The rotational structure of ${}^{246}$Fm has been investigated using in-beam $\gamma$-ray spectroscopic techniques. The experiment was performed using the JUROGAMII germanium detector array coupled to the gas-filled recoil ion transport unit (RITU) and the gamma recoil electron alpha tagging (GREAT) focal plane detection system. Nuclei of ${}^{246}$Fm were produced using a 186 MeV beam of ${}^{40}$Ar impinging on a ${}^{208}$Pb target. The JUROGAMII array was fully instrumented with Tracking Numerical Treatment 2 Dubna (TNT2D) digital acquisition cards. The use of digital electronics and a rotating target allowed for unprecedented beam intensities of up to 71 particle-nanoamperes for prompt $\gamma$-ray spectroscopy at a level of approximately 11 nb. With all these major experimental advances a rotational band is observed in ${}^{246}$Fm.

Abstract. Analysis of energies and widths of the lowest 1/2${}^{+}$ $T$ $=$ 3/2 states in $A$ $=$ 11 nuclei suggests that the excitation energy in ${}^{11}$C should be about 200 keV below the energy in the literature, and the width should be 4 to 5 times the literature value. Properties of the state in ${}^{11}$B and ${}^{11}$N are in agreement with the present model.

We examined the effect of an imaginary part of the ladder approximation Schwinger-Dyson equation. We show that the imaginary part enhances the effect of the first-order transition and affects a tricritical point. In particular, a chemical potential at the tricritical point is displaced about 200 MeV. Thus, one should not ignore the imaginary part. However, because the imaginary part is small away from the tricritical point, one should be able to ignore the imaginary part. In addition, we also examined the contribution of the wave-function renormalization constant.

We investigate the effects of newly measured $\beta$-decay half-lives on $r$-process nucleosynthesis. These new rates were determined by recent experiments at the radioactive isotope beam factory facility in the RIKEN Nishina Center. We adopt an $r$-process nucleosynthesis environment based on a magnetohydrodynamic supernova explosion model that includes strong magnetic fields and rapid rotation of the progenitor. A number of the new $\beta$-decay rates are for nuclei on or near the $r$-process path, and hence they affect the nucleosynthesis yields and time scale of the $r$-process. The main effect of the newly measured $\beta$-decay half-lives is an enhancement in the calculated abundance of isotopes with mass number $A=110$–120 relative to calculated abundances based upon $\beta$-decay rates estimated with the finite-range droplet mass model. This effect slightly alleviates, but does not fully explain, the tendency of $r$-process models to underproduce isotopes with $A=110$–120 compared to the solar-system $r$-process abundances.

By using a newly developed dinuclear system model with a dynamical potential energy surface—the DNS-DyPES model—hot fusion reactions for synthesizing superheavy nuclei (SHN) with charge numbers $Z$ = 112–120 are studied. The calculated evaporation residue cross sections are in good agreement with available data. In the reaction ${}^{50}$Ti+${}^{249}$Bk ${\to }^{299\text{--}x}$119 $+x$$n$, the maximal evaporation-residue (ER) cross section is found to be about 0.11 pb for the 4$n$-emission channel. For projectile-target combinations producing SHN with $Z=120$, the ER cross section increases as the mass asymmetry in the incident channel increases. The maximal ER cross sections for ${}^{58}$Fe+${}^{244}$Pu and ${}^{54}$Cr+${}^{248}$Cm are relatively small (less than 0.01 pb) and those for ${}^{50}$Ti+${}^{249}$Cf and ${}^{50}$Ti+${}^{251}$Cf are about 0.05 and 0.25 pb, respectively.

Models of the $r$ process are sensitive to the production rate of ${}^9$Be because, in explosive environments rich in neutrons, $\alpha (\alpha n,\gamma ){}^9$Be is the primary mechanism for bridging the stability gaps at $A=5$ and $A=8$. The $\alpha (\alpha n,\gamma ){}^9$Be reaction represents a two-step process, consisting of $\alpha +\alpha \to {}^8$Be followed by ${}^8\text{Be}(n,\gamma ){}^9$Be. We report here on a new absolute cross-section measurement for the ${}^9\text{Be}(\gamma ,n){}^8$Be reaction conducted using a highly efficient, ${}^3$He-based neutron detector and nearly monoenergetic photon beams, covering energies from $E_{\gamma }=1.5$ MeV to $E_{\gamma }=5.2$ MeV, produced by the High Intensity $\gamma$-ray Source of Triangle Universities Nuclear Laboratory. In the astrophysically important threshold energy region, the present cross sections are 40$\%$ larger than those found in most previous measurements and are accurate to $\pm 10\%$ (95$\%$ confidence). The revised thermonuclear $\alpha (\alpha n,\gamma ){}^9$Be reaction rate could have implications for the $r$ process in explosive environments such as type II supernovae.

