The gamma spectrum of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$ was measured by means of a low-level shielded and Compton-suppressed HpGe spectrometer. The gamma line with the energy 283.4 keV and absolute intensity of 5.3(14)×${10}^{\mathrm{-}6}$ was found. It was concluded that the 283.4 keV intermediate level in ${}_{}{}^{137}{}_{}{}^{}\mathrm{Ba}$ [seen earlier in (n,n′γ) measurements] is populated in the β decay of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$ with the comparative half-life of log ft=15.3(3). © 1996 The American Physical Society.

Statistical compound-nucleus contributions to enhanced back-angle cross sections for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ elastic scattering and for inelastic scattering to the channels, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$($3^{+}$, 2.18 MeV) + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(g.s.) and ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$(g.s.) + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$($2^{+}$, 4.44 MeV), are studied. Differential cross sections and vector analyzing powers in the range ${\mathrm{\Theta }}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$≊130°–165° have been measured at ${\mathit{E}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ = 20 MeV by detecting recoil ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nuclei from ${}_{}{}^6{}_{}{}^{}\to$ elastic scattering and inelastic scattering to the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$($3^{+}$, 2.18 MeV) state. Adding a statistical compound-nucleus contribution is shown in general to reduce the magnitude, and to leave unaffected the sign, of theoretical calculations of vector analyzing powers. Analysis, including Hauser-Feshbach calculations, of the above data along with previous data indicates that compound-nucleus contributions are unimportant in the elastic and inelastic ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$(2.18 MeV) scattering channels, and are insufficient to resolve discrepancies between current coupled-channels calculations and large-angle data for inelastic ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(4.44 MeV) scattering. © 1996 The American Physical Society.

Distribution between final states of the ion ${\mathrm{He}}^{+}$ in β decay of atomic tritium is obtained. The final state interactions between β-ray and atomic shell are accounted for in the lowest order of expansion in powers of the Sommerfeld parameter. © 1996 The American Physical Society.

The coupling between single-particle resonances and two-particle–one-hole excitations are studied within a representation that includes correlated bound and resonant states. Good agreement with available experimental data is obtained. © 1996 The American Physical Society.

Within the framework of a relativistic transport model (ART) for heavy-ion collisions at AGS energies, we examine the effects of a kaon dispersion relation on the transverse flow of kaons and their transverse momentum and azimuthal angle distributions. We find that the transverse flow is the most sensitive observable for studying the kaon dispersion relation in dense medium. © 1996 The American Physical Society.

The differences between optical model (OM) and the barrier transmission approaches for fusion are studied in detail at low energy. In the heavy ion case at deep subbarrier energies, the absorption mean square spin of an optical model calculation using a short ranged imaginary potential differs significantly from the results of the WKB transmission method. This discrepancy of OM results is shown to be due to absorption occurring beyond the barrier position. The coupled reaction channel calculations for fusion based on OM approach are shown to be sensitive to the choice of imaginary fusion potentials, whereas the coupling effects on fusion are dominant for energies only around the barrier. © 1996 The American Physical Society.

The entrance-channel mass-asymmetry dependence of the compound nucleus formation time in light heavy-ion reactions has been investigated within the framework of semiclassical dissipative collision models. The model calculations have been applied successfully to the formation of the ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$ compound nucleus as populated via the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${+}^{29}$Si, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$${+}^{27}$Al, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{26}$Mg, and ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$${+}^{19}$F entrance channels. The shape evolution of several other light composite systems appears to be consistent with the so-called ‘‘Fusion Inhibition Factor’’ which has been observed experimentally. As found previously in more massive systems for the fusion-evaporation process, the entrance-channel mass-asymmetry degree of freedom appears to determine the competition between the different mechanisms as well as the time scales involved. © 1996 The American Physical Society.

An approach for the delineation of the compound nucleus excitation energy, from the photofission cross section at intermediate energies, is worked out. An application for ${}_{}{}^{182}{}_{}{}^{}\mathrm{W}$, Au, and Ta is presented. The potential of this formalism, for the study of pion properties inside the nuclear medium, is discussed. © 1996 The American Physical Society.

We give evidence that the production of disoriented chiral condensates during a nonequilibrium phase transition can lead to an anomalous transverse distribution of secondary pions when compared to a more conventional boost invariant hydrodynamic flow in local thermal equilibrium. Our results pertain to the linear σ model, treated in leading order in large N, in a boost invariant approximation. We also show that the interpolating number density of the field theory calculation plays the role of a classical relativistic phase space number distribution in determining the momentum distribution of pions in the center of mass frame. © 1996 The American Physical Society.

The time scale required to reach thermal equilibrium in intermediate-energy nucleon-induced preequilibrium reactions was investigated by quantum molecular dynamics (QMD). The average kinetic energy of two colliding particles in their center-of-mass system was taken to be the measure of such thermal equilibration. The corresponding time was found to be of the order of 20 fm/c (∼7 × ${10}^{\mathrm{-}23}$ sec), a time scale that is much shorter than the time believed for the compound reaction, i.e., ∼${10}^{\mathrm{-}18}$ sec. An interpretation of the reason why the kinetic energy brought by the projectile is dumped so fastly to thermal equilibrium is discussed. The equilibration time of 20 fm/c gives a justification of our ‘‘hybrid’’ approach of using the QMD plus the statistical decay model (SDM) which are connected at a time scale of ∼100 fm/c. © 1996 The American Physical Society.

