Development of separation techniques for analysis of Nb-94 in radwaste samples.

A chemical separation technique for removing interfering gamma-ray radionuclides by combined precipitation of Nb pentoxide and anion exchange was proposed, thereby allowing detection of trace 94Nb in low-level radwastes. The detection limit for 94Nb was improved by a factor of 10-103, and the scaling factor (94Nb/60Co) of the radwastes was estimated to be less than 10-5. This technique can be used for low-level radwaste classification and power reactor decommissioning.

Magnetic field enhanced resonant tunneling in a silicon nanowire single-electron-transistor.

We report fabrication, measurement and simulation of silicon single-electron-transistors made on silicon-on-insulator wafers. At T-2 K, these devices showed clear Coulomb blockade structures. An external perpendicular magnetic field was found to enhance the resonant tunneling peak and was used to predict the presence of two laterally coupled quantum dots in the narrow constriction between the source-drain electrodes. The proposed model and measured experimental data were consistently explained using numerical simulations.