We derive a simple formula relating the cross section for light cluster production (defined via a coalescence factor) to the two-proton correlation function measured in heavy-ion collisions. The formula generalizes earlier coalescence-correlation relations found by Scheibl & Heinz and by Mrowczynski for Gaussian source models. It motivates joint experimental analyses of Hanbury-Brown–Twiss (HBT) and cluster yield measurements in existing and future data sets.

We performed an experimental search for the bound-state singlet deuteron predicted in some microscopic calculations. The predicted energy of this metastable level is in the vicinity of the deuteron disintegration threshold. This state should manifest itself in a two-photon transition following thermal neutron capture by protons. The experiment consists in the search for the second $\gamma$ ray in the cascade through a high-statistics measurement of $\gamma$-ray spectra after cold neutron capture by hydrogen nuclei. The upper limit $2\mu \mathrm{b}(2\sigma$ level) is obtained for the cross section of the singlet deuteron production with the binding energy in the range 10–125 keV.

Structure of weakly bound/unbound light nuclei is often related to the low-energy decay channels involving composite particles like deuteron or $\alpha$ particle. These channels are essential to understand the appearance of light nuclei in the Big Bang nucleosynthesis or the helium fusion. We generalize the Gamow shell model (GSM) in coupled-channel (GSM-CC) representation to include reaction channels with the composite particles. In the core + valence particle formulation, this unified microscopic approach for structure and reactions involving weakly bound/unbound nuclei can be also applied to study low-energy properties of heavy nuclei. As the first application of this generalized GSM-CC approach, we describe the structure of ${}^6\mathrm{Li}$ and deuteron-$\alpha$-particle elastic scattering using the same effective Furutani-Horiuchi-Tamagaki (FHT)-type nucleon-nucleon interaction. Asymptotically, the deuteron structure including its continuum is described using the ${\mathrm{N}}^3\mathrm{LO}$ chiral force. The bulk of the data, including low-energy spectrum of ${}^6\mathrm{Li}$, asymptotic normalization coefficients, and angular differential cross sections are satisfactorily described.

Relativistic hydrodynamic equations for particles with spin $\frac{1}{2}$ are used to determine the space-time evolution of the spin polarization in a boost-invariant and transversely homogeneous background. The hydrodynamic approach uses the forms of the energy-momentum and spin tensors based on the de Groot, van Leeuwen, and van Weert formalism. Our calculations illustrate how the formalism of hydrodynamics with spin can be used to determine physical observables related to the spin polarization and how the latter can be compared with the experimental data.

We study the charm quark elliptic flow $\left(v_2\right)$ in heavy ion as well as small system collisions by tracking the evolution history of quarks of different flavors within a multiphase transport model. The charm quark $v_2$ is studied as a function of the number of collisions the charm quark suffers with other quarks and then compared to the $v_2$ of lighter quarks. We find that the common escape mechanism is at work for both the charm and light quark $v_2$. However, contrary to the naive expectation, the hydrodynamics-type flow is found to contribute more to the final state charm $v_2$ than the light quark $v_2$. This could be explained by the smaller average deflection angle the heavier charm quark undergoes in each collision, so that heavy quarks need more scatterings to accumulate a significant $v_2$, while lighter quarks can more easily change directions with scatterings with their $v_2$ coming more from the escape mechanism. Our finding thus suggests that the charm $v_2$ is a better probe for studying the hydrodynamic properties of the quark-gluon plasma.

The yields of 42 projectile-like fragments (PLFs) and fission fragments and 36 target-like fragments (TLFs) were measured using off-line $\gamma$-ray spectroscopy in a thin target experiment involving the ${}^{136}\mathrm{Xe}+{}^{198}\mathrm{Pt}$ reaction. The center of target beam energy was 760.5 MeV $({\mathrm{E}}_{\mathrm{c}.\mathrm{m}.}=450$ MeV). The reported yields are compared with those from previous measurements for this reaction and with predictions of the GRAZING, di-nuclear systems (DNS), and improved quantum molecular dynamics (ImQMD) models. The yields of the TLFs and PLFs are, in general, substantially smaller than those previously observed at a beam energy of 1085 MeV. Neither the GRAZING nor the DNS model correctly describes the measured TLF and PLF yields in this lower- energy reaction but the ImQMD model describes these yields adequately.

