${}^{10}\mathrm{B}+{}^{10}\mathrm{B}$ reactions are measured with 50 and 72 MeV beams. The large spin of both beam and target nuclei ($J^{\pi }=3^{+}$) is particularly suitable for the population of high spin states in the exit channels. Population and decay of different states in ${}^{12}\mathrm{C}$ are studied through sequential decay reactions. The ${}^{12}\mathrm{C}$ excitation energy spectrum obtained from the ${}^{10}\mathrm{B}({}^{10}\mathrm{B},{}^8\mathrm{Be})$ reaction shows a number of both known and new states. In particular, a new state at $E_x=24.4\mathrm{MeV}$ is observed to be strongly populated in the triple $\alpha$-particle coincidences. The rarely seen state at $E_x=30.3\mathrm{MeV}$ is found to be strong in the $d+{}^{10}\mathrm{B}$ decay channel, reinforcing the previous suggestions that it has the exotic $2\alpha +2d$ molecular structure.

Recent astronomical observations, nuclear-reaction experiments, and microscopic calculations have placed new constraints on the nuclear equation of state (EoS) and revealed that most nuclear-structure models fail to satisfy those constraints upon extrapolation to infinite matter. A reverse procedure for imposing EoS constraints on nuclear structures has been elusive. Here, we present for the first time a method to generate a microscopic energy density functional (EDF) for nuclei from a given immutable EoS. The method takes advantage of a natural ansatz for homogeneous nuclear matter, the Kohn-Sham framework, and the Skyrme formalism. We apply it to the nuclear EoS of Akmal-Pandharipande-Ravenhall and describe successfully closed-(sub)shell nuclei. In the process, we provide predictions for the neutron-skin thickness of nuclei based directly on the given EoS. Crucially, bulk and static nuclear properties are found practically independent of the assumed effective mass value—a unique result in bridging EDF of finite and homogeneous systems in general.

Using the improved scission-point model, the mass and charge distributions of fragments resulting from the fission of californium isotopes are calculated and compared with the available experimental data. The change of the shape of mass and charge distributions with increasing excitation energy is predicted for future experiments.

Xe+Xe collisions at relativistic energies provide us with an opportunity to study a possible system with deconfined quarks and gluons, whose size is in between those produced by $p+p$ and Pb+Pb collisions. In the present work, we have used a multiphase transport (AMPT) model with nuclear deformation to study the identified particle production, such as (${\pi }^{+}+{\pi }^{-}$), ($K^{+}+K^{-}$), $K_s^0$, ($p+\overline{p}$), $\varphi$, and ($\mathrm{\Lambda }+\overline{\mathrm{\Lambda }}$) in Xe+Xe collisions at $\sqrt{s_{NN}}=5.44\mathrm{TeV}$. We study the $p{}_{\mathrm{T}}$ spectra, integrated yield, and $p{}_{\mathrm{T}}$-differential and $p{}_{\mathrm{T}}$-integrated particle ratios to (${\pi }^{+}+{\pi }^{-}$) and ($K^{+}+K^{-}$) as a function of collision centrality. The particle ratios are focused on strange to nonstrange ratios and baryon to meson ratios. The effect of deformations has also been highlighted by comparing our results to the nondeformation case. We have also compared the results from AMPT string melting and the AMPT default version to explore possible effects of the coalescence mechanism. We observe that the differential particle ratios show strong dependence on centrality while the integrated particle ratios show no centrality dependence. We give a thermal model estimation of chemical freeze-out temperature and the Boltzmann-Gibbs Blast Wave analysis of kinetic freeze-out temperature and collective radial flow in Xe+Xe collisions at $\sqrt{s_{NN}}=5.44\mathrm{TeV}$.

The precise reconstruction of jet transverse momenta in heavy-ion collisions is a challenging task. A major obstacle is the large number of (mainly) low-$p_{\mathrm{T}}$ particles overlaying the jets. Strong region-to-region fluctuations of this background complicate the jet measurement and lead to significant uncertainties. In this paper, a novel approach to correct jet momenta (or energies) for the underlying background in heavy-ion collisions is introduced. The proposed method makes use of common machine learning techniques to estimate the jet transverse momentum based on several parameters, including properties of the jet constituents. Using a toy model and HIJING simulations, the performance of the new method is shown to be superior to the established standard area-based background estimator. The application of the new method to data promises the measurement of jets down to extremely low transverse momenta, unprecedented thus far in data on heavy-ion collisions.

