The three parameter variable moment of inertia (VMI) nuclear softness model named VMINS3 is shown to be adequate in reproducing the main features of the VMI model. Its failure for deformed nuclei reported by earlier workers is shown to be the result of a wrong approach in the calculation. The variation of the softness parameter σ and of the stretching parameter $K=\left(\frac{1}{2}\right)C{\theta }_0^2$ with increasing deformation of the nuclear core is now consistent with results of the variable moment of inertia model.

Recent optical model analyses of near-barrier ${}^7$Li+${}^{208}$Pb elastic scattering data found a peak in the energy dependence of $W_{\mathrm{OM}},$ the strength of the imaginary part of the optical model potential at the strong absorption radius. It was speculated that this might be due to the polarization potentials produced by couplings to the ${}^{208}$Pb${(}^7$Li,${}^6$Li)${}^{209}$Pb transfer channels. In this Brief Report we show explicitly that such couplings do indeed produce polarization potentials with the same energy dependence as that observed for the empirical optical potentials.

The procedure proposed by Mohr et al. [Phys. Rev. C 55, 1591 (1997)] for extracting the spectroscopic factor for a bound $s$-wave neutron state from the scattering length appears to be of doubtful validity and accuracy.

In a recent comment Barker [Phys. Rev. C 56, 3423 (1997), the preceding paper] criticized our procedure for the extraction of spectroscopic factors from neutron scattering lengths [Phys. Rev. C 55, 1591 (1997)]. In this reply we compare the $R$-matrix analysis by Barker to our potential model calculation, and we discuss the applicability of both models for the extraction of spectroscopic factors.

The angular distributions of fission fragments have been measured over a range of near- and sub-barrier energies for reactions involving ${}^{12}\mathrm{C}$ projectiles on ${}^{235,236,238}\mathrm{U}$ targets. For the reactions involving the zero spin targets, the discrepancies between the experimental fission anisotropies and the transition state model increase dramatically as the beam energy decreases through the region of the fusion barriers. However, the ${}^{12}\mathrm{C}{+(I=7/2\mathrm{})\mathrm{}}^{235}\mathrm{U}$ fission anisotropies exhibit a much less dramatic departure from the transition state model.

By means of the on-line mass separator at Gesellschaft für Schwerionenforschung, Darmstadt, we produced ${}^{114}\mathrm{Ba}$ through the ${}^{51}{\mathrm{N}\mathrm{i}(}^{58}\mathrm{N}\mathrm{i},2n)$ reaction, separated it as a ${}^{114}{\mathrm{Ba}}^{19}{\mathrm{F}}^{+}$ beam, and implanted it into a stopper foil positioned in the center of an array of track detectors, which were used to search for ${}^{12}\mathrm{C}$ radioactivity of ${}^{114}\mathrm{Ba}$. A total number of $(5.4\mathrm{}\pm 1.7)\times {10}^4$ ${}^{114}\mathrm{Ba}$ atoms were implanted. No ${}^{12}\mathrm{C}$ event was found after a total exposure time of 116 h, corresponding to a ${}^{58}\mathrm{Ni}$ beam dose of $1.3\times {10}^{17}$. The resulting upper limit of $3.4\times {10}^{-5}$ (84% C.L.) for the branching ratio for ${}^{12}\mathrm{C}$ decay of ${}^{114}\mathrm{Ba}$ is considerably lower than the limits obtained in previous experiments, which represents an inconsistency at levels of more than 90%. A semiempirical estimate of 19.3 MeV for the upper limit of the $Q$ value for ${}^{12}\mathrm{C}$ decay of ${}^{114}\mathrm{Ba}$ is derived.

