The Manhattan Project - Personalities and Problems Fromm Institute - - PowerPoint PPT Presentation

The Manhattan Project - Personalities and Problems

Fromm Institute Fall 2020 bebo.white@gmail.com Lecture 2

submitted questions from lecture 1

• 1. While all this nuclear research was happening in Europe, what was happening in the

United States? - Quite a bit, a number of American Nobel Prizes in Physics during this time, e.g., Paul Anderson for the discovery of the positron

• 2. Are any scientists who were part of the Manhattan Project still alive? - I don’t think so
• 3. How big was the atomic test that you worked on? - Project Milk Shake, March 25, 1968 -

~20 kt (Trinity was 22 kt, Hiroshima was ~15 kt)

• 4. How much information about the Manhattan Project is still classified? - ?? I’m reasonably

sure that some of the scientific data and engineering is.

• 5. Will you talk about quarks as being parts of protons and neutrons? - The physics included

in the class is what was known at the time.

“the uranium committee” issued its first report on Nov. 1, 1939

• Recommendations:
• 1. The U.S. should buy a supply of uranium dioxide for R&D
• 2. The U.S. should fund research into uranium isotope separation

(i.e., how to separate U235 from U238 )

• 3. The U.S. should fund Szilárd’s and Fermi’s work at Columbia

University on neutrons and chain reactions NOTE: Alexander Sachs thought that the report was “too academic”

the u.s. should buy uranium dioxide

• Obviously a reaction that the Germans would seize the supply

(Congo and Czechoslovakia) and shut down availability

• 45 tons of uranium dioxide was purchased
• Also purchased was 3.6 tons of graphite - why?

research uranium isotope separation

• It had been established that U235 was the natural occurring isotope

that is fissile (capable of fission) - Niels Bohr

• But, remember that U235 is only ~0.7% of natural uranium
• 1 kg of uranium only has 7 grams of U235
• 1 quart of uranium only has ~1.5 teaspoons of U235
• Since they are the same chemically, the only way to separate them

must be based on their weight

a thought experiment

• You have a giant jar of 1000 jelly beans - all the

same color so they all look the same

• 7 of the 1000 weigh 1% less than the other 993
• I will give you $100 apiece for each of those 7
• You cannot take them out of the jar individually

and weigh them

• What strategy would you use?

harold urey🥈

• American chemist - but had “his fingers in lots of pies”
• Won the 1934 Nobel Prize in Chemistry for the discovery of

deuterium (an isotope of hydrogen)

• Funded by the Uranium Committee to study uranium isotope

separation at Columbia University

• Favored (at first) the “jelly bean jar method of separation” (my

description) using a centrifuge to separate U238 and U235

calutrons in berkeley

• Lawrence (of course) thought that separation was a good

job for cyclotrons

• The “calutron” is a new variation of the familiar mass

spectrometer using a cyclotron

• This is not totally based on weight, but also on the ion’s

magnetic moment

• Also another excuse for Lawrence to get more $ to build

more and bigger machines

• He suggested that he could “crank out U235 by the ton”

szilárd, fermi, fission, chain reactions at columbia

• There were still doubters about
• whether it was possible to do chain reactions at scale
• whether it was possible to control chain reactions without blowing

yourself up

• The biggest problem was neutron moderation

enrico fermi🥈!!

• Italian physicist (later naturalized)
• One of the greatest physicists in history - both a theoretician and an

experimentalist

• Winner of the 1938 Nobel Prize - “demonstrations of the existence of new

radioactive elements produced by neutron irradiation”

• Maybe discovered fission in 1934 (before Hahn and Strassmann) with Segrè (?)
• Emigrated to the U.S. in 1938 because his wife was Jewish
• Major contributions to statistical and quantum mechanics and particle physics
• Some of you may remember The Fermi Paradox from Fraknoi classes - “where

are they?”

neutron moderation (1/2)

