The properties of the kinetic energy spectra of light isotopes produced in the breakup of a nuclear source and during the de-excitation of its products are examined. The initial stage, at which the hot fragments are created, is modeled by the statistical multifragmentation model, whereas the Weisskopf-Ewing evaporation treatment is adopted to describe the subsequent fragment de-excitation, as they follow their classical trajectories dictated by the Coulomb repulsion among them. The energy spectra obtained are compared to available experimental data. The influence of the fusion cross section entering into the evaporation treatment is investigated and its influence on the qualitative aspects of the energy spectra turns out to be small. Although these aspects can be fairly well described by the model, the underlying physics associated with the quantitative discrepancies remains to be understood.

The isospin dissipation dynamics in multinucleon transfer reactions has been investigated within the dinuclear system model. Production cross sections of neutron-rich isotopes around projectile-like and target-like fragments are estimated in collisions of ${}^{58,64}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ and ${}^{78,86,91}\mathrm{Kr}+{}^{198}\mathrm{Pt}$ near Coulomb barrier energies. The isospin diffusion in the nucleon transfer process is coupled to the dissipation of relative motion energy and angular momentum of colliding system. The available data of projectile-like fragments via multinucleon transfer reactions are nicely reproduced. It is found that the light projectile-like fragments are produced in the neutron-rich region because of the isospin equilibrium in two colliding nuclei. However, the heavy target-like fragments tend to be formed on the neutron-poor side above the $\beta$-stability line. The neutron-rich projectiles move the maximal yields of heavy nuclei to the neutron-rich domain and are available for producing the heavy exotic isotopes, in particular around the neutron shell closure of $N=126$.

The impact of cluster correlations has been studied in the intermediate mass fragment (IMF) emission in ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ at 95 MeV/nucleon, using antisymmetrized molecular dynamics (AMD) model simulations. In AMD, the cluster correlation is introduced as a process to form light clusters with $A\le 4$ in the final states of a collision induced by the nucleon-nucleon residual interaction. Correlations between light clusters are also considered to form light nuclei with $A\le 9$. This version of AMD, combined with GEMINI to calculate the decay of primary fragments, reproduces the experimental energy spectra of IMFs well overall with reasonable reproduction of light charged particles when we carefully analyze the excitation energies of primary fragments produced by AMD and their secondary decays. The results indicate that the cluster correlation plays a crucial role for producing fragments at relatively low excitation energies in the intermediate-energy heavy-ion collisions.

The averaged effective two-body interaction (AEI), which can be generated through the lowest order constrained variational (LOCV) method for symmetric nuclear matter (SNM) with the input [Reid68, Ann. Phys. 50, 411 (1968)] nucleon-nucleon potential, is used as the effective nucleon-nucleon potential in the folding model to describe the heavy-ion (HI) elastic scattering cross sections. The elastic scattering cross sections of ${}^{12}\mathrm{C}\text{−}{}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}\text{−}{}^{16}\mathrm{O}$ systems are calculated in the above framework. The results are compared with the corresponding calculations coming from the fitting procedures with the input finite range $DDM3Y1$-Reid potential and the available experimental data at different incident energies. It is shown that a reasonable description of the elastic ${}^{12}\mathrm{C}\text{−}{}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}\text{−}{}^{16}\mathrm{O}$ scattering data at the low and medium energies can be obtained by using the above LOCV AEI, without any need to define a parametrized density-dependent function in the effective nucleon-nucleon potential, which is formally considered in the typical $DDM3Y1$-Reid interactions.

