Scientific Discoveries⌗

Conservation Laws - 1895⌗

  • Mass, Charge, Energy

X-Rays⌗

  • Discovered in November 1895
  • Discovered by Wilhelm Röntgen
  • Discovered by setting up another experiment and noticing a fluorscent material glowing when it shouldn’t have been

Radioactivity⌗

  • Discovered in 1896
  • Discovered by Antoine Henri Becquerel
  • Discovered by researching X-Rays and accidentally found radioactivity
    • Tried to see if fluorescing materials would produce x-rays and used radioactive materials instead
  • Marie Curie discovered it was ionizing and based on the amount of elementals uranium/thorium
  • Pierre Curie showed that it carried energy
  • Pierre Curie also discovered that there were 3 types: positive, negative, and neutral

The Electron⌗

  • Discovered in 1897
  • Discovered by J.J. Thompson
  • Observed cathode rays and by using formulas found their mass to charge ratio
    • They had to come from somewhere

Plum Pudding Model⌗

Quantized Light⌗

Special Theory of Relativity⌗

Rutherford’s McGill Radioactivity Discoveries⌗

  • Made by Ernest Rutherford
  • Radioactive things have half-lives
  • \(\alpha\) versus \(\beta\) radiation and named them
  • Showed that \(\gamma\) radiation existed
  • Showed that radioactivity transmuted elements

The Nucleus⌗

  • Discovered in 1911
  • Discovered by Ernest Rutherford
  • Based on experiment done by Hans Geiger and Ernest Marsden
  • Figured out that if alpha particles were coming back at extreme angles it had to have been because of some electrically charged center

Millikan Oil Drop Experiment⌗

Balmer-Rydberg Formula⌗

  • Explained the atomic spectra for Hydrogen
  • \(\frac{1}{\lambda} = R(\frac{1}{n^2_1} - \frac{1}{n^2_2})\)

Bohr’s Atom⌗

Particles can act as waves⌗

Forms of Quantum Mechanics⌗

Complmentarity⌗

  • Made by Niels Bohr
  • Some observables cannot be measured without spoiling the measurement of others

Heisenberg’s Uncertainty Principle⌗

Nuclear Reactions⌗

  • Discovered in 1917
  • Discovered by Ernest Rutherford
  • Found that bombarding nitrogen with an alpha source produced hydrogen (knocking a proton out of nitrogen)

Mass Spectrograph⌗

  • Made by Francis Aston
  • Sending charged atoms through a magnetic fields will bend atoms of different masses by different radii
    • You can determine the mass to charge ratio and from there find mass

The Neutron⌗

  • Discovered by James Chadwick
  • Almost discovered by Frederic Joliot-Curie and Irene Joliot-Curie
    • They thought that they were seeing gamma rays
    • They didn’t think about neutral particles
  • Chadwick showed that shooting beryllium with an alpha source produced in fact a neutral particle

The Cyclotron⌗

  • Invented by Ernest Lawrence
  • Kick a particle a bunch instead of one massive kick

General Theory of Relativity⌗

Positron⌗

Induced Radioactivity⌗

  • Discovered by Irene Joliot-Curie and Frederic Joliot-Curie
  • Were bombarding nuclei with \(\alpha\) particles, and saw neutron and positrons
  • Lise Meitner didn’t see this and they tried to see why by moving it back
  • They realized that the positrons stayed for a bit then faded: they had made a radioactive element

Slower neutrons have bigger cross-sections⌗

  • Enrico Fermi’s group
  • However, they thought they made transuranics when it was actually fission

Liquid Drop Model⌗

  • Made by Niels Bohr
  • Literally guessed it from intuition and prior evidence

Semi-Empirical Mass Formula⌗

Fission⌗

Uranium Slow Neutron Fission⌗

  • Made by Niels Bohr
  • U235 needs less energy to undergo fission because it becomes an even mass