• Neutrons from fission travel very fast - ~1/15 of the

speed of light ~12,400 miles/second

• When a neutron traveling at this speed hits a U238

nucleus, one of two things happen

• It bounces off
• It is absorbed - this squelches any possible chain

reaction

• That’s why chain reactions don’t happen in nature

neutron moderation (2/2)

• If fast neutrons can be slowed down, something else happens
• They are less likely to be captured by U238 nuclei and just bounce off
• So they bounce around until they find a U235 nucleus that they can

do business with

• So, how to slow down (moderate) fast neutrons?
• Fermi had actually discovered years before that light nuclei slow down

neutrons

so, szilárd and fermi began to work their way down the periodic table (1/2)

• Hydrogen would be best since it is a single proton but it occasionally

captures neutrons

• Managing a gaseous moderator would hard especially since hydrogen is

explosive (remember the Hindenburg in 1937) - who wants to pump energy into hydrogen?

• Dihydrogen oxide (water) where the hydrogen atoms were Urey’s

deuterium would be great since the atoms already had a neutron - heavy water (11% heavier than normal) - rare (150 ppm) and expensive (more later)

so, szilárd and fermi began to work their way down the periodic table (2/2)

• Helium - does not absorb neutrons (remember alpha particles?) - isn’t

practical (suspending uranium in a tank of helium?)

• Lithium - 3 protons - strong neutron absorber
• Beryllium - 4 protons - not a strong absorber but is very toxic
• Boron - 5 protons - absorbs neutrons like crazy
• Carbon - 6 protons - it captures neutrons at 1% of the rate of

hydrogen

so, carbon it is…

• Szilárd to Fermi - “It seems to me now that there is a good chance

that carbon might be an excellent element to use [as a moderator]. I personally would be in favor of trying a large-scale experiment with a carbon-uranium-oxide mixture if we can get hold of the material.”

• The Uranium Committee gave them the money to do it.
• Hence the purchase of 3.6 tons of graphite.

the international research community was jumping on the uranium, fission bandwagon

• A flurry of journal articles and conference talks
• Edwin McMillan🥈 used the cyclotron in Berkeley
• To create new radioisotopes (transmutation)
• To discover/create (?) the first transuranic element - neptunium
• Won the Nobel Prize in Chemistry (after the war)

digression - discovered or invented?

and the great niels bohr🥈!!

• Danish physicist and philosopher
• Another of the greatest physicists in history
• Developer of the Bohr atomic model and one of the

pioneers of quantum mechanics

• Nobel Prize in Physics in 1922- “for his services in

the investigation of the structure of atoms and of the radiation emanating from them”

• Remember his connection with Otto Frisch?

meanwhile, “across the pond”

the paris group

• Collège de France - included Frédéric Joliot-Curie, Francis Perrin and others
• By February 1939 had verified that a uranium chain reaction might be possible - Perrin coined the

term “critical mass”

• Verified that graphite and heavy water would be good moderators but chose heavy water
• Convinced the French Ministry of Armaments to try and buy all the heavy water possible from the

fertilizer and hydroelectric plant in Vermonk, Norway but were told that Germany had ordered it all; this verified German efforts

• Norway gave the entire stock to France just before the invasion of Norway; France smuggled the

entire stock to England just after the invasion of France

• The Paris Group (except) for Joliot-Curie moved to Cambridge in England and joined research there

serious research moves to england

• The big question (as in the U.S.) was whether fission weapons were do-able

and/or practical

• At the University of Liverpool, James Chadwick’s work was inconclusive
• At Cambridge University, George Paget Thomson and William

Lawrence Bragg (both Nobel Prize winners) wanted the government to buy uranium ore before supplies from the Congo got shut down

• At the University of Birmingham, Mark Oliphant🥈 gave the job to two

refugee scientists - Rudolf Peierls and Otto Frisch🥈

the frisch-peierls memorandum (march 1940)

