Background: Recent studies of deuteron-induced reactions around the Coulomb barrier $B$ pointed out that numerical calculations for deuteron-induced reactions are beyond current capabilities. The statistical model of nuclear reactions was used in this respect since the compound-nucleus (CN) mechanism was considered to be responsible for most of the total-reaction cross section ${\sigma }_R$ in this energy range. However, specific noncompound processes such as the breakup (BU) and direct reactions (DR) should be also considered for the deuteron-induced reactions, making them different from reactions with other incident particles.

Purpose: The unitary and consistent BU and DR consideration in deuteron-induced reactions is proved to yield results at variance with the assumption of negligible noncompound components.

Method: The CN fractions of ${\sigma }_R$ obtained by analysis of measured neutron angular distributions in deuteron-induced reactions on ${}^{27}\mathrm{Al}$, ${}^{56}\mathrm{Fe}$, ${}^{63,65}\mathrm{Cu}$, and ${}^{89}\mathrm{Y}$ target nuclei, around $B$, are compared with the results of an unitary analysis of every reaction mechanism. The latter values have been supported by the previously established agreement with all available deuteron data for ${}^{27}\mathrm{Al}$, ${}^{54,56-58,\mathrm{nat}}\mathrm{Fe}$, ${}^{63,65,\mathrm{nat}}\mathrm{Cu}$, and ${}^{93}\mathrm{Nb}$.

Results: There is a significant difference between the larger CN contributions obtained from measured neutron angular distributions and calculated results of an unitary analysis of every deuteron-interaction mechanism. The decrease of the latter values is mainly due to the BU component.

Conclusions: The above-mentioned differences underline the key role of the breakup and direct reactions that should be considered explicitly in the case of deuteron-induced reactions.

By solving exact three-body equations, we study the three-baryon system with charm $+1$. We look for possible bound states using baryon-baryon interactions obtained from a chiral constituent quark model. The smaller effect of the ${\mathrm{\Lambda }}_c\leftrightarrow {\mathrm{\Sigma }}_c$ conversion reverses the order of the $(I,J)=(0,1/2)$ and $(I,J)=(0,3/2)$ states, rather close on the strange sector. The diminishing of the kinetic energy due to the large reduced mass gives rise to a bound state in the $(I,J)=(0,3/2)$ channel. After correcting for Coulomb effects, the binding energy would be between 140 and 715 keV.

Prompt gamma-ray spectroscopy of fission fragments produced in the heavy-ion induced fusion-fission reaction ${}^{208}\mathrm{Pb}({}^{18}\mathrm{O},f)$ at $E=90$ MeV has been performed. The relative isotopic yields of the fission fragments and the fragment mass distribution have been studied. Structures in the mass distribution have been discussed in the light of earlier results. Relative yields of several odd-$A$ isotopes of Mo, Ru, Pd, and Cd and the odd-$A$ isotones with $N=62$ and 64 have been studied along with the yields of the neighboring even-$Z$, even-$N$ fragments and correlated to nuclear structural effects. The average total neutron multiplicity during fission has been measured to be $5.48\pm 0.59$. The level schemes of the two neutron-rich nuclei ${}^{110}\mathrm{Pd}$ and ${}^{116}\mathrm{Cd}$ have been studied from $\gamma$-ray triple coincidence data. A large number of transitions, previously reported only from $\beta$-decay studies, have been observed in ${}^{110}\mathrm{Pd}$ for the first time. The yrast band in ${}^{116}\mathrm{Cd}$ has been extended up to spin $\left({16}^{+}\right)$. In addition, a rotational sequence built upon an excited $5^{-}$ state in ${}^{116}\mathrm{Cd}$ has been observed up to $\left({13}^{-}\right)$. The level schemes have been discussed in the context of existing results, both experimental and theoretical, in the literature.

