Precision mass measurements of neutron-rich rhodium isotopes have been performed at the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. We report results on ground- and isomeric-state masses in ${}^{110,112,114,116,118}\mathrm{Rh}$ and the very first mass measurement of ${}^{120}\mathrm{Rh}$. The isomeric states were separated and measured for the first time using the phase-imaging ion-cyclotron-resonance (PI-ICR) technique. For ${}^{112}\mathrm{Rh}$, we also report new half-lives for both the ground state and the isomer. The results are compared to theoretical predictions using the BSkG1 mass model and discussed in terms of triaxial deformation.

The high-spin spectroscopy of ${}^{61}\mathrm{Ni}$ has been studied by the fusion-evaporation reaction ${}^{54}\mathrm{Cr}({}^{11}\mathrm{B},4n){}^{61}\mathrm{Ni}$ at a beam energy of 54 MeV. One dipole band and one quadrupole band in ${}^{61}\mathrm{Ni}$ are established for the first time. They can be respectively taken as candidates of magnetic and antimagnetic rotational bands based on the comparison with the well-known cases in ${}^{110}\mathrm{Cd}$ and the calculations of the classical particles-plus-rotor model. These two new bands are further investigated by the microscopic tilted axis cranking covariant density functional theory with configurations $\pi \left[{\left(1f_{7/2}\right)}^{-1}{\left(fp\right)}^1\right]\otimes \nu \left[{\left(1g_{9/2}\right)}^1{\left(fp\right)}^4\right]$ and $\pi \left[{\left(1f_{7/2}\right)}^{-2}{\left(fp\right)}^2\right]\otimes \nu \left[{\left(1g_{9/2}\right)}^1{\left(fp\right)}^4\right]$, respectively, and good agreement between experiment and calculation is obtained. By examining the angular-momentum coupling, the dipole band is characterized by the shears mechanism whereas the quadrupole band is characterized by the two-shears-like mechanism. This study provides evidence for possible coexistence of magnetic and antimagnetic rotations in the $A\approx 60$ mass region.

The fusion evaporation residue cross sections for the decay of the compound nuclear system ${}^{287,288,290,292}\mathrm{Fl}^{*}$ via $2n$- to $5n$-decay channels, synthesized in ${}^{239,240,242,244}\mathrm{Pu}+{}^{48}\mathrm{Ca}$, are studied using the dynamical cluster-decay model (DCM), including quadrupole deformations ${\beta }_{2i}$ for compact hot orientations ${\theta }_i$ at various excitation energies $E^{*}=32.5$ to 52.6 MeV. For the nucleus-nucleus interaction potentials, we have employed the Skyrme energy density functional based on the semiclassical extended Thomas-Fermi approach under frozen density approximation. Here, within the DCM, the Skyrme forces used are SLy4, ${\mathrm{SkM}}^{*}$, and, KDE0(v1). The DCM makes use of a single parameter, the neck-length parameter $\mathrm{\Delta }R$ that takes different values for different processes at a given temperature and provides an excellent fit to the measured data, independently of the choice of Skyrme force used. We make predictions of probable fusion-fission and quasifission mass regions of fragments and then calculate the evaporation residue cross sections ${\sigma }_{\mathrm{ER}}$ for experimentally unobserved neutron channels. Further, the product $P_{\mathrm{CN}}{P}_{\mathrm{surv}}$ of compound nucleus (CN) fusion probability $P_{\mathrm{CN}}$ and survival probability $P_{\mathrm{surv}}$ is calculated to determine the reduced evaporation residue cross section ${\sigma }_{\mathrm{ER}}/{\sigma }_{\mathrm{fusion}}$, denoted as ${\sigma }_{\mathrm{ER}}^{\mathrm{reduced}}$, and we have seen that $P_{\mathrm{surv}}$ is the main dominant factor in the product $P_{\mathrm{CN}}{P}_{\mathrm{surv}}$. To this end, we have analyzed the effects of mass asymmetry and isospin effect of target nucleus on the ${\sigma }_{\mathrm{ER}}$ and have found that the ${\sigma }_{\mathrm{ER}}$ for the production of superheavy element ${\mathrm{Fl}}^{*}$ increases slowly with increasing neutron number of the target nucleus. We have also searched for all possible target-projectile combinations forming the hot compound nucleus ${\mathrm{Fl}}^{*}$ at the excitation energy $E^{*}$ for compact-hot configurations and have also calculated the fusion evaporation residue cross sections for the proposed new reactions synthesizing Fl.