Possibility of Chain Reactions⌗

First Reactor⌗

  • Led by Enrico Fermi
  • Found that there is a chain reaction but not to the level wanted
  • Water absorbed too many neutrons
  • Graphite was found to not have a massive absorption cross section
    • Enrico Fermi wanted to publish this, but Leo Szilard and George Pegram convinced him otherwise
    • This stopped the Germans from finding out that graphite would work, because they had found it wouldn’t
    • It forced them to use heavy water which we could much more easily control
  • He introduced a variable \(k\)
    • This was the average number of chainable neutrons if the system was infintely big
    • No matter what he did with the first reactor, he only got \(k=0.87\)
  • Leo Szilard’s main contribution was to negotiate for and find hig quality materials

Critical Mass⌗

  • Smallest mass that will undergo a chain reaction
  • You need a mass such that particles won’t escape before they can react to often
  • Therefore you want its size to be around the Mean Free Path
  • The big issue with U238 bombs is that its size and that its so slow that it’ll fizzle

Mean Free Path⌗

  • How far a particle moves before it interacts with something

Plutonium⌗

  • Theorized by Louis Turner
  • Say \(U^{238}\) captures a neutron and becomes \(U^{239}\), then it would beata decay into \(N^{239}\), and then beta decay into \(Pu^{239}\), which since it’s a more stable odd nucleus would be as fissionable as \(U^{235}\)
  • Edwin McMillan and Phil Abelson found indirect evidence but couldn’t isolate it
  • In 1949, Glenn Seaborg and Emilio Segre isolated a tiny bit
  • Plutonium is much easier to separate to make a bomb
    • However, it couldn’t be used in a gun-type design because it would detonate before the two masses could completely join
    • It was found to have a 1.7 times greater fission cross section than \(U^{235}\)

Frisch-Peirels Memoranda⌗

  • Otto Frisch and Rudolf Peirels wrote a memo describing just how possible it would be make a bomb and estimate of its power, along with the first estimate of the critical mass

Isotope Separation⌗

  • Otto Frisch was one of the earliest thinkers about this
    • He was thinking about thermal diffusion
    • That didn’t work, but then he considered barrier diffusion, which ended up being used

Gaseous Diffusion⌗

  • Operates on the basic idea that temperature determines kinetic energy and different masses with the same KE have different velocities
  • It only works for gases and Uranium is not urually a gas
  • They had to uranium hexafluoride which is very corrosive and needed a barrier with multiple little holes that wouldn’t be corroded
  • Plus, uranium is so massive, the mass different is very, very small so you need a lot of stages to do proper separation
    • You need a lot of stages
  • They started building without knowing what they were going to use for the barrier

Electromagnetic Separation⌗

  • Use a mass spectrometer type thing and put them through a magnetic field, and they will have different arcs
  • They were called calutrons
  • They were put into configurations called racetracks and they needed a lot of conductors so they got 13,000 tons of silver from Fort Knox
  • Faced a lot of delays

Moderator Importance⌗

  • The better the moderator, the more the fission cross section can be increased
  • The moderator works by elastically scattering the neutrons

Self-sustaining Reactors⌗

  • Enrico Fermi led reactor work
  • They had reacted \(k=0.995\) before May 1942 and wanted to build a self-sustaining one next
  • They got \(k=1.05\), which is good but not self-sustaining
    • They had to find more pure materials
    • Du Pont was hired to build reactors for $1 (yes, really)
  • They needed to control the reactors to stop a runaway reactors (which wouldn’t explode but release a ton of very bad material)
  • Karl Compton decided to just send it even if it ran away without other authority (who would’ve definely said no)
  • They used control rods to control reactions: stick absorbing rod into material to stop the reaction
    • A big thing that kept neutrons under control was that about 1% of neutrons are delayed a bit because they come from beta decay of fission product on the time scale of second, so if \(k\) is just above 1, only these fissions keep growth going at, and because they’re slow we can actually control the reaction
    • They had horizontal (precise, rate-determining rods) and vertical (backup, safety) rods, which were both electronically and manually controlled
  • They got it on December 2, 1942
    • A finite \(k=1.006\)
    • Only a small amount of power and not run for much more than 5 minutes (4.5 about), but vastly important

Atomic Bomb Triggers⌗

Gun Type⌗

  • They realized they didn’t need a good, stable gun: it was only going to be used once
  • In addition, it didn’t even need to impact, just pass through
  • But it wouldn’t work for plutonium: the gun would need to shoot the bullet very fast, faster than possible then
    • In addition, \(Pu^{240}\) had a very high spontaenous fission rate and would cause fizzle
    • This turned much focus for Plutonium bombs to an Implosion design

