Argonne国家实验室ECR离子源在固体材料离子束流产生方面的研究进展

Development work with solid materials at the Argonne National Laboratory ECR ion sources has been focused on two areas-introduction of materials with low vapour pressures,and increasing the beam intensities of heavy beams(i.e.-lead and uranium).An induction oven,with a demonstrated operating temperature extending to 2000℃,has been utilized to produce a Ti-50 beam with an intensity of 5.5eμA (12 ).In addition,a refinement of the sputter technique has been employed which has resulted in a 42% improvement in lead beam intensities.Details of the induction oven as well as the refined sputter technique will be presented.     

Determination of the 8B neutrino spectrum

We have measured the total energy of the alpha particles following the beta decay of 8B by implanting 8B into a planar silicon surface barrier detector. Calibration was performed using alpha particles following the beta decay of 20Na, similarly implanted. The alpha spectrum is used to infer the 8B neutrino spectrum which is an important input in the interpretation of experiments that detect energetic neutrinos from the Sun. The alpha spectrum reported here is in disagreement with the previous best measurement which used two detectors in coincidence.     

Tailoring of the functional properties of sol–gel films on Pt/TiO2/SiO2/(100)Si substrates: (Pb,La)TiO3/(Pb,Ca)TiO3 multilayer heterostructures

Preferentially oriented sol–gel (Pb,Ca)TiO₃/(Pb,La)TiO₃/(Pb,Ca)TiO₃ and (Pb,La)TiO₃/(Pb,Ca)TiO₃/(Pb,La)TiO₃ multilayer heterostructure thin films deposited on silicon-based substrates have been studied and compared with identically prepared (Pb,La)TiO₃ (PTL) and (Pb,Ca)TiO₃ (PTC) films. The existence in their texture of two components that contribute to the net polarization in the direction normal to the plane of the film, 001 and 111, results in significant ferroelectric and pyroelectric properties. P_r=26 Ccm^-2 and =28.5×10^-9 Ccm^-2K^-1, and P_r=17 Ccm^-2 and =22.8×10^-9 Ccm^-2K^-1, have been achieved, respectively, in the PTL/PTC/PTL and PTC/PTL/PTC heterostructures. The surface roughness of these films provides a high specific surface that can be interesting for infrared detectivity. An increase of the dielectric permittivity in the whole temperature interval up to the transition temperature has been observed for both heterostructures with respect to the PTL and PTC films. This effect is due to a release of stress in the heterostructures that is revealed by the increase of the tetragonal distortion, c/a, of these films. PACS 68.55.Jk; 77.80.-e; 77.84.Dy     

The 44Ti(alpha,p) reaction and its implication on the 44Ti yield in supernovae

Cross sections for the 44Ti(alpha,p)47V reaction which significantly affects the yield of 44Ti in supernovae were measured in the energy range 5.7 MeV相似文献   

Conjugate addition of allylsilanes to α,β-enones. Obtention of cyclobutyl derivatives

By conjugate addition of allylsilanes to α,β-enones, cyclobutyl derivatives are formed.     

Polarographic determination of zirconium at trace level

An indirect polarographic method has been developed for the determination of zirconium by formation of molybdozirconophosphoric acid, its extraction with MIBK or a mixture of diethyl ether and 1-butanol, stripping with alkali and measurement of the Mo(VI) by its catalytic effect on the polarographic reduction of hydrogen peroxide. Depending on the extradant, a detection limit of 2.5 or 8.9 mu/gl, can be achieved.