Zhengmin Liu

M -subshell ionization of Th and U by alpha particle bombardment

The M x-rays of Th and U have been produced by alpha particle bombardment in the energy range of 2.5-4.5 MeV. N6,7 → M5(Mα), N6 → M4(Mβ), N5 → M3(Mγ), N4 → M2 and N2 → M1 lines were selected to deduce M-subshell x-ray production cross sections. The radiative transition rates and the Coster-Kronig yields and M-subshell fluorescence yields were used to convert the x-ray production cross sections into M-subshell ionization cross sections. The deduced M-subshell ionization cross sections were compared with the ECPSSR predictions. The discrepancies of our experimental results from the theoretical calculations are discussed.

L-subshell ionisation of 71Lu, 73Ta and 79Au by 1.5–4.5 MeV alpha particles

Abstract The L X-rays of 71 Lu, 73 Ta and 79 Au were produced by 1.5–4.5 MeV alpha particle bombardment. The emitted L α , L γ1 and L γ2,3 lines were selected to convert X-ray production cross sections into ionisation cross sections. The ionisation cross sections obtained were compared with the predictions of the ECPSSR theory. A reasonable agreement of L 3 -subshell ionisation cross sections between the present experiment and the ECPSSR theory is found. The departures of the measured L 2 -subshell ionisation cross sections from the ECPSSR theory are discussed.

Non-Rutherford elastic scattering cross sections of natural magnesium for protons

Abstract The elastic scattering cross sections of natural magnesium for protons have been measured for beam energies below 2.5 MeV and in the angular range from 140° to 170° in steps of 10°. The overall standard error (Δ σ Exp / σ Exp ) in the measured cross sections is estimated to be better than ±5% at all the beam energies and angles. The results are compared with the previous data and presented in graphical and tabular forms.

ONE AND TWO ELECTRON TRANSITIONS IN ENERGETIC ION AND HELIUM COLLISIONS

Abstract The single ionization (SI) and double ionization (DI), single and double ionization accompanying one electron loss (SS) of the projectile and the single and double electron capture of the projectile from target atom are investigated for 2.0–8.0 MeV Na q + –He and C1 q + –He collisions. The cross-section ratio of the double ionization (DI) to that of the SI, the ratio of SS+DI to SS+SI, and ratio of double capture (DC) cross-section to that of single capture (SC), are measured by means of time-of-flight technique. The velocity and charge state dependences of the measured cross-section ratios are studied and discussed. The obtained capture cross-section ratios are compared with the theoretical calculations using the classical over-barrier model.

The ionization of helium by 1.5–7.5 MeV partially stripped Cq+ ions

Abstract The double to single ionization cross section ratios of helium by partially stripped carbon ions have been measured for projectile charge states ranging from +1 to +4 and impact energies from 1.5 to 7.5 MeV. The effective charge effect in partially stripped ion-helium collision is presented. It is found that the effective charge qeff increases as the impinging energy increases and qeff shows a modest dependence upon the projectile charge state in the present energy range. The projectile charge state, projectile and target electronic state dependences of the effective charge effect is discussed using orbital interpenetrating. The nCTMC calculations were carried out to investigate the energy dependence of the effective charge. By introducing effective charge the cross section ratio of helium obtained in the present work is in good agreement with the ( V q eff ) −2 law.

The investigation of the multiple ionization of argon by energetic oxygen ions

The cross section ratios of the double, triple and quadruplicate ionization to the single ionization of argon were measured by 1.5–7.5 MeV partially stripped oxygen ion (q = 1–4) bombardment. The Auger and the charge exchange processes are discussed and subtracted from the total multiple ionization ratios in order to study the mechanism of the direct multiple ionization of argon by partially stripped ions in the present energy range. It is found that the obtained ratios of the multiple ionization cross sections to those of the direct single ionization of argon agree well with the (νqeff)−2n+2 law for 1.5–7.5 MeV Oq+ (q = 1–4) impinging ions.

TRANSFER IONIZATION IN COLLISIONS OF PARTIALLY STRIPPED Fq+ WITH HELIUM ATOMS

The cross-section ratios R of transfer ionization to single electron capture of Helium atom induced by fluorine ions in the strong-interaction region were measured by means of the position-sensitive-detection and the time-of-flight (TOF) technologies. The velocity and charge state dependence of R were studied. It is found that the R decreases when the 2q/v increases, where q and v are the charge state and velocity of projectile respectively. In this energy region the transfer ionization can be look as Two-Step process that one target electron is captured, and another electron is ionized.

Proton channeling effect in the smectic liquid crystal

Abstract The planar channeling phenomenon in the smectic liquid crystal molten sodium oleate, has been investigated. A 2.0 MeV proton beam was used for the experiment. The angular distributions observed by proton backscattering show a typical channeling characteristics, indicating that the channeling technique may be used for the liquid crystal research.

Effective charge effect in 2.0–7.0 MeV partially stripped F q + -helium collisions

The ratio of the double ionisation cross section to that of the single ionisation of helium was measured for 2·0–7·0 MeV Fq+ (q = 1,2,3,4) bombardment. The effective charge effect in partially stripped Fq+ – helium collisions is studied. It is found that the effective charge qeff increases as the impinging energy increases and that qeff shows almost no dependence upon the projectile charge state in the present energy range.

Optimization experiments on a pixe system and its application to the analysis of trace elements in shaji

Abstract This paper describes briefly the optimization of a PIXE setup. Three proton energies 1.5, 2.0 and 2.5 MeV and four kinds of absorbers BE (132 μm), Be (460 μm), Al (28 μm) and Be plus Mylar (460 μm+600 μm) were used. The minimum detection limits (MDL) of PIXE for these various combinations were computed and compared. PIXE analysis of Shaji ∗∗ was performed as an application. The result shows that the stack absorber of 460 μm Be and 600 μm Mylar films and a 2.0 MeV proton energy are most suitable for PIXE analysis of Shaji. Results of the Shaji analysis are presented.