A comparative study of fission of actinides, especially ${}^{238}\mathrm{U}$, by proton and bremsstrahlung photon is performed. The relative mass distribution of ${}^{238}\mathrm{U}$ fission fragments has been explored theoretically for both proton- and photon-induced fission. The integrated yield along with charge distribution of the products are calculated to find the neutron richness in comparison with the nuclei produced by the $r$ process in nucleosynthesis. Some $r$-process nuclei in the intermediate-mass range for symmetric fission mode are found to be produced almost two orders of magnitude more for proton-induced fission than for photofission, although the rest of the neutron-rich nuclei in the asymmetric mode are produced in comparable proportion for both processes.

In order to produce more unknown neutron-rich transcalifornium nuclei, the collisions of ${}^{238}\mathrm{U}$ with the targets ${}^{248}\mathrm{Cm}$, ${}^{249}\mathrm{Cf}$, and ${}^{250}\mathrm{Cm}$ are investigated within the framework of the dinuclear system model. The production cross sections of unknown neutron-rich nuclei with $Z=99–104$ in these reactions are predicted. The influences of $N/Z$ ratios and charge numbers of the targets on the production cross sections are studied. It is found that high $N/Z$ ratios of ${}^{248}\mathrm{Cm}$ and ${}^{250}\mathrm{Cm}$ targets enhance the production cross sections of neutron-rich transcalifornium nuclei. However, due to high charge number of the target ${}^{249}\mathrm{Cf}$ the predicted production cross sections of unknown neutron-rich nuclei with $Z=104$ in the reaction ${}^{238}\mathrm{U}+{}^{249}\mathrm{Cf}$ are higher than those in ${}^{238}\mathrm{U}+{}^{248}\mathrm{Cm}$. We also have studied the entrance angular momentum effects on production probabilities of transfer products in the reaction ${}^{238}\mathrm{U}+{}^{248}\mathrm{Cm}$. It is found that the formation probabilities of the final neutron-rich products increase first and then decrease with the increasing $J$.

We study the triple-$\alpha$ reaction process at low temperatures, which is known to play an important role in stellar physics. The Schrödinger equation for three $\alpha$ particles is solved by using hyperspherical coordinates, while a complex absorbing potential is introduced in order to describe correctly the three-body continuum states. We use an angular-momentum-independent $\alpha -\alpha$ potential and introduce three-body potentials to reproduce the energies of both the Hoyle state and the first $2^{+}$ state. The triple-$\alpha$ reaction rate is computed accurately at temperatures from $T=0.01$ to 10 GK and compared with those available in the literature. Our reaction rate is found to be up to three orders of magnitude larger than the NACRE rate at low temperatures $T\approx 0.01$ GK, while we find a reasonable agreement between them at higher temperatures $T\gtrsim 0.1$ GK.

A new generation of cryogenic light detectors exploiting the Neganov-Luke effect to enhance the thermal signal has been used to detect the Cherenkov light emitted by electrons interacting in ${\mathrm{TeO}}_2$ crystals. With this mechanism a high significance event-by-event discrimination between $\alpha$ and $\beta /\gamma$ interactions at the ${}^{130}\mathrm{Te}$ neutrino-less double-$\beta$ decay $Q$ value of $2527.515\pm 0.013$ keV has been demonstrated. This measurement opens the possibility of drastically reducing the background in cryogenic experiments based on ${\mathrm{TeO}}_2$.

Background: Meticulous modeling of neutrino-nucleus interactions is essential to achieve the unprecedented precision goals of present and future accelerator-based neutrino-oscillation experiments.

Purpose: Confront our calculations of charged-current quasielastic cross sections with the measurements of MiniBooNE and T2K, and to quantitatively investigate the role of nuclear-structure effects, in particular, low-energy nuclear excitations in forward muon scattering.

Method: The model takes the mean-field approach as the starting point, and solves Hartree-Fock (HF) equations using a Skyrme (SkE2) nucleon-nucleon interaction. Long-range nuclear correlations are taken into account by means of the continuum random-phase approximation (CRPA) framework.

