Vol.4,

The epitaxial growth features of YBa₂Cu₃O_(7-x) (YBCO) films on (100) SrTiO₃ substrates have been studied by Rutherford backscattering spectrometry and axial channeling technique. A typical minimum yield value, X_min, of Ba yielded in channeling spectrum is 4.6 % for the film of 166 nm. Only (00L) peaks appeared in X ray diffraction patterns of the films. The results indicate that the YBCO films have good epitaxial growth quality with c- axis orientation perpendicular to the substrate surface. Simulation of RB process in films and substrates have also been performed using RUMP program, and analysis shows that compositions of the films are uniform with near (123) stoichiometry. The higher interface yields in the aligned spectrum reveal that there are extra defects in the interface layer owing to lattice mismatch and interface interaction.

199

The angular distributions of sputtered Cd atoms were measured with 27 keV Ar⁺ ion bombardment at normal incidence for different target temperatures by using collector technique and RBS analysis. After the sputtering experiment the surface structures were observed using scanning electron microscope. For all samples the angular distributions are over-cosine. But the exponent n from fits of cosⁿ θ to experimental angular distributions changes with target temperature. A simple model is proposed to explain the relation between shape of angular distribution and topography of sputtered surface.

219

Studies show that ²³⁵UO₂F₂ was chiefly localized in kidneys, then in skeleton and liver. Its radioactivity in skeleton rose steadily while the concentration in kidneys and liver droped. ²³⁵UO₂F₂ was difficult to pass through the blood- testes barrier. With 1 to 6 h contact period, only 1.4- 1.6% ²³⁵UO₂F₂ was found in the intact skin, but 41-54% in the abrasive skin. The dynamic retention of ²³⁵UO₂F₂ through intact or abrasive skins was also dominantly localized in kidneys, skeleton and liver. Accumulation of insoluble ²³⁵U₃O₈ in gastrointestinal tract was well described by a double- exponential- term expression. Values of retention were estimated for fast component T₁=0.34 d, and for relatively long term component T₂=4.05 d.

315

359

Aerosol samples were collected from three typical areas during three years: 1) north suburb of Shanghai city (NSSC); 2) north part of Shanghai city; 3) a lead-zinc smeltery and its surrounding areas. The hair samples were collected from lead-exposed workers and control people. Aerosol samples have been analyzed by PIXE, and hair samples by EDXRF (energy-dispersive X-ray fluorescence) method. S, Cl, K, Ca, Mn, Fe, Cu, Zn, Pb etc were detected in most of the aerosol and hair samples. According to the analytical results, the compositions of NSSC aerosol samples were quite similar to those from north part of Shanghai city, both the lead concentrations of these samples were less than the limit of the National Standard (70 µ g/m³); There was serious air pollution in smeltery and its surrounding areas. Especially, the lead concentration in the aerosol exceeded 200 µ g/m³; The average lead concentration of hair samples for half-year exposed group was about 3-fold higher than that of unexposed group.

232

The coal filter cake is a product of fine coal after floatation which has an ash content of 7-13%, water content of 30±2%, and a particle size of less than 1 mm. The ash content was measured by the intensity of the single backscattered gamma-ray, and its accuracy is mainly dependent on the energy of the gamma-ray. The ²³⁸Pu low energy photon source is selected in this work. The energy of its gamma-ray is 15 keV, which can result not only in the best sensitivity, but also in the lowest contribution to the environment radiation. The root mean square deviation of the ash measurement is ±0.33% (±1σ).

284

285

224

This paper deals with the matrix absorption and enhancement effects of thick targets in energy dispersive X-ray fluorescence analysis. Two kinds of absorption correction methods are studied especially for medium thick targets (5-10 mg/cm²). For analysis of hair samples, both the measurement of absorption correction coefficients and the determination of sensitivity factors using an addition method are introduced. Quantitative analysis of medial thick samples is established. The relative deviation between different methods for most of the elements is found to be less than 5 %.

460

The polonium-210 activity in raw material targets which was used to make the start neutron source rods of Qinshan Nuclear Power Station was determined in calorimetry. The calorimeter used is a twin-cup isothermal one. It works at room temperature and does not need any device of constant temperature. The instruments used for calorimetry are simple and have good properties. The background is from -1 µ V to +2 µ V when the room temperature changs between 16℃ and 28℃. The data gotten in calorimetry are in correspondence within ±3.4% with those from liquid scintillation method after the targets were dissolved, additionally in correspondence within ±1.7% with the data given by Amersham Laboratories for ²⁴¹Am determination.

312