It is shown that the difference between the multiplicity associated to high $p_T$ events and the unbiased multiplicity is given by the normalized variance of the multiplicity distribution, as a consequence of high $p_T$ events being self-shadowed. We discuss the possibility of checking the nonmonotonic behavior with centrality of the normalized variance by measuring the difference between multiplicities.

We present new accurate measurements of the differential cross section $\sigma (\theta )$ and the proton analyzing power $A_y$ for proton-${}^3\mathrm{He}$ elastic scattering at various energies. A supersonic gas-jet target has been employed to obtain these low-energy cross-section measurements. The $\sigma (\theta )$ distributions have been measured at $E_p=0.99$, 1.59, 2.24, 3.11, and 4.02 MeV. Full angular distributions of $A_y$ have been measured at $E_p=1.60$, 2.25, 3.13, and 4.05 MeV. This set of high-precision data is compared to four-body variational calculations employing realistic nucleon-nucleon ($\mathit{NN}$) and three-nucleon ($3N$) interactions. For the unpolarized cross section, the agreement between the theoretical calculation and data is good when a $3N$ potential is used. The comparison between the calculated and measured proton analyzing powers reveals discrepancies of approximately 50% at the maximum of each distribution. This is analogous to the existing “$A_y$ puzzle” known for the past 20 years in nucleon-deuteron elastic scattering.

The dependence of spallation neutron production double-differential cross sections on the density of the quantum molecular dynamics potential is investigated in $p$+Al, Fe, Zr, and Pb reactions at 1.2 GeV. It is shown that the cascade component of the neutron spectra is largely unaffected by the parameters of the density-dependent potential. As for the evaporative part ($<20$ MeV), some differences are marked only for Pb. Calculated results with a Skyrme-type equation of state of $K=300$ MeV reproduce the neutron spectra for the reactions under study.

The Coulomb dissociation (CD) of ${}^8\mathrm{B}$ has emerged as a landmark testing ground of the very method of CD for measuring the cross section of the low-energy ${}^7\mathrm{Be}$($p,\gamma$)${}^8\mathrm{B}$ direct capture (DC) reaction. Recent claims of evidence of slope difference between CD and DC results are critically examined. We include all relevant RIKEN2 data and all previously published DC data, and we examine the extracted so-called average scale-independent slope ($b$). The parametrization used by the Seattle group to extract the so-called $b$-slope parameter is also examined at energies above 300 keV. Considering the physical slope ($S^{\text{'}}=\mathit{dS}/\mathit{dE}$) above 300 keV, we observe a ($1.7\sigma$) agreement between slopes ($S^{\text{'}}$) measured in CD and DC above 300 keV. The claim that $S_{17}(0)$ values extracted from CD data are inconsistent and lower than DC results arises from a neglect of substantial systematic uncertainty of low-energy CD data. A consideration of the published CD $S_{17}(0)$ results yields very consistent $S_{17}(0)$ values that agree with most recent DC measurements. The recent correction of the $b$-slope parameter suggested by Esbensen, Bertsch, and Snover (EBS) was applied to the wrong $b$ slope calculated using part of the RIKEN2 data. When the correct slope of the RIKEN2 data is used, the EBS correction in fact leads to a substantial disagreement between the slopes of the RIKEN2 data and DC data. In spite of an agreement between CD and DC data neither allow for extracting the slope above 300 keV with high accuracy. Uncertainty of the slope ($S^{\text{'}}$) leads to an additional uncertainty of the extrapolated $S_{17}(0)$. The slope of the astrophysical cross-section factor $S_{17}$ must be measured with high precision to enable extraction of the $d/s$ ratio and a high-precision extrapolation of $S_{17}(0)$.

Nuclear mass autocorrelations are investigated as a function of the number of nucleons. The fluctuating part of these autocorrelations is modeled by a parameter free model in which the nucleons are confined in a rigid sphere. Explicit results are obtained by using periodic orbit theory. Despite the simplicity of the model we have found a remarkable quantitative agreement of the mass autocorrelations for all nuclei in the nuclear data chart. In order to achieve a similar degree of agreement for the nuclear masses themselves it is necessary to consider additional variables such as multipolar corrections to the spherical shape and an effective number of nucleons. Our findings suggest that higher order effects like nuclear deformations or residual interactions have little relevance in the description of the fluctuations of the nuclear autocorrelations.