When two heavy ions near the Fermi energy collide, a warm and low-density region can form in which fragments appear. This region is mainly dominated by proton $\left(p\right)$ and alpha $\left(\alpha \right)$ particles. In such an environment, the $\alpha$ particles interact with each other and, especially through strong resonances, form complex systems such as ${}^8\mathrm{Be}$ and ${}^{12}\mathrm{C}$. Our experiments show that ${}^{70\left(64\right)}\mathrm{Zn}\left({}^{64}\mathrm{Ni}\right)+{}^{70\left(64\right)}\mathrm{Zn}\left({}^{64}\mathrm{Ni}\right)$ reactions at $E/A=35$ MeV/nucleon levels of ${}^8\mathrm{Be}$ appear around relative energies $E_{ij}=0.092$ MeV, 3.03 MeV as well as above 10 and 100 MeV. We propose a different method to derive the correlation function based on the relative transverse energy distribution to minimize the experimental uncertainties. For the $3\alpha$ systems, multiresonance processes give rise to excited levels of ${}^{12}\mathrm{C}$. In particular, the Hoyle state at 7.654 MeV excitation energy shows a decay component through the ground state of ${}^8\mathrm{Be}$ and also components where two different $\alpha$ couples are at relative energies consistent with the ground state of ${}^8\mathrm{Be}$ at the same time.

Due to a directional asymmetry of neutrino emission caused by parity violation, a sample of radioactive atoms experiences a small recoil force from neutrino radiation accompanying electron capture by polarized nuclei. An expression for this force is obtained for the case of allowed nuclear transitions. Prospects to measure this force by the use of modern micromechanical devices are considered. Numerical estimates for the force are presented for a number of most suitable radioactive isotopes. Potential applications for the weak interaction studies are discussed, including the possibility to search for hypothetical Lorentz invariance violation.

Viable theoretical predictions of photon strength functions (PSFs) covering the whole nuclear chart are of great interest for different nuclear applications, including, in particular, nuclear astrophysics. Recently, such a global PSF model consisting of axially deformed Hartree-Fock-Bogolyubov (HFB) + quasiparticle random phase approximation (QRPA) calculations with the D1M Gogny interaction and a phenomenological low-energy contribution was proposed. In the present paper, we test this model predictions against previously published data from measurements of multistep $\gamma$ cascades following neutron capture on isolated resonances performed with the DANCE detector. Such data present a stringent test of the PSFs models, in particular for the properties of the $M1$ scissors mode and the possible low-energy PSFs enhancement. A detailed comparison is made for spectra obtained from resonances for spherical, quasispherical, and well-deformed nuclei. This comparison indicates that the location and strength of the scissors mode is reasonably described by the HFB + QRPA approach. Moreover, a low-energy PSF contribution, not predicted by the HFB + QRPA calculation of the photoabsorption PSF, should be present in all nuclei. A systematics of this low-energy contribution, assumed in the $M1$ PSF, is proposed.

Background: Calculating microscopic optical potentials for elastic nucleon-nucleus scattering has already led to large body of work in the past. For folding first-order calculations the nucleon-nucleon ($NN$) interaction and the one-body density of the nucleus were taken as input to rigorous calculations in a spectator expansion of the multiple scattering series.

Purpose: Based on the Watson expansion of the multiple scattering series we employ a nonlocal translationally invariant nuclear density derived from a chiral next-to-next-to-leading order (NNLO) and the very same interaction for consistent full-folding calculation of the effective (optical) potential for nucleon-nucleus scattering for light nuclei.

Methods: The first order effective (optical) folding potential is computed by integrating over the nonlocal, translationally invariant NCSM one-body density and the off-shell Wolfenstein amplitudes A and C. The resulting nonlocal potential serves as input for a momentum-space Lippmann-Schwinger equation, whose solutions are summed to obtain the nucleon-nucleus scattering observables.

Results: We calculate scattering observables, such as total, reaction, and differential cross sections as well as the analyzing power and the spin-rotation parameter, for elastic scattering of protons and neutrons from ${}^4\mathrm{He}$, ${}^6\mathrm{He}$, ${}^{12}\mathrm{C}$, and ${}^{16}\mathrm{O}$, in the energy regime between 100 and 200 MeV projectile kinetic energy, and compare to available data.

Conclusions: Our calculations show that the effective nucleon-nucleus potential obtained from the first-order term in the spectator expansion of the multiple scattering expansion describes experiments very well to about 60 degrees in the center-of-mass frame, which coincides roughly with the validity of the NNLO chiral interaction used to calculate both the $NN$ amplitudes and the one-body nuclear density.