Reactions involving the group of nuclei commonly known as $p$ nuclei are part of the nucleosynthetic mechanisms at astrophysical sites. The ${}^{113}\mathrm{In}$ nucleus is such a case with several open questions regarding its origin at extreme stellar environments. In this paper, the experimental study of the cross sections of the radiative proton-capture reaction ${}^{112}\mathrm{Cd}(p,\gamma ){}^{113}\mathrm{In}$ is attempted for the first time at energies lying inside the Gamow window with an isotopically enriched ${}^{112}\mathrm{Cd}$ target. Two different techniques, the in-beam $\gamma$-ray spectroscopy and the activation method, have been applied. The latter method is required to account for the presence of a low-lying ${}^{113}\mathrm{In}$ isomer at 392 keV having a half-life of $\approx 100\min$. From the cross sections, the astrophysical $S$ factors and the isomeric ratios have been additionally deduced. The experimental results are compared to detailed Hauser-Feshbach theoretical calculations using talys and discussed in terms of their significance to the optical model potential involved.

An $\alpha$-decay study of ${}^{218}\mathrm{At}$ was performed at the CERN-ISOLDE facility. Laser-ionized beams of ${}^{218}\mathrm{At}$ were mass separated and implanted into an $\alpha -\gamma$ detection setup. Coincidence $\alpha -\gamma$ data were collected for the first time and a more precise half-life value of $T_{1/2}=1.27\left(6\right)$ s was measured. A new $\alpha$-decay scheme was deduced based on the extracted reduced $\alpha$-decay widths for fine-structure decays. The results from this work lead to a preferred spin and parity assignment of $J^{\pi }=\left(3^{-}\right)$; however, $J^{\pi }={\left(2\right)}^{-}$ cannot be fully excluded.

Background: Recent theoretical and experimental researches using proton-induced $\alpha$-knockout reactions provide direct manifestation of $\alpha$-cluster formation in nuclei. In recent and future experiments, $\alpha$-knockout data are available for neutron-rich beryllium isotopes. In ${}^{12}\mathrm{Be}$, rich phenomena are induced by the formation of $\alpha$ clusters surrounded by neutrons; for instance, breaking of the neutron magic number $N=8$.

Purpose: Our objective is to provide direct probing of the $\alpha$-cluster formation in the ${}^{12}\mathrm{Be}$ target through associating the structure information obtained by a microscopic theory with the experimental observables of $\alpha$-knockout reactions.

Method: We formulate a new wave function of the Tohsaki–Horiuchi–Schuck–Röpke (THSR) type for the structure calculation of ${}^{12}\mathrm{Be}$ nucleus and integrate it with the distorted-wave impulse-approximation framework for the $\alpha$-knockout reaction calculation of ${}^{12}\mathrm{Be}(p,p\alpha ){}^8\mathrm{He}$.

Results: We reproduce the low-lying spectrum of the ${}^{12}\mathrm{Be}$ nucleus by using the THSR wave function and discuss the cluster structure of the ground state. Based on the microscopic wave function, the optical potentials and $\alpha$-cluster wave function are determined and utilized in the calculation of ${}^{12}\mathrm{Be}(p,p\alpha ){}^8\mathrm{He}$ reaction at 250 MeV. The possibility of probing the clustering state of ${}^{12}\mathrm{Be}$ through this reaction is demonstrated by analysis of the triple differential cross sections that depend sensitively on the $\alpha$-cluster amplitude at the nuclear surface.

Conclusions: This study provides a feasible approach to validate directly the theoretical predictions of clustering features in the ${}^{12}\mathrm{Be}$ nucleus through the $\alpha$-knockout reaction.

Background: ${}^{97}\mathrm{Ru}$, a good hepatobiliary agent, is used in delayed investigations, diagnostic and therapeutic purposes, due to its favorable physicochemical properties. Various experimental studies have been carried out to investigate its production and chemical separation. However, in the interest of the subject, a lot of investigation is still required to identify the suitable routes for its optimum production, particularly for heavy-ion reactions, and to understand the reaction mechanisms.

Purpose: Measurement and analysis of excitation function of the residues from the ${}^{12}\mathrm{C}+{}^{89}\mathrm{Y}$ reaction at the low-energy region and to estimate the cross-section of ${}^{97}\mathrm{Ru}$ expected to be produced through the direct channel, and indirectly via the decay of its short-lived precursors ${}^{97g,97m}\mathrm{Rh}$.

