Atomic Bomb Chronology: 1945-1946

1945.1.2 U.S.A. David Greenglass's contact with Julius Rosenberg, a Soviet intelligence agent, handing a sketch of implosion lens and a list of asset candidates.
1945.1.16 U.S.A. Start of plutonium separation at Hanford.
1945.1.20 U.S.A. Start of operation in the gaseous diffusion plant using a supply of poorly enriched uranium to Calutron. Development of teflon as a sealant.
1945.1.20 U.S.A. Low altitude incendiary bombing of Japan proposed by C.LeMay, Commander of B-29 bombers corps.
1945.1 U.S.A. Verification of critical mass of uranium235by Otto Frisch. Named Dragon experiment by R. Feynman. Accident in February of neutron irradiation. A victim died.
1945.1 U.S.A. An ignition device for implosion completed by Luis W. Alvarez.
1945.2.4 Yalta talk. F. Roosevelt, W. Churchill and Y. Stalin. Demanded unconditional surrender of Japan: A secret agreement of attacking of Japan by Soviet Union.
1945.2.5 U.S.A. Transport of plutonium239 from Hanford to Los Alamos as nitric acid solution.
1945.2.7 U.S.A. Implosion lens completed by G. Kistiakowsky.
1945.2 U.S.A. Schedule of Trinity test decided. Implosion will be employed only in plutonium bomb.
1945.2 U.S.A. Start of operation in Liquid Thermal Diffusion plant, supplying poorly enriched uranium to Calutron. After June, uranium was processed in the order of liquid thermal diffusion plant, gaseous diffusion plant and Calutron. Improvement of enrichment with gaseous diffusion plant.
1945.2 U.S.A. Tinian recommended as the Dispatch base for A-bomb B-29 by commander Frederick L. Ashworth.
1945.2.16 U.S.A. Klaus Fuchs handed Soviet intelligence agent data of implosion system. He refused to receive 1500 dollars reward.
1945.2.28 U.S.A. Leaders of Manhattan Project including Groves, Office of Scientific Research and Development section head and Harvard President James Bryant Conant, Hans Bethe, George Kitiakowsky and Richard Tolman met in Oppenheimer's office and decided tentatively to develop the lensed, solid-core Christy implosion design as a combat weapon.
1945.3.10 U.S.A. 100,000 victims killed in large air attack on Tokyo: 234 B-29 bombers with 1665 tons of incendiary bombs.
1945.3.15 U.S.A. Germany US air force attacked Metal-refining plant in Oranienburg (15 miles north of Berlin) to prevent German production of metallic uranium.
1945.3 Germany Start of experimental operation of B-8 nuclear reactor by W. Heisenberg, K. Diebner, Carl F. von Weizsaocker, Hans Bethe and others. A cylinder type reactor employing graphite as neutron reflector and heavy water as modulator. Did not achieve the critical state.
1945.4.12 U.S.A. Verification of critical mass of Plutonium 239 by O.Frisch in Dragon Experiment.
1945.4.12 Japan Riken Scientific Institute destroyed: End of Japanese A-bomb project.
1945.4.12 U.S.A. Sudden death of President Roosevelt. Replaced by Harry S. Truman, the vice president. H. Stimson first explained Manhattan Project to President Truman in the evening.
1945.4.17 Germany German uranium ore found by commander John Lansdale, Jr. of US army special unit (ALSOS). At a shed in Stuttgart. Supplied to Manhattan Project
1945.4.23 Germany Reactor at Heigerloch seized by U.S. army (ALSOS). Commanders B. Pash and Samuel A. Goudsmit. Goudsmit is Heisenberg's friend. Goudsmit's parents had been killed by Nazi in a gas chamber.
1945.4.24 Germany German atomic scientists arrested in Hebingen. [C. Weizsaecker, O. Hahn, Max von Laue]
1945.4.25 U.S.A. Truman and Stimson discuss details of Manhattan Project.
1945.4.26 Germany Metal uranium and heavy water found by ALSOS.
1945.4.27 U.S.A. The 1st Target Committee meets. [L.Groves, Thomas F.Farrell,J.Neumann and William G.Penny] Japan, July or August. Visual flying by a B-29 bomber with the range of 2500km or less.
1945.5.1 Germany Death of Adolf Hitler.
1945. 5. 2 Germany Berlin occupied.
1945,5.3 U.S.A. W. Heisenberg arrested by U. S. army ALSOS in Welfeld.
