Masakatsu Sakisaka

Coulomb excitation of 45Sc, 75As, 127I and 133Cs

Abstract The Coulomb excitation of 45 Sc, 75 As, 127 I and 133 Cs has been studied using 11.5 MeV nitrogen ions as bombarding particles. From the thick target yields of de-excitation gamma rays, the B (E2)↑ values are obtained as 45 Sc: 378 keV, 0.0086±0.0017; 75 As: 280 and 199 keV, 0.051±0.012 and 0.015±0.003; 127 I: 203 and 59 keV, 0.072±0.014 and 0.054±0.011; 133 Cs: 160 and 81 keV, 0.13±0.03 and 0.022±0.004, respectively, in units of e 2 b 2 . The results for 127 I and 133 Cs are compared with theoretical predictions.

ISOTOPE DEPENDENCE IN K-, L-, AND M-SHELL IONIZATION CROSS SECTIONS BY PROTON AND DEUTERON BOMBARDMENTS.

The ionization cross sections of Al-K, Ti-K, Cu-L, Mo-L, Ag-L and W-M shells have been presented for the incident protons and deuterons in the energy range from 90 to 180 keV/amu. The cross sections are derived from the thick target yields of the respective characteristic X-rays. In contrast with the prediction by Born approximation, isotope dependence is clearly found in the ionization of each target atom. The cross section ratios for K and L shells against the projectile energy per nucleon line up systematically according to the shell binding energies of target atoms. The magnitudes of the K shell ionization cross sections are in good agreement with “binding theory” of Brandt et al. . This means that, in the present energy range, the ionization cross sections depend strongly on the Coulomb deflection of the incident particle and the transient additional binding energy of the K shell electron with the incident particle during the collision.

Standard samples and calibration of PIXE analysis

Abstract Standard samples were prepared by the vacuum evaporation method to calibrate the PIXE analysis. The sensitivities for each standard element were determined experimentally first using the standard samples and then the sensitivities for other than standard elements were determined theoretically based on the experimental results. It is confirmed that the high purity carbon plate was useful as the backing for PIXE standard samples and that the single element samples prepared in this study can be effectively applied to the PIXE calibration.

K Shell Ionizations of Carbon, Nitrogen, Oxygen, Fluorine and Neon by Proton and Alpha Particle Bombardments

The K Auger electron spectra have been measured for carbon, nitrogen, oxygen, fluorine and neon excited by protons and alpha particles of 0.5–2.6 MeV. In comparison with the spectra obtained by electron impact, the satellite lines have grown more intensively as projectiles become heavier. This indicates the presence of a contribution of simultaneous L shell ionization. A quantitative analysis has been made for the created L vacancies of nitrogen due to N+ p and N+α collisions. The ionization cross sections derived from the Auger yields have been compared with the theories of Born approximation and binary encounter approximation. The deviations from the theories found in O+α, F+α and Ne+α collisions might be explained by a shielding action of L shell electrons against nuclear charge of projectiles.

Be^9(n, 2n)Be^8 and Bn^ (n, α)Li^8(β)Be^8 Reactions by 14Mev Neutrons

Be 9 ( n , 2 n )Be 8 and Bn 11 ( n , α)Li 8 (β)Be 8 reactions induced by 14 Mev neutrons were studied by the method of beryllium and boron loaded nuclear emulsions. In the former reaction, the angular distributions of Be 8 nuclei were strongly peaked backward in the center-of-mass system, suggesting that the direct interaction of the incident neutrons with beryllium–an inelastic scattering process before second neutron emission and a pick-up process probably–had a major contribution to the reaction. The cross sections were measured as 0.18±0.07, 0.03±0.02, 0.11±0.04 and 0.05±0.03 barns for the 3, 5, 7.5 and more than 9 Mev excited states of Be 8 respectively. When 0.17±0.03 barns was cited to the cross section with respect to its ground state, the total ( n , 2 n ) cross section was estimated as 0.54±0.09 barns. The cross section of the latter reaction was measured as 35±7 millibarns in which the contribution of Be 8 in the ground state was not included. Most Li 8 nuclei were found to be left at the state...

Sample Sandwiched Plastic Scintillators for Activation Measurements by Use of Fast Neutrons

Plastic scintillator plates sandwiched between thin radioactive samples were viewed with two photomultipliers and the coincident outputs were measured. For β - -rays, the pulse-height distributions...

Thick Target Yields of Characteristic X-Rays by p, d, 3He+ and 4He+ Bombardments

Characteristic X-ray yields by p, d, 3He+ and 4He+ bombardments have been measured for various thick metallic elements in the incident energy range from 90 to 360 keV. The combination of incident particles, target materials and produced characteristic X-rays is given as: (a) Al–K, Ti–K, Ni–K, Cu–K, Ni–L, Cu–L, Zr–L, Mo-L, Ag–L, Cd–L, Sn–L, Ta–M, W–M, Pt–M and Pb–M for proton bombardment, (b) Al–K, Ti–K, Cu–K, Ni-L, Cu–L, Zr–L, Mo–L, Ag–L, Cd–L, Sn–L, Ta–M, W–M, Pt–M and Pb–M for deuteron bombardment, (c) Al–K, Ni–L, Cu–L, Mo–L, Ag–L and W–M for 3He+ bombardment, (d) Al–K, Ni–L, Cu–L, Mo–L, Ag–L, W–M, Pt–M and Pb–M for 4He+ bombardment. The thick target yields against particle energy have been found to increase more steeply as target atomic number becomes larger. The behaviors of yield ratios of Iµ(d)/Iµ(P) and Iµ(4He+)/Iµ(3He+) have been qualitatively explained by the effect of average charge of the incident particles.

Multiple Scattering of Protons and Nitrogen Ions on Copper

Multiple scattering of protons (0.407, 0.851 and 1.45 MeV) and nitrogen ions (1.28 and 2.29 MeV) on copper has been studied. The observed angular distributions are compared with Molieres theory and some deviations are found. However, these can be diminished by introducing the effective atomic number, z eff of incident ions. The appropriate z eff s are estimated as 0.87, 0.90 and 0.94 for the protons, respectively. The values 5.2 and 6.2 are obtained for the respective nitrogen ions. The effective atomic number is attributed to the electron screening of slow ion during the collision process.

A PIXE-RBS method for measuring partial sputtering yields of stainless steel

Abstract A collector method has been developed for measuring the partial sputtering yields of stainless steel constituents. The sticking probabilities of Cr-, Fe-, and Ni-atoms to a carbon collector are found to be close to unity. By combining a PIXE with an RBS analysis, each quantity of the constituent atoms deposited on the collector surface is micro-quantitatively measured with a good accuracy. When an SS304 plate is exposed to 25 keV He + ions in a vacuum of 10 −6 Torr range , no evident preferential sputtering is found among three constituent elements at a fluence of 4.9×10 19 He/cm 2 .

L shell ionizations of chlorine and argon by proton and alpha particle bombardments

The L Auger electron spectra have been observed for chlorine and argon bombarded with protons and alpha particles of 0.3–2.6 MeV in energy. The satellite lines, which are attributable to a simultaneous M shell ionization, have increased in comparison with the spectra obtained by electron impact. The numbers of created M shell vacancies of argon are estimated as 0.3±0.1 and 1.1±0.4 in average for protons and alpha particles at 1.8 MeV, respectively. The ionization cross sections for both projectiles have been compared with the theory of binary encounter approximation, resulting in a few tens percent reduction for argon and an overestimation for chlorine. The projectile z dependence of ionization cross section has been confirmed for chlorine and argon.