History of Nuclear Physics and Glossary

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Anti-Ballistic Missile or National Missile Defense (ABM or NMD)
A system with the ability to destroy enemy missiles or their warheads before they hit their targets. This is usually presented as a “defensive” capability, but it is worth noting that this is a counterforce capability
A particle of matter indivisible by chemical means. It is the fundamental building block of elements.
Canadian heavy-water-moderated pressure tube natural uranium reactor. The name is made up of: “CAN” for Canada, “D” for the technical term deuterium oxide i.e. heavy water, and “U” for the uranium fuel.
Counterforce Targeting
A targeting doctrine designed to destroy the enemy’s nuclear forces. The objective is to limit the enemy’s ability to harm your population. The danger is that this may undermine deterrence. It is usually correlated to NUTS
Countervalue Targeting
A targeting doctrine which is focused on destroying those things you assume your adversary values the most. These usually include population, economic, and cultural centers. It is correlated to MAD and has the goal of making nuclear war “unthinkable.”
Critical Mass
The minimum amount of fissile material needed to achieve a chain fission reaction. It takes less plutonium that uranium to achieve critical mass. The IAEA calls 25 kg of HEU and 8 kg of plutonium “significant quantities.” Unclassified U.S. government documents indicate that as little as 4 kg of plutonium could produce a bomb. Non-government sources claim that a sophisticated design could produce a 1 kiloton bomb with as little as 1-2 kg of plutonium and 8-10 kg of uranium.
The ability to create fear in the minds of potential adversaries that will prevent them from attacking. The objective is to deter.
Dirty Bomb
One type of a radiological dispersal device (RDD) that combines conventional explosives, such as dynamite, with radioactive material. Weapon of Mass Disruption.
Highly Enriched Uranium (HEU)
Uranium that is 20% U235 or higher. This is the level the IAEA (International Atomic Energy Agency) has set for requiring monitoring. This level was selected because the amount of time and energy needed to go from 20% to levels practical for constructing weapons is far less than that required to get to 20%. It is theoretically possible to build a crude, inefficient weapon with 20% enriched uranium.
First Strike Capability
The belief that a nation has the ability to launch a nuclear attack and disarm an adversary so quickly and so completely that the adversary’s retaliation would be so limited as to be acceptable to the attacker. Deterrence was no longer in effect. Generally correlated to counterforce targeting.
Nucleus of an atom splits into two or more smaller nuclei. This results in the release of massive amounts of energy in both thermal and non-thermal forms. It also produces so-called “fission products.” These may include neutrons and the nuclei of other elements – some of which occur almost solely as a result of fission. The most common fission associated with nuclear weapons and nuclear power involves the collision of uranium-235 and plutonium-239 with neutrons.
Flexible Response
A strategy or doctrine whereby a nation plans to respond to an attack with a level of response appropriate to the level of that attack. This has usually assumed that nuclear weapons might be one of the defender’s options.
The formation of a heavy nucleus from lighter nuclei, thereby releasing energy – the binding energy. A deuterium-tritium reaction is the easiest to realize among all possible fusion reactions. Deuterium is available in sufficient quantity in the oceans of the world, while tritium can be “bred” from the element lithium, which is also available in abundance. This requires neutrons and the heat generated during a fission reaction.
Hydrogen Bomb
The nuclear weapon that uses the energy released by nuclear fusion reaction. An atomic (fission) bomb is used to fire the hydrogen bomb, i.e. to reach the temperature required for fusion. The explosive force of a hydrogen or “thermonuclear” bomb far surpasses that of atomic bombs. The destruction potential can be the equivalent of several megatons of TNT. The first hydrogen bomb was detonated on the Bikini Atoll on 1 March 1954.
International Atomic Energy Agency
Agency created in 1954 within the United Nations to create and apply international safeguards consistent with promoting the peaceful uses of atomic energy, while simultaneously preventing new nations from making nuclear weapons. The IAEA has issued internationally agreed radiation protection standards based on the recommendations of the International Commission on Radiological Protection (ICRP). It monitors nations as regards their compliance with the Non-Proliferation Treaty.
Intercontinental Ballistic Missile (ICBM)
This is a ballistic missile with a range of at least 3,400 miles. These are typically based in underground silos and may carry single or multiple warheads.
Multiple Re-entry Vehicles and Multiple Independently Targetable Re-entry Vehicles (MRV and MIRV)
The former are multple warheads on a single missile launch vehicle which can hit multiple targets in close proximity to one another. The latter type has the ability to hit targets that are farther apart and which require independent targeting guidance.
