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60th Anniversary of the Atomic Bomb
An anonymous reader writes "On July 16, 1945, the world's first nuclear bomb exploded at Trinity Site, New Mexico, marking the beginning of the Nuclear Age. Manhattan Project veteran Herb Lehr has no regrets: 'In a lot of respects I felt as if I had done something worthwhile. I am in no way ashamed of what I had done in any way, shape, matter or form. I did what I was told to do. I did it to the best of my ability.' Lehr will return to Trinity Site for the first time since the explosion. He said, 'I'm just interested in going and seeing it and maybe getting some memories back. Los Alamos was a whole interesting experience. It was something unique. I worked very hard down there.'"
The actual physics involved in building a bomb will be covered by any standard undergraduate physics course. Thats not the tricky bit. It gets difficult when the recipe called for a few kgs of U235 or Pu-239. Even if you could get your hands on some Uranium you would still have to process it to extract the fissile U235 from the U233, requiring all kinds of highly restricted and monitored hardware.
Natural uranium contains U-238, U-235 and a TINY amount of U-234. U-233 is an isotope of uranium created by neutron bombardment of thorium and is not present in natural uranium. Above should read seperating the U-235 from the U-238.
Nope. B-29 was the first bomber that could fly really high (indeed, USAF discovered jet stream when they first flew at those heights), and japanese had no AA equipment that could deal with them at 30000+ feet.
Altough, actually most of the air raids with B-29's were done at low altitudes - japanese had 88 mm AA cannons, so they could not turn fast enough for low-altitude bombing. This saved fuel and allowed for higher payloads (and also prevented some engine troubles - flying at high altitudes caused overheating problems).
So yeah, that demo could have been done without any problems for subsequent real droppings.
most of the second guessing has come from succeeding generations that had the luxury of self-relection...
...the Secretary, upon giving me the news of the successful bomb test in New Mexico, and of the plan for using it, asked for my reaction, apparently expecting a vigorous assent.
... When I asked General MacArthur about the decision to drop the bomb, I was surprised to learn he had not even been consulted. What, I asked, would his advice have been? He replied that he saw no military justification for the dropping of the bomb. The war might have ended weeks earlier, he said, if the United States had agreed, as it later did anyway, to the retention of the institution of the emperor." -- Norman Cousins, The Pathology of Power, pg. 65, 70-71.
"Prof. Albert Einstein... said that he was sure that President Roosevelt would have forbidden the atomic bombing of Hiroshima had he been alive and that it was probably carried out to end the Pacific war before Russia could participate." --Einstein Deplores Use of Atom Bomb, New York Times, 8/19/46, pg. 1
"...in [July] 1945... Secretary of War Stimson, visiting my headquarters in Germany, informed me that our government was preparing to drop an atomic bomb on Japan. I was one of those who felt that there were a number of cogent reasons to question the wisdom of such an act.
"During his recitation of the relevant facts, I had been conscious of a feeling of depression and so I voiced to him my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and secondly because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives. It was my belief that Japan was, at that very moment, seeking some way to surrender with a minimum loss of 'face'. The Secretary was deeply perturbed by my attitude..." -- Dwight Eisenhower, Mandate for Change
"...the Japanese were ready to surrender and it wasn't necessary to hit them with that awful thing." -- Dwight Eisenhower, Ike on Ike, Newsweek, 11/11/63
On August 8, 1945, after the atomic bombing of Hiroshima, [Herbert] Hoover wrote to Army and Navy Journal publisher Colonel John Callan O'Laughlin, "The use of the atomic bomb, with its indiscriminate killing of women and children, revolts my soul." -- quoted from Gar Alperovitz, The Decision to Use the Atomic Bomb, pg. 635.
"MacArthur's views about the decision to drop the atomic bomb on Hiroshima and Nagasaki were starkly different from what the general public supposed.
The first bomb had two hemispherses of Uranium that were polished smooth.
This is slightly inaccurate the first bomb (Gadget) did indeed consist of two hollow hemispheres, but it was two nickel plated plutonium hemispheres (with some gold foil added to smooth it out after the nickle blistered) and not uranium hemispheres.
The first uranium bomb (Little Boy) was a gun type system with a cannon firing a bullet of uranium into a barely subcritical mass of uranium.
This is not to say that a bomb can't be made with two hemispheres of uranium, but this was not done with either the first bomb or the first uranium bomb. The idea of converting the Little Boy bomb into an implosion design (with two hemispheres of uranium) was raised after the Gadget test as it would permit more efficent use of the uranium, but it was decided not to as this would delay the use of the weapon.
Not quite. The Nuclear weapons Archive story about it has this to say.
The Tsar Bomba (referred to as the Big Bomb by Sakharov in his Memoirs [Sakharov 1990]) was the largest nuclear weapon ever constructed or detonated. This three stage weapon was actually a 100 megaton bomb design, but the uranium fusion stage tamper of the tertiary (and possibly the secondary) stage(s) was replaced by one(s) made of lead. This reduced the yield by 50% by eliminating the fast fissioning of the uranium tamper by the fusion neutrons, and eliminated 97% of the fallout (1.5 megatons of fission, instead of 51.5), yet still proved the full yield design. The result was the "cleanest" weapon ever tested with 97% of the energy coming from fusion reactions. The effect of this bomb at full yield on global fallout would have been tremendous. It would have increased the world's total fission fallout since the invention of the atomic bomb by 25%.
There was some bickering as to weither it had a yield of 50 or 57MT. The designed yield was 50MT, but the americans believed it was 57 based on what fallout they managed to sample, and shortly thereafter the soviets started using this figure as well.