T. Mikumo

Equilibrium charge state distributions of ions (Z1≥4) after passage through foils: compilation of data after 1972

Tables are presented for equilibrium charge distributions, mean charges, and distribution widths of energetic heavy ions (Z/sub 1/> or =4) passing through thin foils. Data reported since May 1972 are included here, updating tables compiled by Wittkower and Betz in AtomIc Data 5, 113 (1973).

Empirical formula for the average equilibrium charge-state of heavy ions behind various foils

A new empirical formula for the average equilibrium charge-state, q, of heavy ions observed after traversal of various foils is presented. The formula is nq=[1−exp(−1.25X+0.32X2−0.11X3)]1−0.0019(Z2−6)X+0.00001(Z2−6)2X nwhere Z1 and Z2 are the ion and target foil atomic numbers respectively, and X is the reduced ion velocity as defined by Nikolaev and Dmitriev [1]. The present formula is useful for the collision range Z1 ⩾ 8, 4 ⩽ Z2 ⩽ 79 and E < 6 MeV/amu, to within an accuracy of Δq/Z1 < 0.04.

Measurement of the low energy tail spectra adjacent to the x-ray photopeak in Si(Li) x-ray detectors☆

Abstract Low energy tail spectra, which are inherently observed adjacent to the X-ray photopeak in the use of a Si(Li) X-ray detector, have been measured for the 1.3–3.7 keV X-ray energy range. Three different Si(Li) detectors have been tested. The tail/peak count ratios as a function of incident X-ray energy have exhibited a rapid change at the boundary energy of the Si K absorption edge. From the observed tail/peak count ratios, the thickness of the Si layer which produces the tail spectrum has been estimated; the thicknesses for the three tested detectors are about 0.05, 0.1 and 0.2 μm. In addition to the carrier diffusion effect, it is proposed in the case of a Si(Li) detector that the effect of the escape (penetration) of Auger and phtoelectrons from (into) the intrinsic region plays an important role in the production of the tail spectra.

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.

Z2 oscillation of mean charge states of fast Si and Cl ions after passage through thin foils

Abstract Z 2 (target atomic number) oscillation of equilibrium charge states has been observed for 30–110 MeV Si and 70 and 110 MeV Cl ions after the passage through 22 different Z 2 foils. This oscillation may be related to the Z 2 oscillation of electron capture cross sections into the projectile K vacancy.

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.

Charge distribution width of heavy ions after passage through carbon foils

Abstract Equilibrium charge state distributions have been measured for 45–166 MeV Br ions after passage through carbon foils. Including the Br ion data, systematic investigation has been carried out for the charge distribution width ( d ) of various heavy ions (Z 1 ) over a wide range of projectile velocity ( v ). It is found that the variation of d as a function of v is closely related to the variation of projectile shell structure. Based on this concept, trials have been performed to present the expression of d values using new co-ordinates.

Lα x‐ray production efficiency from Z=50–82 thick target elements by electron impacts from threshold energy to 30 keV

Thick target yields of Lα x rays (x rays/stru2009electron) under electron bombardments from around threshold energy to 30 keV are presented for pure elements of Sn, Sm, Ta, W, Pt, Au, and Pb. The calculation of K x‐ray yields by Green and Cosslett has been applied to the deduction of Lα x‐ray yields and observed data have been compared with the calculation. A good agreement has been obtained for high Z elements. An empirical formula for observed Lα x‐ray yields ILα (x rays/stru2009electron) has been found to be expressed by ILα =1.3×10−7×Z1.3(UL3−1)1.46 ×0.938[ln(UL3−1)]2 in impact energies less than 30 keV, where UL3 is the overvoltage ratio defined by the ratio of electron impact energy to L3 shell ionization energy.

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.

The 12 UD pelletron accelerator at the University of Tsukuba

Abstract The 12 UD Pelletron installed at the Tandem Accelerator Center of the University of Tsukuba has been in operation for nearly four years. The installation of the accelerator is described and the operational experience with the accelerator and associate facilities are summarized.