Method: Thin ${}^{89}\mathrm{Y}$ foils backed by aluminium were bombarded by the ${}^{12}\mathrm{C}^{6+}$ beam within 40–75 MeV energy range. The excitation functions of the residues have been measured with the help of off-line $\gamma$-ray spectroscopy. Experimental cross-sections are compared with the various reaction models to understand the reaction mechanism involved in the production of residual radionuclides.

Results: The measured cross-sections of ${}^{97}\mathrm{Ru}, {}^{98,97m+g,96}\mathrm{Rh}, {}^{96,95,94,93}\mathrm{Tc},$ and ${}^{93m}\mathrm{Mo}$ radionuclides show reasonably good agreement with the calculations based on the equilibrium (EQ) and preequilibrium (PEQ) models. The contribution of PEQ emissions is observed in the $3n$ and $\alpha xn$ ($x=1,2$) channels.

Conclusion: Comparative analysis of the residual cross-sections demonstrates the dominance of compound nuclear process in the energy range considered. The measured cumulative production cross-section of ${}^{97}\mathrm{Ru}$ is maximum, $\sim 850$ mb, at 66.6 MeV. The detailed analysis presented in this article would help to optimize the production parameters for ${}^{97}\mathrm{Ru}$ and also to understand the reliability of the theoretical models.

In this paper we propose a new method for measuring the cross section of low-yield nuclear reactions by capturing the products in a cryogenically frozen noble gas solid. Once embedded in the noble gas solid, which is optically transparent, the product atoms can be selectively identified by laser-induced fluorescence and individually counted via optical imaging to determine the cross section. Single-atom sensitivity by optical imaging is feasible because the surrounding lattice of noble gas atoms facilitates a large wavelength shift between the excitation and the emission spectrum of the product atoms. The tools and techniques from the fields of single-molecule spectroscopy and superresolution imaging in combination with an electromagnetic recoil separator, for beam and isotopic differentiation, allow for a detection scheme with near-unity efficiency, a high degree of selectivity, and single-atom sensitivity. This technique could be used to determine a number of astrophysically important nuclear reaction rates.

The nuclear level density and $\gamma$-decay strength of ${}^{192}\mathrm{Os}$ have been extracted using particle-$\gamma$ coincidence data from the ${}^{192}\mathrm{Os}(\alpha ,{\alpha }^{\prime }\gamma ){}^{192}\mathrm{Os}$ reaction by means of the Oslo method. The level density is found to be a rather smooth function of excitation energy, approximately following the constant temperature model. The $\gamma$-decay strength is compared to photoneutron cross-section data above the neutron separation energy, and to $E1$ and $M1$ strengths for nuclei in this mass region derived from primary transitions following neutron capture. Our results are in good agreement with these previous data and draw a consistent picture of the $\gamma$-strength function in the range $E_{\gamma }\approx 1.5–6\mathrm{MeV}$. Using the measured nuclear level density and $\gamma$-decay strength as input to the nuclear-reaction code talys, we provide the first experimentally constrained Maxwellian-averaged cross section (MACS) for the ${}^{191}\mathrm{Os}(n,\gamma ){}^{192}\mathrm{Os}$ reaction relevant to $s$-process nucleosynthesis. The systematic uncertainties introduced by the normalization procedure of the level density and $\gamma$-strength function were investigated and propagated to the calculated Maxwellian-averaged cross section. The obtained result of the Maxwellian-averaged cross section at $k_{B}T=30\mathrm{keV}$, ${\langle \sigma \rangle }_{n,\gamma }=1134\pm 375\mathrm{mb}$, is in very good agreement with the theoretical estimate provided by the KADoNiS project, giving experimental support to the adopted KADoNiS value. Good agreement is also found with MACS values obtained from other libraries, such as TENDL-2017, ENDF/B-VII.0, and JEFF.

A multinucleon transfer and cluster-decay experiment, namely ${}^9\mathrm{Be}({}^{13}\mathrm{C},{}^{18}\mathrm{O}^{*}\to {}^{14}\mathrm{C}+\alpha )\alpha$, was performed at a beam energy of 65 MeV. Resonant states in ${}^{18}\mathrm{O}$ from 7 to 19 MeV, including some newly observed ones, are reconstructed with high resolution, based on the coincident detection of various combinations of the final fragments. The $\alpha$-decay branching ratios for 14 states are extracted from both the invariant-mass and the missing-mass measurements. Angular correlation analysis was conducted for the 10.3-MeV ($4^{+}$) state. The present work supports the existence of the positive-parity rotational band associated with the ${}^{14}\mathrm{C}+\alpha$ molecular structure in ${}^{18}\mathrm{O}$, but the negative-parity band members were not identified.