The microscopic description of nuclear fission still remains a topic of intense basic research. Understanding nuclear fission, apart from a theoretical point of view, is of practical importance for energy production and the transmutation of nuclear waste. In nuclear astrophysics, fission sets the upper limit to the nucleosynthesis of heavy elements via the $r$ process. In this work we initiated a systematic study of intermediate-energy proton-induced fission using the constrained molecular dynamics (CoMD) code. The CoMD code implements an effective interaction with a nuclear matter compressibility of $K=200$ (soft equation of state) with several forms of the density dependence of the nucleon-nucleon symmetry potential. Moreover, a constraint is imposed in the phase-space occupation for each nucleon restoring the Pauli principle at each time step of the collision. A proper choice of the surface parameter of the effective interaction has been made to describe fission. In this work, we present results of fission calculations for proton-induced reactions on: (a) ${}^{232}\mathrm{Th}$ at 27 and 63 MeV; (b) ${}^{235}\mathrm{U}$ at 10, 30, 60, and 100 MeV; and (c) ${}^{238}\mathrm{U}$ at 100 and 660 MeV. The calculated observables include fission-fragment mass distributions, total fission energies, neutron multiplicities, and fission times. These observables are compared to available experimental data. We show that the microscopic CoMD code is able to describe the complicated many-body dynamics of the fission process at intermediate and high energy and give a reasonable estimate of the fission time scale. Sensitivity of the results to the density dependence of the nucleon symmetry potential (and, thus, the nuclear symmetry energy) is found. Further improvements of the code are necessary to achieve a satisfactory description of low-energy fission in which shell effects play a dominant role.

Differential cross sections for the $\gamma p\to {\pi }^{0}p$ reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy $W=1.9\mathrm{GeV}$. The new results, obtained with a fine energy and angular binning, increase the existing quantity of ${\pi }^0$ photoproduction data by $\sim 47\%$. Owing to the unprecedented statistical accuracy and the full angular coverage, the results are sensitive to high partial-wave amplitudes. This is demonstrated by the decomposition of the differential cross sections in terms of Legendre polynomials and by further comparison to model predictions. A new solution of the SAID partial-wave analysis obtained after adding the new data into the fit is presented.

We report on measurements of dielectron $\left(e^{+}{e}^{-}\right)$ production in $\mathrm{Au}+\mathrm{Au}$ collisions at a center-of-mass energy of 200 GeV per nucleon-nucleon pair using the STAR detector at BNL Relativistic Heavy Ion Collider. Systematic measurements of the dielectron yield as a function of transverse momentum $\left(p_{\mathrm{T}}\right)$ and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region $(M_{ee}<1\text{GeV}/c^2)$. This enhancement cannot be reproduced by the $\rho$-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of $0.30–0.76\mathrm{GeV}/c^2$, integrated over the full $p_{\mathrm{T}}$ acceptance, the enhancement factor is $1.76\pm 0.06(\mathrm{stat}.)\pm 0.26(\mathrm{sys}.)\pm 0.29\left(\mathrm{cocktail}\right)$. The enhancement factor exhibits weak centrality and $p_{\mathrm{T}}$ dependence in STAR's accessible kinematic regions, while the excess yield in this invariant-mass region as a function of the number of participating nucleons follows a power-law shape with a power of $1.44\pm 0.10$. Models that assume an in-medium broadening of the $\rho$-meson spectral function consistently describe the observed excess in these measurements. Additionally, we report on measurements of $\omega$- and $\varphi$-meson production through their $e^{+}{e}^{-}$ decay channel. These measurements show good agreement with Tsallis blast-wave model predictions, as well as, in the case of the $\varphi$ meson, results through its $K^{+}{K}^{-}$ decay channel. In the intermediate invariant-mass region $(1.1<M_{ee}<3\text{GeV}/c^2)$, we investigate the spectral shapes from different collision centralities. Physics implications for possible in-medium modification of charmed hadron production and other physics sources are discussed.