Tensors describing boost-invariant and cylindrically symmetric expansion of a relativistic dissipative fluid are decomposed in a suitable chosen basis of projection operators. This leads to a simple set of scalar equations which determine the fluid behavior. As special examples, we discuss the case of the Israel-Stewart theory and the model of highly anisotropic and strongly dissipative hydrodynamics (ADHYDRO). We also introduce the matching conditions between the ADHYDRO description suitable for the very early stages of heavy-ion collisions and the Israel-Stewart theory applicable to later stages when the system is close to equilibrium.

Hard probes in the context of ultrarelativistic heavy-ion collisions represent a key class of observables studied to gain information about the QCD medium created in such collisions. However, in practice, the so-called jet tomography has turned out to be more difficult than expected initially. One of the major obstacles in extracting reliable tomographic information from the data is that neither the parton-medium interaction nor the medium geometry are known with great precision, and thus a difference in model assumptions in the hard perturbative Quantum Choromdynamics (pQCD) modeling can usually be compensated by a corresponding change of assumptions in the soft bulk medium sector and vice versa. The only way to overcome this problem is to study the full systematics of combinations of parton-medium interaction and bulk medium evolution models. This work presents a meta-analysis summarizing results from a number of such systematical studies and discusses in detail how certain data sets provide specific constraints for models. Combining all available information, only a small group of models exhibiting certain characteristic features consistent with a pQCD picture of parton-medium interaction is found to be viable given the data. In this picture, the dominant mechanism is medium-induced radiation combined with a surprisingly small component of elastic energy transfer into the medium.

Photoproduction of heavy quarks and exclusive production of vector mesons in ultraperipheral proton-nucleus and nucleus-nucleus collisions depend significantly on nuclear gluon distributions. In the present study, we investigate quantitatively the extent of the applicability of these processes at the Large Hadron Collider in constraining the shadowing component of nuclear gluon modifications.

The higher order moments of the net-baryon distributions in relativistic heavy ion collisions are useful probes for the QCD critical point and fluctuations. Within a simple model we study the colliding energy and centrality dependence of the net-proton distributions in the central rapidity region. The model is based on considering the baryon stopping and pair production effects in the processes. Based on some physical reasoning, the dependence is parameterized. Predictions for the net-proton distributions for $\text{Au}+\text{Au}$ and $\text{Pb}+\text{Pb}$ collisions at different centralities at $\sqrt{s_{NN}}=39$ and 2760 GeV, respectively, are presented from the parametrizations for the model parameters. A possible test of our model is proposed from investigating the net-proton distributions in the noncentral rapidity region for different colliding centralities and energies.

Proton resonant states in ${}^{27}$P were studied by the resonant elastic scattering of ${}^{26}$Si+$p$ with a ${}^{26}$Si radioactive ion beam bombarding a thick H${}_2$ gas target with the inverse kinematics method. The properties of these resonance states are important to better constrain the production rates of the ${}^{26}$Si($p$,$\gamma$)${}^{27}$P reaction. This is one of the astrophysically important reactions needed to understand proton-rich nucleosynthesis such as the galactic production of ${}^{26}$Al and energy generation in explosive stellar environments. Although there are recent studies on the resonant structure in ${}^{27}$P, large uncertainties remain, and only a few levels are known. In this work, resonant states were observed over the excitation energies range of 2.3 to 3.8 MeV with high statistics and without background contamination within the target. The resonance parameters were extracted by an $R$-matrix analysis of the excitation function. The ${}^{26}$Si($p$,$\gamma$)${}^{27}$P stellar reaction rate has been evaluated, including high-lying resonances found in this work.

In the framework of a Chiral effective theory with dibaryon fields, we calculate the pion mass dependence of the inverse scattering length of the nucleon-nucleon system in the ${}^3{S}_1$ channel at order $(m_{\pi }^3/{\Lambda }_{\chi }^2)\times {(m_{\pi }^{1/2}{m}_N^{3/2}/8\pi f_{\pi }^2)}^n$ for all $n\ge 0$. We show that certain sets of potentially large higher-order contributions vanish. We discuss the difficulties of extending the proof to the ${}^1{S}_0$ channel. We apply our results to chiral extrapolations of current lattice data.

The $\gamma$ decays of neutron-rich Ca isotopes around ${}^{48}$Ca were measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using the heavy-ion transfer reactions ${}^{48}$Ca on ${}^{64}$Ni and ${}^{48}$Ca on ${}^{208}$Pb at $\approx$6 MeV/A. The work shows the feasibility to perform full in-beam $\gamma$ spectroscopy with heavy-ion transfer reactions (in terms of angular distributions, polarizations, and lifetimes analysis), providing a method that can be further exploited in the future with heavy targets and radioactive beams. For the one-neutron transfer channels, ${}^{49}$Ca and ${}^{47}$Ca, shell-model and particle-vibration coupling calculations are used to understand the nature of the states. In particular, in both nuclei evidence is found for particle-vibration coupled states based on the 3${}^{-}$ phonon of ${}^{48}$Ca. In the two-neutron transfer channels, ${}^{46}$Ca and ${}^{50}$Ca, the experimental data are in global agreement with predictions based on full $fp$ shell-model calculations.