The impact of beyond-mean-field effects on the ground state and fission properties of superheavy nuclei has been investigated in a five-dimensional collective Hamiltonian based on covariant density functional theory. The inclusion of dynamical correlations reduces the impact of the $Z=120$ shell closure and induces substantial collectivity for the majority of the $Z=120$ nuclei which otherwise are spherical at the mean-field level (as seen in the calculations with the PC-PK1 functional). Thus, they lead to a substantial convergence of the predictions of the functionals DD-PC1 and PC-PK1 which are different at the mean-field level. On the contrary, the predictions of these two functionals remain distinctly different for the $N=184$ nuclei even when dynamical correlations are included. These nuclei are mostly spherical (oblate) in the calculations with PC-PK1 (DD-PC1). Our calculations for the first time reveal significant impact of dynamical correlations on the heights of inner fission barriers of superheavy nuclei with soft potential energy surfaces, the minimum of which at the mean-field level is located at spherical shape. These correlations affect the fission barriers of the nuclei, which are deformed in the ground state at the mean-field level, to a lesser degree.

The $\alpha$ inelastic scattering on ${}^{16}\mathrm{O}$ is investigated with the coupled-channels calculation using the $\alpha$-nucleus coupled-channels potentials, which are microscopically derived by folding the the Melbourne $g$-matrix $NN$ interaction with the ${}^{16}\mathrm{O}$ and $\alpha$ densities. The matter and transition densities of ${}^{16}\mathrm{O}$ are calculated by a microscopic structure model of the variation after the spin-parity projections combined with the generator coordinate method of ${}^{12}\mathrm{C}+\alpha$ in the framework of the antisymmetrized molecular dynamics. The calculation reproduces the observed elastic and inelastic cross sections at incident energies of $E_{\alpha }=104$, 130, 146, and 386 MeV. The coupled-channels effect on the cross sections is also discussed.

We used the $8\pi \gamma$-ray spectrometer at the TRIUMF-ISAC radiocative ion beam facility to obtain high-precision branching ratios for ${}^{19}\mathrm{Ne}{\beta }^{+}$ decay to excited states in ${}^{19}\mathrm{F}$. Together with other previous work, our measurements determine the superallowed $1/2^{+}\to 1/2^{+}\beta$ branch to the ground state in ${}^{19}\mathrm{F}$ to be 99.9878(7)%, which is three times more precise than known previously. The implications of these measurements for testing a variety of weak interaction symmetries are discussed briefly.

Mass measurements of fission and projectile fragments, produced via ${}^{238}\mathrm{U}$ and ${}^{124}\mathrm{Xe}$ primary beams, have been performed with the multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) of the Fragment Separator (FRS) Ion Catcher with a mass resolving power (FWHM) of up to 410 000 and an uncertainty of down to $6\times {10}^{-8}$. The nuclides were produced and separated in flight with the fragment separator FRS at 300 to 1000 MeV/u and thermalized in a cryogenic stopping cell. The data-analysis procedure was developed to determine with highest accuracy the mass values and the corresponding uncertainties for the most challenging conditions: down to a few events in a spectrum and overlapping distributions, which can be distinguished from a single peak only by a broader peak shape. With this procedure, the resolution of low-lying isomers is increased by a factor of up to 3 compared to standard data analysis. The ground-state masses of 31 short-lived nuclides of 15 different elements with half-lives of down to 17.9 ms and count rates as low as 11 events per nuclide were determined. This is the first direct mass measurement for seven nuclides. The excitation energies and the isomer-to-ground-state ratios of six isomeric states with excitation energies of as little as 280 keV were measured. For nuclides with known mass values, the average relative deviation from the literature values is $(4.5\pm 5.3)\times {10}^{-8}$. The measured two-neutron separation energies and their slopes near and at the $N=126$ and $Z=82$ shell closures indicate a strong element-dependent binding energy of the first neutron above the closed proton shell $Z=82$. The experimental results deviate strongly from the theoretical predictions, especially for $N=126$ and $N=127$.

New proposed orbital occupancies for $0^{+}$ states in ${}^{12}\mathrm{Be}$ are at variance with those normally in use. I have investigated implications for single-particle energies, ${}^{12}\mathrm{Be}/{}^{12}\mathrm{O}$ mass difference, cross sections for the reaction ${}^{10}\mathrm{Be}\left(\mathrm{t},\mathrm{p}\right)$, B(GT) from ${}^{12}\mathrm{B}$, and other observables.

