The low-lying level structure of the unbound neutron-rich nucleus ${}^{13}$Be has been investigated via breakup on a carbon target of secondary beams of ${}^{14,15}$B at 35 MeV/nucleon. The coincident detection of the beam velocity ${}^{12}$Be fragments and neutrons permitted the invariant mass of the ${}^{12}\mathrm{Be}+n$ and ${}^{12}\mathrm{Be}+n+n$ systems to be reconstructed. In the case of the breakup of ${}^{15}$B, a very narrow structure at threshold was observed in the ${}^{12}\mathrm{Be}+n$ channel. Analysis of the ${}^{12}\mathrm{Be}+n+n$ events demonstrated that this resulted from the sequential decay of the unbound ${}^{14}$Be(2${}^{+}$) state rather than a strongly interacting $s$-wave virtual state in ${}^{13}$Be, as had been surmised in stable beam fragmentation studies. Single-proton removal from ${}^{14}$B was found to populate a broad low-lying structure some 0.7 MeV above the neutron-decay threshold, in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with ($0-3)\hslash \omega$ shell-model calculations, the low-lying structure is concluded to arise from closely spaced $J^{\pi }=1/2^{+}$ and 5/2${}^{+}$ resonances ($E_r=0.40\pm 0.03$ and 0.85${}_{-0.11}^{+0.15}$ MeV), while the broad higher-lying feature is a second 5/2${}^{+}$ level ($E_r=2.35\pm 0.14$ MeV). Taken in conjunction with earlier studies, the results suggest that the lowest 1/2${}^{+}$ and 1/2${}^{-}$ levels lie relatively close together below 1 MeV.

Background: Several inclusive and few exclusive [evaporation residue (ER) gated] measurements for symmetric systems reported in the literature describe the anomalous deviations of light particle evaporation spectra from the statistical model predictions. However, no consistent description exists for these deviations.

Purpose: To establish the consistent interpretation of reported anomalous deviations.

Method: The inclusive and exclusive measurements of $\alpha$-particle, proton, and neutron spectra were carried out for the fusion of two relatively symmetric systems ${}^{28}$Si + ${}^{45}$Sc (E${}_{\mathrm{lab}}$ = 125 MeV and l${}_{\max }$ = 47$\hslash$) and ${}^{32}$S + ${}^{45}$Sc (E${}_{\mathrm{lab}}$ = 125 MeV and l${}_{\max }$ = 43$\hslash$) leading to the compound nuclei ${}^{73}$Br and ${}^{77}$Rb with excitation energies 78 MeV and 71 MeV, respectively.

Results: The experimental light particle spectra for both the reactions show anomalous deviations from the statistical model predictions. The charged particles spectra are found to be suppressed, whereas the neutron spectra exhibit a bump at the higher energy tail. These spectra are investigated in terms of the modification of the important ingredients of the statistical model viz. the level density parameter, rescaling of the yrast line, and the use of $l$ value suggested by the dynamical models.

Conclusions: It is conjectured that the higher partial waves do not fuse, but result in the formation of a deformed dinuclear system. The binding energy of neutrons is reduced while those for protons and $\alpha$ particles are enhanced in the deformed dinuclear system as compared to those in the shape-equilibrated system. Hence, the higher partial waves inhibit their contributions to the $\alpha$-particle spectra and lead to the preshape equilibrium of neutrons and protons, with the neutron emission dominating over the proton emission.

The production cross section of neutron-rich isotopes of Ca, Zn, Te, Xe, and Pt are predicted in the diffusive multinucleon transfer reactions with stable and radioactive beams. With these isotopes one can treat the neutron shell evolution beyond $N=28$, 50, 82, and 126. Because of the small cross sections, the production of nuclei near the neutron drip line requires the optimal choice of reaction partners and bombarding energies.

The time-dependent equations of motion for the pair-breaking effect were corroborated with a condition that fixes dynamically the number of particles on the two-fission fragment. The single-particle level scheme was calculated with the Woods–Saxon superasymmetric two-center shell model. This model provides a continuous variation of the energies from one nucleus up to two separated fragments. The dissipated energy resorts from the time-dependent pairing equations. A peculiar phenomenon was observed experimentally in cold fission: the odd partition yields are favored over the even ones. This odd-even effect for cold fission was explained microscopically.

In this paper we study the energy loss of jets in the Quark Gluon Plasma via the nuclear modification factor $R_{AA}$ for unidentified particles at high $p_{\mathrm{T}}$ ($\gtrsim$$10\mathrm{GeV}/\mathrm{c}$) in and out of the reaction plane of the collision. We argue that at such a high $p_{\mathrm{T}}$ there are no genuine flow effects and, assuming that the energy loss is only sensitive to initial characteristics such as the density and geometry, find that $R_{AA}$ depends linearly on the (rms) length extracted from Glauber simulations. Furthermore, we observe that for different centrality classes the density dependence of the energy loss enters as the square root of the charged-particle multiplicity normalized to the initial overlap area. The energy loss extracted for BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider data from the $R_{AA}$ is found to exhibit a universal behavior.