Results: We present our calculations on flux-folded double differential, and flux-unfolded total cross sections off ${}^{12}\mathrm{C}$ and compare them with MiniBooNE and (off-axis) T2K measurements. We discuss the importance of low-energy nuclear excitations for the forward bins.

Conclusions: The HF and CRPA predictions describe the gross features of the measured cross sections. They underpredict the data (more in the neutrino than in the antineutrino case) because of the absence of processes beyond pure quasielastic scattering in our model. At very forward muon scattering, low-energy HF-CRPA nuclear excitations ($\omega <50$ MeV) account for nearly 50% of the flux-folded cross section. This extra low-energy strength is a feature of the detailed microscopic nuclear model used here, that is not accessed in a Fermi-gas based approach.

The conditions of local thermodynamic equilibrium of baryons (nonstrange, strange) and mesons (strange) are presented for central Au + Au collisions at Facility for Antiproton and Ion Research (FAIR) energies using the microscopic transport model UrQMD. The net particle density, longitudinal-to-transverse pressure anisotropy, and inverse slope parameters of the energy spectra of nonstrange and strange hadrons are calculated inside a cell in the central region within rapidity window $\left|y\right|<1.0$ at different time steps after the collisions. We observed that the strangeness content is dominated by baryons at all energies; however, contributions from mesons become significant at higher energies. The time scale obtained from local pressure (momentum) isotropization and thermalization of energy spectra are nearly equal and found to decrease with increase in laboratory energy. The equilibrium thermodynamic properties of the system are obtained with a statistical thermal model. The time evolution of the entropy densities at FAIR energies are found to be very similar to the ideal hydrodynamic behavior at top Relativistic Heavy Ion Collider (RHIC) energy.

The case of gluon bremsstrahlung off a heavy quark in extended nuclear matter is revisited within the higher twist formalism. In particular, the in-medium modification of “semihard” heavy quarks is studied, where the momentum of the heavy quark is larger but comparable to the mass of the heavy quark $(p\gtrsim M)$. In contrast to all prior calculations, where the gluon emission spectrum is entirely controlled by the transverse momentum diffusion parameter $\left(\widehat{q}\right)$, both for light and heavy quarks, in this work, we demonstrate that the gluon emission spectrum for a heavy quark (unlike that for light flavors) is also sensitive to $\widehat{e}$, which so far has been used to quantify the amount of light-cone drag experienced by a parton. This mass dependent effect, due to the non-light-like momentum of a semihard heavy quark, leads to an additional energy loss term for heavy quarks, while resulting in a negligible modification of light flavor (and high energy heavy flavor) energy loss. This result can be used to estimate the value of this subleading nonperturbative jet transport parameter $\left(\widehat{e}\right)$ from heavy flavor suppression in ultrarelativistic heavy-ion collisions.

After identifying the nuclei in the $A\simeq 80$ and $A\simeq 160$ regions for which $\beta$-decay rates have the greatest effect on weak and main $r$-process abundance patterns, we apply the finite-amplitude method (FAM) with Skyrme energy-density functionals (EDFs) to calculate $\beta$-decay half-lives of those nuclei in the quasiparticle random-phase approximation (QRPA). We use the equal filling approximation to extend our implementation of the charge-changing FAM, which incorporates pairing correlations and allows axially symmetric deformation, to odd-$A$ and odd-odd nuclei. Repeated calculations with $A\simeq 160$ nuclei and multiple EDFs show a spread of 1.9–3.3 in $\beta$-decay half-lives, with differences in calculated $Q$ values playing an important role. We compare our results with those of previous work and investigate their implications for $r$-process simulations.

Background: Deformed neutron-rich magnesium isotopes constitute a fascinating territory where the interplay between collective rotation and single-particle motion is strongly affected by the neutron continuum. The unbound $fp$-shell nucleus ${}^{39}\mathrm{Mg}$ is an ideal candidate to study this interplay.

Purpose: In this work, we predict the properties of low-lying resonant states of ${}^{39}\mathrm{Mg}$, using a suite of realistic theoretical approaches rooted in the open quantum system framework.

Method: To describe the spectrum and decay modes of ${}^{39}\mathrm{Mg}$ we use the conventional shell model, Gamow shell model, resonating group method, density matrix renormalization group method, and the nonadiabatic particle-plus-rotor model formulated in the Berggren basis.

