Cheng Huansheng

Cross sections for 170° backscattering of 4He from oxygen in the energy range of 2.0–9.0 MeV

Abstract We report the 170° backscattering cross sections of 4He from O in the energy range of 2.0–9.0 MeV. Our measurements show that the alpha-oxygen scattering remains Rutherfordlike up to Eα = 2.35 MeV, and there exist two energy regions, 5.55–5.85 MeV and 8.50–8.80 MeV, where the cross sections present an enhanced and smooth variation. The measured cross sections in these two regions exhibit enhancement factors of 9.7 and 34, respectively, compared to the Rutherford values. In the 8.50–8.80 MeV region, the cross sections at scattering angles of 160°, 165°, 170° and 175° were measured and found to be strongly angle-dependent. The strongest resonance was seen at 7.60 MeV, where the cross section is 200 times its Rutherford value. We report the use of this resonance to measure the O areal density on a Cu surface, with a sensitivity of 1 × 1015 oxygen atoms cm 2 . We have also studied the scattering angle dependence of the threshold energy at which the cross section begins to depart from its Rutherford value. Our experimental results are not in agreement with the prediction from the analytical formula developed by Bozoian et al. [Nucl. Instr. and Meth. B 51 (1990) 311].

Origin of Chinese ancient glasses—study on the earliest Chinese ancient glasses

The earliest Chinese ancient glasses before the West Han Dynasty (200 BC) from different regions are studied. The glass samples were unearthed from Hunan, Hubei, Yunnan, Sichuan, Guizhou, Guangdong and Xinjiang of China. The chemical composition of these glasses samples is analyzed by proton induced X-ray emission (PIXE) technique, energy dispersive X-ray fluorescence (EDXRF) method and inductively coupled plasma atomic emission spectrometry (ICP-AES). It is shown that the glass chemical compositions belong to barium-lead silicate BaO-PbO-SiO2, potash soda lime silicate K2O (Na2O)-CaO-SiO2 (K2O/Na2O>1), soda potash lime silicate Na2O (K2O)-CaO-SiO2 (K2O/Na2O<1) and potash silicate K2O-SiO2 glass systems, respectively. The origins of the earliest Chinese ancient glasses are discussed from the archaeological and historical points of view. These four types of Chinese ancient glasses were all made in Chinese territory using local raw materials. The glass preparation technology was related to the Chinese ancient bronze metallurgy and proto-porcelain glaze technology. The glass technology relationship between the East and the West is analyzed at the same time.

Comments on the classical approach to non-Rutherford cross section calculations

Abstract Non-Rutherford cross sections are needed in high energy backscattering spectroscopy. Bozoian et al. have developed a classical model and derived an analytical expression to calculate the projectile energy E nr at which the scattering cross section begins to deviate from its Rutherford value. We make comments on the model and conclude, through discussions and experiments, that (1) it is useful in estimating the energy value but gives incorrect dependences of E nr on the departure factor F and the scattering angle χ, and (2) these inadequacies originate from the classical approach, which is an over-simplified and phenomenal description of nature.

Evaluation of non-Rutherford cross sections

Abstract The R-matrix theory is used to analyze the elastic scattering cross sections of 4 He from 16 O in the energy range 2.0–9.0 MeV. Level parameters of the compound nucleus 20 Ne, i.e., the spins, parities, resonant energies, and widths of the excited levels for alpha energies from 2.5 to 9.7 MeV, were identified. These level parameters can then be used, for application purposes, to check either the measured values of resonant cross sections or the cross sections at certain particular angles according to the experimental conditions.

Proton induced X-ray emission (PIXE) analysis of sources of porcelain body of Ru Guan and Jun Guan porcelains

Abstract34 samples of Ru Guan porcelain body and 50 samples of Jun Guan porcelain body (both kinds being in different body colors) were selected with the purpose of finding out the source of raw materials and their classification relationship so as to search for ways of non-destructive discrimination. Proton induced X-ray emission (PIXE) has been applied to these samples to determine their chemical elements. The data of seven major chemical elements collected from these samples were further studied through fuzzy cluster analysis. Results indicate that the origin of raw materials of Jun Guan porcelain body samples is comparatively more concentrated in certain places, while that of Ru Guan porcelain body samples is scattered about. The places of origin of raw materials of the majority of Ru Guan and Jun Guan porcelain body samples have something in common, but some differences still exist. It might be an important way for non-destructive discrimination among Ru Guan and Jun Guan porcelains by combining PIXE with fuzzy cluster analysis.