The role of $\Lambda$ hyperons is investigated in the dynamical collapse of a nonrotating massive star to a black hole using a one-dimensional general-relativistic (gr1d) code. The dynamical formation and evolution of a protoneutron star (PNS) to a black hole is followed using various progenitor models, adopting a hyperonic equation of state (EoS) generated by Shen et al. [Shen, Toki, Oyamatsu, and Sumiyoshi, Astrophys. J., Suppl. Ser. 197, 20 (2011)]. The results are compared with those of a nuclear EoS by Shen et al. [Shen, Toki, Oyamatsu, and Sumiyoshi, Nucl. Phys. A 637, 435 (1998)] to understand the role of $\Lambda$ hyperons in the core-collapse supernova. The neutrino signals that may be used as a probe for core collapse is also discussed. Further, an exotic EoS may support a cold neutron star with a maximum mass much lower than that of a PNS. In this regard, the metastability of a PNS in the presence of $\Lambda$ hyperons is studied in the long-time evolution of the progenitors, relevant to supernova SN1987A.

Fast-neutron-capture cross-section data on ${}^{136}\mathrm{Xe}$ have been measured with the activation method between 0.4 and 14.8 MeV. The cross section was found to be of the order of 1 mb at the eleven energies investigated. This result is important to interpret potential neutron-induced backgrounds in the enriched xenon observatory and KamLAND-Zen neutrinoless double-$\beta$ decay searches that use xenon as both source and detector. A high-pressure sphere filled with ${}^{136}\mathrm{Xe}$ was irradiated with monoenergetic neutrons produced by the reactions ${}^3$H($p,n$)${}^3$He, ${}^2$H($d,n$)${}^3$He, and ${}^3$H($d,n$)${}^4$He. Indium and gold monitor foils were irradiated simultaneously with the ${}^{136}\mathrm{Xe}$ to determine the incident neutron flux. The activities of the reaction products were measured with high-resolution $\gamma$-ray spectroscopy. The present results are compared to predictions from ENDF/B-VII.1 and TENDL-2012.

The high-spin level structure of the semi-magic nucleus ${}^{91}\mathrm{Nb}$ has been investigated via the ${}^{82}$Se(${}^{14}$N,$5n$)${}^{91}\mathrm{Nb}$ reaction at a beam energy of 60 MeV. Based on these experimental results, a new level scheme is established that modifies and extends earlier schemes. Shell-model calculations have been carried out to interpret the level structure of ${}^{91}\mathrm{Nb}$. The calculated results show that the inclusion of neutron particle-hole excitation across the $N=50$ shell gap is essential to adequately describe states above $I=(21/2–23/2)\hslash$, with excitation energies above $\sim$6.0 MeV.

The proton inelastic scattering of ${}^{24}\mathrm{O}$($p,p^{\prime }$) at 62 MeV/nucleon is described by a self-consistent microscopic calculation with the continuum particle-vibration coupling (cPVC) method. The SLy5, SkM*, and SGII parameters are adopted as alternative effective nucleon-nucleon interactions. For all the Skyrme parameters the cPVC calculation reproduces reasonably well the absolute values of the first and second peaks of the excitation energy spectrum of ${}^{24}\mathrm{O}$ and the absolute value of the angular distribution corresponding to the first peak at 4.65 MeV. The relative energy between the two peaks is well reproduced by the cPVC method with SLy5 and SkM*. The role of the cPVC self-energy strongly depends on the effective interactions. The second peak around 7.3 MeV is suggested to be a superposition of the $3^{-}$ and $4^{+}$ states by the results with SLy5 and SGII, whereas the SkM* calculation indicates it is a pure $3^{-}$ state. This difference gives a rather strong interaction dependence of the angular distribution corresponding to the second peak.

We study nuclear dependencies of azimuthal asymmetries in the Drell-Yan lepton pair production in nucleon-nucleus collisions with polarized nucleons. We use the “maximal two-gluon correlation approximation,” so that we can relate the transverse-momentum-dependent quark distribution in a nucleus to that in a nucleon by a convolution with a Gaussian broadening. We use the Gaussian ansatz for the transverse momentum dependence of such quark distribution functions and obtain the numerical results for the nuclear dependencies. These results show that the $q_T$-integrated azimuthal asymmetries are suppressed.

The net-baryon production at forward rapidities is investigated considering the color glass condensate formalism. We assume that at large energies the coherence of the projectile quarks is lost and that the leading baryon production mechanism changes from recombination to independent fragmentation. The phenomenological implications for net-baryon production in $pp/pA/AA$ collisions are analyzed and predictions for Large Hadron Collider energies are presented.

