An experimental investigation of radioactivity induced by ions associated with the operation of pulsed power accelerators

Energetic light ion beams are being studied in Sandia National Laboratories' Particle Beam Fusion Accelerator 11 (PBFA II) for the purpose of studying the physics of applied B-diodes with the hope that these beams can be applied to inertial confinement fusion. These beams induce nuclear reactions both in the diode itself and in the materials surrounding the diode. A series of experiments was conducted wherein samples of metals typically used in the diode/gas cell region of PBFA II were exposed to ion beams at energies expected to be achieved in PBFA II. The metals studied were aluminum alloys 2024 and 6061, brass, copper, inconel alloys 625 and 718, Stainless Steel 304, tantalum, titanium, and tungsten. The ion beams studied consisted of protons at energies of 6, 12, and 19 MeV, Lithium-7 at energies of 10, 15, 20, and 30 MeV; Lithium-6 at 30 MeV; and Boron-10 and Boron-11 at 30 MeV. The induced activity of each sample was measured as a function of time with an ion chamber and was used to estimate the rate at which the initial short-lived activity of the sample decayed. In addition, the activity of each sample was periodically measured with a Geiger counter in contact with the irradiated surface of the sample, was normalized to the total amount of energy incident on the sample, and was used as a basis to compare the amount of activity generated per mega-joule of energy for each sample. Additionally, gamma-ray spectra of the activated samples were collected using a germanium detector, and these spectra were analyzed qualitatively to identify the long-lived radioisotopes present in the sample. Future work will also be discussed