Charged particle evaporation from compound nuclei formed by bombardment of58Ni with 70 MeV16O ions II

The experimental data have been compared with the result of extensive compound nucleus calculations based on the statistical theory. The shapes and the absolute cross sections for the high energy parts of the proton- and -spectra are reproduced with a level density parametera 0·11 A MeV^–1 and a moment of inertiaJ1·3J _rig. The same parameters fairly well reproduce the angular distributions corresponding to the high energy parts of the spectra whereas deviations between theory and experiment are observed for the lower energies where particles emitted by higher order processes contribute. The observed total cross section for emission of an -particle is 500 mb or 1·7 times calculated value. For protons the corresponding numbers are 2313 mb and 3·0. The increase in cross section is ascribed to the process in which several particles are evaporated. Various methods are discussed for determination of the average orbital angular momentum of the emitted particle or the average spin of the daughter nucleus.On leave fromFaculty of Matematics and Physics, Charles University, Prague, Czechoslovakia.     

Charged particle evaporation from compound nuclei formed by bombardment of58Ni with 70 MeV16O ions part I

Highly excited compound nuclei of⁷⁴Kr have been formed by bombardment of⁵⁸Ni with 70 MeV¹⁶O ions. The spectra of protons and -particles resulting from the decay of the compound nucleus (and several daughter nuclei) have been recorded at laboratory angles from 30° to 155°. The CM differential cross sections corresponding to definite energies for the particles emitted were calculated from the data. The charged particle spectra and the angular distributions show that evaporation processes are dominant. A study of spectral shapes and angular distributions has to some extent made it possible to distinguish primary particles from those evaporated after the emission of one or several particles.On leave fromFaculty of Mathematics and Physics, Charles University, Prague, Czechoslovakia.     

A new experimental method for the study of regions of high spin and excitation energy

The excitation energy in ⁷²Se populated in the reaction ⁵⁸Ni(¹⁶O, 2pγ) for energies between 54.5 and 64.5 MeV has been measured by summing the γ-energy released in each γ-ray cascade. The average γ-multiplicity is simultaneously measured as a function of summed γ-energy. The method is useful for studying the highest regions of angular momentum and excitation energy.     

Electrospun ceramic fibers: Composition, structure and the fate of precursors

Fibers are electrospun from aluminum acetate/polymer mixtures and characterized by an array of techniques before and after annealing at 1200 °C. We demonstrate that sodium and boron present in the initial starting materials as adducts and stabilizers remain incorporated into the resulting fibers after annealing and pyrolysis of the host polymer. The influence of these minor constituents on the surfaces of the fibers is suggested by infrared and X-ray photoelectron spectroscopic data. The presence of these species may impact potential chemical applications of small diameter ceramic fibers, such as their use as catalytic supports or for chemical decomposition.     

High-spin particle states in 151Sm studied with the (α, 3He) reaction

High-spin states have been located in ¹⁵¹Sm by means of the (α, ³He) reaction with 40 MeV α-particles. The scattered particles were momentum analyzed in a QMG/2 magnetic spectrometer and recorded in a position sensitive detector. Several high-spin states were observed in the energy range below 1.7 MeV excitation. The previously unknown strongly populated levels at 867 and 1480 keV can most likely be interpreted as $\text{13}\text{2}{}^{\mathrm{+}}$ states. Both the deduced nuclear structure factors and the energy location of these levels are in excellent agreement with a simple Coriolis coupling calculation.