Although the overall time scale for nuclear fission is long, suggesting a slow process, rapid shape evolution occurs in its later stages near scission. Theoretical prediction of the fission fragments and their characteristics are often based on the assumption that the internal degrees of freedom are equilibrated along the fission path. However, this adiabatic approximation may break down near scission. This is studied for the symmetric fission of ${}^{258,264}$Fm. The nonadiabatic evolution is computed using the time-dependent Hartree-Fock method, starting from an adiabatic configuration where the fragments have acquired their identity. It is shown that dynamics has an important effect on the kinetic and excitation energies of the fragments. The vibrational modes of the fragments in the post-scission evolution are also analyzed.

The highly forbidden ${\beta }^{-}$ decay of ${}^{48}\mathrm{Ca}$ is reexamined by performing shell-model calculations with the GXPF1A effective interaction. We examine the three available decay branches to the lowest $6^{+}$, $5^{+}$, and $4^{+}$ states of ${}^{48}$Sc, and extract a theoretical half-life of $T_{1/2}^{\beta }=5.2_{-1.3}^{+1.7}\times {10}^{20}{g}_A^{-2}$ yr for the ${\beta }^{-}$ decay, where $g_A$ is the value of the axial-vector coupling constant. The current half-life estimate suggests stronger competition between the single-$\beta$-decay and double-$\beta$-decay branches of ${}^{48}\mathrm{Ca}$ than previously expected on theoretical grounds.

I investigate the magicity of the isotopes ${}^{52}\mathrm{Ca}$ and ${}^{54}\mathrm{Ca}$, which was recently confirmed by two experimental measurements, and relate it to like-particle and neutron-proton tensor effects within a mean-field description. By analyzing Ca isotopes, it is shown that the like-particle tensor contribution induces shell effects that render these nuclei more magic than would be predicted by neglecting it. In particular, such induced shell effects are stronger in the ${}^{52}\mathrm{Ca}$ nucleus, and the single-particle gaps are increased in both isotopes due to the tensor force. By studying $N=32$ and $N=34$ isotones, neutron-proton tensor effects may be isolated and their role analyzed. It is shown that neutron-proton tensor effects lead to increasing $N=32$ and $N=34$ gaps, when going along isotonic chains, from ${}^{58}\mathrm{Fe}$ to ${}^{52}\mathrm{Ca}$ and from ${}^{60}\mathrm{Fe}$ to ${}^{54}\mathrm{Ca}$, respectively. Mean-field calculations are perfomed by employing one Skyrme parameter set, which was introduced in a previous work by fitting the tensor parameters together with the spin-orbit strength. The signs and values of the tensor strengths are thus checked within this specific application. The obtained results indicate that the employed parameter set, even if generated with a partial adjustment of the parameters of the force, leads to the correct shell behavior and provides, in particular, a description of the magicity of ${}^{52}\mathrm{Ca}$ and ${}^{54}\mathrm{Ca}$ within a pure mean-field picture with the effective two-body Skyrme interaction.

Background: Near N = 40, rapid development of collectivity has been inferred based on the low-energy level schemes of the even-even Fe and Cr isotopes and attributed to deformation arising primarily from the influence of the $\nu g_{9/2}$ intruder orbital. The level schemes of the odd-A Co and Fe isotopes, as well as the odd-odd Co and Mn isotopes, are also influenced by the $g_{9/2}$ orbital and suggest prolate deformation. However, scarce information is available regarding the neutron-rich odd-A Cr isotopes.

Purpose: Determine low-energy level schemes of the neutron-rich Cr isotopes approaching N = 40 and investigate the influence of the $\nu g_{9/2}$ orbital.

Method: Neutron-rich V isotopes were produced at the NSCL through projectile fragmentation. The $\beta$ decay of the V isotopes into Cr isotopes was studied, and the observed $\beta$-delayed $\gamma$ rays were used to determine the low-energy level schemes of the neutron-rich Cr isotopes.

Results: A greatly expanded level scheme is constructed for ${}^{61}\mathrm{Cr}$, which has an increased low-energy level density relative to isotopic ${}^{55,57,59}$Cr. Excited states are discovered in ${}^{63}\mathrm{Cr}$ for the first time.

Conclusion: The distinct difference between the low-energy level scheme of ${}^{61}\mathrm{Cr}$ and the lighter neutron-rich odd-A Cr isotopes is inferred to be due to the influence of the $\nu g_{9/2}$ intruder orbital and suggests the possibility of low-energy positive-parity states in ${}^{61}\mathrm{Cr}$, leading to the conclusion that a significant change in deformation and orbital occupancies has taken place when $N$ exceeds 36.