We present the event-by-event next-to-leading-order perturbative-QCD + saturation + viscous hydrodynamics (EKRT) model predictions for the centrality dependence of the charged hadron multiplicity in the pseudorapidity interval $\left|\eta \right|\le 0.5$, and for the centrality dependence of the charged hadron flow harmonics $v_n\left\{2\right\}$ obtained from two-particle cumulants, in $\sqrt{s_{NN}}=5.44$ TeV Xe+Xe collisions at the CERN Large Hadron Collider. Our prediction for the 0–5 % central charged multiplicity is $d{N}_{\mathrm{ch}}/d\eta =1218\pm 46$. We also predict $v_n\left\{2\right\}$ in Xe+Xe collisions to increase more slowly from central towards peripheral collisions than those in a Pb+Pb system. We find that at $10,\cdots ,50\%$ centralities $v_2\left\{2\right\}$ is smaller and $v_3\left\{2\right\}$ is larger than in the Pb+Pb system while $v_4\left\{2\right\}$ is of the same magnitude in both systems. We also find that the ratio of flow harmonics in Xe+Xe collisions and in Pb+Pb collisions shows a slight sensitivity to the temperature dependence of the shear-viscosity–to–entropy ratio. As we discuss here, the new nuclear mass-number systematics especially in the flow harmonics serves as a welcome further constraint for describing the space-time evolution of a heavy-ion system and for determining the shear viscosity and other transport properties of strongly interacting matter.

Background: About 50% of the heavy elements are produced in stars during the slow neutron capture process. The analysis of branching points allows to set constraints on the temperature and the neutron density in the interior of stars. The temperature dependence of the branch point ${}^{171}\mathrm{Tm}$ is weak. Hence, the ${}^{171}\mathrm{Tm}$ neutron capture cross section can be used to constrain the neutron density during the main component of the s process in thermally pulsing asymptotic giant branch stars.

Purpose: In order to perform neutron capture experiments on ${}^{171}\mathrm{Tm}$, sample material has to be produced and characterized. The characterization is done by $\gamma$ spectroscopy, relying on the intensities of the involved $\gamma$ lines. Only the 66.7-keV $\gamma$ line can be observed whose intensity was uncertain so far.

Method: An enriched ${}^{170}\mathrm{Er}$ sample was activated with thermal neutrons at the TRIGA (Training, Research, Isotopes, General Atomics) research reactor at the Johannes Gutenberg-Universität Mainz. The activation resulted in an easily quantifiable number of ${}^{171}\mathrm{Er}$ nuclei that subsequently decayed to ${}^{171}\mathrm{Tm}$.

Result: The intensity of the 66.7-keV $\gamma$ line of the ${}^{171}\mathrm{Tm}$ decay was measured to $I_{\gamma }=(0.144\pm 0.010)\%$.

Conclusions: Our result is in good agreement with the value found in the literature.

The Hauser-Feshbach statistical model is applied to the de-excitation of primary fission fragments using input mass yields calculated with macroscopic-microscopic models of the potential energy surface. We test the sensitivity of the prompt fission observables to the input mass yields for two important reactions, ${}^{235}\mathrm{U}(n_{\mathrm{th}},f)$ and ${}^{239}\mathrm{Pu}(n_{\mathrm{th}},f)$, for which good experimental data exist. General traits of the mass yields, such as the location of the peaks and their widths, can impact both the prompt neutron and $\gamma$-ray multiplicities, as well as their spectra. Specifically, we use several mass yields to determine a linear correlation between the calculated prompt neutron multiplicity $\overline{\nu }$ and the average heavy-fragment mass $\langle A_h\rangle$ of the input mass yields $\partial \overline{\nu }/\partial \langle A_h\rangle =\pm 0.1(n/f)/\mathrm{u}$. The mass peak width influences the correlation between the total kinetic energy of the fission fragments and the total number of prompt neutrons emitted, ${\overline{\nu }}_T\left(\mathrm{TKE}\right)$. Typical biases on prompt particle observables from using calculated mass yields instead of experimental ones are $\delta \overline{\nu }=4\%$ for the average prompt neutron multiplicity, $\delta \overline{M}{}_{\gamma }=1\%$ for the average prompt $\gamma$-ray multiplicity, $\delta {\overline{\epsilon }}_n^{\mathrm{LAB}}=1\%$ for the average outgoing neutron energy, $\delta {\overline{\epsilon }}_{\gamma }=1\%$ for the average $\gamma$-ray energy, and $\delta \langle \mathrm{TKE}\rangle =0.4\%$ for the average total kinetic energy of the fission fragments.

