A Multi-Analytical Approach for Developing Nuclear Forensic Methods for Source Attribution using Trinitite Post-Detonation Material

On July 16, 1945, the United States successfully detonated the world's first nuclear weapon in the White Sands Missile Range, N.M. The 'Trinity Test,' was a Pu-implosion device and upon detonation, produced a large and extremely hot fireball; this caused the bomb components and natural material to melt and mix within ~300 meters radius from ground zero. Subsequent the explosion and cooling, a green, glassy material covered the detonation site and was given the name 'Trinitite.' It is an ideal post-detonation material to study and develop methods for nuclear forensics as the device's composition is well documented and declassified. This thesis reports a detailed investigation of Trinitite's chemical and isotopic composition as well as development of methodologies towards improving nuclear forensic investigations. Using analytical techniques such as gamma spectroscopy, electron microprobe, and solution mode- and laser ablation-(multicollector) inductively coupled plasma mass spectrometry (ICP-MS), a large sample set (n= 68) of Trinitite was fully characterized for its major and trace element abundances and isotopic (O, Pb, U, Pu) compositions. This dissertation also includes development and application of novel techniques for the purposes of nuclear forensics; e.g., a methodology using a fluorinating thermal treatment to separate natural and anthropogenic components, and 3D imagery techniques (e.g., FIB-focused ion beam) to find bomb components at the nanoscale within Trinitite. Overall, the results reported in this doctoral research clearly indicate that a multi-analytical approach can effectively provide accurate and reliable chemical and isotopic signatures of Trinitite in a timely fashion (within hours to days), and these can be employed for source attribution in future investigations of nuclear post-detonation samples.