The Poincaré invariant coupled-channel formalism for two-particle systems interacting via one-particle exchange, which has been developed and applied to vector mesons, is now applied to axial vector mesons. We thereby extend the previous study of a dynamical treatment of the Goldstone-boson exchange by comparison with the commonly used instantaneous approximation to the case of orbital angular momentum $l=1$. Effects in the mass shifts show more variations than for the vector-meson case. Results for the decay widths are sizable, but comparison with sparse experimental data is inconclusive.

The β decay of ${}^{135}\mathrm{Sn}$ was studied at CERN/ISOLDE using a resonance ionization laser ion source and mass separator to achieve elemental and mass selectivity, respectively. γ-ray singles and $\gamma$-$\gamma$ coincidence spectra were collected as a function of time with the laser on and with the laser off. These data were used to establish the positions of new levels in ${}^{135}\mathrm{Sb}$, including new low-spin states at 440 and 798 keV, which are given tentative spin and parity assignments of $3/2^{+}$ and $9/2^{+}$, respectively. The observed levels of ${}^{135}\mathrm{Sb}$ are compared with shell-model calculations using different single-particle energies and different interactions.

We investigate the Gamow-Teller strength distributions in the electron-capture direction in nuclei having mass $A=90\text{−}97$, assuming a ${}^{88}\mathrm{Sr}$ core and using a realistic interaction that reasonably reproduces nuclear spectroscopy for a wide range of nuclei in the region as well as experimental data on Gamow-Teller strength distributions. We discuss the systematics of the distributions and their centroids. We also predict the strength distributions for several nuclei involving stable isotopes that should be experimentally accessible for one-particle exchange reactions in the near future.

The ${}^{92\text{−}96}\mathrm{Zr}$ nuclei were produced as fission fragments following the fusion reactions ${}^{28}\mathrm{Si}+{}^{176}\mathrm{Yb}$ and ${}^{31}\mathrm{P}+{}^{176}\mathrm{Yb}$ at 145 and 152 MeV bombarding energy, respectively. Prompt $\gamma$ rays emitted in the two reactions were detected with the EUROGAM II and EUROBALL IV arrays. Sequences of $\gamma$-ray transitions observed in coincidence were newly assigned to ${}^{93\text{−}96}\mathrm{Zr}$. The previously known level schemes have been extended to higher excitation energies and higher spins. The experimental results are discussed in the framework of shell-model calculations with ${}^{88}\mathrm{Sr}$ assumed to be an inert core and the valence protons and neutrons filling the $\pi (2p_{1/2},1g_{9/2})$ and $\nu (2d_{5/2},3s_{1/2})$ orbitals.

The kinetic-energy variation of emitted light clusters has been employed as a clock to explore the time evolution of the temperature for thermalizing composite systems produced in the reactions of 26A, 35A, and 47A MeV ${}^{64}\mathrm{Zn}$ with ${}^{58}\mathrm{Ni}$, ${}^{92}\mathrm{Mo}$, and ${}^{197}\mathrm{Au}$. For each system investigated, the double-isotope ratio temperature curve exhibits a high maximum apparent temperature, in the range of 10–25 MeV, at high ejectile velocity. These maximum values increase with increasing projectile energy and decrease with increasing target mass. The time at which the maximum in the temperature curve is reached ranges from 80 to 130 fm/c after contact. For each different target, the subsequent cooling curves for all three projectile energies are quite similar. Temperatures comparable with those of limiting temperature systematics are reached 30 to 40 fm/c after the times corresponding to the maxima, at a time when antisymmetrized molecular dynamics transport model calculations predict entry into the final evaporative or fragmentation stage of deexcitation of the hot composite systems. Evidence for the establishment of thermal and chemical equilibrium is discussed.

An isospin-dependent coupled-channels optical model potential containing a dispersive term (including nonlocal contribution) is used to simultaneously fit the available experimental database (including strength functions and scattering radius) for neutron and proton scattering on strongly deformed ${}^{232}\mathrm{Th}$ nucleus. The energy range 0.001–200 MeV is covered. A dispersive coupled-channel optical model potential with parameters that show a smooth energy dependence and energy independent geometry are determined from fits to the entire data set. Dispersive contribution is shown to be the dominant Coulomb correction to the proton real potential below the Coulomb barrier. Inclusion of nonlocality effects in the absorptive volume potential and its corresponding dispersive contribution to the real potential is needed to achieve an excellent agreement above 100 MeV.