Analysis of a high-Tc superconductor by high-energy elastic backscattering

Abstract High-energy ion backscattering can be used to enhance the sensitivity of oxygen analysis. At a He ++ ion energy of 8.8 MeV, the yield due to oxygen is about 25 times larger than that predicted by the Rutherford formula. The elemental stoichiometry of some bulk and thin-film superconductor samples was determined. The details of the measuring method are described.

Studies of surface atomic structure of Al(l00) by MeV ion scattering

Abstract An UHV system specially designed for studying surface and interface atomic structure by MeV ion scattering and channeling is described. The vacuum in the UHV chamber is 1 × 10−10 Torr. The chamber is equipped with an ion gun used for sample cleaning, a translatable four-grid LEED-Auger system used for characterization of the crystal surface, and a three-dimensional goniometer. The crystal preparation and cleaning procedure of Al(100) are presented. The surface peak intensity of Al(100)-〈100〉 and Al(100)-〈110〉 has been measured by MeV ion channeling and scattering. The measured surface peak intensity was compared with that of a Monte Carlo simulation. The experimental results indicate that the thermal vibration amplitude of Al(100) surface atoms is 1.2–1.3 times that of bulk atoms. The relaxation of the first layer for Al(100) is less than −0.05 A.

Main chemical ingredients of the celadon glaze from Qingliangsi kiln and Zhanggongxiang kiln

The proton induced X-ray emission (PIXE) is used to determine the chemical ingredients of seven main elements in the samples of Ru Guan porcelain glazes and Ru Civil porcelain from Qingliangsi kiln in Baofeng County and the samples of celadon glaze from Zhanggongxiang kiln in Ruzhou City. The PIXE data are then analyzed by scatter analysis and fuzzy cluster method for determining their classification and provenance. The results show that there are obvious differences between the ingredients of glaze material of Ru Guan porcelain and Ru Civil porcelain from Qingliangsi kiln, of which the former ingredients are stable and its source is localized, and that the sources and ingredients of the glaze of Ru Guan porcelain and those of celadon glaze from Zhanggongxiang kiln are not wholly the same, of which the latter sources are much scattering.

Diffusion of Silver in Nanometer Ni-B Amorphous Alloy

Diffusion of Ag in nanometer Ni-B amorphous alloy, has been studied by heavy-ion Rutherford backscattering spectroscopy. The values of the diffusion coefficient which were found at 293, 323 and 373 K, are 3.5 × 10-16, 4.3 × 10-15 and 5.0 × 10-14 cm2/s, respectively. Moreover, small values for the activation energy, 0.58 eV, and the pre-exponential factor of the diffusion coefficient, 3.9 × 10-6 cm2/s, were derived from Arrhenius plot. Finally, a possible free volume controlled diffusion mechanism was discussed.

The studies of non-Rutherford backscattering cross sections of 4He from 16O

In this article, we report the 170° backscattering cross sections of 4He from 16O in the energy range of 2.0-9.0 MeV. Our measurements show that the alpha-oxygen scattering remains Rutherford scattering up to Eα=2.35 MeV, and there exist two energy regions, namely 5.55-5.85 MeV and 8.50-8.80 MeV, where the cross sections are enhanced and show a smooth variation. The measured laboratory cross sections are 9.50-9.97 and 35.0-33.0 times greater than the Rutherford values, respectively. In the 8.50-8.80 MeV region, the cross sections at scattering angles of 160°, 165°, 170° and 175° were measured and found to be strongly angle-dependent. A most strong resonance occurred at 7.60 MeV, where the cross section is 200 times of its Rutherford value. This resonance has been used to measure the 16O concentration on a Cu surface, with a sensitivity of 1×1015 oxygen atoms/cm2. Besides, we have studied the backscattering angle dependence of the threshold energy, i. e., the energy at which the elastic cross section begins to deviate from its Rutherford value. The experimental result seems not in agreement with the prediction made from the analytical formula developed by Bozoian et al.