Results: The unbound ground state of ${}^{39}\mathrm{Mg}$ is predicted to be either a $J^{\pi }={7/2}^{-}$ state or a ${3/2}^{-}$ state. A narrow $J^{\pi }={7/2}^{-}$ ground-state candidate exhibits a resonant structure reminiscent of that of its one-neutron halo neighbor ${}^{37}\mathrm{Mg}$, which is dominated by the $f_{7/2}$ partial wave at short distances and a $p_{3/2}$ component at large distances. A $J^{\pi }={3/2}^{-}$ ground-state candidate is favored by the large deformation of the system. It can be associated with the ${1/2}^{-}\left[321\right]$ Nilsson orbital dominated by the $\ell =1$ wave; hence its predicted width is large. The excited $J^{\pi }={1/2}^{-}$ and $5/2^{-}$ states are expected to be broad resonances, while the $J^{\pi }={9/2}^{-}$ and ${11/2}^{-}$ members of the ground-state rotational band are predicted to have very small neutron decay widths.

Conclusion: We demonstrate that the subtle interplay between deformation, shell structure, and continuum coupling can result in a variety of excitations in an unbound nucleus just outside the neutron drip line.

We report on low-spin states of ${}^{154}\mathrm{Dy}$ populated via the reaction ${}^{155}\mathrm{Gd}$ $\left({}^3\mathrm{He},4n\right)$ with a beam energy of 37.5 MeV from the Separated Sector Cyclotron at iThemba Laboratory. The AFRODITE γ-ray spectrometer was used to establish new $E1$ transitions between bands of opposite parity. The measurements broaden the $N=88$ systematics on the relationship between the first excited positive-parity pairing isomer band and the lowest-lying negative-parity band as the nuclear quadrupole deformation decreases with increasing proton number. In a region of strong octupole correlations the data suggest that the spectroscopy of $N=88$ nuclei is driven by stable octupole deformations and not by vibrations.

The excitation function of ${}^{28}\mathrm{Mg}$ above the $\alpha$-decay threshold has been measured for the first time using the resonant scattering of $\alpha$ particles with the technique of a thick target in inverse kinematics. Thirteen new states are reported between $E_x=15.5$ and $E_x=20.5$ MeV, and suggestions for spin-parity assignments are given for two of these. Calculations of the branching ratio to $\alpha$ decay for these states as well as comparison of the measured cross sections to calculations suggest that $\alpha +{}^{24}\mathrm{Ne}_{\mathrm{g.s.}}$ clustering is not dominant in this energy regime.

Combined decay and laser spectroscopy measurements of the isotope ${}^{214}\mathrm{Fr}$ are reported, using the collinear resonance ionization spectroscopy (CRIS) technique at the ISOLDE facility at CERN. For the $I^{\pi }=(1^{-})$ spin assignment, the $g$-factor value of $g({}^{214}\mathrm{Fr})=+0.241(16)$ corresponds to a relatively pure $(\pi 1h_{9/2}$ $\otimes$ $\nu 2g_{9/2})$ ground-state configuration. An alternative interpretation with $g({}^{214}\mathrm{Fr})=+0.144(10)$, for a $\left(2^{-}\right)$ spin assignment suggests a greater contribution of configuration mixing with the $\nu 1i_{11/2}$ orbital. As the $N=126$ shell closure is passed, a kink is observed at the $\delta {\langle r^2\rangle }^{213,214}$ value, which is analogous to the behavior observed in the neighboring isotopic chains.

The fragment mass and kinetic energy in neutron-induced fission of ${}^{238}\mathrm{U}$ has been measured for incident energies from 1 to 30 MeV at the Los Alamos Neutron Science Center. The change in mass distributions over this energy range were studied, and the transition from highly asymmetric to more symmetric mass distributions is observed. A decrease in average total kinetic energy $\left(\overline{\mathrm{TKE}}\right)$ with increasing excitation energy is observed, consistent with previous experimental work. Additional structure at multichance fission thresholds is present in the $\overline{\mathrm{TKE}}$ data. The correlations between fragment masses and total kinetic energy and how that changes with excitation energy of the fissioning compound nucleus were also measured. The fission mass yields and average total kinetic energy are important for fission-based technologies such as nuclear reactors to understand nuclear waste generation and energy output when developing new and advanced concepts. The correlations between fragment mass and kinetic energy are needed both as input for theoretical calculations of the deexcitation process in fission fragments by prompt radiation emission and for validating advanced theoretical fission models describing the formation of the primordial fragments.