A particular three-body mechanism is responsible for the missing strength that has been reported in ${}^3\mathrm{He}$$(e,e^{\text{'}}p)$ reactions at missing momentum above 700 MeV/c. It corresponds to the absorption of the virtual photon by a nucleon at rest which subsequently propagates on shell and emits a meson which is reabsorbed by the pair formed by the two other nucleons. Its amplitude, which is negligible in photon-induced reactions as well as in the electroproduction of an on-shell meson, becomes maximal in the quasifree kinematics ($X=1$). This mechanism relates the amplitude of the ${}^3\mathrm{He}$$(e,e^{\text{'}}p){}^2$H reaction to the amplitude of pd elastic scattering at backward angles.

We studied the β-decay properties of the $N=Z+1$ nucleus ${}^{95}\mathrm{Ag}$ by measuring β-delayed γ rays and $\beta -\gamma -\gamma$ coincidences with a plastic scintillator as β detector and a Ge-detector array. The ${}^{95}\mathrm{Ag}$ nuclei were produced by means of the ${}^{58}\mathrm{Ni}$(${}^{40}\mathrm{Ca},p2n$) reaction and separated with the GSI online mass separator. The previously reported level scheme of the ${}^{95}\mathrm{Pd}$ daughter nucleus was extended considerably. The deduced level scheme is compared with different shell-model calculations with or without breaking the ${}^{100}\mathrm{Sn}$ core.

We identify a length scale that simultaneously accounts for the observed proton-nucleus reaction cross section and diffraction peak in the proton elastic differential cross section. This scale is the nuclear radius, a, deduced from proton elastic scattering data of incident energies higher than $~800\text{MeV}$ by assuming that the target nucleus is a “black” sphere. The values of a are determined so as to reproduce the angle of the first diffraction maximum in the scattering data for stable nuclei. We find that the absorption cross section, $\pi a^2$, agrees with the empirical total reaction cross section for C, Sn, and Pb to within error bars. This agreement persists in the case of the interaction cross section measured for a carbon target. We also find that $\sqrt{3/5}a$ systematically deviates from the empirically deduced values of the root-mean-square matter radius for nuclei having masses less than about 50, while it almost completely agrees with the deduced values for $A\gtrsim 50$. This tendency suggests a significant change of the nuclear matter distribution from a rectangular one for $A\lesssim 50$, which is consistent with the behavior of the empirical charge distribution.

The transverse momentum dependence of the azimuthal anisotropy parameter $v_2$, the second harmonic of the azimuthal distribution, for electrons at midrapidity ($\left|\eta \right|<0.35$) has been measured with the PHENIX detector in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV. The measurement was made with respect to the reaction plane defined at high rapidities ($\left|\eta \right|=3.1\text{−}3.9$). From the result we have measured the $v_2$ of electrons from heavy flavor decay after subtraction of the $v_2$ of electrons from other sources such as photon conversions and Dalitz decay from light neutral mesons. We observe a nonzero single electron $v_2$ with a 90% confidence level in the intermediate-$p_T$ region. The precision of the present data set does not permit us to conclude definitively that heavy quarks exhibit thermalization with the transverse flow of the bulk matter.

We have implemented a Monte Carlo simulation of fission fragment statistical decay by sequential neutron emission. Within this approach, we calculate the center-of-mass and laboratory prompt neutron energy spectra as a function of the mass of fission fragments and integrated over the whole mass distribution. We also assess the prompt neutron multiplicity distribution $P(\nu )$, both the average number of emitted neutrons and the average neutron energy as a function of the mass of the fission fragments [respectively $\overline{\nu }(A)$ and $\langle \varepsilon \rangle (A)$]. We investigate the average total energy available for prompt γ-ray emission as a function of the mass of the fission fragments ${\overline{E}}_{\gamma }(A)$. We also calculate neutron-neutron correlations such as the full matrix $\overline{\nu }(A,\mathrm{TKE})$ as well as correlations between neutron energies. Two assumptions for partitioning the total available excitation energy among the light and heavy fragments are considered. Results are reported for the neutron-induced fission of ${}^{235}\mathrm{U}$ (at neutron energy of 0.53 MeV) and for the spontaneous fission of ${}^{252}\mathrm{Cf}$.