We describe ultrarelativistic heavy ion collisions at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider with a hybrid model using the IP-Glasma model for the earliest stage and viscous hydrodynamics and microscopic transport for the later stages of the collision. We demonstrate that within this framework the bulk viscosity of the plasma plays an important role in describing the experimentally observed radial flow and azimuthal anisotropy simultaneously. We further investigate the dependence of observables on the temperature below which we employ the microscopic transport description.

An intruder configuration mixing scheme with $2n$-particle and $2n$-hole configurations from $n=0$ up to $n\to \infty$ in the U(5) (vibrational) limit of the interacting boson model is proposed. A simple Hamiltonian suitable to describe the intruder and normal configuration mixing is found to be exactly solvable, and its eigenstates can be expressed as the SU(1,1) coherent states built on the U(5) basis vectors of the interacting boson model. It is shown that the configuration mixing scheme keeps lower part of the vibrational spectrum unchanged and generates the intruder states due to the mixing. Some low-lying level energies and experimentally known $B\left(E2\right)$ ratios of ${}^{108,110}\mathrm{Cd}$ are fitted and compared with the experimental results.

We measured neutron emission spectra for ${}^{19}\mathrm{F}$-induced reactions on ${}^{181}\mathrm{Ta}$, ${}^{89}\mathrm{Y}$, and ${}^{51}\mathrm{V}$ at beam energies of 130, 140, 145, and 150 MeV. Measurements were made using liquid scintillator detectors at eight angles in the range of ${25}^{\circ }-{143}^{\circ }$ using time-of-flight and pulse-shape discrimination. A comparison has been made with alice2014 and pace4 calculations to understand the role of incomplete fusion and pre-equilibrium effects. Global predictions with alice2014 without parameter adjustment gives a fair agreement with the measured data.

Background: The exotic ${}^9\mathrm{He}$ nucleus, which presents one of the most extreme neutron-to-proton ratios, belongs to the $N=7$ isotonic chain famous for the phenomenon of ground-state parity inversion with decreasing number of protons. Consequently, it would be expected to have an unnatural (positive) parity ground state similar to ${}^{11}\mathrm{Be}$ and ${}^{10}\mathrm{Li}$. Despite many experimental and theoretical investigations, its structure remains uncertain. Apart from the fact that it is unbound, other properties including the spin and parity of its ground state, and the very existence of additional low-lying resonances are still a matter of debate.

Purpose: In this work, we study the properties of ${}^9\mathrm{He}$ by analyzing the $n+{}^8\mathrm{He}$ continuum in the context of the ab initio no-core shell model with continuum (NCSMC) formalism with chiral nucleon-nucleon interactions as the only input.

Methods: The NCSMC is a state-of-the-art approach for the ab initio description of light nuclei. With its capability to predict properties of bound states, resonances, and scattering states in a unified framework, the method is particularly well suited for the study of unbound nuclei such as ${}^9\mathrm{He}$.

Results: Our analysis produces an unbound ${}^9\mathrm{He}$ nucleus. Two resonant states are found at the energies of $\sim 1$ and $\sim 3.5$ MeV, respectively, above the $n+{}^8\mathrm{He}$ breakup threshold. The first state has a spin-parity assignment of $J^{\pi }={1/2}^{-}$ and can be associated with the ground state of ${}^9\mathrm{He}$, while the second, broader state has a spin parity of ${3/2}^{-}$. No resonance is found in the ${1/2}^{+}$ channel, only a very weak attraction.

Conclusions: We find that the ${}^9\mathrm{He}$ ground-state resonance has a negative parity and thus breaks the parity-inversion mechanism found in the ${}^{11}\mathrm{Be}$ and ${}^{10}\mathrm{Li}$ nuclei of the same $N=7$ isotonic chain.