We develop the formalism for calculating the decay rate of neutrinoless double $\beta$ decay to the $2^{+}$ excited states within the L-R symmetric model. We consider the effects from induced hadronic currents up to next to leading order. The quasiparticle random phase approximation method in a spherical basis is adopted for the nuclear many-body calculation and the corresponding nuclear matrix elements are given. Also, the phase space factors are obtained with numerical electron wave functions. Our results suggest that the nuclear matrix elements are nucleus dependent and they are generally smaller than that of the decay to the ground states. And finally, we give a naive analysis of how current experiment data constrains the L-R symmetric model.

The PHENIX experiment reports systematic measurements at the Relativistic Heavy Ion Collider of $\varphi$-meson production in asymmetric $\mathrm{Cu}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ and in $\mathrm{U}+\mathrm{U}$ collisions at $\sqrt{s_{NN}}=193\mathrm{GeV}$. Measurements were performed via the $\varphi \to K^{+}{K}^{-}$ decay channel at midrapidity $\left|\eta \right|<0.35$. Features of $\varphi$-meson production measured in $\mathrm{Cu}+\mathrm{Cu}, \mathrm{Cu}+\mathrm{Au}, \mathrm{Au}+\mathrm{Au}$, and $\mathrm{U}+\mathrm{U}$ collisions were found to not depend on the collision geometry, which was expected because the yields are averaged over the azimuthal angle and follow the expected scaling with nuclear-overlap size. The elliptic flow of the $\varphi$ meson in $\mathrm{Cu}+\mathrm{Au}, \mathrm{Au}+\mathrm{Au}$, and $\mathrm{U}+\mathrm{U}$ collisions scales with second-order-participant eccentricity and the length scale of the nuclear-overlap region (estimated with the number of participating nucleons). At moderate $p_T, \varphi$-meson production measured in $\mathrm{Cu}+\mathrm{Au}$ and $\mathrm{U}+\mathrm{U}$ collisions is consistent with coalescence-model predictions, whereas at high $p_T$ the production is in agreement with expectations for in-medium energy loss of parent partons prior to their fragmentation. The elliptic flow for $\varphi$ mesons measured in $\mathrm{Cu}+\mathrm{Au}$ and $\mathrm{U}+\mathrm{U}$ collisions is well described by a ($2+1$)-dimensional viscous-hydrodynamic model with specific-shear viscosity $\eta /s=1/4\pi$.

We investigate the differences and analogies between the equation of motion phonon method (EMPM) and second Tamm-Dancoff and random-phase approximations (STDA and SRPA) paying special attention to the problem of spurious center-of-mass (c.m.) admixtures. In order to compare them on an equal footing, we perform self-consistent calculations of the multipole strength distributions in selected doubly magic nuclei within a space including up to two-particle–two-hole (2p-2h) basis states using the unitary correlation operator method two-body intrinsic Hamiltonian and we explore the tools each approach supplies for removing the spurious c.m. admixtures. We find that the EMPM and STDA yield exactly the same results when the same intrinsic Hamiltonian is used and the coupling of the Hartree-Fock state with the 2p-2h space is neglected, but, unlike STDA and SRPA, the EMPM offers the possibility to completely remove c.m. admixtures.

We argue why the recently observed $T_{cc}$ could either be a compact multiquark configuration or a loosely bound molecular configuration composed of charmed mesons, whereas the $X\left(3872\right)$ is most likely a molecular configuration. The argument is based on different short range interactions for these tetraquark states coming from the color-color and color-spin interaction in a quark model, and the presence of a common strong $D$-wave mixing at larger distance similar to the deuteron case, which for the molecular configurations leads to large sizes. Such an analogy at large distance allows us to calculate the transverse momentum dependence of the loosely bound molecular configuration of tetraquarks produced in heavy ion collisions using the coalescence model that successfully reproduces the deuteron data using the proton spectra. The ratio of the integrated $X\left(3872\right)$ yield obtained from our method to the $\psi \left(2S\right)$ yield obtained from the statistical hadronization model method is calculated to be $0.806\pm 0.234$, which is a factor of 2.47 larger than that obtained by using statistical model predictions for both particles and in line with the data from the CMS experiment. As the previously calculated transverse momentum distribution of the $T_{cc}$ assuming the structure to be a compact multiquark configuration is markedly different, experimental measurements of the transverse distribution of the tetraquark states will discriminate between their two possible structures.