1945.5.8 Germany Germany surrenders to allied forces.
1945.5.9 U.S.A. Interim committee on nuclear power meets: Henry Stimson, Ralph Bard, Vannevar Bush, James Byrnes, William Clayton, Karl Compton, George Harrison: By invitation: Harvey Bundy. Predicts development of nuclear weapons by Soviet Union in 7 years.
1945.5.10 U.S.A. The second Target Committee meets in Los Alamos: L. Groves, General Farrel, Colonel Seeman, Captain Parsons, C. Lauritsen, Major Derry, Drs Ramsey, Dennison, Stearns, Tolman, Oppenheimer, von Neumann, Wilson, Penny, Bethe, Robert. The first choices of targets for nuclear weapons are: a. Kyoto, b. Hiroshima, c. Yokohama, d. Kokura Arsenal.
1945.5.25 U.S.A. Operation of Kyushu invasion decided by Douglas MacArthur (army), Chester Nimitz (navy) and Henry H. Arnold (army air corps). Named " Operation Olympiad," scheduled for November 1.
1945.5.28 U.S.A. Joseph C. Grew, undersecretary of the State Department, of predicts Japanese surrender to President Truman.
1945.5.28 U.S.A. L. Szilard expresses his opinion against use of A-bomb to Presidential advisor J. Byrnes. Rejected.
1945.5.28 U.S.A. The third Target Committee meets. Given report of test bombing carried out in Cuba by Colonel P. Tibbets.
1945.5.30 U.S.A. Stimson tells L. Groves to exclude Kyoto from list of A-bomb targets.
1945.5.31 U.S.A. Recommendation on the immediate use of nuclear weapons given by the Interim Committee: Byrnes, Stimson, G. C. Marshall, Groves, Harvey H. Bundy, J. Conant, Compton, Lawrence, Fermi, Oppenheimer. Inviting Soviet Union to Trinity proposed by Oppenheimer. Decided not to notify Japan before dropping A-bomb. Objections by Szilard discussed.
1945.5 U.S.S.R. German 130 tons uranium oxide found in a tannery in Berlin right on the border of American-occupied territory was seized by Soviet army and shipped to Soviet Union.
1945.5 U.S.A. Joseph Rotblat resigns of from Los Alamos because of Germany's surrender. Later he founded Pugwash Conference.
1945.5 Soviet Union German uranium seized: over 100 tons in Belgium.
1945.6.2 U.S.A. Confidential data including information of Trinity, atomic bomb, explosive materials handed by Klaus Fuchs to a Soviet agent.
1945.6.3 U.S.A. David Greenglass handed to the same agent contacting with Klaus Fuchs the sketch of implosion lens and names of asset candidates. Received 500 dollars reward.
1945.6.6 U.S.A. Recommendation of A-bomb use by Interim Committee conveyed to President Truman by Stimson.
1945.6.10 U.S.A. The 509th Composite Group arrives at Tinian with 11 B-29 bombers.
1945.6.11 U.S.A. James Frank committee recommends notification before use of A-bomb: J. Frank, Leo Szilard, Eugene Rabinowitch. Seven scientists in Chicago recommended a show of force demonstration.
1945.6.18 U.S.A. Estimation of 63000 war dead or wounded in Operation Olympiad (Kyusyu invasion) by General G.C.Marshall.
1945.6 U.S.A. Assembly of the plutonium bomb for Trinity.
1945.7.2 U.S.S.R. Confidential data obtained by espionage agents from USA were shown to Igor Kurchatov.)
1945.7.3 U.S.A. Casting of a warhead for uranium235 bomb.
1945.7.12 U.S.A. Plutonium core arrives at Alamogordo.
1945.7.13 U.S.A. Explosive assembly arrival at Alamogordo.
1945.7.14 U.S.A. A preparatory implosive experiment for Trinity failed. The defect explosive was replaced by hand work.
1945.7.14 U.S.A. Gadget for Trinity completed by Norris E. Bradberry and others. Installed at top of 30m high tower.
1945.7.15 U.S.A. Preparatory implosion experiment declared indecisive by H. Bethe.
1945.7.16 U.S.A. TRINITY test. After 90 minute delay for bad weather, at 5:29:45. Explosive force of 18.6 kilotons of TNT.