Implosion⌗

  • Seth Neddermeyer proposed this idea
  • It was hard and people were pessimistic but it was followed and investigated despite being treated like a bit of a joke
  • John von Neumann was incredibly useful for this and developed a lot the math along with knowing how to focus on the shock wave for spherical compression
    • In addition, along with Edward Teller, they realized you could compress a material into a critical mass by increasing its density
  • George Kistiakowsky was brought in to help because Seth was having trouble with spherical compression
  • They needed hydrodynamic but you can’t solve the equations directly, they need to repeated mechanical computation, which Richard Feynman helped with
    • To help with this, they used shaped charges to direct the shock wave
  • Edward Teller was not helping and so he was replaced with Rudolf Peirels
    • Teller was allowed to work for a super and would meet with Robert Oppenheimer for one hour a week
  • Since the reactor irraddiated materials with a lot of neutrons, there was more Pu240 than expected an so implosion was required
  • At the end of 1944, bomb ideas were still crude but they developed multiple technologies to fix them
    • Initiator ideas were more complex

Plutonium Production⌗

  • They didn’t want to build them in Dogpath where the Isotope Separation plants were being held, in case something went wrong
  • They built them in Hanford
  • Since the reactors had a k a decent bit higher than 1, Eugene Wigner realized you could use water for cooling and still have a proper reaction
  • Eugene Wigner designed the base reactor
    • Uranium is in slugs (tubes) and after being irradiated to become enough Pu, they were pushed into water and could sit until radioactivity decreased to proper level
  • Phil Abelson was working with the Navy and realized that he could use thermal diffusion, which isn’t efficient, to slightly enrich uranium which then could be used by calutrons to improve their efficiency a lot
  • The Hanford reactors went online and worked but then strangely died and then came back after a period of time
    • This was found to be due to neutron absorbing decacy product that would poison the reaction before it decayed away
    • Fixed by adding more uranium slugs to increase \(k\)
    • Thankfully this was possible due to John Wheeler who insisted on extra just in case of this exact situation
    • Most uranium came from the calutraons in dogpatch
  • To separate the plutonium required massive, complete remote plans
    • They were dubbed Queen Marys

Tickling the Dragon⌗

  • Otto Frisch assembled nearly critical masses and had to measure the \(k\) for these, it almost ended in disaster

Scientists⌗

Wilhelm Röntgen⌗

Antoine Henri Becquerel⌗

Marie Curie⌗

  • Born Maria Skłodowska
  • Was a strong nationalist
  • Had to hold off education for a while for money’s sake

Pierre Curie⌗

Ernest Rutherford⌗

  • Became director of Cavendish where he trained many, many generations of physicists

J.J. Thompson⌗

Max Planck⌗

Albert Einstein⌗

  • Annus Mirablis
    • Brownian Motion
    • Light Quantum
    • Wave particle duality
    • Special Theory

Hans Geiger⌗

Ernest Marsden⌗

Robert Millikan⌗

Niels Bohr⌗

Otto Hahn⌗

Lise Meitner⌗

Henry Moseley⌗

Chaim Weizmann⌗

  • Developed industrial fermentation for acetone for cordite

Fritz Haber⌗

  • Developed ammonia synthesis and made multiple poison gases

George De Hevesy⌗

John von Neumann⌗

Eugene Wigner⌗

Edward Teller⌗

Werner Heisenberg⌗

Louis de Broglie⌗

Erwin Schrödinger⌗

Paul Dirac⌗

Robert Oppenheimer⌗

  • Was sickly but smart as a kid
  • did well in harvard
  • Struggled a bit until he turned to theoretical physics with Max Born
    • They did a lot
  • Trained the first generation of American theorists in the quantum age

