question: How exactly do you "bombard" an atom in a nuclear reaction?
comment: Uranium-235 when hit by a neutron it spit and you get 1 Barium atom, 1 Krypton atom and 3 neutrons. It is the released neutrons that will hit other Uranium atoms and you have a chain reaction. & #x200B; In a reactor you have control road of material that absorb neutrons that you can move to control the reaction. In most reactor they are also slowed down by hitting water or in the past graphite. & #x200B; There is natural release of neutrons from some radioactive elements like the daughter product that is produced in a reactor so when it has been in used so restart a not a problem. But the initial start might use som neutrons source that you put in there if I am not misstanke & #x200B; In a nuclear bomb they initially used small pellets as neutron generators. It have have a outer part of beryllium that will release neutron when hit by alpha particles. The inside have gold and nickle layer and finally Polonium in the center. The gold and nickle will block the alpha radiation from the highly radioactive polonium from hitting the Beryllium but when the pellets get crushed by the conventional exposives in the bomb the beryllium and polonium will mix and release neutrons that start the chain reaction in the bomb. & #x200B; In the nuclear weapons that exist today you have [Neutron\_generator]( URL_0 ). They used electricity to accelerate deuterium of tritium atoms that hit a target of the same material and the result is nuclear fusion and you release neutrons. They are small linear particle accelerators that is also used for medical, pressurize and material analysis. So you have a electric device that sit a couple of centimeters away from conventional and is activated after the explosive detonate but before the shock wave hit the neutron generator and destroy it
passages: Usually at moderately low energy, one or more nucleons are transferred between the projectile and target. These are useful in studying outer shell structure of nuclei.
  
  BULLET::::- (α,n) and (α,p) reactions. Some of the earliest nuclear reactions studied involved an alpha particle produced by alpha decay, knocking a nucleon from a target nucleus.
   Section::::Continuous flow fast atom bombardment.
   BULLET::::4. Pushed from both sides (from the primary and the spark plug), the lithium deuteride fuel is highly compressed and heated to thermonuclear temperatures. Also, by being bombarded with neutrons, each lithium-6 atom splits into one tritium atom and one alpha particle. Then begins a fusion reaction between the tritium and the deuterium, releasing even more neutrons, and a huge amount of energy.
   BULLET::::- Our Friend the Atom: This "Disneyland" episode talks about the history of the atom, hosted by Dr. Heinz Haber, who compares the discovery of the atom to an Arabian Nights fable of "The Fisherman and the Genie". He uses well-known theories, formulas and experiments to discuss the atom, such as "E" = "mc"² and a light beam passing through a gold sheet. He illustrates chain reactions in nuclear fission using a table filled with mousetraps represents the atoms and pingpong balls stand in for the new neutrons created from the split.
   Section::::Bomb design.:Deuterium and lithium.:Jetter's cycle.
   In 1919, Ernest Rutherford was able to accomplish transmutation of nitrogen into oxygen at the University of Manchester, using alpha particles directed at nitrogen N + α → O + p.  This was the first observation of an induced nuclear reaction, that is, a reaction in which particles from one decay are used to transform another atomic nucleus. Eventually, in 1932 at Cambridge University, a fully artificial nuclear reaction and nuclear transmutation was achieved by Rutherford's colleagues John Cockcroft and Ernest Walton, who used artificially accelerated protons against lithium-7, to split the nucleus into two alpha particles. The feat was popularly known as "splitting the atom", although it was not the modern nuclear fission reaction later discovered in heavy elements, in 1938 by the German scientists Otto Hahn and Fritz Strassmann.
   The neutron was discovered by James Chadwick at the Cavendish Laboratory at the University of Cambridge in February 1932, and in April 1932, his Cavendish colleagues John Cockcroft and Ernest Walton split lithium atoms with accelerated protons. In December 1938, Otto Hahn and Fritz Strassmann at Hahn's laboratory in Berlin-Dahlem bombarded uranium with slow neutrons, and discovered that barium had been produced, and therefore that the uranium nucleus had been split. Hahn wrote to his colleague Lise Meitner, who, with her nephew Otto Robert Frisch, developed a theoretical explanation of the process. By analogy with the division of biological cells, they named the process "fission".
   Nuclear fission in fissile fuels are the result of the nuclear excitation energy produced when a fissile nucleus captures a neutron. This energy, resulting from the neutron capture, is a result of the attractive nuclear force acting between the neutron and nucleus. It is enough to deform the nucleus into a double-lobed "drop", to the point that nuclear fragments exceed the distances at which the nuclear force can hold two groups of charged nucleons together and, when this happens, the two fragments complete their separation and then are driven further apart by their mutually repulsive charges, in a process which becomes irreversible with greater and greater distance. A similar process occurs in fissionable isotopes (such as uranium-238), but in order to fission, these isotopes require additional energy provided by fast neutrons (such as those produced by nuclear fusion in thermonuclear weapons).
   An intermediate energy projectile transfers energy or picks up or loses nucleons to the nucleus in a single quick (10 second) event. Energy and momentum transfer are relatively small. These are particularly useful in experimental nuclear physics, because the reaction mechanisms are often simple enough to calculate with sufficient accuracy to probe the structure of the target nucleus.
  