An improved formalism of the two-neutrino double-beta decay ($2\nu \beta \beta$-decay) rate is presented, which takes into account the dependence of energy denominators on lepton energies via the Taylor expansion. Until now, only the leading term in this expansion has been considered. The revised $2\nu \beta \beta$-decay rate and differential characteristics depend on additional phase-space factors weighted by the ratios of $2\nu \beta \beta$-decay nuclear matrix elements with different powers of the energy denominator. For nuclei of experimental interest all phase-space factors are calculated by using exact Dirac wave functions with finite nuclear size and electron screening. For isotopes with measured $2\nu \beta \beta$-decay half-life the involved nuclear matrix elements are determined within the quasiparticle random-phase approximation with partial isospin restoration. The importance of correction terms to the $2\nu \beta \beta$-decay rate due to Taylor expansion is established and the modification of shape of single and summed electron energy distributions is discussed. It is found that the improved calculation of the $2\nu \beta \beta$-decay predicts slightly suppressed $2\nu \beta \beta$-decay background to the neutrinoless double-beta decay signal. Furthermore, an approach to determine the value of effective weak-coupling constant in nuclear medium $g_{\mathrm{A}}^{\mathrm{eff}}$ is proposed.

Because the properties of the QCD phase transition and the chiral magnetic effect (CME) depend on the number of quark flavors ($N_f$) and quark mass, relativistic heavy-ion collisions provide a natural environment to investigate the flavor features if quark deconfinement occurs. We introduce an initial two-flavor or three-flavor dipole charge separation into a multiphase transport (AMPT) model to investigate the flavor dependence of the CME. By taking advantage of the recent ALICE data of charge azimuthal correlations with identified hadrons, we attempt to disentangle two-flavor and three-flavor CME scenarios in Pb+Pb collisions at 2.76 TeV. We find that the experimental data show a certain potential to distinguish the two scenarios, therefore we further suggest to collect more data to clarify the possible flavor dependence in future experiments.

Background: The precise determination of the $\mathcal{F}t$ value in $T=1/2$ mixed mirror decays is an important avenue for testing the standard model of the electroweak interaction through the determination of $V_{ud}$ in nuclear $\beta$ decays. ${}^{11}\mathrm{C}$ is an interesting case, as its low mass and small $Q_{EC}$ value make it particularly sensitive to violations of the conserved vector current hypothesis. The present dominant source of uncertainty in the ${}^{11}\mathrm{C}\mathcal{F}t$ value is the half-life.

Purpose: A high-precision measurement of the ${}^{11}\mathrm{C}$ half-life was performed, and a new world average half-life was calculated.

Method: ${}^{11}\mathrm{C}$ was created by transfer reactions and separated using the TwinSol facility at the Nuclear Science Laboratory at the University of Notre Dame. It was then implanted into a tantalum foil, and $\beta$ counting was used to determine the half-life.

Results: The new half-life, $t_{1/2}=1220.27\left(26\right)$ s, is consistent with the previous values but significantly more precise. A new world average was calculated, $t_{1/2}^{\text{world}}=1220.41\left(32\right)$ s, and a new estimate for the Gamow-Teller to Fermi mixing ratio $\rho$ is presented along with standard model correlation parameters.

Conclusions: The new ${}^{11}\mathrm{C}$ world average half-life allows the calculation of a $\mathcal{F}{t}^{\text{mirror}}$ value that is now the most precise value for all superallowed mixed mirror transitions. This gives a strong impetus for an experimental determination of $\rho$, to allow for the determination of $V_{ud}$ from this decay.

