Author:Ari Vogel
Course:EEE 460
Date:Spring 2002

Scientists of the Manhattan Project

  If not for the great minds of numerous scientists from many different nations working together during the World War II era, the goals of the Manhattan Project never would have been realized.  This web page investigates the significance of some of these partnerships, along with what blossomed out of each discovery.

 

Albert Einstein (left) and Leo Szilard after the war [1]

 

In early August 1939, Szilard drafted a letter in consultation with Einstein that was sent to President F.D. Roosevelt warning him of the possibility of nuclear weapons.  Ten days after the President received the letter, the “Briggs Uranium Committee” held its first meeting in Washington, DC on President Roosevelt’s orders.  MORE

 

 

The opening paragraph of the “Memorandum on the properties of a radioactive “super-bomb” [2]

 

In 1940, Otto Frisch and Rudolph Peierls, living in England, authored what would become known as the “Frisch-Peierls Memorandum,” which explained to the British government how a uranium fission bomb could become a weapon with the potential to win World War II.  Greatly interested, the British government formed the “MAUD Committee” to coordinate further research into Frisch’s and Peierls’ extraordinary claims.  MORE   

 

Basic concept of implosion in an atomic bomb [3]

 

By mid-May 1944, six months after the start of accelerated implosion research, little progress towards successful implosion of the atomic bomb had been made. Two British scientists joined Los Alamos who had important impacts on the implosion program. Geoffrey Taylor pointed out implosion instability problems (especially the Rayleigh-Taylor instability), which ultimately lead to a very conservative design to minimize possible instability, and James Tuck brought the critical idea of explosive lenses for detonation wave shaping.  Tuck’s method for producing a super-critical mass of plutonium for a nuclear explosion was to fashion a sub-critical mass of Pu-239 in a spherical shape and then set off high explosives to drive it inward.  He proposed a spherical shell of high-explosive material made up of fitting pieces called “lenses” to focus the explosion inward.  The lenses were wired with detonators in order to set them off simultaneously.  Using the spherical arrangement with lenses produces enough force to increase the density of the sphere of plutonium to the point where it is supercritical [4].  The term supercritical means that more neutrons are produced than lost (the neutron population increases) in a nuclear reaction.  This condition occurs when

                                                                        k > 1,                                                                     [5]

where k is the multiplication factor (net number of neutrons per initial neutron).  The multiplication factor, k, is determined from the four factor formula which is the product of the reproduction factor, h, the thermal utilization factor, ¦, the fast fission factor, e, the resonance escape probability,Ã, and the non-leakage probabilities, L.     

Why did the Germans fail at building a nuclear bomb? [6]

 

Since the German’s discovered uranium fission in 1939, Nazi Germany had a three-year head start in the research of an atomic bomb.  In the spring of 1940, a large part of the Kaiser Wilhelm Institute in Berlin had been set aside for uranium research.  By 1941, Nazi Germany was leading the race for the atomic bomb.  They had a heavy-water plant, high-grade uranium compounds, a nearly complete cyclotron, capable scientists and engineers, and the greatest chemical engineering industry in the world.  With all these factors in the German’s favor, how did the German’s nuclear program fail?  There are many theories to this question.  Factors include internal struggles, a major scientific error (or maybe not an error), and the devastation of total war compromised any successful research.  Unlike the American program, the Germans never had a clear mission under continuously unified leadership.  MORE

References

 

[1]  Reinhardt, Joachim.  Pictures of Famous Physicists.  http://www.th.physik.uni-frankfurt.de/~jr/portraits.html.  April 4, 2002.

[2]  Atomic Weapons Establishment (AWE).  Frisch-Peierls Memorandum.  http://www.awe.co.uk/main_site/about_awe/keeping_the_peace/1940.htm.  April 28, 2002.

[3]  Lawrence Livermore National Laboratory.  Figures and Tables.  http://www.llnl.gov/science_on_lasers/01Figure_list2.html.  April 4, 2002.

[4]  Nuclear Weapons.  Hyperphysics.  http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/bomb3.html.  April 4, 2002.

[5]  Holbert, Dr. Keith.  Nuclear Concepts of the 21st Century.  Arizona State University.  Lecture, April 15, 2002.

[6]  Australian National Botanic Gardens.  http://www.anbg.gov.au/images/flags/nation/germany.gif.  April 28, 2002.