• Not only is a uranium fission weapon do-able, but it could be much smaller than originally thought
• Key points (Bebo’s summary)
• 1. Such a weapon is irresistible - no material or structure could be expected to survive it;
• 2. The spread of radioactive substances by the wind would cause many more casualties;
• 3. There is no information that suggests the same idea has not occurred to other scientists given all

the theoretical data that has been published;

• 4. It is quite conceivable that Germany is working on a weapon given their stockpiling of resources;
• 5. If Germany acquires a weapon, no shelters in England are sufficient, and no infrastructure is

available for detection of and response to radioactive effects.

the maud committee

• Organized in April 1940 to respond to the Frisch-Peierls memorandum
• Originally called “The Thomson Committee” since it was chaired by George Paget

Thomson

• Coordinated research and policy amongst four English universities
• University of Liverpool - James Chadwick, Otto Frisch, and more
• University of Oxford - Francis Simon (inventor of gaseous diffusion - more later)
• University of Cambridge - William Lawrence Bragg, John Cockroft, the Paris Group,

and more

• University of Birmingham - Rudolf Peierls (and infamously, Klaus Fuchs…)

the “maud” behind the maud committee

The name MAUD adopted as a name for “The Thomson Committee” is not an acronym (“Military Application of Uranium Detonation”). Actually “Maud” is the name of a former governess of Niels Bohr in England. After Germany occupied Denmark in April 1940, Lise Meitner sent a telegram to her old colleague Otto Frisch in England, “Met Niels and Margrethe recently, both well but unhappy about events, please inform Cockcroft and Maud Ray Kent.” When Cockcroft got the message he wrote James Chadwick with the theory that “Maud Ray Kent” was an anagram for “radyum taken” and that the phrase agreed with the information that the Germans were collecting all the radium that they could. Mistakenly thinking that “Maud” was a cryptic reference, the committee called itself the M.A.U.D. [or MAUD] Committee. Not until after the war was Maud Ray (from Kent) identified as Bohr’s governess.

meanwhile back in washington - things get frantic with bureaucrats, scientists, and the military (1/2)

• The Advisory Committee on Uranium met again on April 27, 1940
• Germany began invasions of France, Belgium, Luxembourg, and the Netherlands in May 1940
• “There is no competent organization to handle all aspects [of fission which is] floating about

loose [and] most decidedly cannot be ignored in times like these” - Vannevar Bush, May 15, 1940

• According to Bush’s biographer,
• “As late as 1940, Bush dismissed the idea of an atomic bomb, given that no one had any real

idea of how to build one. But he liked to be in charge, so decided that whatever fission work was being done should be done under his purview.”

• “Bush presented FDR with a single piece of paper containing a plan for coordinating the

country’s military research. Within 15 minutes, the President had approved the plan.”

who was vannevar bush?

• An American electrical engineer, inventor, scientific advisor/administrator/

policymaker/visionary and according to some “one of the great overachievers

• f the 20th century”
• Co-founder of Raytheon and started a trend of “big defense contractors”
• Did significant pioneering work in the design and use of analog computers

which attracted the attention of the U.S. military

• Dean of Engineering at MIT
• President of the Carnegie Institution for Science
• One of his graduate students was Frederick Terman, “The Father of Silicon

Valley”

• “To understand the world of Bill Gates and Bill Clinton, start with

understanding Vannevar Bush” (Michael Sherry, historian)

march 29, 1940 in Berkeley

Lawrence, Arthur Compton, Bush, james Conant, Karl Compton, Alfred Loomis lawrence trying to sell them on a 184-inch cyclotron (the biggest ever)

meanwhile back in washington - things get frantic with bureaucrats, scientists, and the military (2/2)

• June 27, 1940, a National Defense Research Committee (NDRC) was formed

with Bush as Chair - it immediately absorbed and renamed the Advisory Committee on Uranium as the NDRC Committee on Uranium (Briggs remained as Chair)

• The NDRC Committee on Uranium
• Banned publication of research into uranium, fission, and isotope separation
• Forbade membership to foreign-born scientists - Fermi and “The Martians”

were “removed from the policy-making loop”

“There were those who protested that the action of setting up NDRC was an end run, a grab by which a small company of scientists and engineers, acting

• utside established channels, got hold of the

authority and money for the program of developing new weapons. That, in fact, is exactly what it was.”