The contribution of core nucleons to a static magnetic quadrupole moment is calculated in the presence of an interaction that violates P and T invariance. The contribution found can be comparable or even larger than the contribution of a valence nucleon, in contrast to the case of the P-violating but T-invariant anapole moment. The core contribution appears to be sensitive to the spin-orbit single-particle potential, which enhances it by a factor of ∼2. © 1996 The American Physical Society.

In the present work, we test the validity of replacing the nondiagonal matrix ρ(r→,r→′) appearing in the exchange part of the α-nucleus optical potential by an approximation based on the density matrix expansion (DME) used frequently in nuclear structure calculations. We have found that for the recently derived BDM3Y nucleon-nucleon force the DME may produce a maximum error more than 29% in the α-nucleus potential. © 1996 The American Physical Society.

Recently, calculations of (γ,NN) cross sections in the Δ(1232) region have been reported by J. Ryckebusch et al. [Phys. Rev. C 49, 2704 (1994)]. However, these calculations use an unjustified ansatz for the Δ propagation, which leads to an underestimation of the (γ,NN) cross section in the resonance region for quasifree kinematics. © 1996 The American Physical Society.

It is pointed out that shell-model effects are likely to affect the energy dependence of the ${\mathrm{\Delta }}_{33}$ propagator in finite nuclei. © 1996 The American Physical Society.

γ rays following the ${}_{}{}^{160}{}_{}{}^{}\mathrm{Dy}$${(}^{36}$Ar,4n${)}^{192}$Po reaction have been identified by employing a high-transmission gas-filled separator in recoil decay tagging measurements. The deduced level scheme reveals a flattening of the energy systematics, when going towards the neutron midshell indicating that the deformed intruder structures have become yrast. © 1996 The American Physical Society.

We report on the first production and identification of two neutron-rich nuclei ${}_{}{}^{31}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{37}{}_{}{}^{}\mathrm{Mg}$. They were produced in the projectile fragmentation of an 80A MeV ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$ beam on a ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ target, and were efficiently analyzed and identified through the fragment separator RIPS at RIKEN, by measuring the magnetic rigidity, time of flight, energy loss, and total kinetic energy. The particle stability of the new isotopes is discussed in comparison with various mass predictions. © 1996 The American Physical Society.

A superdeformed band of 15 transitions has been found in the ${}_{}{}^{155}{}_{}{}^{}\mathrm{Dy}$ nucleus. The measurement was performed with a backed target and the large deformation was inferred from the measured Doppler shifts. The new band displays an intensity pattern much different from typical superdeformed bands in this mass region. The dynamic moment of inertia is essentially identical to that of band 1 in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Dy}$ and is somewhat larger than those of the yrast superdeformed bands in ${}_{}{}^{152,154}{}_{}{}^{}\mathrm{Dy}$, suggesting that the associated configuration has an additional N=7, ${\mathit{j}}_{15/2}$ intruder orbital occupied with respect to the ${}_{}{}^{154}{}_{}{}^{}\mathrm{Dy}$ core. © 1996 The American Physical Society.

Gamma-rays following the decay of the neutron-rich isotope ${}_{}{}^{124}{}_{}{}^{}\mathrm{Ag}$ have been studied at the ISOLDE facility using a chemically selective laser ion source. Excited structures beyond the first $2^{+}$ level in ${}_{}{}^{124}{}_{}{}^{}\mathrm{Cd}$ have been identified for the first time, and are discussed in terms of a recent anharmonic vibration model. © 1996 The American Physical Society.

A simple valence correlation scheme is presented in which empirical neutron and proton separation energies, ${\mathit{S}}_{\mathit{n}}$ and ${\mathit{S}}_{\mathit{p}}$, follow extremely compact, linear trajectories in terms of the variables α${\mathit{N}}_{\mathit{p}}$-${\mathit{N}}_{\mathit{n}}$. This scheme often allows predictions for unknown nuclei by interpolation rather than extrapolation. A Taylor expansion shows that the Weizsäcker mass formula in fact behaves in first order as α${\mathit{N}}_{\mathit{p}}$-${\mathit{N}}_{\mathit{n}}$ though such a functional dependence is not explicit and has not been noted before. © 1996 The American Physical Society.

Determination of temperature from experimental data has become important in searches for critical phenomena in heavy-ion collisions. Widely used methods are ratios of isotopes (which rely on chemical and thermal equilibrium), population ratios of excited states, etc. Using the lattice gas model we propose a new observable: ${\mathit{n}}_{\mathrm{ch}}$/Z where ${\mathit{n}}_{\mathrm{ch}}$ is the charge multiplicity and Z is the charge of the fragmenting system. We show that the reduced multiplicity is a good measure of the average temperature of the fragmenting system. © 1996 The American Physical Society.