The bulk properties of nuclear matter and neutron stars with the newly generated relativisticinteraction Dev Bhoomi Himachal Pradesh (DBHP) are investigated, which provides an opportunity to modify the coupling parameters keeping in view the finite nuclei, nuclear matter, PREX-II data for neutron skin thickness in ${}^{208}\mathrm{Pb}$, and astrophysical constraints. The relativistic interaction has been generated by including all possible self and mixed interactions among $\sigma$, $\omega$, and $\rho$ mesons up to the quartic order satisfying the naturalness behavior of parameters. A covariance analysis is performed to assess the statistical uncertainties of the model parameters and observables of interest along with correlations amongst them. We obtained a value of neutron skin thickness for the ${}^{208}\mathrm{Pb}$ nucleus of $\mathrm{\Delta }{r}_{\mathrm{np}}=0.24\pm 0.02$ fm. The maximum gravitational mass of a neutron star and the radius corresponding to the canonical mass ($R_{1.4}$) come out to be $2.03\pm 0.04$ $M_{\odot }$ and $13.39\pm 0.41$ km, respectively. The dimensionless tidal deformability $\mathrm{\Lambda }$ for a neutron star is also analyzed.

Transfer reactions are essential to determine spectroscopic factors and astrophysical reaction rates. However, their theoretical evaluation is typically effected using standard reaction theory, from which structure degrees of freedom are absent. While reaction cross sections have been implemented in the frame of the no-core shell model with continuum, this model can be applied in practice only to the lightest nuclei. The use of the core $+$ valence nucleon picture is then necessary to include internucleon correlations in reaction cross sections involving medium nuclei. For this, we will use the recently developed coupled-channel Gamow shell model (GSM-CC) for direct reactions and extend it to the evaluation of transfer cross sections. As an example, we will study the ${}^{40}\mathrm{Ca}(d,p)$ transfer reaction with GSM-CC. Experimental data can be successfully reproduced, but at the price of the use of a very phenomenological Hamiltonian.

Masses of ${}^{112}\mathrm{Sn}$ projectile fragments were measured employing isochronous mass spectrometry at the Cooler Storage Ring in Lanzhou. Different from the previous data analysis method, relying on the arithmetic mean revolution times of the stored fragments, we introduce an exponentially modified Gaussian function to describe the asymmetric peak shapes. This new approach enables us to properly deconvolute the overlapping peaks of stored ions and to accurately determine their masses. The mass excesses of ${}^{103}\mathrm{Sn}$ and the low-lying $1/2^{-}$ isomers in ${}^{87}\mathrm{Mo}, {}^{91}\mathrm{Ru}$, and ${}^{95}\mathrm{Pd}$ were directly measured for the first time, and the masses of ${}^{69}\mathrm{As}, {}^{73}\mathrm{Br}, {}^{75}\mathrm{Kr}, {}^{79}\mathrm{Sr}$, and ${}^{81}\mathrm{Y}$ were redetermined with higher precision comparable to that of Penning-trap mass spectrometry. Based on the new mass value of ${}^{103}\mathrm{Sn}$, the previously unknown masses of ${}^{104}\mathrm{Sb}, {}^{107}\mathrm{Te}, {}^{108}\mathrm{I}, {}^{111}\mathrm{Xe}$, and ${}^{112}\mathrm{Cs}$ were obtained indirectly by using the literature proton and/or $\alpha$ decay energies. Systematic trends of the excitation energies of the $J^{\pi }=1/2^{-}$ isomers in the $N=47,49$ isotones are well reproduced by the state-of-the-art shell model calculations with the tensor forces included.