• Vannevar Bush (1970)

14 december 1940- uranium gets a “partner in crime”

• Chemist Glenn Seaborg, using Lawrence’s cyclotron in Berkeley,

discovers (?) plutonium

another seaborg “claim to fame”

Father of Fromm Professor David Seaborg

why is plutonium special?

• It is generated from U238 which is abundant
• It is highly fissionable
• It decays very slowly
• Since it is a separate element, it can be separated chemically
• Can be produced on an industrial scale
• Discussion of plutonium properties and research quickly went “into

lockdown”

“…Have you ever held plutonium in your hand? Someone once gave me a piece shaped and nickel- plated so alpha particles couldn’t reach the skin. It was the temperature you see, the element producing heat to keep itself warm - not for ten or a hundred years, but thousands of years.”

• Kathleen Flenniken, “A Great Physicist Recalls the Manhattan Project”

the ladenburg note

• On April 15, 1941, Lyman Briggs received a note from Rudolf Ladenburg, a

physicist at Princeton: “It may interest you that a colleague of mine who arrived from Berlin via Lisbon a few days ago, brought the following message: a reliable colleague who is working at a technical research laboratory asked him to let us know that a large number of German physicists are working intensively on the problem of the uranium bomb under direction of [Werner]Heisenberg, that Heisenberg himself tries to delay the work as much as possible, fearing catastrophic results of a success. But, he cannot help fulfilling the orders given to him, and if the problem can be solved, it will be solved probably in the near future. So he gave the advice to us to hurry up if U.S.A. will not come too late.”

who was heisenberg?

• Werner Heisenberg - German theoretical physicist - another one
• f history’s greatest physicists
• Met Niels Bohr in 1922 and they became good friends
• Key pioneer in quantum mechanics - “The Heisenberg

Uncertainty Principle” (1927)

• 1932 Nobel Prize in Physics - “for the creation of quantum

mechanics”

• Edward Teller was one of his doctoral students
• In pop culture: use of the name Heisenberg in “Breaking Bad”

supposedly relays uncertainty

was ladenburg accurate in his note to briggs?

• The Germans were reading and listening, but not talking or publishing much…
• It was assumed that if the Germans were serious about fission then Werner Heisenberg

was involved

• The Germans had actually started a secret fission program Uranverein (“uranium club”)

in April 1939 just months after Hahn and Strassman

• The play Copenhagen speculates on what might have happened at the famous and secret

meeting in September 1941 between Bohr and Heisenberg.

but not just the germans

• In September 1940, Germany, Japan, and Italy signed a defense alliance against the U.S.
• Fermi and Segrè had done vital work in Italy before emigrating
• Russian physicist Georgy Flyorov expressed concerned when publications about fission stopped

and warned that the U.S. and England might be collaborating

• In May 1941, Prof. Tokutaro Hagiwara gave a lecture at the University of Kyoto on chain

reactions with U235

• Was Japan in the race to build a bomb? How far along were they? Was there any collaboration

with the Germans?

• Hagiwara also speculated how a U235 fission chain reaction could be used to initiate a hydrogen

fusion reaction (basis of the H-Bomb), but they had to figure out fission first.

while the british wait for american leadership, power struggles continue in washington

• “If each necessary step requires ten months of deliberation, then obviously it will not be possible to

carry out this development efficiently” - Leo Szilárd to Alexander Sachs

• Bush commissioned an evaluation of the uranium project by the National Academy of Sciences. The

effort was chaired by Arthur Compton and included Ernest Lawrence and others.