Mutual Assured Destruction (MAD)
A nuclear strategy or doctrine based on the premise that the best way to avoid nuclear war is to guarantee that both sides have the ability to destroy the other. It also assumes that the only use for nuclear weapons is to deter their use by making nuclear war “unthinkable”
Non Proliferation Treaty (NPT)
An international treaty ratified in 1970 in which signatory nations agreed to submit to international safeguards (administered by the IAEA) to prevent the spread of nuclear weapons.
Nuclear Utilization Targeting Selection (NUTS)
A nuclear strategy or doctrine that rejects MAD as simplistic and maintains that nuclear weapons have military utility beyond simple deterrence. NUTS can encompass a variety of assumptions and strategies ranging from pre-emptive nuclear strikes to extended deterrence and flexible response
Second Strike Capability
The belief that a nation has the retaliatory ability to inflict unacceptable damage on a potential adversary even under a “worst case scenario” first strike. This is the foundation of MAD.
Strategic Bomber
Manned aircraft designed to deliver nuclear weapons. These are long range bombers that can fly thousands of miles. They can extend their range even farther by air-to-air refueling. They may be armed with gravity bombs and air to ground missiles.
Submarine Launched Ballistic Missile
This ballistic missile which can be launched from a submerged submarine. Current variants have ranges in excess of 4,000 miles. Like ICBMs, they may carry single or multiple warheads.
The intentional and calculated use of terror to achieve political objectives.
The development and deployment of three types of delivery systems for strategic nuclear weapons – manned bombers, ICBMs, and SLBMs. This assures redundancy and increased credibility as all three systems possess complementary capabilities.
Electromagnetic Isotope Separation
Using a mass spectrometer, a stream of charged particles are sent through a magnetic field. Lighter Isotopes (U-235) are deflected more by the magnetic field, thus separating the U-235 and U-238. US stopped using the method in the 1950’s. Iraq used it in the 1980s.
Gaseous Diffusion
Uranium hexafluoride is forced through a porous barrier. Different qualities of isotopes are separated as they pass through gaps of various sizes. Primary method after WWII through the Cold War. 1/3 of all enriched uranium was processed this way.
Gas Centrifuge
Uranium hexafluoride is swirled in a cylinder at a very high speed. Weight differences separate the isotopes. Gas centrifuge techniques produce about 54% of enriched uranium.
Zippe Centrifuge
Improvement on the Gas Centrifuge. Uses heat in addition to the centrifuge method. Forces U235 up the cylinder where it is collected. Apparently used by Pakistan.
Laser Separation
Promises lower energy inputs, lower capital costs, and lower tails assays. If practical, there will be significant economic advantages. Currently in development. Iran and South Korea seem to be working on this process.
Aerodynamic Enrichment Process
Diffusion driven by pressure gradients. Many regard it as a form of non-rotating centrifuge. South Africa appears to have used this method.
Chemical Processes
Been done in France but not commercially. Exploits a slight difference in the two uranium isotopes to change valence in oxidation/reduction.
Plasma Separation Process (PSP)
Uses superconducting magnets and plasma physics. Ion cyclotron resonance is used to selectively energize the U235 isotopes in plasma containing a mix of ions.
1985 (History of Nuclear Physics)
Wilhelm Roentgen (German) discovered X-Rays
1897 (History of Nuclear Physics)
JJ Thomson (British) discovered the electron
1898 (History of Nuclear Physics)
Marie Curie (France) discovers radioactive elements radium and polonium
1899 (History of Nuclear Physics)
Ernest Rutherford (Canada) 2 kinds of rays emitting from radium, calls them alpha and beta rays
1900 (History of Nuclear Physics)
Frederick Soddy (Britain) Spontaneous disintegration of radioactive elements into variants, calls them isotopes
1901 (History of Nuclear Physics)
Rutherford and Soddy publish theory of radioactive decay
1905 (History of Nuclear Physics)
Einstein (US immigrant) writes special theory of relativity. Unified mass, energy, magnetism, electricity and light.
1911 (History of Nuclear Physics)
Rutherford (Britain) discovers nucleus of the atom
1913 (History of Nuclear Physics)
Niels Bohr (Denmark) publishes theory of atomic structure, combining nuclear theory with quantum theory
1915 (History of Nuclear Physics)
Einstein (US immigrant) publishes general theory of relativity. Gravity, as well as motion, could affect the intervals of time and space.
1919 (History of Nuclear Physics)
Rutherford (Britain) bombarded nitrogen gas with alpha rays. Transmutation of nitrogen into oxygen, first artificially induced nuclear reaction.
1925 (History of Nuclear Physics)
Heisenberg, Born (Germany) & Schrodinger (Austria) formulated quantum mechanics.