Francis Aston⌗

Frederic Joliot-Curie⌗

Irene Joliot-Curie⌗

James Chadwick⌗

Ernest Lawrence⌗

Frederick Lindemann⌗

Hans Bethe⌗

Otto Frisch⌗

Carl Anderson⌗

Enrico Fermi⌗

Carl von Weizsäcker⌗

Fritz Strassman⌗

Max von Laue⌗

Dirk Coster⌗

Louis Alvarez⌗

I.I. Rabi⌗

Leo Szilard⌗

Vannevar Bush⌗

Alexander Sachs⌗

Lymann Briggs⌗

James Conant⌗

  • Harvard President

Karl Compton⌗

  • MIT President

Edward Tolman⌗

  • Caltech physicist

Arthur Holly Compton⌗

George Pegram⌗

Louis Turner⌗

Phil Abelson⌗

Edwin McMillan⌗

Glenn Seaborg⌗

Emilio Segre⌗

Rudolf Peirels⌗

Mark Oliphant⌗

George Kistiakowsky⌗

Fritz Houterman⌗

Gregory Breit⌗

Richard Feynman⌗

Seth Neddermeyer⌗

Klaus Fuchs⌗

Stanislaw Ulam⌗

John Wheeler⌗

Samuel Goudsmit⌗

Bureaucrats and Military⌗

FDR⌗

Henry Wallace⌗

Henry Stimson⌗

George Marshall⌗

Albert Speer⌗

Leslie Groves⌗

Felix Frankfurter⌗

Winston Churchill⌗

Paul Tibbets⌗

  • Head of training B-29s to drop the bomb

Boris Pash⌗

Harry Truman⌗

James Byrnes⌗

Spies⌗

Haakon Chevalier⌗

David Greenglass⌗

Theodore Hall⌗

Oscar Seborer⌗

George Koval⌗

History⌗

Circa 1895⌗

  • Was really a modern world compared to the times, but still behind
  • Lots of imperialism
  • Very nationalistic tendencies
  • Very racial viewpoints as well
  • Lots of industrialization
  • Scientists were really just gentlemen who could afford to do it, but this changed

Origin of WWI⌗

  • Gavrilo Princip murdered the Austrian Archduke
  • Austria blamed Serbia
  • Russia supported Serbia
  • Germany supported Austria
  • France had a treaty with Russia
  • England agreeed to help France

WWI⌗

  • France attacked west Germany
  • Germany attacked France through Belgium
  • Russia attacked east Germany
  • After a fluid period, it stalled
  • US was staying out of it, but was going to join
    • Germany sent the Zimmerman telegram to stop that, but ended up causing it
  • Henry Moseley was killed in the Galli

Ending of WWI⌗

  • Europe was kinda screwed
  • Germany and Russia had basically collapsed
  • Austro-Hungarian and Ottoman empires entirely collapsed

The Dual Monarchy⌗

  • Hungary got more independence and immediately flourished
  • But after WWI, communicst revolutions changed the country and were taken over by nationalist and fascist goverments
    • This drove out jewish peoples

After WWI⌗

  • Communists took over Russia
  • Bela Kun staged a revolution of Hungary
    • Immediately turned into a basically fascist government
  • Germany
    • Much more of a racial component
    • Economic turmoil + great depression
    • Nazis slowly took over
    • Immediately started discriminating against Jewish peoples
    • Germany had been where everyone went to do science
      • People didn;t think it could go that bad
    • When Germany banned Jewish peoples from holding state positions, many scientists left
      • Even if they weren’t Jewish, they left because of what they saw and for other opportunities

Before WWII⌗

  • Italy invaded Ethiopia
  • Spain became fascist
  • Germany started expanding
    • They absorbed Austria
    • Wanted the Sudeten Germans (next to Czechoslovakia)
      • Told them to demand stupid things from the Czechs to declare war, but the Czechs aggred because of pressure from the French and British
      • This stopped Hitler for a bit
    • Hitler got it because the western europeans really didn’t want a fight
  • Kristallnact happened where the state organized a riot to attack Jewish peoples
  • Molotov-Ribbentrop Pact in 1939 said that Germany and Soviet Union would come to each others aid if someone else were to attack either of them

