Neutron activation analysis determination of all 14 stable rare-earth elements with group separation and Ge(Li) spectrometry

A lithium-drifted germanium detector, 40 cm³, combined with a radiochemical group separation, has been utilized to determine the concentrations of 14 stable rare-earth elements in a silicate rock sample, following thermal-neutron activation. Thirteen rare earths could be determined within an 8-day decay period. The remaining rare-earth element (Tm) required a longer delay, and subtraction of the interfering contribution from¹⁶⁰Tb. Samples of standard rock G-1 and W-1 were also analyzed by this procedure for 13 rare earth elements, results of which are compared with literature values.     

Universal distribution of transparencies in highly conductive Nb/AlO(x)/Nb junctions

We report the observation of the universal distribution of transparencies, predicted by Schep and Bauer [Phys. Rev. Lett. 78, 3015 (1997)] for dirty sharp interfaces, in uniform Nb/AlO(x)/Nb junctions with high specific conductance (10(8) ohm(-1) cm(-2)). Experiments used the BCS density of states in superconducting niobium for transparency distribution probing. Experimental results for both the dc I-V curves at magnetic-field-suppressed supercurrent and the Josephson critical current in zero magnetic field coincide remarkably well with calculations based on the multimode theory of multiple Andreev reflections and the Schep-Bauer distribution.