The p-process of stellar nucleosynthesis produces the stable neutron-deficient nuclides heavier than the iron peak elements. An accurate determination of the isotopic composition of tantalum is required to enable p-process nucleosynthetic calculations to be evaluated in terms of an accurate isotope abundance for ${}^{180}\mathrm{Ta}$. This odd-odd nuclide has the remarkable property of having a long-lived isomeric state and a short-lived ground state, so that in reality one is measuring the isotope abundance of ${}^{180}\mathrm{Ta}{}^m$, which is a unique situation in nature. ${}^{180}\mathrm{Ta}{}^m$ is the rarest isotope of nature's rarest element and is therefore an important isotope in deciphering the origin of the p-process. Because the isotopic composition of tantalum has only been measured on two occasions with relatively large uncertainties, an accurate determination is required to provide a better basis for p-process production calculations. A thermal ionization mass spectrometer was used to measure the isotope abundance of ${}^{180}\mathrm{Ta}{}^m$ with high precision. The linearity of this instrument was verified by measuring the isotopically certified reference material for potassium (NIST 985), whose isotopes span a wide range of isotope ratios. The abundance sensitivity of the mass spectrometer for the measured ion beams has been examined to ensure the absence of tailing effects and interfering isotopes. These procedures are essential because of the extremely low isotope abundance of ${}^{180}\mathrm{Ta}{}^m$. The isotope fractionation of the tantalum isotopes was estimated by reference to the isotope fractionation of the isotopically certified reference material for rhenium (NIST 989). The isotopic composition of tantalum has been determined to be ${}^{181}\mathrm{Ta}/{}^{180}\mathrm{Ta}{}^m$=8325 ± 43, which gives isotope abundances for ${}^{180}\mathrm{Ta}{}^m$=0.0001201 ± 0.0000008 and ${}^{181}\mathrm{Ta}$=0.9998799 ± 0.0000008. This gives a Solar System abundance of ${}^{180}\mathrm{Ta}{}^m$ of 2.49 × 10${}^{-6}$ with reference to silicon=10${}^6$. These isotope abundances, together with the relative atomic masses, give an atomic weight for tantalum of 180.947878 ± 0.000002.

Solving the Schrödinger equation in coordinate space with the appropriate asymptotic boundary conditions, neutron one-particle resonant levels in $Y_{20}$-deformed Woods-Saxon potentials are studied. These resonance levels are the natural extension of one-particle bound levels to the continuum and are defined in terms of eigenphase. For one-particle bound levels with ${\Omega }^{\pi }\ne 1/2^{+}$ the corresponding one-particle resonant levels can be always found for small positive energies. For one-particle bound levels with ${\Omega }^{\pi }=1/2^{+}$ the corresponding one-particle resonant levels are either absent or disappearing quickly as energy increases, when we use well-deformed potentials with a realistic size of diffuseness. The possible presence of ${\Omega }^{\pi }=1/2^{+}$ one-particle resonant levels, in which $\ell =0$ components in the wave functions play a crucial role, is further studied using a simplified model without spin-orbit potential.

The dominance of S and D pairs in the description of deformed nuclei is one of the facts that provided sustenance to the interacting boson approximation. In Dukelsky and Pittel [Phys. Rev. Lett. 86, 4791 (2001)], using an exactly solvable model with a repulsive pairing interaction between bosons, it has been shown that the ground state is described almost completely in terms of S and D bosons. In the present paper we study the excited states obtained within this exactly solvable Hamiltonian and show that in order to obtain a rotational spectrum all the other degrees of freedom are needed.

In-beam $\gamma \gamma$ coincidence data have been collected for ${}^{186}\mathrm{Pb}$ by combining the JUROGAM Ge-detector array and the GREAT spectrometer with the RITU gas-filled recoil separator for recoil-decay tagging measurements. In addition to the known prolate yrast band in ${}^{186}\mathrm{Pb}$, these data have enabled a new low-lying side band to be identified. Based on the analysis of its decay pattern and comparison with Interacting Boson Model (IBM) calculations, the new band is associated with an oblate shape.