In the present work, we describe the results obtained with a large ($\approx 133{\mathrm{cm}}^3$) ${\mathrm{TeO}}_2$ bolometer, with a view to a search for neutrinoless double-$\beta$ decay ($0\nu \beta \beta$) of ${}^{130}\mathrm{Te}$. We demonstrate an efficient $\alpha$-particle discrimination (99.9%) with a high acceptance of the $0\nu \beta \beta$ signal (about 96%), expected at $\approx 2.5$ MeV. This unprecedented result was possible thanks to the superior performance (10-eV rms baseline noise) of a Neganov-Luke-assisted germanium bolometer used to detect a tiny (70-eV) light signal from the ${\mathrm{TeO}}_2$ detector, dominated by $\gamma$($\beta$)-induced Cherenkov radiation but exhibiting also a clear scintillation component. The obtained results represent a major breakthrough toward the ${\mathrm{TeO}}_2$-based version of the CUORE Upgrade with Particle IDentification (CUPID), a ton-scale cryogenic $0\nu \beta \beta$ experiment proposed as a followup to the Cryogenic Underground Observatory for Rare Events (CUORE) project with particle identification. The CUORE experiment recently began a search for neutrinoless double-$\beta$ decay of ${}^{130}\mathrm{Te}$ with an array of 988 125-${\mathrm{cm}}^3{\mathrm{TeO}}_2$ bolometers. The lack of $\alpha$ discrimination in CUORE makes $\alpha$ decays at the detector surface the dominant background component, at the level of $\approx 0.01$ counts/(keV kg y) in the region of interest. We show here, for the first time with a CUORE-size bolometer and using the same technology as CUORE for the readout of both heat and light signals, that surface $\alpha$ background can be fully rejected.

The half-lives of ${}^{135}\mathrm{La}$ and ${}^{132}\mathrm{La}$ were determined via serial gamma spectroscopy, and the half-life of ${}^{135}\mathrm{La}$ was further determined by a high-precision ionization-chamber measurement. The results are 18.91(2) hr for ${}^{135}\mathrm{La}$ and 4.59(4) hr for ${}^{132}\mathrm{La}$ compared with the previously compiled values of 19.5(2) hr and 4.8(2) hr, respectively. These lanthanum isotopes comprise a medically interesting system with positron emitter ${}^{132}\mathrm{La}$ and Auger-electron emitter ${}^{135}\mathrm{La}$ forming a theranostic pair for internal diagnostics and therapeutics. The precise half-lives are necessary for proper evaluation of their value in medicine and for a more representative tabulation of nuclear data.

We investigate the possibility that some nuclei show density distributions with a depletion in the center, a semibubble structure, by using a Hartree-Fock plus Bardeen-Cooper-Schrieffer approach. We separately study the proton, neutron, and matter distributions in 37 spherical nuclei mainly in the $s\text{−}d$ shell region. We found a relation between the semibubble structure and the energy splitting of spin-orbit partner single particle levels. The presence of semibubble structure reduces this splitting, and we study its consequences on the excitation spectrum of the nuclei under investigation by using a quasiparticle random-phase-approximation approach. The excitation energies of the low-lying $4^{+}$ states can be related to the presence of semibubble structure in nuclei.

The experimental search for the chiral magnetic effect in heavy-ion collisions is based on charge-dependent correlations between emitted particles. Recently, a sensitive observable comparing event-by-event distributions of the charge splitting projected on the directions along and perpendicular to the direction of the elliptic flow has been proposed. The results of a (3 + 1)-dimensional hydrodynamic model show that the preliminary experimental data of the STAR Collaboration can be explained as due to background effects, such as resonance decays and local charge conservation in the particle production. A related observable based on the third-order harmonic flow is proposed to further investigate such background effects in charge-dependent correlations.

We study the $K^{*}$ meson reduction in heavy-ion collisions by focusing on the hadronic effects on the $K^{*}$ meson abundance. We evaluate the absorption cross sections of the $K^{*}$ and $K$ meson by light mesons in the hadronic matter, and further investigate the variation in the meson abundances for both particles during the hadronic stage of heavy-ion collisions. We show how the interplay between the interaction of the $K^{*}$ meson and kaon with light mesons in the hadronic medium determines the final yield difference of the statistical hadronization model to the experimental measurements. For the central Au+Au collision at $\sqrt{s_{NN}}=200$ GeV, we find that the $K^{*}/K$ yield ratio at chemical freeze-out decreases by $37\%$ during the expansion of the hadronic matter, resulting in the final ratio comparable to STAR measurements of 0.23 $\pm 0.05$.