arXiv subjects

F. J. Freibert

Publications and source records attributed to F. J. Freibert.

3 recordsLinked to original sources

arXiv2021

Equation of State: Manhattan Project Developments and Beyond

The hydrodynamic response of materials under extreme conditions of pressure, temperature and strain is dependent on the equation of state of the matter in all its states of existence. The Trinity plutonium implosion device development required the Los Alamos research community to advance the understanding of equations of state further and faster than ever before. The unpredicted high yield from the Trinity fission device explosion and the push to design the "Super" thermonuclear device initiated 75 years of unprecedented research and technological progress in equation of state development. This article describes the progress made on equation of state development during and since the Manhattan Project at Los Alamos.

physics.hist-ph↗

arXiv2021

The Taming of Plutonium: Pu Metallurgy and the Manhattan Project

We describe the wartime challenges associated with the rapid developments in plutonium chemistry and metallurgy that were necessary to produce the core of the Trinity Device. Beginning with microgram quantities of plutonium metal late in 1943, initial measurements showed a wide and confusing variance in density and other properties. These confusing results were the first clues to the astounding complexity of plutonium. As this complexity was revealed, it introduced new challenges for the fabrication of kilogram-scale parts. In a remarkable period from January 1944 to June 1945, Manhattan Project scientists made rapid progress in understanding plutonium chemistry and metallurgy. By early 1945, they had discovered five of the six ambient-pressure phases of unalloyed plutonium and reported the density of these phases to within a value of 0.1 g/cm$^3$ of those accepted today. They solved the stability problem introduced by these phases with a rapid alloy development program that ultimately identified gallium as the preferred element to stabilize the delta-phase, producing a plutonium alloy still of scientific and technical interest today. We conclude with a description of post-war developments in these areas, including applications of wartime plutonium metallurgy to civilian applications in nuclear reactors. We dedicate this paper to the memory of Ed Hammel, the Manhattan Project plutonium metallurgist whose previous description and documentation of plutonium history during the war has been essential in our research.

physics.hist-ph↗

arXiv2016

Isochronal annealing effects on local structure, crystalline fraction, and undamaged region size of radiation damage in Ga-stabilized $δ$-Pu

The effects on the local structure due to self-irradiation damage of Ga stabilized $δ$-Pu stored at cryogenic temperatures have been examined using extended x-ray absorption fine structure (EXAFS) experiments. Extensive damage, seen as a loss of local order, was evident after 72 days of storage below 15 K. The effect was observed from both the Pu and Ga sites, although less pronounced around Ga. Isochronal annealing was performed on this sample to study the annealing processes that occur between cryogenic and room temperature storage conditions, where damage is mostly reversed. Damage fractions at various points along the annealing curve have been determined using an amplitude-ratio method, standard EXAFS fitting, and a spherical crystallite model, and provide information complementary to previous electrical resistivity- and susceptibility-based isochronal annealing studies. The use of a spherical crystallite model accounts for the changes in EXAFS spectra using just two parameters, namely, the crystalline fraction and the particle radius. Together, these results are discussed in terms of changes to the local structure around Ga and Pu throughout the annealing process and highlight the unusual role of Ga in the behavior of the lowest temperature anneals.

cond-mat.mtrl-sci↗