Wu Songmao

ELECTRON IMPACT IONIZATION CROSS SECTION OF AR+, KR+, IN+ AND GE+

Abstract The single electron impact ionization cross sections of Ar+, Kr+, In+ and Ge+ were measured on the improved electron-ion impact apparatus at Fudan University. The Ar+, Kr+ and In+ experimental results are in good agreement with data from other laboratories. The cross section of Ge+ was measured for the first time. The experimental results indicate that the indirect ionization process gives a larger contribution to the total ionization cross section of In+, as compared to the other three targets. The experimental data were compared with our Distorted-Wave-Born-Exchange-Approximation (DWBEA) calculation, the Lotz formula, and Configuration-Averaged-Distorted-Wave (CADW) calculations.

Lifetime measurement for the (23537)°9/2 level of NdII using the collinear ion beam-laser interaction

The collinear fast ion beam-laser spectroscopy has been used to measure the radiative lifetime of the (23537)°9/2 level of the rare earth ions NdII. The measurement was carried out by the interaction between the 30keV NdII ion beam and tunable collinear dye laser which resonantly excited a metastable level to the (23537)°9/2 level, and by the observation of its time-resolved decay downstream. The lifetime value obtained from a fit program was 27.6±0.9ns. The result may provide a possibility of determining the unknown configuration of the (23537)°9/2 level.

Absolute Cross Sections for Single Ionization of Ar+ and Cl+ by Electron Impact

A crossed-beam facility for electron impact ionization of ions was constructed. The absolute cross sections for single ionization of Ar+ and Cl+ ions at electron energies ranging from 30 to 500 eV were measured. The uncertainty is about ±13%.

Optical isotope shift measurements using collinear ion beam laser spectroscopy and the configuration of the NdII(23537)9/20 level

The optical isotope shifts of five even isotopes of neodymium have been measured by using collinear ion beam laser spectroscopy (CIBLS). Isotopically pure NdII ions with energy of 30ke V from an isotope separator were collinearly interacted with light from a tunable dye laser and selectively excited from a metastable level of 4f4 5d6 K9/2 to the (23537)9/20 level by Doppler tuning technique. The resonant excitation frequency values for each Nd isotope with mass number of 142, 144, 146, 148 and 150 were obtained. After the separation of the normal and specific mass shift and the field shift from the experimentally measured isotope shift, the configuration of the (23537)9/20 level was decomposed into 4f4 6p, 4f3 5d2 and 4f3 5d6p, and their fractions, for the first time. were determined to be 0.12-0.13, 0.88-0.85 and 0-0.02, respectively.

Determination of the concentrations of tritium and helium in titanium tritide targets

Abstract Atom ratios of T to Ti in T-Ti targets have been determined by the 4He+ Rutherford backscattering (RBS) and the proton elastic scattering (PES) techniques, and that of 3He to T in aged T-Ti targets by the 3He(d, p)4He and T(d, n)4He reactions. The results from RBS show that the depth distribution of T is uniform in a region of 8000 A under the target surface. For the results from the nuclear reaction analysis (NRA), a discrepancy between the experimentally measured and the calculated concentration of 3He in a heavily bombarded T-Ti target obviously exists.