1945.7.16 U.S.A. Shipping of Little Boy by cruiser Indianapolis, 4 hours after Trinity.
1945.7.17 U.S.A. Petition to President Truman against the use of nuclear weapons by L. Szilard and 70 scientists.
1945.7.20 U.S.A. Allied Commander D. Eisenhauer advises President Truman not to use A-bomb; it is unnecessary.
1945.7.21 U.S.A. Report from L. Groves of successful Trinity conveyed to President Truman staying in Potsdam: Later W. Churchill told H. Stimson that Truman's reaction was clearly observable.
1945.7.23 U.S.A. Telegraph by George L.Harrison to Potsdam informing that dropping A-bomb on Japan is possible after August 1.
1945.7.23 U.S.A. Completion of the 2nd plutonium core.
1945.7.24 U.S.A. H. Truman told Y. Stalin about A-bomb experiment. Stalin was already informed by spy of Trinity but never revealed it.
1945.7.25 U.S.A. Approval by President Truman staying at Potsdam of the order to bomb Japan with A-bomb. The order was written by L. Groves.
1945.7.26 U.S.A. Cruiser Indianapolis arrives at Tinian. Little Boy is unloaded.
1945.7.26 U.S.A. Shipping of uranium-235 warhead to Tinian: by C-54 transport plane.
1945.7.26 U.S.A. Shipping of plutonium core and the initiator to Tinian by C-54 transport plane.
1945.7.26 Potsdam Declaration announced, demanding unconditional surrender of Japan.
1945.7.30 U.S.A. Cruiser Indianapolis sunk by a torpedo attack from a Japanese submarine, only 4 days after unloading of A-bomb.
1945.7.31 U.S.A. Assembling Little Boy, waiting recovery of weather.
1945.8.2 U.S.A. Parts of Fat Man arrive at Tinian.
1945.8.4 U.S.A. Briefing to crew of B-29 bombers of the 509th corps. Presentation by William Parsons of documentary film of Trinity.
1945.8.5 U.S.A. Bombing date of August 6 decided by Curtis LeMay. Installation of Little Boy in a B-29 bomber named Enola Gay, after Captain Tibbets' mother.
1945.8.6 U.S.A. Bombing Hiroshima with Little Boy by Paul W. Tibbets, Robert Lewis, Thomas Ferebee, William S. Parsons, Morris Jeppson, and others, at 08:16: 45. Explosion equivalent to 12.5 kilotons of TNT from 60 kg uranium235. Bomb's gross weigh was 4 tons. 140,000 civilian citizens were killed. Hibakusya (survivors) more than 300,000.Physical ailnesses due to radiation exposure, short term and long term effects.
1945. 8. 7 U.S.S.R. Lavrenti Pavlovich Beria was appointed to the head of Soviet atomic bomb project by Stalin.
1945.8.7 U.S.A. Statement by President Truman of A-bomb attack from Cruiser Augusta in Atlantic Ocean on the way back from Potsdam.
1945.8.8 Soviet Union Declaration of war against Japan, just after the German surrender, as promised in Yalta talk.
1945.8.8 U.S.A. Fat Man assembled and installed in a B-29 bomber.
1945.8.9 Soviet Union Attacks Japan by invasion of Manchuria.
1945.8.9 U.S.A. Bombing Nagasaki with Fat Man by Charles W.Sweeney, Frederick L.Ashworth, and others. Target changed from Kokura to Nagasaki because of poor visibility. 20 seconds visibility over Nagasaki. Time 11:02:00. Explosion equivalent to 22 kilotons of TNT, using 8 kg plutonium 239. Bomb's gross weight 4.5 tons. 70,000 civilian citizens were killed.
1945.8.9 Japan Decision accepting Potsdam Declaration at midnight meeting of ministers before Tennou Hirohito.
1945.8.10 Japan Sending word of acceptance of Potsdam Declaration through Switzerland, requesting Tennou's position to be kept. J. Byrnes wished to reject it, nevertheless, H. Truman accepted.
1945.8.11 U.S.A. Interruption of transport to Tinian of the 2nd Plutonium core and initiator by the order of G.C. Marshall. The next plutonium bomb could possibly have been dropped on August 17 or 18.
1945.8.12 Japan Response of U.S.A. to Japanese request.
1945.8.15 Japan Unconditional Surrender by Japan. The end of the World War II.
1945.8.20 U.S.S.R. Special Commitee on the Atomic Bomb formed. [Georgi Malenkov, Boris Vannikov, Avrami Zavenyagin, Mikhail Peruvuhin, Peter Kapitza and Igor Kurchatov]
1945.9.5 Canada Igor Gouzenko, a Soviet espionage, escaped from Soviet Embassy carrying 109 reports, resulting in arrest of 22 Soviet agents.
