Editing Nth Country Experiment (section)

==Summary==
In April 1964, [[Lawrence Livermore National Laboratory]] (then known as Livermore Radiation Laboratory) hired physicists David A. Dobson and David N. Pipkorn to design a nuclear explosive with "militarily significant yield".<ref>{{Cite book | url=https://books.google.com/books?id=lQxKAQAAQBAJ&q=david+pipkorn+nth&pg=PA15 |title = Defusing Armageddon: Inside NEST, America's Secret Nuclear Bomb Squad|isbn = 9780393244069|last1 = Richelson|first1 = Jeffrey T.|date = 2009-02-02| publisher=W. W. Norton & Company }}</ref>

The next year, Pipkorn dropped out of the project and was replaced by Robert W. Seldon, a [[captain]] in the [[United States Army Reserve]]. Like Pipkorn and Dobson, Seldon had a physics PhD and no nuclear expertise.<ref>{{Cite web|url=https://www.theguardian.com/world/2003/jun/24/usa.science|title=How to build an A-bomb|website=[[TheGuardian.com]]|date=24 June 2003}}</ref>

The experiments the physicists completed were split into three phases, each representing the "attainment of a physical level of understanding." Phase I was the understanding of basic concepts and considerations of bomb design, much like the process of creation originally undertaken by [[J. Robert Oppenheimer]] at [[Los Alamos National Laboratory|Los Alamos]]. Phase II was the quantitative expansion of those basic concepts into practical application by calculating core mass, hole size, explosive thickness, etc., which are essential to the careful design of atomic weapons. Finally, Phase III was an "extension of Phase II" that involved actual implosion and fission calculations. Plutonium implosion-style designs were then formulated. 

Historical fission designs began with many-point triggers for the chemical detonation, up to a 92-point design in the [[Ivy King]] fission test. The physicists selected the more novel two-point implosion. This had first appeared in open literature in a Swedish nuclear weapon design in 1956. The [[Swan (nuclear primary)|Swan nuclear primary]] was another early two-point design, first tested in 1956. Certain aspects of the UCRL-50239, including the two-point nature of the implosion, have been omitted from the report.<ref>{{Cite journal |last=Frank |first=W.J. |date=March 1967 |title=Summary Report of the Nth Country Experiment |url=https://blog.nuclearsecrecy.com/wp-content/uploads/2012/01/1967-Summary-Report-of-the-Nth-Country-Experiment.pdf |journal=Summary Report of the NTH Country Experiment |volume=1 |pages=66 |via=University of California Livermore}}</ref><ref name="h359">{{cite journal |last=Lewis |first=Jeffrey |date=2014-04-03 |title=Nuclear-weapons design and testing |journal=Adelphi Series |volume=54 |issue=446 |pages=43–76 |doi=10.1080/19445571.2014.995420 |issn=1944-5571}}</ref>