• Bush was not satisfied with the NAS report since it focussed on nuclear power rather than weapons, so

he requested a second report - released later, it told him what he wanted to hear.

• On June 28, 1941, the Office of Scientific Research and Development (OSRD) with Bush as director

reporting directly to FDR.

• OSRD absorbed the NDRC, now chaired by James Conant (chemist, President of Harvard)
• The Uranium Committee became The Uranium Section of the OSRD but soon changed its name to

The S-1 Section in order to remove references to Uranium. Lyman Briggs remained the chair.

the maud report was released

• n july 15, 1941
• James Chadwick wrote the forward
• The report had two sections - (1) the feasibility of a U235 bomb and

(2) using fission for power and the production of radioisotopes

• A copy of the report was sent immediately to Lyman Briggs
• As an immediate consequence of the report, England formalized its

atomic bomb program codename “Tube Alloys.”

“I remember the spring of 1941 to this day. I realized that a nuclear bomb was not only possible - it was inevitable. …And I had then to start taking sleeping pills. It was the only remedy, I’ve never stopped since then. It’s 28 years, and I don’t think that I’ve missed a single night in all those 28 years.”

• James Chadwick, 20 April 1969

august 1941 - oliphant trip to the u.s. (1/4)

• Mark Oliphant🥈 (University of Birmingham) was concerned that there had

been no U.S. response to The Maud Report, so he took a dangerous flight to the U.S. to find out why (while pretending to be discussing radar)

• “If Congress knew the true history of the atomic energy project, I have no

doubt that it would create a special medal to be given to meddling foreigners for distinguished services, and Dr. [Mark] Oliphant would be the first to receive one” (Leo Szilárd)

august 1941 - oliphant trip to the u.s. (2/4)

• “I called on Briggs in Washington, only to find out that this inarticulate and unimpressive man had put the reports in his

safe and had not shown them to members of his committee! I was amazed and distressed.”

• Oliphant met with the S-1 Section
• “Oliphant came to a meeting and said ‘bomb’ in no uncertain terms. He told us we must concentrate every effort on

the bomb and said that we had no right to work on power plants or anything but the bomb. The bomb would cost 25 million dollars he said, and Britain didn’t have the money or the manpower, so it was up to us.” (Samuel Allison, S-1 Section member)

• “They [Oliphant and Lawrence] were as alike as two peas in a pod. Oliphant knew a little more physics than Lawrence,

but both were energetic developers, essentially promoters” (James Tuck, physicist)

• On September 21, he visited Lawrence, who he felt might be sympathetic to his concerns. He was given a tour of the

cyclotron facility.

• When they got back to Lawrence’s office. Lawrence telephoned Bush and Conant expressing his support of Oliphant’s
• position. Also in the office…

august 1941 - oliphant trip to the u.s. (3/4)

“When Oliphant and Lawrence returned to Lawrence’s office, they were joined by another UCB professor. Assuming that this professor was privy to the official secrets that he and Lawrence had been discussing, Oliphant continued to talk about the MAUD report, about the optimism that British scientists had expressed concerning the possibility of building an atomic bomb, and about the cooperation between Britain and the States on the research and development of the bomb. Noting that Lawrence had begun to look extremely uncomfortable, and registering the shocked expression on the professor’s face, Oliphant realized that he had just revealed to the professor for the first time the existence of a project to build an atomic bomb. Clearing his throat, the professor suggested to Oliphant that it might be advisable not to continue this conversation, since he was not involved with the project. ‘But that’s terrible,’ replied

• Oliphant. ‘We need you.’” (from Ray Monk)

that professor was j.robert

• ppenheimer (oppie) !

august 1941 - oliphant trip to the u.s. (4/4)

• In summary, Oliphant’s trip to the U.S.
• Kickstarted the U.S. effort in large part by getting Lawrence excited

enough to goad the OSRD (remember that he was a great lobbyist!)

