The emission probability of the 21.54 keV γ ray in the decay of ${}^{151}$Sm was experimentally determined by means of the measurements of the 21.54 keV γ-ray emission rate and the activity of ${}^{151}$Sm with high-resolution Ge, Si(Li) γ-ray spectrometry and liquid scintillation counting (LSC), respectively. The resulting emission probability of the 21.54 keV γ ray is 0.0324$\%$ with a standard uncertainty of 0.0013$\%$ based on a quadratic summation of the uncertainty components from the measurements of the γ-ray emission rate and the activity of ${}^{151}$Sm. The result agrees with the latest literature value (partially theoretically based), 0.0318 ± 0.0022$\%$, with reduced uncertainty.

We develop a model to evaluate the formation rate of the heavy mesic nuclei in two-nucleon pick-up reactions and apply it to the ${}^6$Li target cases for the formation of heavy meson–$\alpha$ bound states, as examples. The existence of the quasideuteron in the target nucleus is assumed in this model. It is found that mesic nuclei formation in recoilless kinematics is possible even for heavier mesons than the nucleon in two-nucleon pick-up reactions. We find the formation rate of the meson-$\alpha$ bound states can be around half of the elementary cross sections at the recoilless kinematics with small distortions.

Due to gluon saturation, the growth of the inelastic nucleon-nucleon cross section with increasing collision energy $\sqrt{s}$ results in a broadening of the nucleon's density distribution in position space. This leads to a natural smoothing of the initial energy density distribution in the transverse plane of the matter created near midrapidity in heavy-ion collisions. We study this effect for fluctuating initial conditions generated with the Monte Carlo Kharzeev-Levin-Nardi model for $\mathrm{Au}+\mathrm{Au}$ collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). We argue that at the LHC, viscous hydrodynamics is applicable at earlier times than at the RHIC, not only because of the higher temperature but also since the length scale over which the initial pressure fluctuates increases with collision energy.

We update our calculations of thermal-photon production in nuclear collisions at the BNL Relativistic Heavy-Ion Collider (RHIC). Specifically, we address the recent experimental observation of an elliptic flow of direct photons comparable in magnitude to that of pions, which is at variance with expectations based on quark-gluon plasma (QGP) dominated photon radiation. Our thermal emission rate is based on previous work, i.e., resummed leading-order QGP emission and in-medium hadronic rates in the confined phase. These rates are nearly degenerate at temperatures close to the expected QCD-phase change. The rates are convoluted over an improved elliptic-fireball expansion with transverse- and elliptic-flow fields quantitatively constrained by empirical light- and strange-hadron spectra. The resulting direct-photon spectra in central Au-Au collisions are characterized by hadron-dominated emission up to transverse momenta of $\sim 2$–$3\mathrm{GeV}$. The associated large elliptic flow in the hadronic phase mitigates the discrepancy with the measured photon-$v_2$ compared to scenarios with QGP-dominated emission.

Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction $\gamma p\to p{\pi }^0$ for photon energies between 0.85 and 2.50 GeV. The ${\pi }^0$ mesons are observed in their dominant neutral decay mode: ${\pi }^0\to \gamma \gamma$. For the first time, the differential cross sections cover the very forward region, ${\theta }_{\mathrm{c}.\mathrm{m}.}<{60}^{\circ }$. A partial-wave analysis of these data within the Bonn-Gatchina framework observes the high-mass resonances $G_{17}$(2190), $D_{13}$(2080), and $D_{15}$(2070).

High-spin states in ${}^{139}$Pm are investigated via the ${}^{116}$Cd(${}^{27}$Al, 4$n$)${}^{139}$Pm fusion-evaporation reaction at a beam energy of 120 MeV. The previously reported level scheme has been modified because of identifications of some linking and doublet transitions. The revised yrast $\pi h_{11/2}$ band obviously undergoes $\pi h_{11/2}$ $\to$ $\pi {\left(h_{11/2}\right)}^3$ $\to$ $\pi {\left(h_{11/2}\right)}^3$$\otimes$$\nu {\left(h_{11/2}\right)}^{-2}$ band crossings at $\hslash \omega =0.45$ and 0.39 MeV. Two negative-parity dipole bands have been assigned as $\pi h_{11/2}$$\otimes$$\nu {\left(h_{11/2}\right)}^{-2}$ and $\pi h_{11/2}$$\otimes$$\nu {\left(h_{11/2}\right)}^{-4}$ configurations, respectively, and can be considered as examples of magnetic rotational bands.