We study the nature of the scalar $D_0^{*}$ meson from the viewpoint of chiral symmetry. With the linear representation of chiral symmetry, we construct the $D\pi$ scattering amplitude satisfying the chiral low-energy theorem, in which the $D_0^{*}$ meson appears as an $s$-wave resonance. We show that the properties of the $D_0^{*}$ meson can be successfully reproduced as the chiral partner of the $D$ meson coupled with the $D\pi$ scattering states. At the same time, we find that the spectral function and the pole position of $D_0^{*}$ are not very sensitive to the reduction of the chiral condensate, indicating the importance of the dressing of the bare state by the $D\pi$ molecular component.

Background: $\beta$-decay spectroscopy provides valuable nuclear physics input for accurate modeling of nova and x-ray burst observables and a stringent test for shell-model theories far from the stability line. The decay scheme of ${}^{27}\mathrm{S}$ is complicated and far from being understood due to a lack of experimental data prior to this work.

Purpose: We aim to experimentally constrain the thermonuclear ${}^{26}\mathrm{Si}(p,\gamma ){}^{27}\mathrm{P}$ reaction rate and to probe the possible mirror asymmetry in ${}^{27}\mathrm{S}$ and ${}^{27}\mathrm{Na}$ decays.

Method: The ${}^{27}\mathrm{S}$ ions were collected by double-sided silicon strip detectors operating in conjunction with high-purity germanium detectors, so the positrons, protons, and $\gamma$ rays emitted in the decay were measured simultaneously.

Results: The precise resonance energy and the ratio between $\gamma$ and proton partial widths of the key $3/2^{+}$ resonance were obtained, thereby determining the ${}^{26}\mathrm{Si}(p,\gamma ){}^{27}\mathrm{P}$ reaction rate based mainly on experimental constraints. The half-life of ${}^{27}\mathrm{S}$, the excitation energies, $\beta$-feeding intensities, log ft values, and Gamow-Teller transition strengths for the states of ${}^{27}\mathrm{P}$ populated in the $\beta$ decay of ${}^{27}\mathrm{S}$ were determined. A more complete ${}^{27}\mathrm{S}\beta$-decay scheme was constructed and compared to the $\beta$ decay of mirror nucleus ${}^{27}\mathrm{Na}$ and to the shell-model calculations with the universal sd (USD) Hamiltonian taking into account the shift of single-particle energies and the reduction of two-body matrix elements.

Conclusions: This work yields a new ${}^{26}\mathrm{Si}(p,\gamma ){}^{27}\mathrm{P}$ reaction rate two orders of magnitude lower than the rate recommended in the reaction rate libraries at around 0.1 GK. Experimental evidence for the observation of mirror asymmetries for the Gamow-Teller transitions of ${}^{27}\mathrm{S}$ and ${}^{27}\mathrm{Na}$ is also provided. The shell-model calculations using a modified USD interaction related to the weakly bound proton $1s_{1/2}$ orbit give a reasonable description of the decay properties of ${}^{27}\mathrm{S}$.

The mass and total kinetic energy distributions of the fission fragments in the fission of even-even isotopes of superheavy elements from Hs ($Z=108$) to Og ($Z=118$) are estimated using a prescission point model. We restrict to nuclei for which spontaneous fission has been experimentally observed. The potential energy surfaces are calculated with Strutinsky's shell correction procedure. The parametrization of the nuclear shapes is based on Cassini ovals. For the just-before-scission configuration we fix $\alpha =0.98$, which corresponds to $r_{\mathrm{neck}}\approx 2$ fm, and take into account another four deformation parameters: ${\alpha }_1,{\alpha }_3,{\alpha }_4,{\alpha }_6$. The fragment-mass distributions are estimated supposing they are due to thermal fluctuations in the mass asymmetry degree of freedom just before scission. The influence of the excitation energy of the fissioning system on these distributions is studied. The distributions of the total kinetic energy (TKE) of the fragments are also calculated (in the point-charge approximation). In Hs, Ds, and Cn isotopes a transition from symmetric to asymmetric fission is predicted with increasing neutron number $N$ (at $N\approx 168$). Supersymmetric fission occurs at $N\approx 160$. When the excitation energy increases from 0 to 30 MeV, the peaks (one or two) of the mass distributions become only slightly wider. The first two moments of the TKE distributions are displayed as a function of the mass number $A$ of the fissioning nucleus. A slow decrease of the average energy and a minimum of the width (at $N\approx 162$) is found.