Background: Low-lying collective excitations of the inner crust matter in neutron stars are expected to affect observables such as the quasiperiodic oscillation in giant flares or cooling of the inner crust in transient phenomena. The coupling between the Anderson-Bogoliubov (AB) superfluid phonon in superfluid neutron gas and collective excitations of nuclear clusters is crucially important.

Purpose: Our aim is to describe the characteristics of the low-lying excitation modes of the superfluid inner crust matter, focusing on quadrupole excitations around a spherical nuclear cluster. We studied the effect of the inhomogeneous structure of the inner crust matter on the AB phonon of neutron superfluid and on the possible quadrupole shape vibration of clusters.

Methods: The coordinate-space Hartree-Fock-Bogoliubov method and the quasiparticle random phase approximation formulated in a spherical Wigner-Seitz cell were used to describe the neutron superfluidity and low-lying collective excitations. We performed systematic numerical calculations for the quadrupole excitations by varying the neutron chemical potential and the number of protons in the cell.

Results: The calculated results indicate the appearance of both AB phonon and quadrupole shape vibration of the cluster with small mixing between the two collective modes. The quadruple AB phonon is similar to that in the uniform superfluid, apart from the small admixture of the shape vibration of cluster. The excitation energy and the collectivity of the cluster vibration mode show a strong and oscillatory dependence on the neutron chemical potential (the neutron gas density), resulting in softening and instability under certain conditions. This is due to the resonance shell effect, where unbound, but resonant single-particle states of neutrons are crucially important.

Conclusions: The AB phonon of the superfluid neutron gas and the quadrupole shape vibration of the nuclear cluster coexist in the inner crust. The coupling between the AB phonon and the quadrupole shape vibration is weak. The collectivity of the quadrupole shape vibration is controlled by the resonance shell effect, which suggests that the appearance of deformed nuclear clusters is possible in any layer of the inner crust.

We suggest a generalized method for elimination of spurious admixtures (SA) from intrinsic nuclear excitations described within the quasiparticle random-phase approximation (QRPA). Various kinds of SA corrections are treated at the same theoretical ground. The known corrections are well reproduced. As relevant cases, we consider subtraction of SA related with (i) violation of the translational invariance (isovector $E1$ and isoscalar toroidal and compression $E1$ modes), (ii) pairing-induced nonconservation of the particle number $\left(E2\right(K=0)$ and $E0$ modes), and (iii) rotational invariance $\left(E2\right(K=1)$ and $M1(K=1)$ modes). The SA subtraction can be done at the level of QRPA states, electromagnetic responses, and even transition operators. The additional deformation-induced corrections for $E1$ excitations are proposed and shown to be essential for the compression isoscalar mode. The accuracy of the method is demonstrated by Skyrme QRPA calculations for axially deformed ${}^{154}\mathrm{Sm}$.

We study multiparticle azimuthal correlations in relativistic heavy-ion collisions at a center-of-mass energy of 200 GeV. We use the impact parameter-dependent Glasma model to initialize the viscous hydrodynamic simulation MUSIC and employ the UrQMD transport model for the low-temperature region of the collisions. In addition, we study effects of local charge and global momentum conservation among the sampled particles. With the exception of the lowest-order three-particle correlator $C_{112}$, our framework provides a good description of the existing charge-inclusive azimuthal correlation data for Au+Au and U+U collisions at the Relativistic Heavy-Ion Collider (RHIC). We also present results for charge-dependent two- and three-particle correlators in Au+Au and U+U collisions and make predictions for isobar (Ru+Ru and Zr+Zr) collisions to provide a much-needed baseline for the search for the chiral magnetic effect at RHIC.

For the first time, we present the empirical evidence of superrigid character of the “flat” superdeformed bands in the Tl and Pb isotopes. For this purpose, we have used various rotational energy formulas. The free parameters of superdeformed (SD) bands in the Tl and Pb isotopes have been extracted and systematically studied to obtain the proposed empirical evidence. In particular, the intraband transition energies of the SD bands have been split into rotational and shape fluctuation energies. The role of the vibrational factor in the evolution of dynamic moment of inertia, softness parameter, alignment, and effective pairing gap parameter of the flat SD bands has been studied. Using these models, two distinct natures have been identified for the SD bands in the Tl and Pb isotopes. Our study establishes the role of shape fluctuations, vibrational effect, deformation, and pairing correlations for the unusual behavior of the dynamic moment of inertia in the flat SD bands of the $A\approx 190$ mass region.