Nuclear resonance fluorescence experiments were carried out at the High-Intensity $\gamma$-ray Source facility at Triangle Universities Nuclear Laboratory to characterize the low-energy dipole structure of ${}^{238}$U using 100$\%$ linearly polarized photon beams from 2.0 to 6.2 MeV. 113 transitions corresponding to de-excitations to the ground state in ${}^{238}$U were observed and the energy, spin, parity, integrated cross section, reduced width, and branching ratio were determined for each of these identified levels. The total $E1$ $\gamma$-ray interaction cross section was calculated and it was deduced that the observed concentration of low-lying $E1$ transitions were excited from the low-energy tail of the giant dipole resonance and were not a pygmy dipole resonance. Comparisons were made between quasiparticle random-phase approximation calculations and the experimentally observed strength. The observed and predicted $M1$ strength agreed well with each other. However, there was no similar agreement for the $E1$ strength.

The high-spin structure of the nucleus ${}^{104}$Pd was studied through the ${}^{96}$Zr(${}^{13}$C,5$n$) reaction at incident energies of 51 and 58 MeV, using the Euroball IV $\gamma$-ray spectrometer in conjunction with the DIAMANT charged-particle array. Several new medium- and high-spin bands were revealed. The already known positive-parity yrast and the negative-parity cascades were extended up to $E_x\sim 13$, $\sim 11$, and $\sim 9$ MeV with $I^{\pi }=({26}^{+}$), $I^{\pi }=({23}^{-}$), and (20${}^{-}$), respectively. The deduced band structures were compared with Woods-Saxon total Routhian surface (TRS) calculations. In addition, non-yrast low-lying positive-parity bands were identified, which were assigned to soft $\gamma$-vibrational excitations.

The partition between the light ($L$) and the heavy ($H$) fission fragments of the excitation energy available at scission is studied in the framework of the sudden approximation, i.e., under the assumption that the neck rupture and the absorption of the neck pieces by the fragments happen infinitely fast. We are dealing with a sudden transition between two different nuclear configurations (${\alpha }_i\to {\alpha }_f$) and we only need to know the two sets of neutron eigenstates involved. The accent in the present work is put on the dependence of this share of energy on the mass asymmetry $A_L/A_H$ of the primary fission fragments during the low-energy fission of ${}^{236}$U. In particular, for every fragment mass $A$ we estimate the scission neutron multiplicity ${\nu }_{\mathrm{sc}}$, the average energy cost for their release $\langle E_{\nu \mathrm{sc}}\rangle$, the primary fragments' excitation energy $E_{\mathrm{sc}}^{*}$, and the corresponding temperature $T_{\mathrm{sc}}$. The results are analyzed separately for each value of $\Omega$ (the projection of the angular momentum on the symmetry axis). As general trends, a decrease of $E_{\mathrm{sc}}^{*}$ ($T_{\mathrm{sc}}$) and an increase of ${\nu }_{\mathrm{sc}}$ ($\langle E_{\nu \mathrm{sc}}\rangle$) with increasing $A$ were observed.

In this paper, we study the connection between the interaction and the low energy observables, in particular the cross section for He and He$X$, the helium nucleus with a heavier particle attached, to explain problems with the observed lithium abundance in the big-bang nucleosynthesis. We treat the processes ${}^4\text{He}+{}^2\text{H}\to {}^6\text{Li}+\gamma$ and ${}^4\mathrm{HE}{\mathit{X}}^{-}+{}^2\text{H}\to {}^6\text{Li}+{\mathit{X}}^{-}$ and primarily focus on the effects of the long-range part of the total potential on the cross section. Our results indicate that relatively small changes in the long-range part of the potential can have a profound affect. Additionally, we compare the relative impacts on the low energy cross section of the Coulomb barrier peak and the long-range part of the interaction. Our results confirm that the long-range potential dominantly influences the low energy observables.

The energy derivatives of probabilities are functions suited to a best understanding of certain mechanisms. Applied to compound nuclear reactions, they can bring information on fusion barrier distributions as originally introduced [1,2], and also, as presented here, on fission barrier distributions and heights. Extendedly, they permit to access the compound nucleus spin-parity states preferentially populated according to an entrance channel, at a given energy.

Breakup reactions of loosely bound nuclei are often used to extract structure and/or astrophysical information. Here we compare three nonperturbative reaction theories often used when analyzing breakup experiments, namely the continuum discretized coupled channel model, the time-dependent approach relying on a semiclassical approximation, and the dynamical eikonal approximation. Our test case consists of the breakup of ${}^{15}$C on Pb at 68 MeV/nucleon and 20 MeV/nucleon.