The $\mathcal{S}$ shape of the canonical heat-capacity curve is known as a signature of the pairing transition, and along an isotopic chain it is significantly more pronounced for nuclei with an even number of neutrons than for those with an odd number. Although the heat capacities extracted from experimental level densities in ${}^{93-98}\mathrm{Mo}$ exhibit a clear $\mathcal{S}$ shape, they do not show such an odd-even staggering. To understand the underlying physics, we analyze thermal quantities evaluated from the partition function calculated using the static-path plus random-phase approximation (SPA+RPA) in a monopole pairing model with number-parity projection. The calculated level densities reproduce very well the experimental data, and they also agree with estimates made using the back-shifted Fermi-gas model. We clarify the reason why the heat capacities for Mo isotopes do not show odd-even staggering of the $\mathcal{S}$ shape. We also discuss thermal odd-even mass differences in ${}^{94-97}\mathrm{Mo}$ that were calculated using the three-, four-, and five-point formulas. These thermal mass differences are regarded as indicators of pairing correlations at finite temperature.

We use the random phase approximation to systematically describe the total muon capture rates on all nuclei where they have been measured. We reproduce the experimental values on these nuclei to better than 15% accuracy using the free nucleon weak form factors and residual interactions with a mild $A$ dependency. The isospin dependence and the effects associated with shell closures are fairly well reproduced as well. However, the calculated rates for the same residual interactions would be significantly lower than the experimental data if the in-medium quenching of the axial-vector coupling constant were employed to other than the true Gamow-Teller amplitudes. Our calculation thus suggests that no quenching is needed in the description of semileptonic weak processes involving higher multipole transitions and momentum transfer $~m_{\mu }$, with obvious importance to analogous weak processes.

The β-NQR (nuclear quadrupole resonance) signals of ${}^8\mathrm{B}$ ($I^{\pi }=2^{+},T_{1/2}=770$ ms) implanted in ${\mathrm{TiO}}_2$ (rutile) have been detected to determine the electric quadrupole moment of ${}^8\mathrm{B}$ with high precision. The ratio of the quadrupole moments of ${}^8\mathrm{B}$ and ${}^{12}\mathrm{B}$ was determined as $|Q$(${}^8\mathrm{B}$)$/Q$(${}^{12}\mathrm{B}$)$|=4.88\pm 0.04$. Combined with the known sign, the quadrupole moment of ${}^8\mathrm{B}$ was obtained as $Q$(${}^8\mathrm{B}$)$=+(64.5\pm 1.4)$ mb, which is consistent with and more precise than the previously reported value. The experimental values of the $Q$ moment, the proton and neutron radii and the density distribution of ${}^8\mathrm{B}$ were compared with several theoretical predictions and were found to be best reproduced by a microscopic cluster model, which suggests the existence of a proton halo.

Simplistic shape and orientation fluctuation calculations are compared with the data for the system ${}^{28}\mathrm{Si}+{}^{58}\mathrm{Ni}$ at E(${}^{28}\mathrm{Si}$)$=100$ and 125 MeV. The collisional damping width (${\Gamma }_0$) is extracted under the shape fluctuation model analysis. A constant value of ${\Gamma }_0$ cannot reproduce the measured γ-spectra. The extracted value of ${\Gamma }_0$ is found to be independent of the average angular momentum $\langle J\rangle$, while showing a mild temperature dependence above an average temperature, $\langle T\rangle ~1.3$ MeV. Below, a very small value of ${\Gamma }_0~3.8$ MeV is found.

In many simulations of high-energy heavy-ion collisions on an event-by-event analysis, it is known that the initial energy density distribution in the transverse plane is highly fluctuating. Subsequent longitudinal expansion will lead to many longitudinal tubes of quark-gluon plasma that have tendencies to break up into many spherical droplets because of sausage instabilities. We are therefore motivated to use a model of quark-gluon plasma granular droplets that evolve hydrodynamically to investigate pion elliptic flows and Hanbury-Brown–Twiss (HBT) interferometry. We find that the data of pion transverse momentum spectra, elliptic flows, and HBT radii in $\sqrt{s_{\mathit{NN}}}=200$ GeV Au+Au collisions at the BNL Relativistic Heavy Ion Collider can be described well by an expanding source of granular droplets with an anisotropic velocity distribution.