1927 (History of Nuclear Physics)
Blumgart (US) uses radioactive tracers to diagnose heart disease.
1929a (History of Nuclear Physics)
Lawrence (US) conceives the cyclotron, used to produce high-energy beams for nuclear experiments.
1929b (History of Nuclear Physics)
Crockcroft & Walton (UK) develop high-voltage apparatus for accelerating protons, called a linear accelerator
1929c (History of Nuclear Physics)
Atkinson & Houtermans investigate nuclear fusion as a source of stellar radiation
1930 (History of Nuclear Physics)
Eddington (UK) suggests that the radiation coming from stars originates from lighter constituents building up heavier nuclei (Fusion)
1932a (History of Nuclear Physics)
Chadwick (UK) discovers neutron and studies deuterium
1932b (History of Nuclear Physics)
Crockcroft & Walton (UK) split the atom with protons accelerated by their linear accelerator
1932c (History of Nuclear Physics)
Heisenberg (Germany) awarded Nobel Prize for the creation of quantum mechanics
1933 (History of Nuclear Physics)
Szilard conceives the concept of the nuclear chain reaction
1934 (History of Nuclear Physics)
Fermi (US immigrant) irradiated uranium with neutrons. Didn’t realize he split the atom, achieving the first nuclear fission
1938, December (History of Nuclear Physics)
Hahn & Strassman (Germany) detect barium after bombarding uranium with neutrons. Meitner and Frisch identify this as nuclear fission
1939, January (History of Nuclear Physics)
Frisch experimentally confirms Hahn and Strassman’s discovery of nuclear fission
1939, April (History of Nuclear Physics)
Nazi Germany begins a nuclear energy project
1939, October (History of Nuclear Physics)
President FDR receives Einstein-Szilard letter and authorized the Advisory Committee on Uranium
1940, April (History of Nuclear Physics)
Military Application of Uranium Detonation (MAUD) Committee established to investigate bomb feasibility
1941, February (History of Nuclear Physics)
Seaborg & Wahl discover plutonium
1941, October (History of Nuclear Physics)
FDR receives the MAUD report and approves a project to confirm the MAUD’s findings
1941, December (History of Nuclear Physics)
Japan attacks Pearl Harbor, US enters WWII
1942, April (History of Nuclear Physics)
Stalin becomes aware of the efforts to develop nuclear weapons. Starts a Soviet nuclear weapons program.
1942, July (History of Nuclear Physics)
The HWA relinquishes control of the German nuclear project to the RFR, making it a research project. Not a weaponry project.
1942, July-September (History of Nuclear Physics)
Oppenheimer hosts a conference to discuss the design of a fission bomb. Teller introduces the hydrogen bomb concept.
1942, August-November (History of Nuclear Physics)
Manhattan Project established under Gen. Groves. Site X – Oak Ridge. Site Y – Los Alamos.
1943, March (History of Nuclear Physics)
Japanese Committee of Research in the Application of Nuclear Physics concludes the bomb was feasible but unlikely to be produced during the war.
1943, April (History of Nuclear Physics)
Intro lectures began at Low Alamos
1943, August (History of Nuclear Physics)
Quebec Agreement signed by FDR and Churchill. British scientists join the Manhattan Project.
1944, April (History of Nuclear Physics)
Segre discovers the spontaneous fission rate of plutonium is too high to be used in a gun-type weapon. Focus changed to implosion type.
1945, May (History of Nuclear Physics)
Nazi Germany surrenders to Allied powers. End of WWII in Europe
1945, July 16 (History of Nuclear Physics)
First nuclear explosion in New Mexico. Implosion style known as gadget
1945, August 6 (History of Nuclear Physics)
“Little Boy”, a gun-type uranium-235 weapon, was dropped on Hiroshima
1945, August 8 (History of Nuclear Physics)
USSR declared war on Japan
1945, August 9 (History of Nuclear Physics)
“Fat Man”, implosion-type plutonium-239 weapon, was dropped on Nagasaki
1945, August (History of Nuclear Physics)
Smyth Report published, details the efforts of the Manhattan Project
1945, August 15 (History of Nuclear Physics)
Japan surrenders to the Allied Powers
1946, January (History of Nuclear Physics)
Atomic Energy Act of 1946 takes effect, transfers the Manhattan Project to the US Atomic Energy Commission.
1946, June (History of Nuclear Physics)
1st meeting of the UN Atomic Energy Commission
1946 (History of Nuclear Physics)
Societ Union rejected the Baruch Plan
1949, August 29 (History of Nuclear Physics)
USSR conducts its 1st atomic test
Categories: Atomic Physics