Wang Yu-Yu

Potential and Kinetic Electron Emissions from HOPG Surface Irradiated by Highly Charged Xenon and Neon Ions

Highly charged 129Xeq+ (q = 10−30) and 40Neq+ (q = 4−8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite (HOPG) are reported. The total secondary electron yield is measured as a function of the potential energy of incident ions. The experimental data are used to separate contributions of kinetic and potential electron yields. Our results show that about 4.5% and 13.2% of ions potential energies are consumed in potential electron emission due to different Xeq+ -HOPG and Neq+ -HOPG combinations. A simple formula is introduced to estimate the fraction of ions potential energy for potential electron emission.

Guiding of Highly Charged Ions through PC Nanocapillaries

Angular distribution and current dependence of the transmitted ion fraction are investigated for 40keV Xe7+ bombarding on polycarbonate (PC) nanocapillaries. By measuring the angular distribution of the transmitted ion fraction, a strong guiding effect is found in PC nanocapillaries. Furthermore, with increase of the incident current, a turning point of the transmitted ion fraction is found, which is explained qualitatively by the discharge capacity of the nanocapillaries.

Scale tissue of bighead carp and silver carp as nonlethal surrogates for muscle tissues in freshwater food web studies using stable isotopes

Stable isotope analyses of carbon and nitrogen are now widely used in food web studies. Stable isotope analysis of fishes is often performed using muscle that require sacrificing animals. Nonlethal sampling provides an alternative way for evaluating isotopic composition for species of concern or individuals of exceptional value. In this research we compared stable carbon and nitrogen isotope values of white muscle with those from scales( nonlethal) in bighead carp( Aristichthy nobilis) and silver carp( Hypophthalmichthys molitrix) from Lake Poyang. Scale derived δ13C and δ15N differed significantly with muscle derived isotope values.Averaged scale δ13C value was 2. 54‰ higher than muscle,while scale δ15N value was 0. 7‰ lower than muscle. Both fish showed strong linear correlation in δ15N values between their nonlethal sampled scale and their muscle tissue,support the use of nonlethal sampled tissues for stable isotope analyses of fish. Strong correlation in δ13C only found between H. molitrix scale and muscle. Estimating muscle δ13C values from scale was not suggest for A. nobilis.

Kr L X-ray and Au M X-ray emission for 1.5 MeV—3.9 MeV Kr13+ ions impacting on an Au target

Kr L X-ray and Au M X-ray emission for Kr13+ ions with energies of 1.5 MeV and 3.9 MeV impacting on an Au target are investigated at heavy ion research facility in Lanzhou (HIRFL). The L-shell X-ray yield per ion of Kr is measured as a function of incident energy. In addition, Kr L X-ray production cross section is extracted from the yield and compared with the result obtained from the classical binary-encounter approximation (BEA) model. Furthermore, the intensity ratio of the Au Mβ3 to Mα1 X-ray is investigated as a function of incident energy.

Guiding of 150 keV O6+ ions through nanocapillaries in an uncoated Al2O3 membrane: special time dependence of the transmission profile width

This paper reports that the transmission of O6+ ions with energy of 150keV through capillaries in an uncoated Al2O3 membrane was measured, and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed. Due to using an uncoated capillary membrane, our c is larger than that using a gold-coated one with a smaller value of E-p/q, which suggests a larger equilibrium charge Q(infinity) in our experiment. The observed special width variation with time and a larger width than that using a smaller E-p/q were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation.

Ionization of highly charged iodine ions in collisions near the Bohr velocity

The L-shell X-rays of iodine induced by 3MeV Iq+(q=20,22,25,26) ions impacting on Fe target were measured. The results indicated that, in addition to the ionization of L-shell, the projectile M- and N-shell were multiply ionized. The ratios of the sub-shell X-ray relative intensity were also investigated.

4fσ excitation for L-vacancy production of Mo in collision of highly charged xenon ions near Bohr Velocity

L X-ray emission induced by Xe20+ and Xe30+ impacting on Mo was measured. The dependences of Mo L X-ray yield on the incident energy were investigated. The results provide evidence for the 4fσ excitation in such collision system.

Fe K-shell ionization induced by Xe20+ ions near the Bohr velocity

Fe K-shell ionization cross sections by 2.4-6.0 MeV Xe20+ impact were investigated. It was found that the BEA model corrected both by the Coulomb repulsion and the effective nuclear charge gives the best agreement with the experimental data.

Charge state effect on the K-shell ionization of iron by xenon ions near the Bohr velocity

Fe K-shell ionization cross sections induced by 2.4–6.0 MeV Xe20+ are measured and compared with different binary-encounter-approximation (BEA) models. The results indicate that the BEA model corrected both by the Coulomb repulsion and by the effective nuclear charge (Zeff) agrees well with the experimental data. Comparison of Fe K-shell X-ray emission induced by 5 MeV xenon ions with different initial charge states (20+, 22+, 26+, 30+) verifies the applicability of the effective nuclear charge (Zeff) correction for the BEA model. It is found that Zeff correction is reasonable to describe direct ionization induced by xenon ions with no initial M-shell vacancies. However, when the M shell is opened, the Zeff corrected BEA model is unable to explain the inner-shell ionization, and the electron transfer by molecular-orbital promotion should be considered.

K shell hyper-satellite lines of Cu induced by 300MeV/u C ions

X-ray emission induced by 300 MeV/u C ions impacting on copper was investigated at the Heavy Ion Research Facility in Lanzhou (HIRFL). The results showed a very high yield of K hyper-satellite emission comparing to the satellite emission.