Post Nuclear Detonation Forensics Research at the Idaho Accelerator Center

Dr. Dan Dale
Department of Physics, Nuclear and Electrical Engineering
Idaho State University

Over the course of the last three decades or so, the political situation in regards to nuclear weapons has become a lot more complicated. More countries have them, and the possibility that non-state actors will get them has risen. With this has come an increased emphasis on nuclear forensics, which divides roughly into three areas – pre-detonation, prompt signatures, and post-detonation. In this talk, I will give a brief overview of the field of nuclear forensics, and then focus on two areas of research in post-detonation nuclear forensics currently underway at the Idaho Accelerator Center.  Both of these lines of study utilize electron beams in the several MeV range and are based on the fact that in a nuclear detonation, neutrons will activate bomb components and materials in the environment, potentially revealing both the flux and the energy spectrum of the neutrons.

In a 239Pu based device, the plutonium is typically alloyed with gallium which will experience a high flux of fast neutrons in the event of a detonation. I will discuss measurements performed at the Idaho State University Idaho Accelerator Center of (n,p) reactions on two different isotopes of gallium which are expected to occur in a detonation of a plutonium based weapon.

On the other hand, for a nuclear weapon based on 235U, there is a high likelihood that the weapon design will involve large quantities of tungsten in the vicinity of the fissile material. I will describe a proposed method, based on the photon activation analysis technique, which has the potential to reveal details of the detonation based on measurements of the bomb debris.

This talk will be the first of a two part series on nuclear forensics at the IAC, with the second part covering prompt diagnostic signatures of nuclear explosions.