• Cemented a collaboration between the U.S. and British efforts
• Got Oppenheimer on-board (though accidentally)

Szilárd is right about him deserving a medal!

• ctober 9, 1941
• In a meeting with only Bush and VP Henry Wallace:
• FDR committed the U.S. government to an intensified research

project to develop an atomic bomb

• Since the U.S. was still technically a neutral nation in World

War II, Congressional leaders were not informed

• FDR told Bush to figure out the cost and that “he would find

the money”

• Bush gave an update on collaboration with England; the NDRC

had opened a liaison office in London

• FDR indicated that he would write a letter to Winston Churchill

Head of the London Liaison Office with OSRD

Klaus Fuchs certainly did…

gaseous diffusion (1/2)

• Yet another method for separating U235 from U238
• It was devised by Francis Simon and Nicholas Kurti at Oxford University following

the MAUD Report

• “by April of 1940 I was convinced that gas diffusion was the method” - Enrico

Fermi

• Became an interesting topic for collaboration between the U.S. and British efforts

and one where the British scientists led the way

• Harold Urey (being a chemist) became a major advocate in The Uranium

Committee for this method and coordinated the research

gaseous diffusion (2/2)

• The idea is to force a gaseous uranium compound

(UF6) through a semipermeable membrane which lets the molecules containing U235 go through (reverse osmosis)

• The membrane has many tiny holes and the process is

repeated until the desired concentration of U235 molecules is reached

• A major problem is that UF6 is very corrosive
• The whole concept is kind of like (but not quite) home

water filters that remove mercury, chlorine, copper, etc.

….

the enriched streams get higher and higher concentrations

• f the molecules containing U235

In the end separate the metallic uranium from the UF6 chemically

separation problem solved?

• By the summer of 1941, the The Uranium Section of the OSRD (S-1 Section)

was leaning towards gaseous diffusion and centrifuges as the way to go

• Lawrence still didn’t give up on using his cyclotron for electromagnetic

separation because he calculated that the gaseous diffusion method would require 5,000 separation stages to reach desired level of enrichment

• On December 6, 1941, Bush organized an accelerated research project

managed by Arthur Compton with Urey (gaseous diffusion) and Lawrence (electromagnetic separation)

• On the next day, Japan attacked Pearl Harbor and money became no obstacle

so, away we go

• December 11, 1941 - U.S. declares war on Germany
• At the S-1 Section meeting on December 18, 1941
• Lawrence asked for $400,000 (~$7.5 million in 2020 $) for electromagnetic separation (he got it)
• Compton asked for $618,000 (~$11.5 million in 2020 $) for nuclear reactor research (he got it)
• $500,000 (~$9.3 million in 2020 $) was approved for “raw materials”
• Bush proposed a schedule
• A controlled nuclear chain reaction by July 1942
• An atomic bomb by January 1945
• January 19, 1942 - FDR gives the final go-ahead - 2 years, 5 months, and 18 days after the Einstein letter

the s-1 section takes action

• March 9, 1942 - meeting attended by Brig. Gen. Wilhelm Styer head of

the U.S. Army Services of Supply

• OSRD contracts were due to expire at the end of June and with the

country now at war, competition for raw materials was fierce

• It was agreed that the U.S. Army would fund $53 million of the $85

million program; the U.S. Navy was not involved

• June 18, 1942 - Col. James C. Marshall was ordered to organize the

Army involvement

• Col. Marshall established his district headquarters on the 18th floor
• f 270 Broadway (the Arthur Levitt State Office Building) in New

York City

• For secrecy and consistent with the policy of naming engineering

districts after the city in which their headquarters are located, the

• ffice was named The Manhattan Engineer District (MED)

This is now a mixed-use building of offices, rental apartments and very expensive condos with no historical marker that I am aware of…

who is this guy and why isn’t he smiling?

Hint: Paul Newman played him in a movie