Data from a recent ${}^9$Be(${}^3$He,${t)}^9$B measurement are used to rule out a possible solution to the cosmological lithium problem based on conventional nuclear physics.

Lifetimes of the low-lying excited states in the very neutron-deficient nucleus ${}^{175}$Au have been measured by the recoil-distance Doppler-shift method using $\gamma$-ray spectra obtained with the recoil-decay tagging technique. Transition quadrupole moments and reduced transition probabilities extracted for this odd-$Z$ nucleus indicate the existence of three different shapes and the competition between collective and noncollective structures.

Low-energy strength is predicted for the isoscalar monopole response of neutron-rich Ni isotopes, in calculations performed using the microscopic Skyrme HF + RPA and relativistic RHB + RQRPA models. Both models, although based on different energy density functionals, predict the occurrence of pronounced monopole states in the energy region between 10 and 15 MeV, well separated from the isoscalar giant monopole resonance. The analysis of transition densities and corresponding particle-hole configurations shows that these states represent almost-pure neutron single hole-particle excitations. Even though their location is not modified with respect to the corresponding unperturbed states, their strength is considerably enhanced by the residual interaction. The theoretical analysis predicts the gradual enhancement of low-energy monopole strength with neutron excess.

The ${}^{83,81}$As nuclei have been produced as fission fragments in the fusion reaction ${}^{18}$O + ${}^{208}$Pb at 85 MeV bombarding energy and studied with the Euroball array. Medium-spin states of ${}^{83,81}$As have been established up to $\sim 3.5$ MeV excitation energy. From angular correlation analysis, spin values have been assigned to most of the ${}^{81}$As excited states. The behaviors of the yrast structures identified in this work are discussed in comparison with the general features known in the mass region. Then they are compared to the results of two theoretical approaches: the “rotor + quasiparticle” for ${}^{81}$As and the shell model using the effective interactions JUN45 for ${}^{83,81}$As.

Near yrast positive-parity states of particle-hole nuclei around ${}^{100}$Sn have been studied and found mainly to be the coupling of $g_{9/2}$ valence-proton holes to the $d_{5/2}$ and $g_{7/2}$ valence-neutron particles. The much higher excitation energy for a stretched coupled state involving $\nu g_{7/2}$ rather than $\nu d_{5/2}$ indicates that level structures of particle-hole nuclei around ${}^{100}$Sn might be dominated by the $T=1$ channel of proton-neutron residual interaction. The near yrast states are compared with the results of shell model calculations in the model space of $\pi {(p_{1/2},g_{9/2})}^{-1--4}$ and $\nu {(d_{5/2},s_{1/2},d_{3/2},g_{7/2},h_{11/2})}^{1-3}$ by using the dominant $T=1$ channel proton-neutron quadrupole interaction; and the reasonable agreement with each other gives indirect proof of it being responsible for level structures of particle-hole nuclei around ${}^{100}$Sn.

The production of residual nuclei in the reactions ${}^{25}$Mg + ${}^{206}$Pb, ${}^{36}$S + ${}^{\mathrm{nat}}$Pt, and ${}^{48}$Ca + ${}^{\mathrm{nat}}$W was investigated at low bombarding energies at the velocity filter SHIP (GSI, Darmstadt). The data are discussed within the dinuclear system model. In particular, the emission of complex fragments with $Z>2$ from heavy compound nuclei is treated within the model and supported by the experimental data. The production channels and cross sections, charge, and isotopic distributions of the residual heavy nuclei are presented.

Fusion of heavy ions is largely hindered because of the appearance of an inner barrier between the contact point of the two colliding nuclei and the compound nucleus. But there are still quantitative ambiguities on the size of the barrier and on the role of the dissipation. In this paper we stress the importance of the neck of the composite system on the hindrance of the fusion of heavy nuclei. We show that the “denecking” process is very quick compared to the other collective degrees of freedom as the relative distance. This behavior of the neck will change the potential seen by the relative distance on the way to fusion and its effective initial value through a dynamical coupling. Both effects contribute to the hindrance of fusion.