The neutron-rich nucleus ${}^{132}\mathrm{Cd}$ has been studied at the RIKEN Radioactive Isotope Beam Factory using in-beam $\gamma$-ray spectroscopy with two-proton removal reactions from ${}^{134}\mathrm{Sn}$. A $\gamma$-ray transition was observed at 618(8) keV and was assigned to the $2_1^{+}\to 0_{\mathrm{g}.\mathrm{s}.}^{+}$ decay. The $2_1^{+}$ state provides the first spectroscopic information from the even-even nuclei located in the region “southeast” of the doubly magic nucleus ${}^{132}\mathrm{Sn}$. By comparing with the $2_1^{+}$ excitation energies in the semimagic nuclei ${}^{134}\mathrm{Sn}$ and ${}^{130}\mathrm{Cd}$, it is found that neutron excitations dominate the $2_1^{+}$ state in ${}^{132}\mathrm{Cd}$, in a similar manner to ${}^{136}\mathrm{Te}$. The results are discussed in terms of proton-neutron configuration mixing.

The role of $\alpha$ clustering in the binary complex fragment decay of fully energy-relaxed composites ${}^{24,25}\mathrm{Mg}^{*}$, formed in ${}^{12,13}\mathrm{C}+{}^{12}\mathrm{C}$ reactions, has been studied. The inclusive isotopic energy distributions of the emitted fragments ${}^{6,7}\mathrm{Li}$ and ${}^{7,8,9}\mathrm{Be}$ have been measured. The ratio of the measured fully dissipative (fissionlike) yields of each isotopic fragment obtained in the two reactions was compared with the corresponding statistical model prediction of the same. Unlike in the case of ${}^{6,7}\mathrm{Li}$ fragments, the measured yield ratios of ${}^{7,8,9}\mathrm{Be}$ fragments were found to deviate substantially from the statistical model predictions of the same. The observed deviations were due to the enhancement in the measured yields of ${}^{7,8,9}\mathrm{Be}$ fragments (with respect to the respective statistical model predictions) only in specific exit channels containing either ${}^{16}\mathrm{O}$ or ${}^{18}\mathrm{O}$, both well known $\alpha$-cluster nuclei, as the complementary binary fragment. The present data indicated, for the first time, the survival and sustained influence of cluster correlations on dissipative binary decay of hot composites ${}^{24,25}\mathrm{Mg}^{*}$ at excitation energy of $\sim 2.25$ MeV/nucleon.

The extremely neutron-deficient isotope ${}^{178}\mathrm{Pb}$ has been produced. The GREAT spectrometer at the focal plane position of the gas-filled separator RITU was used to study the $\alpha$ decay of ${}^{178}\mathrm{Pb}$ and its $\alpha$-decay chain through $\alpha \text{−}\alpha$ correlations. The $\alpha$ decay was measured to have an energy and half-life of $E_{\alpha }$= 7610(30) keV and $t_{1/2}=0.{21}_{-0.08}^{+0.21}$ ms, respectively. The half-life is consistent with recent theoretical calculations using the Coulomb and proximity potential model. The $\alpha$-decay reduced width and hindrance factor for ${}^{178}\mathrm{Pb}$ were deduced and correspond to an unhindered $\mathrm{\Delta }l$ = 0 transition. In addition, the mass excess of ${}^{178}\mathrm{Pb}$ and the $\alpha$-decay $Q$ value were calculated from the experimental results and compared to theoretical values.