Data obtained from studies of the $p(d\to ,\gamma {)}^3\mathrm{He}$ and the $d(p\to ,\gamma {)}^3\mathrm{He}$ reactions have been used to extract the transition amplitudes corresponding to $S=1/2\mathrm{}$ (doublet) and $S=3/2\mathrm{}$ (quartet) $M1\mathrm{}$ radiative capture. Protons (deuterons) of 40 keV (80 keV) were stopped in ${\mathrm{D}}_2\mathrm{O}$ $\left({\mathrm{H}}_2\mathrm{O}\right)$ ice targets. Angular distributions of $\sigma$, $A_y,$ $T_{20},$ $P_{\gamma }$, and ${\mathrm{iT}}_{11}$ were fit simultaneously in terms of the four possible $E1\mathrm{}$ $p$-wave capture amplitudes and the two $(S=1/2\mathrm{}$ and $3/2)$ possible $M1\mathrm{}$ $s$-wave capture amplitudes. The results obtained at $E_{\mathrm{cm}}=23.3\mathrm{}$ keV indicate that the $S=1/2\mathrm{}$ $M1\mathrm{}$ capture cross section is 13.77 $\pm$ 0.66 nb, while the $S=3/2\mathrm{}$ $M1\mathrm{}$ capture cross section is 6.74 $\pm$ 0.44 nb. These results agree with the predictions of a recent three-body theoretical calculation which includes two-body currents [e.g., meson-exchange currents (MEC’s)]. They also agree with the previous experimental determination of the doublet and quartet fusion rates obtained using the Wolfenstein-Gerstein effect to vary the relative population of $S=1/2\mathrm{}$ and $3/2$ nuclear spins in the $\mu$-$p$-$d$ molecule prior to fusion.

The Dalitz-decay contributions of ${\pi }^0$ and η mesons to the di-electron invariant-mass spectrum at 1$A$ GeV have been obtained from a systematics of inclusive meson production cross sections measured for the collision systems ${}^{12}\mathrm{C}{+}^{\mathrm{nat}}\mathrm{C}$ and ${}^{40}\mathrm{Ar},{}^{40}\mathrm{Ca}{+}^{\mathrm{nat}}\mathrm{Ca}$ in the bombarding-energy range of 0.8–2.0 $A$ GeV. These results are compared with the recently published di-electron mass spectra of the DLS collaboration. Systematic errors and angular-distribution effects are discussed. We conclude that the low-mass part of the DLS data cannot be explained by the Dalitz decays of light neutral mesons only.

We present the observation of an isomeric decay in the very neutron deficient nucleus ${}_{36}^{74}\mathrm{Kr}.$ The isomer is interpreted as an excited 0${}^{+}$ state, consistent with the long standing prediction of high deformation prolate/oblate shape coexistence in this nucleus. The magnitude of the $E0\mathrm{}$ matrix element deduced for the $0_2^{+}\to 0_1^{+}$ transition gives strong support to the prediction of a highly deformed oblate rotor.

We present new calculations and experimental measurements of the quasielastic cross section angular distribution for ${}^8$He scattering from ${}^{12}$C at 60 MeV/nucleon. ${}^8$He is treated as a five-body $\alpha +4n$ system and the six-body ${}^8$He+target scattering calculations make use of the eikonal few-body method and the cluster orbital shell model approximation for the ${}^8$He wave function. The qualitative features of the new data are successfully described without parameter variation. The sensitivity of the calculations to correlations in the ${}^8$He wave function is assessed.

We formulate a general relativistic mean field theory for rotating nuclei starting from the special relativistic $\sigma$-$\omega$ model Lagrangian. The tetrad formalism is adopted to generalize the model to the accelerated frame.

We show that a recently proposed valence correlation scheme for separation energies is a straightforward conclusion from the approximate major shell lowest seniority mass equation, and both the new scheme and the shell model equation give the same predictions for unknown nuclei. A way to enlarge the predictive power of the new scheme far from stability is indicated.

We propose an oscillation mechanism for meson mixing that causes charge symmetry breaking in nucleon-nucleon interactions. The mixing probabilities of the ρ meson component in the ω meson and vice versa are estimated in a nuclear medium by using the data of the branching ratio $B(\omega \to 2\pi )$ and proton-proton $\mathrm{}(p-p)\mathrm{}$ and neutron-neutron $\mathrm{}(n-n)\mathrm{}$ scattering lengths. It is shown that the mixing probability depends on the nuclear density and is very small at normal density. In a nuclear medium, ρ-ω mixing is larger in the $p-p$ interaction than in the $n-n$ interaction because of Coulomb repulsion.

Equal-time Green’s function is used to derive a three-dimensional integral equation from the Bethe-Salpeter equation. The resultant equation, in the absence of antiparticles, is identical to the use of time-ordered diagrams, and has been used within the framework of ${\phi }^2\sigma$ coupling to study the role of energy dependence and nonlocality when the two-body potential is the sum of $\sigma$ exchange and crossed $\sigma$ exchange. The results show that nonlocality and energy dependence make a substantial contribution to both the on-shell and off-shell amplitudes.