In ${}^{46}\mathrm{V}$ picosecond lifetimes were determined using the recoil distance Doppler-shift technique with the Cologne plunger device coupled to the EUROBALL IV spectrometer. The experiment was carried out using the ${}^{24}\mathrm{Mg}$(${}^{28}\mathrm{Si}$, $\alpha \mathit{pn}$) reaction at 110 MeV at the Strasbourg VIVITRON accelerator. Subsequently the differential decay curve method in coincidence mode was employed to derive lifetimes for four excited states in the $K^{\pi }=0^{-}$ band. The resulting transition probabilities give a comparison of isospin allowed and forbidden $E1$ transitions, which clarifies the decay properties of the $2^{-},T=0$ state. Furthermore the $B(E2)$ values within the $K^{\pi }=0^{-}$ band are discussed.

The results of the first spectroscopic studies of delayed neutron and γ emission following the β decay of ${}^{19}\mathrm{N}$ and ${}^{20}\mathrm{N}$ are reported. Nuclides were produced by fragmenting an 80 MeV/nucleon ${}^{22}\mathrm{Ne}$ beam in a 546 mg/cm${}^2$ thick Be target and were separated at high velocities with the A1200 fragment separator. The nuclides were implanted in a thin plastic scintillator at the center of an array of neutron scintillators to determine the neutron time-of-flight spectrum. Two hyperpure germanium detectors were used to observe coincident γ events. The β–$\gamma ,\beta$–$n$, and β–$n$–γ coincidence spectra were analyzed to obtain the energies of the states populated in ${}^{18}\mathrm{O}$, ${}^{19}\mathrm{O}$, and ${}^{20}\mathrm{O}$ following the β decay. Eight new neutron energies with a total neutron emission probability of 41.8(9)%, six γ transitions among the excited states of ${}^{19}\mathrm{O}$, and four γ transitions among the excited states of ${}^{18}\mathrm{O}$ were identified in the ${}^{19}\mathrm{N}$ β decay. Seven new neutron energies with a total neutron emission probability of 42.9(14)%, ten γ transitions among the excited states of ${}^{20}\mathrm{O}$, and two γ transitions among the exited states of ${}^{19}\mathrm{O}$ were observed from the ${}^{20}\mathrm{N}$ β decay. Half-lives of 336(3) and 136(3) ms were determined for the ${}^{19}\mathrm{N}$ and ${}^{20}\mathrm{N}$ decays, respectively. The branching ratios of both decays were deduced and compared with USD (universal sd-shell) shell model calculations. The β decay schemes for ${}^{19}\mathrm{N}$ and ${}^{20}\mathrm{N}$ were deduced.

Although the neutron ($n$) does not carry a total electric charge, its charge and magnetization distributions represented in momentum space by the electromagnetic form factors, $F_1^{(n)}(q^2)$ and $F_2^{(n)}(q^2)$, lead to an electromagnetic potential of the neutron. Using this fact, we calculate the electromagnetic corrections to the binding energy, $B_d$, of the deuteron and a one-neutron halo nucleus (${}^{11}\mathrm{Be}$) by evaluating the neutron-proton and the neutron-charged core (${}^{10}\mathrm{Be}$) potential, respectively. The correction to $B_d$ (∼9 keV) is comparable to that arising due to the inclusion of the Δ-isobar component in the deuteron wave function. In the case of the more loosely bound halo nucleus, ${}^{11}\mathrm{Be}$, the correction is close to about 2 keV.

We reanalyze Oklo ${}^{149}\mathrm{Sm}$ data using realistic models of the natural nuclear reactors. Disagreements among recent Oklo determinations of the time evolution of α, the electromagnetic fine structure constant, are shown to be due to different reactor models, which led to different neutron spectra used in the calculations. We use known Oklo reactor epithermal spectral indices as criteria for selecting realistic reactor models. Two Oklo reactors, RZ2 and RZ10, were modeled with MCNP. The resulting neutron spectra were used to calculate the change in the ${}^{149}\mathrm{Sm}$ effective neutron capture cross section as a function of a possible shift in the energy of the 97.3-meV resonance. We independently deduce ancient ${}^{149}\mathrm{Sm}$ effective cross sections and use these values to set limits on the time variation of α. Our study resolves a contradictory situation with previous Oklo α results. Our suggested $2\sigma$ bound on a possible time variation of α over 2 billion years is stringent: $-0.11\le \Delta \alpha /\alpha \le 0.24$, in units of ${10}^{-7}$, but model dependent in that it assumes only α has varied over time.

