Differential cross sections for elastic and inelastic scattering of neutrons from isotopically enriched ${\mathrm{B}}^{10}$ samples have been measured for incident neutron energies from 3.02 to 6.45 MeV in 250 keV increments and from 7.02 to 12.01 MeV in 500 keV increments. Inelastic angular distributions for scattering to the states in parentheses in ${\mathrm{B}}^{10}$ have been measured from the indicated energy up to 12.01 MeV: (0.718) from 3.02 MeV; (1.74) from 3.27 MeV; (2.15) from 3.77 MeV; (3.59) from 5.52 MeV; (4.77) from 7.02 MeV. The measurements at 3.02, 3.51, 4.02, and 4.51 MeV were done at nine laboratory angles from 20° to 158° in 17.5° increments with a sample that is isotopically 95.86% ${\mathrm{B}}^{10}$. All other distributions measured scattering at 11 laboratory angles from 18° to 158° in 15° increments from a sample that is isotopically 99.49% ${\mathrm{B}}^{10}$. A multiple scattering code provided a simulation of the experimental scattering process allowing accurate corrections to the small measured inelastic cross sections. An eight-channel, multilevel R-matrix analysis was performed on the data. Level energies, spins, and parities were deduced for twelve levels above 13 MeV excitation in ${\mathrm{B}}^{11}$. Only two definite and three tentative assignments for T=12 levels had been made previously above 13 MeV. The two definite levels were confirmed. Good agreement between the data and the R-matrix calculation in all analyzed channels was obtained for the proposed structure.

Results of measurements of the transverse polarization transfer coefficients ${\mathrm{K}}_{\mathrm{y}}^{\mathrm{y}\prime }$(0°) for ${\mathrm{H}}^2$(p→,n→)pp at 54 and 71 MeV are presented. The magnitude and energy dependence of this parameter have been determined with sufficient precision (4%) to permit the use of this reaction as a source of nearly monoenergetic polarized neutrons in precise measurements. ${\mathrm{K}}_{\mathrm{y}}^{\mathrm{y}\prime }$(0°) is found to have a significant dependence on excitation energy. The results at low excitation energy are in agreement with calculations in the impulse approximation using the nucleon-nucleon phase shifts obtained from the Bonn or Paris potentials. A substantial difference from the results obtained using the empirical phase shifts is found. Results of measurements of the longitudinal polarization transfer coefficient ${\mathrm{K}}_{\mathrm{z}}^{\mathrm{z}\prime }$(0°) at 54 MeV are also presented.

Thermal-neutron-capture gamma rays from natural barium have been studied at the tangential facility of a reactor using a pair spectrometer. Precise transition, level, and neutron separation energies of six isotopes of barium are inferred. The separation energies are ${\mathit{S}}_{\mathit{n}}$${(}^{133}$Ba)=7189.96±0.36, ${\mathit{S}}_{\mathit{n}}$${(}^{135}$Ba)=6972.21±0.18, ${\mathit{S}}_{\mathit{n}}$${(}^{136}$Ba)=9107.84±0.04, ${\mathit{S}}_{\mathit{n}}$${(}^{137}$Ba)=6905.78±0.03, ${\mathit{S}}_{\mathit{n}}$${(}^{138}$Ba) =8611.75 ±0.04, and ${\mathit{S}}_{\mathit{n}}$${(}^{139}$Ba)=4723.44±0.04 keV. The M1 strength functions of ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$ and ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}$ are found to be (27±7)×${10}^{\mathrm{-}9}$ and (5.7±2.1)×${10}^{\mathrm{-}9}$ ${\mathrm{MeV}}^{\mathrm{-}3}$, the former being much higher and the latter much lower than the global average of 18×${10}^{\mathrm{-}9}$ ${\mathrm{MeV}}^{\mathrm{-}3}$. The average B(E2)↓¯ of ${}_{}{}^{136,138}{}_{}{}^{}\mathrm{Ba}$ observed is 53±35 ${\mathit{e}}^2$${\mathrm{fm}}^4$${\mathrm{MeV}}^{\mathrm{-}1}$, which is 0.6±0.4 times the value predicted by the Axel-Brink hypothesis.

We present results of interacting-boson-fermion-fermion approximation (IBFFA) calculations for deformed odd-odd ${}_{}{}^{176}{}_{}{}^{}\mathrm{Re}$ and ${}_{}{}^{178}{}_{}{}^{}\mathrm{Re}$. Such calculations yield accurate structural information for many different rotational band types, including highly distorted and doubly decoupled bands. Thus, they can help in interpreting experimental data, predicting spin-parity assignments that agree with those obtained by other methods, and giving rather good predictions for interband transition energies. We also compare our previously published IBFFA predictions for ${}_{}{}^{180}{}_{}{}^{}\mathrm{Re}$ with new experimental data.

Recent K¯N interaction models are used to construct microscopic momentum-space optical potentials including complete Fermi averaging, three-body dynamics, nonlocalities, and the exclusion principle. Bound states are found with K¯ orbits internal to and external to the nucleus (${\mathrm{\Lambda }}^{\mathrm{*}}$ hypernuclei and kaonic atoms).

