Use of a COTS X-ray scanner for 2-D neutron activation analysis

Results from the use of a commercial, off-the-shelf X-ray scanner using storage phosphors to measure neutron activation in 1- and 2-D are presented. The technique consists of irradiating thin foils or wires of various elements, then placing the activated material on the storage phosphors to expose them. The amount of exposure is proportional to the activation obtained. Examples of wires, small foils, and large area foils with asymmetric irradiation using critical assemblies are presented. Combined with isotope-specific gamma counting of the entire foil or wire, the technique offers a simple way to obtain both qualitative and quantitative 2-D activation information.     

Construction of a shallow underground low-background detector for a CTBT radionuclide laboratory

The International Monitoring System is a verification component of the Comprehensive Nuclear-Test-Ban Treaty, and in addition to a series of radionuclide monitoring stations, contains 16 radionuclide laboratories capable of verification of radionuclide station measurements. This paper presents an overview of a new commercially obtained low-background detector system for radionuclide aerosol measurements recently installed in a shallow (>30 meters water equivalent) underground clean-room facility at Pacific Northwest National Laboratory. Specifics such as low-background shielding materials and active shielding methods will be covered.     

Alignment effects on implantation profiles in silicon

Abstract

Dual species ion implants of Se in conjunction with Ga implant in Cr-doped semi-insulating GaAs have been carried out. Electron concentration and mobility profiles have been investigated for annealed samples using differential Hall-effect and sheet-resistivity measurements.

It has been shown that the dnal implantations give high maximum electron concentrations above 1 × 10¹⁹ cm^?3 when those samples are annealed at 950°C using a low oxygen content CVD Si₃ N₄ encapsulant. Experimental results indicate that the major part of the enhanced maximum electron concentrations arise from Se donors on As vacancy sites.