K. Umetani

Thickness measurement of gold contact layers in Si(Li) and Ge x-ray detectors

Four kinds of Si(Li) and a high‐purity Ge x‐ray detectors have been tested to measure the thicknesses of gold contact layers by comparing the response of the primary Rb‐Kα x‐rays with that of the induced Au‐Lα x rays. Observed thicknesses ranged from 140 to 260 A. Near the x‐ray energies of Au‐M subshell absorption edges, the contribution of x‐ray transmission through the observed gold layers to the detection efficiency is greater than or equivalent to that of the inherently attached 7.6‐μm beryllium window. Hence, one must be careful in the determination of the detection efficiency in x‐ray semiconductor detector when low‐energy x rays of less than about 4 keV are measured.

Equilibrium charge state distributions of fast Si and Cl ions in carbon and gold foils

Abstract Equilibrium charge state distributions have been measured for 30–110 MeV Si ions in carbon and gold foils and 25–142 MeV Cl ions in carbon foils. Obtained values of mean charge states have been well reproduced by the empirical formula by Shima et al. in both ion energy dependence and foil Z 2 dependence. Asymmetric charge state distributions are in fairly good agreement with the prediction of the chi-squared model by Baudinet-Robinet.

Target thickness dependence of projectile K X-ray emission in fast heavy ion bombardments on carbon foils

Abstract Heavy projectile K X-ray emission yields have been measured as a function of carbon target thickness for incident ions of 40 MeV Cl 13+ , 95 MeV Cl 8+, 12+, 15+, 16+, 17+ , 115 MeV Fe 10+ , 120 MeV Cu 11+ , 150 MeV Cu 13+ and 140 MeV Br 12+ . In the thin target foil region where the loss and capture process of projectile L shell electrons is not equilibrated, projectile K X-ray emission cross sections have been found to be significantly influenced by the variation of the number of projectile L shell electrons.

Target thickness dependence of Kα X-ray energy shifts in 80 and 120 MeV Cu + Cu collisions

Abstract Energy shifts of target Kα x-rays in 80 and 120 MeV Cu + Cu collisions have been observed to vary 90–108 and 100–137 eV, respectively, in target thicknesses of 1–20 μg/cm2 range where the projectile charge states change from nonequilibrium to equilibrium.

Charge state and incident energy dependence of K X-ray emission as a function of target thickness for 50–165 MeV Cu ions incident on 11–250 μg/cm2 Cu

Abstract Thin self-supporting Cu targets in 11–250 μg/cm2 thickness were bombarded with 50–165 MeV Cuqi+ ions (7 ⩽qi⩽ 24) to investigate the target thickness dependence of inner shell vacancy production processes in the symmetric collision of Cu + Cu. Doppler-shifted projectile K X-rays were discriminated from the target K X-rays, and the projectile and target K X-ray yields were separately measured as a function of target thickness. The K X-ray yields emitted from the projectile and the target Cu atoms are strongly dependent on the projectile initial charge state and target thickness for all the investigated collision systems of Cuqi+ + Cu. From the observed K X-ray yields, K-shell vacancy production cross sections averaged over the target thickness t of projectile σ KV and target σ ∗ KV were separately derived taking into account the fluorescence yield that can be estimated from the Kα X-ray energy shift. When the values of σ KV and σ ∗ KV are extrapolated to zero foil thickness, the K shell vacancy formed in the collision has been found to be equally shared between projectile and target in a single collision. With the increase of penetration depth, however, the values of σ ∗ KV are greater than those of σ KV presumably due to electron transfer of a target K electron to the projectile K vacancy. the evolution process of projectile excited states as a function of target thickness and the resulting variation of projectile and target K X-ray emissions are discussed.

Projectile and Target X-Ray Energy Shifts in Heavy Ion-Atom Collisions

To date, most of the experiments to obtain the characteristic x-ray energy shifts resulting from the multiple ionization in heavy ion-atom collisions have been done by using a foil or a dense gas target, under the condition that the target is thick enough for the projectile charge to reach the equilibrium state. In this work is reported (1) the variation of projectile or target K x-ray energy shift in the nonequilibrium target thickness region and (2) the correspondence of K x-ray energy shift to the target material dependence of heavy ion equilibrium charge state.

Target Thickness Dependence of K X-Ray Production Cross-Sections in 80–150 MeV Cu + C, Al, Cu, Ag Collisions

Since the discovery of projectile x-ray production nonlinearity as function of solid target thickness by Betz et al.1, many authors have applied the rate equation of projectile inner shell vacancy to the investigation of dynamic processes of heavy ion-atom collisions. In contrast to the existing reports of nonlinearity of target x-ray production cross sections, the experiments to observe the projectile x-rays have been limited.