction model with shell-model structure inputs. The beam-energy dependence of the reduction on the extracted spectroscopic strength for strongly bound nucleon removal is derived from combining the existing intermediate-energy data with the present measurement. The deduced reduction factor $R_s$, defined as the ratio of the measured and theoretical cross sections, for the strongly bound nucleon removal at around 240 MeV/nucleon is consistent with the systematics observed from knockout reactions induced by light nuclear targets at intermediate energies of around 80 MeV/nucleon.

Initial volume fluctuation (VF) arising from the participant fluctuation would be the background which should be subtracted experimentally from the measured higher-order cumulants. We study the validity of the volume fluctuation correction (VFC) on higher-order net-proton cumulants by using a simple toy model and an ultrarelativistic quantum molecular dynamics (UrQMD) model in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV for various centrality definitions. The results are compared to the conventional data-driven method called centrality bin width correction (CBWC). We find VFC works well in a toy model assuming independent particle production, but does not seem to work well in a UrQMD model. It is also found that cumulants are strongly affected by the multiplicity correlation effect as well as the centrality resolution effect. These results show that neither VFC nor CBWC are perfect methods. Thus, both methods should be compared in the real experiment.

Neutron capture data on intermediate mass nuclei are of key importance to nucleosynthesis in the weak component of the slow neutron capture processes, which occurs in massive stars. The $(n,\gamma )$ cross section on ${}^{70}\mathrm{Ge}$, which is mainly produced in the $s$ process, was measured at the neutron time-of-flight facility n_TOF at CERN. Resonance capture kernels were determined up to 40 keV neutron energy and average cross sections up to 300 keV. Stellar cross sections were calculated from $kT=5$ keV to $kT=100$ keV and are in very good agreement with a previous measurement by Walter and Beer (1985) and recent evaluations. Average cross sections are in agreement with Walter and Beer (1985) over most of the neutron energy range covered, while they are systematically smaller for neutron energies above 150 keV. We have calculated isotopic abundances produced in $s$-process environments in a 25 solar mass star for two initial metallicities (below solar and close to solar). While the low metallicity model reproduces best the solar system germanium isotopic abundances, the close to solar model shows a good global match to solar system abundances in the range of mass numbers $A=60–80$.

The influence of magic numbers on nuclear radii is investigated via the Hartree-Fock-Bogolyubov calculations and available experimental data. With the $\ell s$ potential including additional density dependence suggested from the chiral effective-field theory, kinks are universally predicted at the $jj$-closed magic numbers and antikinks (i.e., inverted kinks) are newly predicted at the $\ell s$-closed magic numbers, both in the charge radii and in the matter radii along the isotopic and isotonic chains where nuclei stay spherical. These results seem consistent with the kinks of the charge radii observed in Ca, Sn, and Pb and the antikink in Ca. The kinks and the antikinks could be a peculiar indicator for magic numbers, discriminating $jj$ closure and $\ell s$ closure.

The half-lives of seven nuclei have been determined in the neutron-deficient mass-70 region following their production via fragmentation of a 345 MeV/nucleon ${}^{124}\mathrm{Xe}$ primary beam on a 740 mg/${\mathrm{cm}}^2 {}^9\mathrm{Be}$ target at the RI Beam Factory, RIKEN. The results include two new (${}^{73}\mathrm{Sr}$ and ${}^{76}\mathrm{Y}$) half-lives and a more precise measurement for the ground-state half-life of ${}^{74}\mathrm{Sr}$. The new results are discussed with reference to previously published calculations that predict the location of the proton dripline in the light Sr and Y region of the nuclear chart. In addition, differences in the ground-state structure of ${}^{72}\mathrm{Rb}$ and ${}^{76}\mathrm{Y}$ are discussed with the aid of density functional theory calculations. These provide a possible explanation for why ${}^{72}\mathrm{Rb}$ undergoes proton decay while the $\alpha$-conjugate nucleus ${}^{76}\mathrm{Y}$ predominantly undergoes ${\beta }^{+}$ decay.

Triple $\beta$ decay of ${}^{150}\mathrm{Nd}$ to the ground and excited states of ${}^{150}\mathrm{Eu}$ and quadruple $\beta$ decay of ${}^{150}\mathrm{Nd}$ to the excited states of ${}^{150}\mathrm{Gd}$ have been studied using a 400 ${\mathrm{cm}}^3$ low-background high-purity germanium detector and an external source consisting of 3046 g of natural ${\mathrm{Nd}}_2{\mathrm{O}}_3$ powder. A half-life limit for the quadruple $\beta$ decay to the $0_1^{+}$ state of ${}^{150}\mathrm{Gd}$ was found to be $T_{1/2}(0\nu +4\nu )>8.7\times {10}^{20}$ yr (90% C.L.). For other ($0\nu +4\nu$) transitions to the $2_1^{+}$, $3_1^{-}$, $4_1^{+}$, $2_2^{+}$, and $2_3^{+}$ excited states limits have been obtained for the first time at the level of $(6.1–9.5)\times {10}^{20}$ yr (90% C.L.). We report here also the results for the first search for triple $\beta$ decay to the ground and excited final states of ${}^{150}\mathrm{Eu}$. We find no evidence of this decay and set lower limits on the half-life in the range $T_{1/2}(0\nu +3\nu )>(0.04-4.8)\times {10}^{20}$ yr (90% C.L.).

We study the Kondo effect for a ${\mathrm{\Sigma }}_c$ (${\mathrm{\Sigma }}_c^{*}$) baryon in nuclear matter. In terms of the spin and isospin $[\mathrm{SU}{\left(2\right)}_{\mathrm{spin}}\times \mathrm{SU}{\left(2\right)}_{\mathrm{isospin}}]$ symmetry, the heavy-quark spin symmetry and the $S$-wave interaction, we provide the general form of the Lagrangian for a ${\mathrm{\Sigma }}_c$ (${\mathrm{\Sigma }}_c^{*}$) baryon and a nucleon. We analyze the renormalization equation at the one-loop level and find that the coexistence of spin exchange and isospin exchange magnifies the Kondo effect in comparison with the case where the spin-exchange interaction and the isospin-exchange interaction exist separately. We demonstrate that the solution exists for the ideal sets of the coupling constants, including the $\mathrm{SU}\left(4\right)$ symmetry as an extension of the $\mathrm{SU}{\left(2\right)}_{\mathrm{spin}}\times \mathrm{SU}{\left(2\right)}_{\mathrm{isospin}}$ symmetry. We also conduct a similar analysis for the Kondo effect of a $\overline{D}$ (${\overline{D}}^{*}$) meson in nuclear matter. On the basis of the obtained result, we conjecture that there could exist a “mapping” from the heavy meson (baryon) in vacuum onto the heavy baryon (meson) in nuclear matter.