[en] The absolute cross section for the production of binary encounter electrons has been measured at zero degrees for 1 MeV/u Au^q+ (q=12-37) colliding with helium. It has been experimentally found that as the charge state of the incident ion is increased (1) the binary peak magnitude increases, (2) the electron energy at which the peak occurs decreases, and (3) the peak broadens. The absolute cross sections are compared with theoretical results. Classical Trajectory Monte Carlo calculations are found to give good account for the magnitude and the shift to lower election energy of the peak. The Continuum Distorted Wave-Eikonal Initial State approximation is shown to yield cross sections which are much smaller in magnitude than the experiments, but reproduce well the relative magnitudes and shapes of the peaks for these ions. It is noted that the increase in the binary peak magnitude with increasing ionic charge state is in distinction to previous measurements which showed enhancement of the binary peak with decreasing charge state for clothed ions

[en] Microstructure in single crystalline Al₂O₃ developed during irradiation by swift heavy ions has been investigated. The specimens were irradiated by Xe ions with energies from 70 to 160 MeV at ambient temperature. The fluences were in the range from 1.0 × 10¹³ to 1.0 × 10¹⁵ ions/cm². After irradiations, X-ray diffractometry (XRD) measurements and cross sectional transmission electron microscope (TEM) observations were conducted. The XRD results indicate that in the initial stage of amorphization in single crystalline Al₂O₃, high-density S_e causes the formation of new planes and disordering. The new distorted lattice planes formed in the early stage of irradiation around the fluence of 5.0 × 10¹³ ions/cm² for single crystalline Al₂O₃ irradiated with 160 MeV-Xe ions. Energy dependence on structural modification was also examined in single crystalline Al₂O₃ irradiated by swift heavy ions. The XRD results indicate that the swift heavy ion irradiation causes the lattice expansion and the structural modification leading to amorphization progresses above the energy around 100 MeV in this XRD study. The TEM observations demonstrated that amorphization was induced in surface region in single crystalline Al₂O₃ irradiated by swift heavy ions above the fluence expected from the results of XRD. Obvious boundary was observed in the cross sectional TEM images. The crystal structure of surface region above the boundary was identified to be amorphous and deeper region to be single crystal. The threshold fluence of amorphization was found to be around 1.0 × 10¹⁴ ions/cm² in the case over 80 MeV swift heavy ion irradiation and the fluence did not depend on the crystal structures

[en] Single- and double-electron loss cross sections of He, and single-electron capture and single-electron loss cross sections of He⁺ in collisions with H₂, O₂, CH₄, CO and CO₂ have been measured in the energy range 0.3-1.8 MeV. From the measured cross sections, charge-changing cross sections in collisions of He and He⁺ with C have been determined using the Bragg rule. Scaling is examined for electron capture cross sections. (author)

[en] We have measured the electronic sputtering yields of eight samples of insulating and semiconductor oxides by high energy heavy ions for systematic investigation of the electronic excitation effect on atomic displacement, applying a carbon-film collector method. We have found that the sputtering yields, which include the oxygen contribution, increase super-linearly with the electronic stopping power S_e and that they are larger by 30-2000 than the calculated yields based on the elastic collision cascade. In the plot of the sputtering yields at a given electronic stopping power versus the band gap E_g, the upper limits of the yields are suggested and the maximum yields follow E_g⁴ dependence

[en] Transition rates, oscillator strengths, and line strengths are calculated for electric-dipole (E1) transitions between even-parity 3s3p², 3s²3d, 3p²3d, 3d²3s, and 3d³ states and odd-parity 3s²3p, 3p³, 3s3p3d, and 3d²3p states in Al-like ions with the nuclear charges ranging from Z=15 to 100. Relativistic many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start from a 1s²2s²2p⁶ Dirac-Fock potential. First-order MBPT is used to obtain intermediate coupling coefficients and second-order MBPT is used to calculate transition matrix elements. Contributions from negative-energy states are included in the second-order E1 matrix elements to ensure gauge-independence of transition amplitudes. Transition energies used in the calculation of oscillator strengths and transition rates are from second-order MBPT. Transition rates, line strengths, and oscillator strengths are compared with critically evaluated experimental values and with results from other recent calculations. We present data for selected transitions between 10 of the possible 73 even-parity 3s3p², 3s²3d states and 29 of the possible 75 odd-parity 3s²3p, 3p³, and 3s3p3d states in Al-like ions. Trends of the transition rates as functions of Z are illustrated graphically for 220 of the 3220 possible transitions. Lifetimes of the 10 even-parity lower levels and the 27 odd-parity upper levels are given for Z=15-100

[en] It is recognized that high electronic excitations play an important role in the damage process of solid targets by high-energy heavy ions. However, the conversion mechanism of the energy of the excited electrons into kinetic energy for target atom displacement is not well understood. In order to investigate the electronic excitation effects of high energy heavy ions in solids, we have studied the secondary ions mass spectra from thin conductive solid targets irradiated by swift heavy ion beams from the JAERI tandem accelerator in the energy region where the electronic stopping power is dominant. The results show the importance of the electronic excitation effect even in simple metallic (Cu) target. It is suggested that Coulomb explosion is the major mechanism of producing columnar defects along the incident ion path

No abstract available

[en] We have investigated the crystalline quality as well as the optical and electrical properties of ZnO thin films on MgO subjected to 100 keV Ne ion irradiation. The film with a-axis orientation shows an increase of the grain size and a rearrangement of their orientation after irradiation. On the other hand, the optical transparency in the visible range (<3 eV) remains unaffected up to ∼10 displacement per atom (dpa). It is also found that the resistivity increases by three order of magnitude at small dose (∼0.1 dpa) before it decreases and finally stabilizes at high dose (∼10 dpa) to a value of approximately twice of that before irradiation. The behavior of ZnO films with c-axis orientation under ion irradiation is also discussed

[en] The absolute electron production cross sections for 20 keV H⁺, 5-20 keV H₂⁺ and 5-20 keV He⁺ impacts on argon, differential in angle and energy of the ejected electrons, have been measured for electron energies of 2-26 eV at ejection angles 30⁰ and 90⁰. Some discrete lines in He⁺ impact on argon have been observed for the first time and identified. The continuum spectra derived from the observed spectra are compared for the same velocity of H⁺, H₂⁺ and He⁺ impacts on argon. (author)

[en] Coster-Kronig (C-K) and Auger electron spectra from highly excited states produced by high-energy highly charged ions with a He target have been investigated using zero-degree electron spectroscopy. C-K and Auger electrons produced in 32 MeV O^q+ (q=3,4)+He collisions were measured, where the highly excited states of three-, four- and five-electron O ions were formed by electron excitation/ionization. It is found that the 1s²2pnl states with relatively low angular momenta are excited in the O⁴⁺ ion collisions while the 1s²2s2pnl states with higher angular momenta are excited in the O³⁺ ion collisions. K Auger spectra produced in O^q+ (q=3,4)+He collisions qualitatively agree with the previously measured results