Analysis of correlation of multiplicities between various rapidity bins is carried out in the framework of a superposition approach consisting of three phases of the ultrarelativistic nuclear collision: early partonic phase, intermediate collective evolution, and statistical hadronization. Simple relations between the moments of produced hadrons and the moments of the sources produced in the initial partonic phase are presented. They involve only a few effective parameters describing the microscopic dynamics of the system. We illustrate the practicality of the approach with the Glauber model simulations. Our study bears direct relevance to the interpretation of the upcoming results for the multibin multiplicity correlations from the CERN Large Hadron Collider, which will help in an assessment of the correlation features of the state formed in the earliest stage of the reaction.

We calculate the production of large-mass dileptons from the jet-dilepton conversion in the expanding quark-gluon plasma at Relativistic Heavy Ion Collider and Large Hadron Collider (LHC) energies. The jet-dilepton conversion exceeds the thermal dilepton production and Drell–Yan process in the large-mass region of $3.9\mathrm{GeV}<M<5.8\mathrm{GeV}$ and $6.3\mathrm{GeV}<M<8.7\mathrm{GeV}$ in central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ and 5.5 TeV, respectively. We present the numerical solution of ideal fluid hydrodynamics. We find that the transverse flow leads to a rapid cooling of the fire ball. The suppression due to transverse flow appears from small to large mass, the transverse-flow effect becomes important at LHC energies. The energy loss of jets in the hot and dense medium is also included.

Fluctuation measurements of eventwise mean transverse momentum $\langle p_t\rangle$ for $p\text{−}p$ and Pb-Pb collisions at the CERN Large Hadron Collider (LHC) have been reported recently. In that study it was concluded that the strength of “nonstatistical” $\langle p_t\rangle$ fluctuations decreases with increasing particle multiplicity $n_{\text{ch}}$ (or $A\text{−}A$ centrality) and is nearly independent of collision energy over a large interval. Among several potential mechanisms for those trends the onset of thermalization and collectivity are mentioned. The LHC analysis employed one fluctuation measure selected from several possibilities. An alternative fluctuation measure reveals a strong increase of $p_t$ fluctuations with $n_{ch}$ (or $A\text{−}A$ centrality) and collision energy, consistent with previous measurements at the BNL Relativistic Heavy Ion Collider (RHIC). The $p_t$ fluctuation data for LHC $p\text{−}p$ collisions can be described accurately by a two-component $\left(\mathrm{soft}+\mathrm{hard}\right)$ model (TCM) in which the hard component represents dijet production. The data for Pb-Pb collisions are described accurately by a TCM reference for more-peripheral collisions (suggesting transparent collisions), but the data deviate quantitatively from the reference for more-central collisions, suggesting a modification of jet formation. Overall fluctuation data trends suggest that minimum-bias jets (minijets) dominate $p_t$ fluctuations at both the LHC and the RHIC.

The impact of the experimental acceptance, i.e. transverse-momentum $\left(p_T\right)$ cutoff and limited rapidity region, on the earlier predicted irregularity in the excitation function of the baryon stopping is studied. This irregularity is a consequence of the onset of deconfinement occurring in the compression stage of a nuclear collision and manifests itself as a wiggle in the excitation function of the reduced curvature $\left(C_y\right)$ of the net-proton rapidity distribution at midrapidity. It is demonstrated that the wiggle is a very robust signal of a first-order phase transition that survives even under conditions of a very limited acceptance. At the same time the $C_y$ for pure hadronic and crossover transition scenarios become hardly distinguishable, if the acceptance cuts off too much of the low-$p_T$ proton spectrum and/or puts a rapidity window that is too narrow around midrapidity. It is found that the shape of the net-proton rapidity distribution near midrapidity depends on the $p_T$ cutoff. This implies that the measurements should be taken at the same acceptance for all collision energies in order to reliably conclude the presence or absence of the irregularity.