The meson spectra provide insight into the particle production mechanism and interaction in the hadronic and quark gluon plasma (QGP) phases. The detailed study of systematics of meson spectra is important also because it acts as an ingredient for estimating the hadronic decay backgrounds in the photon, single lepton, and dilepton spectra which are the penetrating probes of quark gluon plasma. In this work, we parametrize experimentally measured pion spectra and then obtain the spectra of other light mesons using a property known as $m_T$ scaling. The $m_T$ scaled spectra for each meson is compared with experimental data for $p+p$, $d$ + Au, and Au + Au systems at $\surd s_{NN}$ = 200 GeV. The agreement of the $m_T$ scaled and experimental data shapes are excellent in most cases and their fitted relative normalization gives ratio of meson to pion $m_T$ spectra. These ratios are useful to obtain the hadronic decay contribution in photonic and leptonic channels but also point to the quantitative changes in the dynamics of the heavy ion collision over $p+p$ collisions. It is shown that, the particles with charm contents behave differently as compared to pions in $d$ + Au systems and particles either with strange or charm contents behave differently from pions in Au + Au systems. For Au + Au system, three centrality classes have been studied which reveal that for the particles, such as kaon and $\phi$, peripheral collision data are better reproduced as compared to central collision data and their relative ratios with pions also increase as the collisions become more central.

A recent discussion of theoretical work on the ${}^{25}$Al($p,\gamma$)${}^{26}$Si astrophysical reaction rate [W.A. Richter, B. Alex Brown, A. Signoracci and M. Wiescher, Phys. Rev. C 83, 065803 (2011)] omits some current and relevant experimental information in forming its scientific conclusions. Accounting for this new information has the potential to significantly alter the reaction rate derived in the paper.

We discuss the implications for the ${}^{25}$Al($p,\gamma$)${}^{26}$Si resonance-capture rate that result from the updates on the experimental data given in the Comment.

The choice of generator in the similarity renormalization group (SRG) flow equation determines the evolution pattern of the Hamiltonian. The kinetic energy has been used in the generator for most prior applications to nuclear interactions, and other options have been largely unexplored. Here we show how variations of this standard choice can allow the evolution to proceed more efficiently without losing its advantages.

Production cross sections and longitudinal velocity distributions of the projectilelike residues produced in the reactions ${}^{112}\text{Sn}+{}^{112}\text{Sn}$ and ${}^{124}\text{Sn}+{}^{124}\text{Sn}$, both at an incident beam energy of 1$A$ GeV, were measured with the high-resolution magnetic spectrometer, the Fragment Separator of GSI. For both reactions the characteristics of the velocity distributions and nuclide production cross sections were determined for residues with atomic number $Z\ge 10$. A comparison of the results of the two reactions is presented.

Inclusive proton emissions from deuteron-induced reactions on ${}^9$Be, ${}^{12}$C, ${}^{27}$Al, ${}^{58}$Ni, ${}^{93}$Nb, ${}^{181}$Ta, ${}^{208}$Pb, and ${}^{238}$U at an incident energy of 100 MeV are analyzed using the continuum discretized coupled-channels theory for the elastic-breakup process and the Glauber model for the neutron-stripping process in order to investigate deuteron-breakup processes over a wide range of target mass numbers. The effects of Coulomb interactions are taken into account to give a proper description of proton emissions at forward angles. Moreover, the phenomenological moving-source model is used to estimate evaporation and preequilibrium components in inclusive $(d,xp)$ spectra. The calculation reproduces fairly well a prominent bump observed around half the incident energy in experimental $(d,xp)$ spectra for light and medium nuclei at forward angles of less than 20${}^{\circ }$ whereas the calculation underestimates the bump component as the target atomic number increases. The underestimation is likely due to the fact that the eikonal approximation used in the Glauber model becomes worse due to strong Coulomb interactions. It is shown that the Glauber-model calculation for the neutron-stripping process leads to an improvement of this discrepancy by substituting the eikonal phase shift for the quantum phase shift given by the optical-model calculation.