It is shown that the quantitative description within the two-rotor model of the low-lying, moderately collective M1 excitation observed in deformed nuclei and known as the scissors mode can be drastically improved by properly computing the relevant physical quantities that determine the properties of such a mode. A two-fluid formulation of the model in which only the nuclear mass external to a rotational invariant inner core of each rotor takes part in the motion is also presented and discussed, especially in relation to the algebraic interacting boson model and to the random phase approximation. The importance of dynamical correlations is stressed in this connection.

We demonstrate that within the relativistic Hartree approximation to quantum hadrodynamics, infinite nuclear matter is unstable for some combinations of the vector and scalar meson masses. In this region of instability, the Hartree ground state of nuclear matter is characterized by a periodic spatial variation of the baryon density that may be interpreted as alpha-particle clustering. The standard values of the meson masses are in a region in which uniform nuclear matter is stable; however, for finite nuclei the presence of the nuclear surface can induce small scale oscillations in the nuclear interior that are related to the periodic instability.

Level energies and decay rates of both negative and positive parity levels of ${}_{}{}^{206,204}{}_{}{}^{}\mathrm{Pb}$ have been calculated through mixed-configuration shell model calculations using the modified surface delta interaction (MSDI), the Schiffer-True central interaction, and another two-body interaction. These calculations were all carried out with a full six-orbit neutron hole space. The predicted low-lying levels with the MSDI are in excellent agreement with experiments, accounting for the energies, spins, and parities of essentially all levels below 3 MeV excitation energy except known particle-hole collective excitations in both nuclei. Almost all calculated $E2\mathrm{}$ and $M1\mathrm{}$ transition rates are consistent with measured branching ratios for $\gamma$-ray decay of excited levels. The comparison of the observed and calculated levels demonstrates the important role played by the neutron-hole $i_{\frac{13}{2}}$ configuration in the levels of ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$, and interprets an apparent discrepancy over the character and energy spacings of $0^{+}$ levels in ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$.

The Schrödinger equation for nuclear quadruple surface vibrations is linearized with the consequence that a new spin degree of freedom appears in the wave function of the linearized equation. This spin is called collective spin and has a value of 3/2. The linearized Schrödinger equation for quadrupole vibrations is used for the description of certain collective aspects of even-odd ${}_{}{}^{187,189,191}{}_{}{}^{}\mathrm{Ir}$ nuclei which have a spin 3/2 in their ground state. As a potential we use the γ-soft collective potential of the neighboring even-even nuclei, which is inserted into the linearized Schrödinger equation via a scalar coupling. This leads to a collective spin-dependent fine structure splitting of the energy levels governed by a collective SO(5) spin-orbit coupling and a correction to the kinetic energy. Further, we consider explicitly spin-dependent potentials which effectively describe the interaction of the valence nucleon with the core of the even-odd Ir nuclei. Already a simple collective SO(3) and SO(5) spin-orbit coupling is sufficient to reproduce the lowest excited states of the even-odd Ir nuclei.

The effect of the partial subshell closure near Z=64 is studied by introducing the effective boson number in the framework of the interacting boson model. The energy spectra and the B(E2) values of the Sm, Gd, and Dy isotope series are calculated. It is found that the agreements between the theoretical results and the observed data are very satisfactory when the partial closure effect is taken into account by a smooth variation of the effective proton-boson numbers.

The self-consistent semiclassical approach, with which the ground state of a nucleus is determined, is combined with the sum rule approach, by which the moments of the strength function can easily be evaluated. This provides a convenient and reasonable way, which is termed as the self-consistent semiclassical sum rule approach, to the average properties of nuclear giant resonances. Both the isoscalar and isovector giant resonances on the ground and excited states of some spherical nuclei are investigated with this approach in a systematical way. Some of the present results are compared with experiments and detailed Hartree-Fock plus random-phase approximation calculations.

We have investigated possible neutron emission from cells containing titanium and palladium under ${\mathrm{D}}_2$, DT, or HD gas at pressures near 10 and 50 atm and at temperatures between -197 °C and room temperature. Spurious backgrounds were eliminated from the data by means of coincidence counting, and through analysis of the energy and temporal distribution of the detected pulses. After 1500 hours of observation, we have seen no evidence for either steady-state neutron production or short (<100 μs) neutron bursts. The limits we obtain, scaled for sample size, are in conflict with all present reports of neutron emission in metal hydrides under high gas pressure and thermal stress.

Neutron-irradiated targets of natural magnesium have been analyzed by mass spectrometry in order to determine the excitation functions of neon from the energy threshold up to 20 MeV. Production cross sections of ${}_{}{}^{20,21,22}{}_{}{}^{}\mathrm{Ne}$ isotopes were measured at 5.20, 7.00, 16.20, and 19.05 MeV.