We report on measurements of the differential cross section $d\sigma /d\mathrm{\Omega }$ in the energy region of $\sqrt{s}=2.5$–$2.9\mathrm{GeV}$ of the reaction $pp\to {\left\{pp\right\}}_s{\pi }^0$, where ${\left\{pp\right\}}_s$ is a ${}^{1}S_0$ proton pair. The experiment has been performed with the ANKE spectrometer at COSY-Jülich. The data reveal a peak in the energy dependence of the forward ${\left\{pp\right\}}_s$ differential cross section at the energy $\sqrt{s}=2.65\mathrm{GeV}$ with the width $\mathrm{\Gamma }=0.26\mathrm{GeV}$, and also the cross section slope changes its sign in the region of the observed peak. This is an indication for the excitation of a new $D\left(2650\right)$ resonant state, that may be a dibaryon resonance system consisting of two excited baryons $\mathrm{\Delta }\left(1232\right)$ and $N^{*}\left(1440\right)$.

The nuclear level density (NLD) is a fundamental measure of the complex structure of atomic nuclei at relatively high energies. Here we present the first model-independent measurement of the absolute partial NLD for a short-lived nucleus. For this purpose we adapt the recently introduced “shape method” for $\beta$-decay experiments, providing the shape of the $\gamma$-ray strength function for exotic nuclei. In this work, we show that combining the shape method with the $\beta$-Oslo technique allows for the extraction of the NLD of the populated states without the need for theoretical input. This development opens the way for the extraction of experimental NLDs far from stability with major implications in astrophysical and other applications. We benchmark our approach using data for the stable ${}^{76}\mathrm{Ge}$ nucleus, finding excellent agreement with previous experimental results. In addition, we present new experimental data and determine the absolute partial level density for the short-lived ${}^{88}\mathrm{Kr}$ nucleus. Our results suggest a fivefold increase in the NLD for the case of ${}^{88}\mathrm{Kr}$, compared to the recommended values from semimicroscopic Hartree-Fock Bogoliubov calculations recommended by the RIPL3 nuclear data library. However, our results are in good agreement with other semimicroscopic level density models. We demonstrate the impact of our method on the ${}^{87}\mathrm{Kr}(n,\gamma$) neutron capture rate and show that our experimental uncertainties for NLDs fulfill the requirements needed for astrophysical calculations predicting $r$-process abundances.

The measurement of environmental neutrons is particularly important in the search for new physics, such as dark matter particles, because neutrons constitute an often irreducible background source. The measurement of the neutron energy spectra in the sub-MeV scale is technically difficult because it requires a very good energy resolution and a very high $\gamma$-ray rejection power. In this study, we used a super-fine-grained nuclear emulsion, called nano imaging tracker, as a neutron detector. The main target of neutrons is the hydrogen (proton) content of emulsion films. Through a topological analysis, proton recoils induced by neutron scattering can be detected as tracks with submicrometric accuracy. This method shows an extremely high $\gamma$-ray rejection power, at the level of $5\times {10}^7\gamma /{\mathrm{cm}}^2$, which is equivalent to five years accumulation of environmental $\gamma$ rays, and a very good energy and direction resolution even in the sub-MeV energy region. In order to carry out this measurement with sufficient statistics, we upgraded the automated scanning system to achieve a speed of 250 g/(year machine). We calibrated the detector performance of this system with 880 keV monochromatic neutrons: a very good agreement with the expectation was found for all the relevant kinematic variables. The application of the developed method to a sample exposed at the INFN Gran Sasso surface laboratory provided the first measurement of sub-MeV environmental neutrons with a flux of $(7.6\pm 1.7)\times {10}^{-3}n/\left({\mathrm{cm}}^2\mathrm{s}\right)$ in the proton energy range between 0.25 and 1 MeV (corresponds to neutron energy range between 0.25 and 10 MeV), consistent with the prediction. The neutron energy and direction distributions also show a good agreement.