Fission Secrecy⌗

WWII⌗

  • Germany declared war on Poland on 9/1/1939, causing the Soviet Union join in and England and France to counter
  • Phony War ends after stalling when Germany invades Norway and Denmark
  • France got invaded from Belgium
  • Germans tried to take down Britain from the air but they couldn’t do it
  • US had not entered war in early 1941, Germany was stopped by Britain but was kinda dominating elsewhere
  • But towards Fall 1941, they overexerted themselves a bit in the Soviet Union and got stopped in Leningrad
    • They were still dominant
  • In December of 1941, the Japanese attacked Pearl Harbor
    • Because the US declared war on Japan, the Germans declared war on the US (even though they didn’t have), which focused our efforts on them
  • In Dec 1941, the Germans had been badly beat out of the Soviet Union and stopped from reaching Moscow
  • Japan had dominated in the Pacific, but started to lose power as 1942 progressed against the US
  • The Germans started to eradicate jewish peoples
  • They tried to push into the South part of the Soviet Union, but lost massively
  • The Allies had started strategic bombing raids that were bery big
    • Attacking cities had become acceptable
  • The Allies were worried about German heavy water production though a Norwegian plant (one of the only ones in the world)
    • Norwegian Commandos took down a year of production’s worth of heavy water
  • In November 1943, we bombed the Norwegian plant at vemork again to stop their heavy water production
    • While it wasn’t destroyed fully, it was severely damaged
    • The Germans decided to move it Germany
    • Norwegian commandos managed to take it out as it was being transported across a lake
  • By 1944, the war was in the Allies favor
    • The Russians were moving west after Stalingrad and had stopped the siege at Leningrad after 900 days
    • Allies stoped the North African campaign and were fighting in Southern Europe
    • The US was also making significant progress against the very ferocious Japanese
  • By 1945, the axis powers were in disaster more
    • The Russians were moving into Germany
    • The Allies had pushed fast through France and entered Germany
    • Much of Germany was destroyed where the allies passed through and the army was spent
    • Japan was pushed back in the pacific
    • Strategic bombing was used extensely, especially with incendiary weapons, in Germany and Japan
  • A team called Alsos headed by Boris Pash and Samuel Goudsmit for science
    • Samuel Goudsmit was chosen mainly because he knew nothing about the Manhattan Project and couldn’t divulge secrets if captured
    • They got most the uranium, an unfinished reactor, the leading scientists
  • Germany surrenders in May 1945, but the scientists keep working
  • By mid 1945, the US had made a lot of headway into the Pacific
    • Japan had lost the war but refused to surrender
      • Sense of Honor
      • Unconditional surrender
      • But they were contemplating it, and talking to the Soviets
  • At the Yalta Conference, the US managed to get Russia to agree to enter the war against Japan 30 days after Germany surrended, but this turned out to be more of a curse than anything because they wouldn’t leave places they occupied
  • Henry Stimson and Leslie Groves briefed Harry Truman in mid 1945 about the bomb
    • They established the Interim Comittee to talk about the use of the bomb after the war
    • James Byrnes dominated this comittee and made many decisions
    • They recommeded directly military use
      • Japan wouldn’t surrender otherwise
      • Need to end the war before Russia moves in
      • Gotta justify money spent on bomb project
    • Byrnes also got ther committee to hold off on telling Russia until after a test
    • Leo Szilard tried to change their decision by talking to Harry Truman through his political connections but was shut down by James Byrnes
  • The only other such attempt was the Franck Report
    • Published by leading scientists working on the project explaining why it wouldn’t be secret for long and demonstrating with Japan watching was the best idea
  • The Target Committee was formed to answer specific technical questions about detonation and planning
    • They needed a good target that wasn’t completely destroyed
      • Hiroshima, Kyoto, Yokohame, Kokura Arsenal, Nagasaki
      • They convinced the air force to spare these
      • People were conflicted about Kyoto because of its importance and it was eventually remove
  • Implosion tests was to be done at Alamogordo before Potsdam so Harry Truman could slip a vague comment to Stalin
    • We tested .1kT of explosive just for equipment
    • Bomb nearly didn’t fit together because of thermal expansion
    • Also a copy meant to test everything else was done and implied the real one wouldn’t work
      • The shockwave wasn’t spherical
      • George Kistiakowsky was getting absolutely destroyed for this
      • Hans Bethe proved the results actually meant nothing and that they had no clue what would happen