A systematic measurement of the $(\alpha ,\gamma )$ reaction for all the stable nickel isotopes has been performed using the $\gamma$-summing technique. For two of the isotopes, ${}^{60}\mathrm{Ni}$ and ${}^{61}\mathrm{Ni}$, the $\alpha$-capture cross sections have been experimentally measured for the first time. For ${}^{58,62,64}\mathrm{Ni}$, the current measurement is in excellent agreement with earlier results found in the literature, and additionally extends the energy range of the measured cross sections up to 8.7 MeV. The data provided a tool for testing the cross section predictions of Hauser-Feshbach calculations. The experimental results were compared to the cross sections calculated with the talys 1.6 code and commonly used databases non-smoker and bruslib. For each of the investigated isotopes a combination of input parameter for talys was identified that best reproduces the experimental data, and recommended reaction rate has been calculated. Additionally, a set of inputs for Hauser-Feshbach calculations was given that, simultaneously for all the isotopes under consideration, reproduces the experimental data within the experimental uncertainties.

Background: The chain of Sm isotopes exhibits a wide range of nuclear shapes and collective behavior. While the onset of deformation for $N>82$ has been well studied both experimentally and theoretically, fundamental data is lacking for some Sm isotopes with $N<82$.

Purpose: Electromagnetic transition rates represent a sensitive test of theoretical nuclear structure models. Lifetime measurements are furthermore complementary to Coulomb excitation experiments, and the two methods together can give access to spectroscopic quadrupole moments.

Method: The lifetime of the $2_1^{+}$ state in ${}^{140}\mathrm{Sm}$ was measured with the recoil-distance Doppler shift technique using the reaction ${}^{124}\mathrm{Te}({}^{20}\mathrm{Ne},4\mathrm{n}){}^{140}\mathrm{Sm}$ at 82 MeV. Theoretical calculations were performed based on a mapped collective Hamiltonian in five quadrupole coordinates (5DCH) and the Gogny D1S interaction.

Results: The lifetime of the $2_1^{+}$ state in ${}^{140}\mathrm{Sm}$ was found to be 9.1(6) ps, corresponding to a $B(E2;2_1^{+}\to 0_1^{+})$ value of 51(4) Weisskopf units. The theoretical calculations are in very good agreement with the experimental result.

Conclusions: The $B(E2;2_1^{+}\to 0_1^{+})$ value for ${}^{140}\mathrm{Sm}$ fits smoothly into the systematic trend for the chain of Sm isotopes. The new beyond-mean field calculations are able to correctly describe the onset of collectivity in the Sm isotopes below the $N=82$ shell closure for the first time.

We present a model which describes the properties of odd-even nuclei with one nucleon more, or less, with respect to the magic number. In addition to the effects related to the unpaired nucleon, we consider those produced by the excitation of the closed shell core. By using a single-particle basis generated with Hartree-Fock calculations, we describe the polarization of the doubly magic-core with random phase approximation collective wave functions. In every step of the calculation, and for all the nuclei considered, we use the same finite-range nucleon-nucleon interaction. We apply our model to the evaluation of electric quadrupole and magnetic dipole moments of odd-even nuclei around oxygen, calcium, zirconium, tin, and lead isotopes. Our random phase approximation description of the polarization of the core improves the agreement with experimental data with respect to the predictions of the independent particle model. We compare our results with those obtained in first-order perturbation theory, with those produced by Hartree-Fock-Bogolioubov calculations and with those generated within the Landau-Migdal theory of finite Fermi systems. The results of our universal, self-consistent, and parameter-free approach have the same quality of those obtained with phenomenological approaches where the various terms of the nucleon-nucleon interaction are adapted to reproduce some specific experimental data. A critical discussion on the validity of the model is presented.

Background: Triplet energy differences (TED) can be studied to yield information on isospin-non-conserving interactions in nuclei.

Purpose: The systematic behavior of triplet energy differences (TED) of $T=1$, $J^{\pi }=2^{+}$ states is examined. The $A=62$ isobar is identified as having a TED value that deviates significantly from an otherwise very consistent trend. This deviation can be attributed to the tentative assignments of the pertinent states in ${}^{62}\mathrm{Ga}$ and ${}^{62}\mathrm{Ge}$.