The covariant spectator (or Gross) equations for the bound state of three identical spin-1/2 particles, in which two of the three interacting particles are always on shell, are developed and reduced to a form suitable for numerical solution. The equations are first written in operator form and compared to the Bethe-Salpeter equation, then expanded into plane wave momentum states, and finally expanded into partial waves using the three-body helicity formalism first introduced by Wick. In order to solve the equations, the two-body scattering amplitudes must be boosted from the overall three-body rest frame to their individual two-body rest frames, and all effects which arise from these boosts, including the Wigner rotations and $\rho$-spin decomposition of the off-shell particle, are treated exactly. In their final form, the equations reduce to a coupled set of Faddeev-like double integral equations with additional channels arising from the negative $\rho$-spin states of the off-shell particle.

Recent measurements of proton spectra issued from neutron beam interactions with a hydrogen target in the $0.2-1.6$ GeV range are exploited to perform a new analysis of the bulk of the available appropriate data and to extract from the latter the $\Delta$-production cross section and related parameters. Among these, the slope parameter of the angular distribution is accurately determined and shown to be close to the slope parameter for $\mathrm{pp}$ elastic scattering for incident momentum larger than approximately $1.4\hspace{0.5em}\mathrm{GeV}/c$. Constraints introduced by isospin conservation are also briefly discussed.

Possible octupole states in ${}^{196}\mathrm{Pt}$ were studied via the ${}^{196}\mathrm{Pt}{(p,p}^{\prime }\gamma )$ reaction with 12.7 MeV protons. The results considerably strengthen the argument made previously that the low-energy octupole state in ${}^{196}\mathrm{Pt}$ is quite fragmented. Furthermore, one of the possible mixed symmetry states previously identified in this nucleus is observed in the present experiment, providing evidence that it has $J^{\pi }{=2\mathrm{}}^{+}$.

Levels in ${}^{99}\mathrm{Zr}$ populated by $\beta$ decay of on-line mass separated ${}^{99}$Y have been studied by $\gamma$-ray spectroscopic methods, including $\gamma$-$\gamma$ coincidences recorded with an array of ten Ge detectors and level-lifetime measurements. The formerly reported strongly collective character of the 53-keV transition turns out to be questionable. This implies a revision of the experimental evidence for shape coexistence in ${}^{99}\mathrm{Zr}.$ Transition rates and $\gamma$-ray branching ratios make a new level at 679 keV with $t_{1/2}=9\mathrm{}$ ns another candidate for a deformed state.

The double β decays of ${}^{100}\mathrm{Mo}$ and ${}^{150}\mathrm{Nd}$ were studied in a time projection chamber located 72 m underground. A 3275-h exposure of a 16.7-g sample of metallic Mo enriched to 97.4% in ${}^{100}\mathrm{Mo}$ resulted in a two-neutrino half-life, $T_{1/2}^{2\nu }{=(6.82\mathrm{}}_{-0.53}^{+0.38\mathrm{}}\pm 0.68)\times {10}^{18}\mathrm{y}.$ Similarly, a 6287-h exposure of 15.5 g of ${\mathrm{Nd}}_2{\mathrm{O}}_3$ enriched to 91% in ${}^{150}\mathrm{Nd}$ yielded $T_{1/2}^{2\nu }{=(6.75\mathrm{}}_{-0.42}^{+0.37\mathrm{}}\pm 0.68)\times {10}^{18}\mathrm{y}.$ Lower limits on half-lives for neutrinoless decay with and without majoron emission also have been measured.

The γ and conversion electron spectra following the β decay of ${}^{147}\mathrm{Nd}$ are measured using the HPGe detector and the miniorange electron spectrometer. The ${}^{147}\mathrm{Pm}$ level scheme comprising of 11 levels up to 686 keV excitation, interconnected by 29 transitions, is presented. The 649 keV ${\frac{11}{2}}^{-}$ level, with six interconnecting (including two $E3\mathrm{}$) transitions, is observed for the first time in decay studies. $K$-shell conversion coefficients for four transitions and $L$-shell conversion coefficients for five transitions are being reported for the first time. The $I^{\pi }={\frac{7}{2}}^{+}$ spin-parity assignment for the 680 keV level is confirmed. Specific structure features of the ${}^{147}\mathrm{Pm}$ level scheme, depicting the unique coexistence of spherical shell model configurations, particle-phonon coupled multiplets, evolution of octupole collectivity, and well-developed rotational bands, are discussed; certain open questions about the spectroscopy and interpretation of the 633 and the 641 keV levels are highlighted.