Thermodynamic functions, the (higher-order) fluctuations and correlations of conserved charges at ${\mu }_B=0$, and the Fourier coefficients of net-baryon density at imaginary ${\mu }_B$, are considered in the framework of a Hagedorn bag-like model with a crossover transition. The qualitative behavior of these observables is found to be compatible with lattice QCD results. Fair quantitative description of the lattice data is obtained when quasiparticle-type quarks and gluons with nonzero masses are introduced into the bag spectrum. The equation of state of the model exhibits a smooth and wide crossover transition.

Neutron-transfer reactions with fast secondary beams of ${}^{17}\mathrm{Ne}, {}^{15}\mathrm{O}$, and ${}^9\mathrm{C}$ have been studied with the HiRA and CAESAR arrays. Excited states of ${}^{18}\mathrm{Ne}, {}^{16}\mathrm{O}$, and ${}^{10}\mathrm{C}$ in the continuum have been identified using invariant-mass spectroscopy. The best experimental resolution of these states is achieved by selecting events where the decay fragments are emitted transverse to the beam direction. We have confirmed a number of spin assignments made in previous works for the negative-parity states of ${}^{18}\mathrm{Ne}$. In addition we have found new higher-lying excited states in ${}^{16}\mathrm{O}$ and ${}^{18}\mathrm{Ne}$, some of which fission into two ground-state ${}^8\mathrm{Be}$ fragments. Finally for ${}^{10}\mathrm{C}$, a new excited state was observed. These transfer reactions were found to leave the remnant of the ${}^9\mathrm{Be}$ target nuclei at very high excitation energies and may be associated with the pickup of a deeply bound ${}^9\mathrm{Be}$ neutron.

The hypothesis of limiting fragmentation (LF), or, as it has been otherwise recently called, longitudinal scaling, is an interesting phenomena in the high-energy multiparticle production process. This paper discusses different regions of phase space and their importance in hadron production, giving special emphasis on the fragmentation region. Although it was conjectured as a universal phenomenon in high-energy physics, with the advent of higher center-of-mass energies, it has become prudent to analyze and understand the validity of such a hypothesis in view of the increasing inelastic nucleon-nucleon cross section (${\sigma }_{\mathrm{in}}$). In this work, we revisit the phenomenon of limiting fragmentation for nucleus-nucleus ($A$+$A$) collisions in the pseudorapidity distribution of charged particles at various energies. We use energy-dependent ${\sigma }_{\mathrm{in}}$ to transform the charged-particle pseudorapidity distributions ($d{N}_{\mathrm{ch}}^{AA}/d\eta$) into differential cross section per unit pseudorapidity ($d{\sigma }^{AA}/d\eta$) of charged particles and study the phenomenon of LF. We find that in $d{\sigma }^{AA}/d\eta$ LF seems to be violated at Large Hadron Collider (LHC) energies while considering the energy-dependent ${\sigma }_{\mathrm{in}}$. We also perform a similar study using the A Multi-Phase Transport model with a string melting scenario and also find that LF is violated at LHC energies.

The production cross sections for the medical isotope ${}^{99}\mathrm{Mo}$ were measured using the ${}^{100}\mathrm{Mo}(n,2n)$ reaction at average neutron energies of $10.95\pm 0.45, 13.97\pm 0.68, 16.99\pm 0.53$, and $20.00\pm 0.58$ MeV using offline $\gamma$-ray spectroscopy. The neutron beam was generated using the ${}^{\mathrm{nat}}\mathrm{Li}(p,n)$ reaction at the 14UD BARC-TIFR Pelletron facility, Mumbai, India. The uncertainties in the measured data were calculated using covariance analysis. The experimental results were compared with the existing data libraries ENDF/B-VII.1, JENDL-4.0, JEFF-3.2, and CENDL-3.1. The present results were also reproduced and compared with the theoretical nuclear model codes talys-1.9 and alice-2017 using different input descriptions. A modified set of parameters were also used in talys-1.9 to fit the existing data more accurately. The present findings show a good agreement with the theoretical predictions and with the existing experimental results from the different data libraries. In addition to this, a comparative study have also been performed between the literature data of $(n,p), (n,2n)$, and $(n,\alpha )$ reaction cross sections at 14.5 MeV using various systematic formulas. The outcomes of the present work are important for the advancement of medical accelerators, dosimetry, and fast reactor systems.