In this work, three astrophysical $S\left(E\right)$ factors of the ${}^6\mathrm{Li}{(d,\alpha )}^4\mathrm{He}, {}^6\mathrm{Li}{(d,p_0)}^7\mathrm{Li}$, and ${}^6\mathrm{Li}(d,p_1{)}^7\mathrm{L}{\mathrm{i}}^{*}$ reactions have been presented, and the value of screening potential was also deduced, where the subsequent two $S\left(E\right)$ factors were reported for the first time. The present extracted astrophysical $S\left(E\right)$ factors result in $S_{\mathrm{bare}}\left(0\right)=19.20\pm 0.52,20.46\pm 0.63$, and $3.79\pm 0.18\mathrm{MeV}\mathrm{b}$ for the ${}^6\mathrm{Li}{(d,\alpha )}^4\mathrm{He}, {}^6\mathrm{Li}{(d,p_0)}^7\mathrm{Li}$, and ${}^6\mathrm{Li}(d,p_1{)}^7\mathrm{L}{\mathrm{i}}^{*}$ reactions, respectively. The deduced screening potential $\left(U_s\right)\mathrm{is}478\pm 42\mathrm{eV}$ in the liquid lithium $(\sim 530\mathrm{K})$ host which is much larger than the expected value of 186 eV calculated by adiabatic approximation. Using these results, the stellar reaction rates for the ${}^6\mathrm{Li}{(d,\alpha )}^4\mathrm{He}$ and ${}^6\mathrm{Li}{(d,p_0+p_1)}^7\mathrm{Li}$ reactions for temperatures up to $T=3\times {10}^9\mathrm{K}$ were calculated, so as to estimate the abundances of ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ in the solar proton-proton burning process.

We calculate neutral-current contributions to the process $\nu +{}^{208}\mathrm{Pb}(\mathrm{g}.\mathrm{s})⟶{\nu }^{\prime }+{}^{208}\mathrm{Pb}^{*}$, for incoming neutrino energies up to 150 MeV. The spectrum of ${}^{208}\mathrm{Pb}$ is calculated by performing a diagonalization of the $\delta$-force interaction in the space of particle-hole pairs, both for neutrons and protons. We study the dependence of the cross section on the energy of the neutrino and present its multipole decomposition for normal and abnormal parity states. We compare our results to the estimate of neutral-current contributions by other authors, and to our previous results for the charged-current channel.

Population transfer of three-level $\mathrm{\Lambda }$-like nuclei interacting with x-ray free electron lasers (XFEL) via a train of coincident pulses has been investigated theoretically. This study uses copropagating beams in which the frequency of the pump laser is different from that of the Stokes laser. We calculate the required laser intensities for each step which satisfy the condition of coincident-pulse technique in different nuclei. By employing the master equation and considering the effect of spontaneous emission, we show that complete nuclear population transfer occurs by choosing the appropriate number of pulse pairs. It is shown that the effect of laser intensity fluctuation is suppressed by increasing the number of pulse pairs. In this scheme, after each step, the populations of system are in stable states and the time delays between the neighboring pulses do not affect the transmission efficiency.

Beam-target double-spin asymmetries and target single-spin asymmetries in exclusive ${\pi }^{+}$ and quasiexclusive ${\pi }^{-}$ electroproduction were obtained from scattering of 1.6- to 5.7-GeV longitudinally polarized electrons from longitudinally polarized protons (for ${\pi }^{+}$) and deuterons (for ${\pi }^{-}$) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The kinematic range covered is $1.1<W<2.6$ GeV and $0.05<Q^2<5{\mathrm{GeV}}^2$, with good angular coverage in the forward hemisphere. The asymmetry results were divided into approximately 40 000 kinematic bins for ${\pi }^{+}$ from free protons and 15 000 bins for ${\pi }^{-}$ production from bound nucleons in the deuteron. The present results are found to be in reasonable agreement with fits to previous world data for $W<1.7$ GeV and $Q^2<0.5{\mathrm{GeV}}^2$, with discrepancies increasing at higher values of $Q^2$, especially for $W>1.5$ GeV. Very large target-spin asymmetries are observed for $W>1.6$ GeV. When combined with cross-section measurements, the present results can provide powerful constraints on nucleon resonance amplitudes at moderate and large values of $Q^2$, for resonances with masses as high as 2.3 GeV.