The production of the very neutron-deficient nuclides ${}^{184-192}\mathrm{Bi}$ and ${}^{186-192}\mathrm{Po}$ in the vicinity of the neutron midshell at N = 104 has been studied by using heavy-ion-induced complete fusion reactions in a series of experiments at the velocity filter SHIP. The cross sections for the xn and pxn evaporation channels of the ${}^{46}\mathrm{Ti}$+${}^{144}\mathrm{Sm}$$\to {}^{190}\mathrm{Po}{}^{*},$${}^{98}\mathrm{Mo}$+${}^{92}\mathrm{Mo}$$\to {}^{190}\mathrm{Po}{}^{*},$${}^{50,52}\mathrm{Cr}$+${}^{142}\mathrm{Nd}$$\to {}^{192,194}\mathrm{Po}{}^{*}$, and ${}^{94,95}\mathrm{Mo}$+${}^{93}\mathrm{Nb}$$\to {}^{187,188}\mathrm{Bi}{}^{*}$ reactions were measured. The results obtained, together with the previously known cross section data for the heavier Bi and Po nuclides, are compared with the results of statistical model calculations carried out with the HIVAP code. It is shown that a satisfactory description of the experimental data requires a significant (up to 35%) reduction of the theoretical fission barriers. The optimal reactions for production of the lightest Bi and Po isotopes are discussed.

Feshbach's projection formalism in the particle-hole model space leads to a microscopic description of scattering in terms of the many-body self-energy. To investigate the feasibility of this approach, an optical potential for ${}^{16}\mathrm{O}$ is constructed starting from two previous calculations of the self-energy for this nucleus. The results reproduce the background phase shifts for positive parity waves and the resonances beyond the mean field. The latter can be computed microscopically for energies of astrophysical interest using Green's function theory.

A unitary coupled-channel effective Lagrangian model is applied to the combined analysis of the $(\pi ,\gamma )N\to K\Lambda$ reactions in the energy region up to 2 GeV. To constrain the resonance couplings to the $K\Lambda$ final state the recent photoproduction data obtained by the SAPHIR, Spring-8, and CLAS groups are included in the calculations. The main resonance contributions to the process stem from the $S_{11}(1650),P_{13}(1720)$, and $P_{13}(1900)$ states. The second peak at 1.9 GeV seen in the photoproduction cross-section data is described as a coherent sum of the resonance and background contributions. The prediction for the beam polarization observable is presented.

We study EMC ratios on the basis of a relation between structure functions (SF) for a nucleus and for a nucleon, which is governed by a SF $f^{\mathrm{PN},A}(x,Q^2)$ of an unphysical nucleus, composed of point nucleons (PN). We demonstrate that the characteristic features of EMC ratios ${\mu }^A$ are determined by the above $f^{\mathrm{PN},A}$ and the SF of free nucleons. We account for the positions of the points $x_{1,2}$ in the interval $0.2\lesssim x\lesssim 0.9$, where ${\mu }^A(x,Q^2)=1$ and also for the minimum $x_m$ in that interval. We similarly describe the oscillations in ${\mu }^A$ for $Q^2\lesssim 3.5-4.0{\text{GeV}}^2$ in the quasielastic peak region $0.95\lesssim x\lesssim 1.05$ and for its subsequent continuous increase up to $x\approx 1.4$. Finally we compute ${\mu }^A$ over the entire range above for $A=$ ${}^4\mathrm{He}$, C, Fe, and Au and several $Q^2$ values. The results are in reasonable agreement with both directly measured and indirectly extracted data.

We develop the formalism based on the S matrix for $3\to 3$ scattering to derive the direct three-body resonant radiative capture reaction rate. Within this formalism, the states that decay only/predominantly directly into the three-body continuum should also be included in the capture rate calculations. Basing our work on the derivation, as well as on the modern experimental data and theoretical calculations concerning ${}^{17}\mathrm{Ne}$ nucleus, we significantly update the reaction rate for the ${}^{15}\mathrm{O}$($2p,\gamma$)${}^{17}\mathrm{Ne}$ process in an explosive environment. We also discuss possible implementations for the ${}^{18}\mathrm{Ne}$($2p,\gamma$)${}^{20}\mathrm{Mg}$, ${}^{38}\mathrm{Ca}$($2p,\gamma$)${}^{40}\mathrm{Ti}$, and ${}^4\mathrm{He}$($n\alpha ,\gamma$)${}^9\mathrm{Be}$ reactions.