Methods: An in-beam $\gamma$-ray spectroscopy experiment was performed to identify excited states in ${}^{62}\mathrm{Ga}$ using Gamma-Ray Energy Tracking In-Beam Nuclear Array with the S800 spectrometer at NSCL using a two-nucleon knockout approach. Cross-section calculations for the knockout process and shell-model calculations have been performed to interpret the population and decay properties observed.

Results: Using the systematics as a guide, a candidate for the transition from the $T=1$, $2^{+}$ state is identified. However, previous work has identified similar states with different $J^{\pi }$ assignments. Cross-section calculations indicate that the relevant $T=1$, $2^{+}$ state should be one of the states directly populated in this reaction.

Conclusions: As spins and parities were not measurable, it is concluded that an unambiguous identification of the first $T=1$, $2^{+}$ state is required to reconcile our understanding of TED systematics.

The fragment production excitation functions of ${}^{12}\mathrm{C}$ interacting with carbon nuclei were measured in the energy range of 100–400 MeV/u. To measure cross sections as excitation functions, fragments produced from a thick carbon target bombarded with a monoenergetic ${}^{12}\mathrm{C}$ ion beam were detected by a telescope detector placed behind the target. By this measurement, eight isotopes—${}^{11}\mathrm{B},{}^{10}\mathrm{B},{}^{10}\mathrm{Be},{}^9\mathrm{Be},{}^7\mathrm{Be},{}^8\mathrm{Li},{}^7\mathrm{Li}$, and ${}^6\mathrm{Li}$—were identified, and the energy dependence of their production cross sections in the few 100 MeV/u range was obtained. Based on the measured cross sections, the JAERI quantum molecular dynamics model was updated to incorporate the mechanisms particularly important for peripheral collisions. The improved version of the model coupled with a statistical decay model reproduces the measured data typically within a few 10% of difference.

The energy and angular distributions of ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ ions produced in the ${}^7\mathrm{Be}+{}^{58}\mathrm{Ni}$ reaction at a bombarding energy of 22 MeV have been measured for the first time. The yield of the heavier helium isotope was four to five times more abundant than that of its lighter counterpart, ruling out the possibility that in this energy range the ${}^7\mathrm{Be}$ reaction dynamics is dominated by the exclusive breakup process ${}^7\mathrm{Be}\to {}^3\mathrm{He}+{}^4\mathrm{He}$ ($S_{\alpha }=1.586$ MeV). Extensive kinematic and theoretical calculations suggest that the ${}^3\mathrm{He}$ ions mostly originate from the ${}^4\mathrm{He}$-stripping process and the ${}^4\mathrm{He}$ production is mainly triggered by the fusion-evaporation channel. The role played by the breakup, ${}^3\mathrm{He}$-stripping, $1n$-stripping, and $1n$-pickup processes is also discussed.

The sensitivity of flow harmonics from cumulants to the event-by-event flow distribution $p\left(v_n\right)$ is investigated using a simple central moment expansion approach. For a narrow distribution whose width is much smaller than the mean ${\sigma }_n\ll \langle v_n\rangle$, the differences between the first three higher-order cumulant estimates $v_n\left\{4\right\},v_n\left\{6\right\}$, and $v_n\left\{8\right\}$ are not very sensitive to the shape of $p\left(v_n\right)$. For a broad distribution ${\sigma }_n\gtrsim 〈v_n〉$, the higher-order cumulant estimates differ from each other but may change sign and become ill defined. This sign change arises from the choice of $p\left(v_n\right)$, without the need to invoke nonflow effects. Direct extraction of $p\left(v_n\right)$ via a data-driven unfolding method used by the ATLAS experiment is a more preferred approach for flow distribution measurement.

We compute the energy and momentum deposited by a fast-moving parton in a quark-gluon plasma using linear viscous hydrodynamics with an energy loss per unit length profile proportional to the path length and with different values of the shear-viscosity to entropy-density ratio. We show that when varying these parameters, the transverse modes dominate over the longitudinal ones and thus energy and momentum is preferentially deposited along the head-shock, as in the case of a constant energy loss per unit length profile and the lowest value for the shear-viscosity to entropy-density ratio.