The influence of nuclear deformation on $\alpha$-decay half-lives is taken into account in the deformed density-dependent cluster model. The microscopic potential between the spherical $\alpha$ particle and the deformed daughter nucleus is evaluated numerically from the double-folding model by the multipole expansion method. A realistic density-dependent nucleon-nucleon ($NN$) interaction with finite-range exchange part, which produces the nuclear matter saturation curve and the energy dependence of the nucleon-nucleus optical potential model is used. The ordinary zero-range exchange $NN$ force, which is commonly used in $\alpha$ decay, is also considered in the present work. We systematically investigate the influence of nuclear deformations on the $\alpha$-particle preformation probability of the deformed medium and heavy nuclei from the ground state to ground-state $\alpha$ transitions within the framework of the Wentzel-Kramers-Brillouin method by considering the Bohr-Sommerfeld quantization condition. Taking the deformation of daughter nuclei into account changes the behavior of the preformation probability, $S_{\alpha }$, by an amount depending on the $Q$ value, the order, values, and signs of deformation parameters. Calculations have been conducted for the spherical nuclei in order to present clearly the effect of the deformation on the preformation probability. The combined effect of both finite-range force and deformation can reduce the value of $S_{\alpha }$ by about an order of magnitude.

We investigate the selectivity of different two-particle transfer reactions [($t,p$), (${}^{18}\mathrm{O}$,${}^{16}\mathrm{O}$), and (${}^{14}\mathrm{C}$,${}^{12}\mathrm{C}$)] with respect to detailed microscopic configuration in initial and final target states. In particular the relative magnitude of the cross sections associated with processes in which the pair is transferred in pure single-particle orbitals depends on the specific reaction and its kinematical conditions. As a consequence also enhancement factors due to pairing correlations may differ in different reactions, and the extraction of information on the correlated wave functions may imply the blending of data from different projectiles. As test cases we have chosen ${}^{112}\mathrm{Sn}$ as an example of superfluid nuclei, and ${}^{32}\mathrm{Mg}$ and ${}^{68}\mathrm{Ni}$ to study shell evolution for exotic nuclei.

We formulate a scattering radius, which will be demonstrated to be a good measure of the spatial size of a general exclusive reaction. The scattering radius is presented in a framework of the partial-wave expansion method in a general two-body scattering problem. A microscopic coupled-channel calculation is performed for proton scattering by ${}^{12}\mathrm{C}$ in the range of the proton's incident energy, $E_p=29.95–200$ MeV, and the scattering radii are evaluated for elastic scattering and inelastic scattering, going to the Hoyle 0${}_2^{+}$ state with a well-developed 3$\alpha$ structure. A prominent enhancement of the scattering radius is clearly confirmed in the 3$\alpha$ final channel in comparison to the elastic channel. The scattering radius is also calculated for excitation to the giant monopole resonance (GMR) in a microscopic coupled-channel framework. The scattering radius for the 3$\alpha$ excitation is much more enhanced than the scattering radius for the GMR excitation. The proton's incident-energy dependence of the scattering radius is also investigated, and the energy systematics strongly suggest that the scattering radius can characterize the spatial size of a reaction area, which is determined by the matter radius of a nucleus excited to a final state.

The evolution of the total energy surface and the nuclear shape in the isotopic chain ${}^{172–194}\mathrm{Pt}$ are studied in the framework of the interacting boson model, including configuration mixing. The results are compared with a self-consistent Hartree-Fock-Bogoliubov calculation using the Gogny-D1S interaction and a good agreement between both approaches is found. The evolution of the deformation parameters points towards the presence of two different coexisting configurations in the region $176\le A\le 186$.

The systematic study of isoscalar (IS) and isovector (IV) giant quadrupole responses (GQRs) in normal and superfluid nuclei presented in Scamps and Lacroix [Phys. Rev. C 88, 044310 (2013)] is extended to the case of axially deformed and triaxial nuclei. The static and dynamical energy density functionals based on Skyrme effective interaction are used to study static properties and dynamical response functions over the whole nuclear chart. Among the 749 nuclei that are considered, 301 and 65 are respectively found to be prolate and oblate, while 54 do not present any symmetry axis. For these nuclei, the IS- and IV-GQR response functions are systematically obtained. In these nuclei, different aspects related to the interplay between deformation and collective motion are studied. We show that some aspects like the fragmentation of the response induced by deformation effects in axially symmetric and triaxial nuclei can be rather well understood using simple arguments. Besides this simplicity, more complex effects show up like the appearance of nontrivial deformation effects on the collective motion damping or the influence of hexadecapole or higher-order effects. A specific study is made on the triaxial nuclei where the absence of symmetry axis adds further complexity to the nuclear response. The relative importance of geometric deformation effects and coupling to other vibrational modes are discussed.