1945.9.15 U.S.A. Manufacturing A-bomb reported: Presented to L.Groves by major Lauris Norstad. An estimation that 204 atomic bombs are required if a hypothetical enemy is Soviet Union. The start of cold war.
1945.9.28 U.S.A. Scientific Panel of the Interim Committee recommends against H-bomb development. [Compton, Lawrence, Germi, Oppenheimer.]
1945.10.16 U.S.A. Resignation of R. Oppenheimer from Los Alamos. Replaced by Norris E. Bradbury.
1945.11.2 U.S.A. " A Message to Los Alamos" speech by Oppenheimer, his resignation lecture foreseeing the atomic age.
1945.11.15 Truman-Attlee-King declaration, the New Quebec agreement. A doctrine that initiative relating with the knowledge of atomic energy is kept by U.S.A., G.B. and Canada. Atomic Energy Commission in United Nations proposed.
1945.11.23 Czechoslovakia Soviet Union concluded a secret agreement with Czechoslovakia granting it exclusive rights to all uranium mined within country. Jachymov ores is that from which Marie Curie first extracted polonium and radium.
1945.11.24 Japan Cyclotrons destroyed by U.S. Army: 2 in Tokyo, 3 in Osaka and Kyoto.
1945.12.22 England Repatriation of German scientists to West Germany by U.S.A.
1945.12.24 Soviet Union Start of developing A-bomb officially notified to U.S. ambassador
1945.12 U.S.A. ENIAC (A computer with 18,800 vacuum tubes, 140 kw, 30 tons) ran a first rough version of the thermonuclear calculations. Los Alamos prepared a half million punched cards of data.
1946.1.25 U.S.S.R. Atomic bomb project decided (imitating US-model).[Stalin, Beria, Morotov, Kurchatov]
1946.3.5 U.S.A. United Kingdom Winston Churchill's speech of Iron Curtain at a small Protestant men's college in Fulton, Missouri. Nothing less than a call to an all-out atomic race.
1946.3.17 U.S.A. International Control of nuclear power proposed: Dean Gooderham Acheson. Report by R. Oppenheimer.
1946. 4. 2 U.S.S.R. Atomic bomb laboratory site at Sarov, 400 km east to Moskow. Soviet Los Alamos.
1946.4 U.S.A. First conference on development of "Super" (h-bomb). Meeting of E. Teller, E. Konopinsky, J. Manley, P. Morrison, von Neumann, S. Ulam, N. Bradberry and K. Fuchs at Los Alamos. Robert Serber opposed the development. Propose a mixture of deuterium and tritium in a cylindrical container ignited by the fireball of atomic bomb.
1946.6.14 U.S.A. Nuclear Control Plan by Bernard M. Baruch presented in United Nations: International control of nuclear power. It was counterattacked by a plan by Soviet Union of prohibition of manufacturing atomic bombs.
1946.6 U.S.A. Stockpile of nuclear weapons: 9 Fat Man bombs. Rate-limiting step is plutonium production.
1946.7.1 U.S.A. The Crossroads Series tests. The purpose of the tests was to examine the effects of nuclear explosions on naval vessels, planes, and animals. A fleet of surplus and captured ships anchored in the Bikini Atoll lagoon in the Marshall Islands were used as targets. The weapons used were Mk 3A ("Model 1561") Fatman-type atomic bombs, essentially unmodified from the wartime designs. Test ABLE at 22:00 30 June 1946, height of burst 160 m. Dropped by B-29 "Dave's Dream", Fell 980 ft short and 1870 ft left of target. Test BAKER at 21:35 24 July 1946, Mk 3A fission bomb (23 Kt) sub-surface test, depth of burst 27.5 m. Wall of intensely radioactive spray contaminates target fleet.
1946.12.25 Soviet Union Start of operation of a nuclear reactor (F-1): 100w, using 400 tons of graphite and 50 tons of uranium seized in Germany.
1946 U.S.A. Edward Teller invented a spherical, layered design of nuclear thermal weapon, called "Alarm Clock" (it might wake up new generation of nuclear explosives).
1946 U.S.S.R. "Utilization of the nuclear energy of the light elements" by I.I.Gurevich, Y.Zeldovich, I.Pomeeranchuk, Y.Khariton.

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