Exclusive measurements have been made of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(p,2p), (p,pd), (p,pt), and (p,ph) at 100 MeV. The primary protons were measured at two angles, 45° and 60°, in coincidence with secondary protons, deuterons, tritons, or helions covering a wide range of angles on the opposite side of the beam, from -15° to -90° in plane, and from 0° to 30° out of plane. The satisfactory agreement in shape between the measured energy-sharing distributions and results of distorted-wave impulse approximation calculations suggests that this formalism is adequate for modeling the quasifree knockout reactions induced by 100 MeV protons on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. It is found that (70±10)% of the inclusive continuum yields in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(p,p’) is attributable to quasifree scattering, with ∼30% arising from multiple scattering. At low energies of the scattered proton, the knockout of nucleons constitutes over 90% of the quasifree component, whereas at high energies the knockout of deuterons, tritons, and helions dominates the yield. Consequently the cluster knockout contributions fill in the yield at higher energies in the inclusive spectra, and quasifree peaks are not discernible.

CR 39 solid state nuclear track detectors have been used to study the reaction products of 17.7, 27, and 35 MeV/nucleon ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$ on Au and Ag. The visual detectors allow studying interactions producing two or more correlated intermediate mass fragments in the final state. The characteristics of these events are such that they probably arise from a fragmentation process of the quasitarget or some intermediate zone. The cross sections of 3, 4, and (5+6) correlated fragments increase with increasing ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$ incident energy for both targets.

Elastic and inelastic scattering of 575 MeV ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ to low-lying states of both target and projectile nucleus were studied. The measured cross sections were analyzed with coupled-channels calculations. A very satisfying description of the data was obtained by using B(EL) values from the literature and proper optical potential parameters. The latter were used as basis to estimate the cross sections for the excitation of the isovector giant dipole and isoscalar giant quadrupole resonances.

Pre- and post-scission ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particle multiplicities for the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$${+}^{197}$Au reaction in the excitation energy range of 43 to 90 MeV have been measured in coincidence with fission fragments. The coincident ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particles measured at backward angles are accounted for by evaporation from a compound nucleus and fission fragments. The most probable center-of-mass energy of the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particles measured at backward angles is shifted towards lower energies by ≊2 MeV compared to a statistical model calculation performed by assuming ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ emission from a spherical compound nucleus. The observed pre-scission ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ multiplicity as a function of excitation energy is compared to a set of statistical-model calculations which also included the delayed onset of fission. The comparison shows that the observed energy dependence of the pre-scission ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ multiplicity is reproduced by the calculation without taking into account the delayed onset of fission if the reduced emission barrier for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is assumed in the calculation. The emission mechanism of the pre-scission ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is discussed.

Evaporation residues resulting from the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$${+}^{27}$Al and ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$${+}^{19}$F fusion reactions leading to the ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$ compound nucleus and from the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$+${(}^{12}$C, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$) reactions have been measured at incident energies 32 MeV≤${\mathit{E}}_{\mathit{L}}$${(}^{19}$F)≤72 MeV and 15 MeV≤${\mathit{E}}_{\mathit{L}}$${(}^{11}$B)≤50 MeV. The hindrance of the fusion cross sections, at energies above the interaction barrier, show a clear dependence on the entrance channel mass asymmetry. This dependence is discussed in terms of model predictions that treat explicitly the mass asymmetry degree of freedom.

Excitation functions were measured for the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(n,p${)}^{90}$${\mathrm{Y}}^{\mathit{m}+\mathit{g}}$ and ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$(n,p${)}^{91}$${\mathrm{Y}}^{\mathit{m}+\mathit{g}}$ reactions over the neutron energy range of 6.5 to 10.6 MeV. Use was made of the activation technique in combination with radiochemical separation and ‘‘low-level’’ ${\mathrm{\beta }}^{\mathrm{-}}$ counting. From the available experimental data isomeric cross-section ratios were determined. Statistical model calculations taking into account precompound effects were performed for the formation of both the isomeric and ground states of the product. The calculational results on the total (n,p) cross sections agree well with the experimental data. The measured and calculated cross sections for the formation of the isomeric states also agree up to an incident neutron energy of 10 MeV; at higher energies, however, the calculated values are appreciably higher. In the case of isomeric cross-section ratios good agreement was found between experiment and theory up to 10 MeV; at higher energies the calculated values are consistently higher.

A test has been devised to check the validity of conventional distorted-wave impulse approximation (DWIA) treatment of knockout reactions. The conventional DWIA formalism separates the three-body final state Schrödinger equation for a knockout reaction into two two-body Schrödinger equations by assuming an asymptotic constant value for the three-body coupling term commonly known as the kinematic coupling approximation (KCA). In the test case, which consists of an extreme asymmetric situation where one of the distorting optical potentials is assumed to vanish, the three-body final state Schrödinger equation can be solved exactly as a product of two two-body solutions using one particular set of relative coordinates. Large influence of the three-body coupling term is seen in the comparison of the exact and KCA results for (α,2α) and (p,pα) knockout reactions when the distorting optical potentials are weakly absorbing.