The semileptonic decays of ${\Omega }_c$ and ${\Omega }_b$ are treated in the framework of a constituent quark model developed in a previous article on the semileptonic decays of heavy Λ baryons. Analytic results for the form factors for the decays to ground states and a number of excited states are evaluated. For ${\Omega }_b$ to ${\Omega }_c$ the form factors obtained are shown to satisfy the relations predicted at leading order in the heavy-quark effective theory at the nonrecoil point. A modified fit of nonrelativistic and semirelativistic Hamiltonians generates configuration-mixed baryon wave functions from the known masses and the measured ${\Lambda }_c^{+}\to \Lambda e^{+}\nu$ rate, with wave functions expanded in both harmonic oscillator and Sturmian bases. Decay rates of ${\Omega }_b$ to pairs of ground and excited ${\Omega }_c$ states related by heavy-quark symmetry calculated using these configuration-mixed wave functions are in the ratios expected from heavy-quark effective theory to a good approximation. Our predictions for the semileptonic elastic branching fraction of ${\Omega }_Q$ vary minimally within the models we use. We obtain an average value of ($84\pm 2$%) for the fraction of ${\Omega }_c\to {\Xi }^{(*)}$ decays to ground states and 91% for the fraction of ${\Omega }_c\to {\Omega }^{(*)}$ decays to the ground state Ω. The elastic fraction of ${\Omega }_b\to {\Omega }_c$ ranges from about 50% calculated with the two harmonic-oscillator models to about 67% calculated with the two Sturmian models.

We briefly review the situation around the claimed deeply bound $K^{-}$ states in different recent experiments and concentrate particularly on the state $K^{-}\mathit{pp}$ advocated by the FINUDA collaboration in nuclear $K^{-}$ absorption. We perform a theoretical simulation of the process and show that the peak in the $\Lambda p$ spectrum that was interpreted as a deep $K^{-}\mathit{pp}$ bound state corresponds mostly to the process $K^{-}pp\to \Lambda p$ followed by final-state interactions of the produced particles with the daughter nucleus.

We present a new method for calculating the heavy-ion interaction potential from a density-constrained time-dependent Hartree-Fock calculation.

Liquid-gas phase transitions in asymmetric nuclear matter give rise to a distillation effect that corresponds to the formation of droplets of high-density symmetric matter in a background of a neutron gas possibly with a very small fraction of protons. In the present work we test the model dependence of this effect. We study the spinodal instabilities of asymmetric nuclear matter within six different mean-field relativistic models with both constant and density-dependent coupling parameters. We also consider the effects of introducing the δ meson and the nonlinear $\omega \text{−}\rho$ coupling. It is shown that the distillation effect within density-dependent models is not so efficient and is comparable to results obtained for nonrelativistic models. Thermodynamical instabilities of nuclear matter neutralized by electrons as found in stellar matter are also investigated. The high Fermi energy of electrons completely erases the instability of density-dependent models. The other models still show a small region of instability but the distillation effect completely disappears because the electron presence freezes the proton fluctuations.

The consistency condition is tested within the particle-particle random-phase approximation (RPA), renormalized RPA (RRPA), and the self-consistent RPA (SCRPA) making use of the Richardson model of pairing. The two-particle separation energy is calculated in two ways, namely, as the energy of the first addition mode, which adds two particles to a core with $N$ particles, and as the energy of the first removal mode, which removes two particles from the $N+2$ particle system to get back to the same $N$-particle core. The corresponding transitions generated by the pairing operators are also calculated. It is found that the results obtained in these two ways of calculations are close to each other only at large values of particle number $N$ and/or small interaction strength. At $N\le 10$ for a given value of the interaction strength, the discrepancy between the results obtained in two ways of calculations within the SCRPA is much smaller than those given by the RPA and RRPA.

We study the phase transitions of two algebraic cluster models, which have similar interactions, but differ from each other in their model spaces. The semimicroscopical model incorporates the Pauli exclusion principle, while the phenomenological one does not. The appearance of the quasidynamical SU(3) symmetry is also investigated in the presence of an explicitly symmetry-breaking interaction. Examples of binary cluster configurations with two, one, or zero closed-shell clusters are studied.