Pre Manhattan Project Research⌗

  • The Uranium Advisory Committee recommended a bit but not a lot of graphite and uranium, but FDR never acted upon it quickly
    • UAC slow and not too progressive
  • Vannevar Bush didn’t like this and so started the National Defense Research Council
  • James Conant talked with Frederick Lindemann to start the US and British Bomb Effort collaboration
  • Ernest Lawrence tried to push harder for a bomb through unoffical means, but Vannevar Bush asserted his leadership and control
    • He asked the National Academy of Science to form a committee chaired by Arthur Holly Compton
      • They were conservative and said at the earliest, bombs would be available by 1945
    • They were asked to do another one with some engineering input
      1. Still cautious
  • After Mark Oliphant pushed Ernest Lawrence who in turn pushed James Conant and Karl Compton, Compton called for another NAS study with George Kistiakowsky and who convinced James Conant to push for the bomb
  • In Dec 1941, The S-1 Program was setup to deal with nuclear weapons research
  • People were scattered and no one wanted to move, so they argued
    • Karl Compton basically ordered everyone to come to Chicago: The Metallurgical lab (Met lab)
      • The second reactor at Columbia achieved a \(k=0.94\), better than the earlier \(k=0.87\)
      • The Chicago reactor was under the footbal field (in a squash court)
  • We decided to go the try all methods approach to solve Isotope Separation
    • Plutonium was much easier to separate but still not easy, and Glenn Seaborg was picked to lead it
      • The all routes method was used for this too
  • Gregory Breit was picked to lead fast neutron studies, but due his difficult personality and his security concerns about Enrico Fermi, he resigned, and Robert Oppenheimer was picked instead
  • We decided to use He to cool reactors
  • To run things, Vannevar Bush proposed to FDR that the Office for Scientific Research and Development (OSRD) and Army Corps of Engineers split it instead of giving the Army full control
  • Robert Oppenheimer scheduled a summer conference with Hans Bethe, Edward Teller and others to talk about bomb building physics, although they got distracted with a fusion bomb, primarily due to Teller
    • They did get concerned on whether a fission bomb would cause the nitrogen in the atmosphere to go off, which Hans Bethe proved would not happen
  • The S-1 committee concluded in 1942, that the bomb would be incredibly important to winning the war
  • The scientists were unhappy with the army’s contracted engineers quality of work

Manhattan Project Research⌗

  • The Manhattan Engineering District was setup in June 192 in Manhattan
    • It was there so it could be close to other things
  • The split of authority was problematic so overall responsiblity went to the army
    • Colonel Leslie Groves was picked to lead it (he wasn’t entirely happy because he wanted to fight)
    • His first meeting with the War Production Board basically involved him bullying them into getting first priority for all material (also Vannevar Bush and Henry Stimson’s influence pulled it off)
  • Chicago needed to be done outside of a city, so Karl Compton decided upon a new lab in the nearby Argonne Forest
  • Security was becoming more and more stringent and important
  • Leslie Groves wanted a new site for the project
    • He met Robert Oppenheimer and wanted to make him its’ lead
    • He was a good choice in some ways but not really in others: mainly his left-wing ties
    • Also, everyone else who was good was busy or not american
    • In addition, he thought Oppie was a legendary leader
  • They found and purchased Los Alamos
    • It was isolated and beautiful
    • But also in the middle of no where and a desert-type area is not something many were used to
  • He recruited many important people like Hans Bethe and Edward Teller but not I.I. Rabi, who was ethically opposed and focused on radar
    • They were initially going to commision them as officers but that was opposed
  • Leslie Groves felt that Leo Szilard was a hindrance and tried to have him booted but Karl Compton talked him out of it and Leo Szilard used his patents to remain in it
  • Oak Ridges was there uranium separation was to happen near Knoxville
    • It was isolated but more non-technical
    • Two methods would be used: Electromagnetic separation and gaseous diffusion
  • At one point, they considered a radioactive attack usin Sr90
    • This was partly because they suspected the Germans were going to do it
  • When the British Bomb Effort merged in, they brought Niels Bohr who showed a design of a german reactor he had obtained and showed that they were behind, or at least seemed to be so
  • Niels Bohr was a consultant and helped with some of the technical aspects but most importantly started getting people to think about the meanings of the weapon and Bohr helped them come to accept it morally
    • He pushed to get political leaders to consider this
    • He got a meeting with Felix Frankfurter, the supreme court justice
      • Felix already knew about some project he called “X”
      • Felix set him up with FDR
      • He then got authorization to talk to the British people about it
        • Winston Churchill didn’t want to meet with him
        • He eventually did and absolutely shut Bohr down
      • Felix asked for a memo from Bohr about this before he was to meet FDR
        • He argued that it wasn’t a regular situation and secrecy wouldn’t work
      • Winston Churchill met with FDR later and talked him out of this entirely and blamed Bohr along with accusing his character
      • They were also considering whether and how to tell the USSR
  • The Army was bringing in Special Engineering Detachments (SEDs) who helped technical staff, although this brought in quite a few spies
  • Hans Bethe was appointed over Edward Teller for head of the theory division
    • Teller really didn’t like this and Bethe made sense
    • He did praise Robert Oppenheimer despite having made the decision
  • Emilio Segre measured the spontaenous fission rate of Pu and found that it was higher in Los Alamos due to its altitude but that could be shielded out