We calculate the longitudinal flow decorrelation coefficients, i.e., $r_n(\eta ,{\eta }_r)$ for $n=2,3$, in the presence of hydro-like flow and the global momentum conservation (GMC) constraint. The longitudinal flow decorrelation is weakened due to the GMC constraint. The GMC effect is sensitive to the total number of particles involved in GMC, the average longitudinal momentum, the transverse momentum, and the reference pseudorapidity. Our results of the $r_2(\eta ,{\eta }_{rA})/r_2(\eta ,{\eta }_{rB})$ ratio between two reference pseudorapidity bins are consistent with the experimental measurements. We predict that the modification effect of GMC on longitudinal flow decorrelation is more noticeable at BNL Relativistic Heavy Ion Collider energies than at CERN Large Hadron Collider energies. Our finding provides a new perspective for understanding the longitudinal flow decorrelation in relativistic heavy-ion collisions.

A fused silica Cherenkov detector was used to measure deuterium-tritium (DT) gammas during a set of 52 direct-drive cryogenic experiments performed at OMEGA. The detector was calibrated using the 4.4 MeV $\gamma$ from the first-excited state of carbon, which is produced when 14-MeV DT neutrons impinge upon a carbon puck. An approximate DT $\gamma$ spectrum as well as neutron yields from a standard neutron time-of-flight detector at OMEGA were used to calculate a DT $\gamma$-to-neutron branching ratio of $(8.42\pm 2.84)\times {10}^{-5}$. Assuming an excited-state to ground-state ratio of $2.1:1$, the measurement detailed in this work results in an approximate ground state only $\gamma$-to-neutron branching ratio of $2.72\times {10}^{-5}$. This value is somewhat lower than accelerator-based measurements of the ground-state DT $\gamma$ only.

Knockout nuclear reactions, in which a nucleon is removed from a nucleus as a result of the collision with another nucleus, have been widely used as an experimental tool, both to populate isotopes further removed from stability and to obtain information about the single-particle nature of the nuclear spectrum. In order to fully exploit the experimental information, theory is needed for the description of both the structure of the nuclei involved, and the dynamics associated with the nucleon removal mechanisms. The standard approach, using theoretical shell-model spectroscopic factors for the structure description coupled with an eikonal model of reaction, has been successful when used in the context of the removal of valence nucleons in nuclei close to stability. However, it has been argued that the reaction theory might need to be revisited in the case of exotic nuclei, more specifically for highly asymmetric nuclei in which the deficient species (neutrons or protons) is being removed. We present here a new formalism for the nucleon-removal and -addition reaction through knockout and transfer reactions, that treats consistently structure and reaction properties using dispersive optical potentials. In particular, our formalism includes the dynamical effects associated with the removal of a nucleon from the projectile, which might explain the long standing puzzle of the quenching of spectroscopic factors in nuclei with extreme neutrons-to-protons ratios.

We investigate the speed of sound in nuclear matter at finite temperature and density (chemical potential) in the nonlinear Walecka model. The numerical results suggest that the behaviors of sound speed are closely related to the the nuclear liquid-gas (LG) phase transition and the associated spinodal structure. The adiabatic sound speed is nonzero at the critical endpoint (CEP) in the mean-field approximation. We further derive the boundary of vanishing sound velocity in the temperature-density phase diagram, and point out the region where the sound wave equation is broken. The distinction between the speed of sound in nuclear matter and that in quark matter contains important information about the equation of state of strongly interacting matter at intermediate and high density. We also formulate the relations between differently defined speeds of sound using the fundamental thermodynamic relations.

We present ($3+1$)-dimensional [($3+1$)D] dynamical simulations of asymmetric nuclear collisions at the BNL Relativistic Heavy Ion Collider (RHIC). Employing a dynamical initial state model coupled to ($3+1$)D viscous relativistic hydrodynamics, we explore the rapidity dependence of anisotropic flow in the RHIC small system scan at 200 GeV center-of-mass energy. We calibrate parameters to describe central ${}^3\mathrm{He}+\mathrm{Au}$ collisions and make extrapolations to $d+\mathrm{Au}$ and $p+\mathrm{Au}$ collisions. Our calculations demonstrate that approximately 50% of the $v_3\left(p_T\right)$ difference between the measurements by the STAR and PHENIX Collaborations can be explained by the use of reference flow vectors from different rapidity regions. This emphasizes the importance of longitudinal flow decorrelation for anisotropic flow measurements in asymmetric nuclear collisions, and the need for ($3+1$)D simulations. We also present results for the beam energy dependence of particle spectra and anisotropic flow in $d+\mathrm{Au}$ collisions.