British Bomb Effort⌗

  • Pushing by Rudolf Peirels and Otto Frisch, who were enemy aliens
  • This created the MAUD committee
    • They started a lot before the US
    • MAUD estimates the bomb yield at 1.8kT
    • Concluded that bomb will probably be decisive, we really need to follow its production, get the americans involved
  • Britain still had issues because they wanted to build in Britain despite the bombing risks
  • Mark Oliphant went to the US for radar research and heavily pushed multiple people on the bomb
  • Towards the end of 1942, the British project merged with Manhattan Project Research and consequently many scientists were given British citizenship (like Otto Frisch)

German Bomb Effort⌗

  • In 1941, they were still pretty behind because not knowing about Plutonium, Isotope Separation, and Moderator Importance
    • This is liekly because they lost scientific talent and the difficulty about chasing something uncertain both for personal safety reasons and ethical reasons (not doing as best as you could)
    • However one person: Fritz Houterman sabotaged the project by not talking about plutonium research he did with the other German Scientists
  • After the war some of the top scientists were captured and taken to Farm Hall in Britain where they were isolated and bugged
    • From their conversation, we find out their research was very primitve and they never really got close to a bomb
    • In addition, they weren’t enthusiastic about building a bomb either
  • Late 1941 led the atomic bomb research to be deemphasized if it wasn’t going to be directly useful
    • Scientists like Werner Heisenberg tried to set up a meeting to avoid this, but a secretary sent out the wrong schedule and no one came
  • When Albert Speer heard about bomb research in Spring 1942, he thought it was important and schedueld meetings
    • Werner Heisenberg gave noncommital answers about time and other excuses
    • The really issue is when he only requested some hundred thousands of dollars and Speer was uninmpressed
    • Reactor work would not continue but not bombs

Dropping the Bombs⌗

  • In mid 1945, the uranium bomb was being shipped to Tinian on the USS Indianapolis
  • Paul Tibbets would pilot the B-29 himself
  • The bombs would be triggered by a radar system and a back up barometer
  • First was dropped on Hiroshima
    • It had women and children which was not significantly in the US’s policy
    • Overall reaction was positive in the US, others were ambivalent
  • Japan still didn’t surrender
    • The US launched a propaganda campaign to drop leaflefts pushing the citizens of Japan to ask for surrender or else more bombs
      • These weren’t ready in time for Nagasaki
    • This was partly due to Japan’s military elite not wanting unconditional surrender
  • USSR wanted to speed up its entry into the war
    • The US got worried and wanted to drop another bomb as quickly as possible
    • Was going to be dropped on the 11th, got pushed to 10th, and because of bad weather then, expedited to the 9th
      • A young Ensign, Bernard O’Keefe, used a soldering iron in an explosives to room that night while he was babysitting to fix a cable mismatch without approval because he wanted the war to end and for that to happen the bomb had to launch that day
  • Was meant to drop on Kokura Arsenal but due to cloudly weather (they wanted filming and visual hit confirmation) and a reserve fuel tank not working they dropped onto Nagasaki through a hole in the clouds
    • Since it was not dropped at its original aim point, it did less damage because it was dropped in a valley area
  • Japan still did not surrender
    • The Emperor stepped in which he wasn’t really supposed to do
    • He called for surrender to save his people despite his earlier views
    • It was technically not unconditional but it was good enough
    • The US accepted on the terms that Potsdam did say the postwar government of Japan could be however they wanted, and therefore it worked
  • The Japanese nearly didn’t accept as many still didn’t want to surrender
    • The military people staged a coup

Espionage⌗

  • Russia did manage to get into the project
  • Robert Oppenheimer was heavily investigated but innocent
  • His friend, Haakon Chevalier tried to get him to report info
    • He didn’t report it until later and tried to cover for him
  • Soviets first heard about it from Klaus Fuchs in Britain when he was working with MAUD
  • Klaus Fuchs confessed as soon as he was confronted
    • He was sentenced to 14 years (soviets were allies at the time so it was a lighter punishment)
  • David Greenglass was a machinist as an SED
    • His BIL was a soviet spy
    • His BIL got him to spy
  • Theodore Hall was a young phyiscist who spied for the same reasons as Klaus Fuchs
    • Soviets learned about implosion through Hall
    • He was incriminated though VENONA but never charged
  • Oscar Seborer
    • Not much known but was involved
  • George Koval
    • Not much known as well but was bad lucked into Los Alamos
  • The Smyth Report was published to public to inform US citizens about what had been going and explain what was classified and what was not

Aftermath⌗

  • The Atomic Energy Commision was established to oversee the project’s continuation and then later absorbed into the DOE
  • Leo Szilard become involved in warning people about nuclear weapons and the Pugwash conferences
    • He switched to bio later in his life
  • Robert Oppenheimer become a national hero and was politically active
  • Enrico Fermi continued to do tons of top-notch research and governmental work
  • Hans Bethe built up Cornell and more research along with being a prominent governmental figure
  • Werner Heisenberg went back to research and made a few contributions in fields that weren’t super important
  • Glenn Seaborg went to Berkely and become an important chemist and public figure
  • George Kistiakowsky went to Harvard and did more govermental work
  • Richard Feynman went to Cornell and then Caltech where he did revolutionary physics along with being a public figure
  • Leslie Groves had much less power after the AEC was formed and soon got phased out
  • Edward Teller was kicked out of the scientific community but made the H-bomb
  • Ernest Lawrence did a lot of big science and lab leading
  • John von Neumann did much work on math and other theories with leading contributions
  • Eugene Wigner became director of Oak Ridge Natinoal Lab but returned to being a professor

Equations and Constants⌗

  • \(1 eV = 3.829 \times 10^{-23}C = 1.60 \times 10^{-19}J\)
  • Alpha radiation is the emission of a helium nucleus (-4A, -2Z)
  • Beta radiation is the emission of a electron and the turning of a proton into a neutron (+1A)
  • Gamma radiation is a photon
  • Level of Radioactivity (decays per second): \(I(t) = \frac{I_0}{2^{(t/\tau_{1/2})}} =I_0 2^{(-t/\tau_{1/2})}\)
  • Level of Radioactivity (decays per second): \(\frac{ln(2)N_0}{\tau_{1/2}}\)
  • Number of radioactive nuclei: \(N(t) = \frac{N_0}{2^{(t/\tau_{1/2})}} =N_0 2^{(-t/\tau_{1/2})}\)
  • \(1 Bq\) is \(1\) decay per second
  • \(1 Ci\) is \(3.7 \times 10^{10}\) decays per second
  • \(E=hf\)
  • Planck’s Constant: \(h = 6.62 \times 10^{-34} Js\)
  • Mean Free Path: \(l = \frac{1}{n*\sigma_{fission}}\)
  • Critical Mass: \(M_{crit} = \frac{m_U}{n^2\sigma^3_{fission}}\)
  • \(v = \sqrt{\frac{3kT}{m}}\)
  • \(\frac{v_1}{v_2} = \sqrt{\frac{m_2}{m_1}}\)
  • \(f_{n+1} = \frac{(1+g)f_n}{1+gf_n}\)