  Section::::Notable types.:Direct reactions.:Inelastic scattering.
  
  Only energy and momentum are transferred.
  
  BULLET::::- (p,p') tests differences between nuclear states.
   In connection with the Strategic Defense Initiative, research into the nuclear pumped laser was conducted under the DOD program Project Excalibur but this did not result in a working weapon. The concept involves the tapping of the energy of an exploding nuclear bomb to power a single-shot laser which is directed at a distant target.
   In fission weapons, a mass of fissile material (enriched uranium or plutonium) is forced into supercriticality—allowing an exponential growth of nuclear chain reactions—either by shooting one piece of sub-critical material into another (the "gun" method) or by compression of a sub-critical sphere or cylinder of fissile material using chemically-fueled explosive lenses. The latter approach, the "implosion" method, is more sophisticated than the former.
   The simplest approach and still one of the most common techniques is known as pump–probe spectroscopy. In this method, two or more optical pulses with variable time delay between them are used to investigate the processes happening during a chemical reaction. The first pulse (pump) initiates the reaction, by breaking a bond or exciting one of the reactants. The second pulse (probe) is then used to interrogate the progress of the reaction a certain period of time after initiation. As the reaction progresses, the response of the reacting system to the probe pulse will change. By continually scanning the time delay between pump and probe pulses and observing the response, workers can reconstruct the progress of the reaction as a function of time.
   Section::::How it worked.
   BULLET::::2. Energy released in the primary stage is transferred to the secondary (or fusion) stage. The exact mechanism whereby this happens is highly classified. This energy compresses the fusion fuel and sparkplug; the compressed sparkplug becomes critical and undergoes a fission chain reaction, further heating the compressed fusion fuel to a high enough temperature to induce fusion, and also supplying neutrons that react with lithium to create tritium for fusion.
   A third important nuclear reaction is the one that creates tritium, essential to the type of fusion used in weapons. Tritium, or hydrogen-3, is made by bombarding lithium-6 (Li) with a neutron (n). This neutron bombardment will cause the lithium-6 nucleus to split, producing helium-4 (He) plus tritium (T) and energy:
   Section::::Matrices and sample introduction.
   Section::::Soviet research.
   A mere seven years after the discovery of nuclear fission, on 6 August 1945, half a gram of uranium was converted into energy when the world's first atomic bomb was dropped on Hiroshima. As Lisa Meitner's calculations suggested, this conversion released energy equivalent to 13,000 tons of TNT. A plutonium bomb was dropped on Nagasaki three days later.
  
  Section::::Episode 3: The Power of the Elements.:GSI Helmholtz Centre for Heavy Ion Research.
   Section::::Bomb design.:Deuterium and lithium.
   BULLET::::- Be + n → 2α + 2n can contribute some additional neutrons in the beryllium neutron reflector of a nuclear weapon.
  
  BULLET::::- Li + n → T + α + n unexpectedly contributed additional yield in Castle Bravo, Castle Romeo, and Castle Yankee, the three highest-yield nuclear tests conducted by the U.S.
  
  Section::::Notable types.:Compound nuclear reactions.
   Rutherford and Soddy were observing natural transmutation as a part of radioactive decay of the alpha decay type. The first artificial transmutation was accomplished in 1925 by Patrick Blackett, a research fellow working under Rutherford, with the transmutation of nitrogen into oxygen, using alpha particles directed at nitrogen N + α → O + p.  Rutherford had shown in 1919 that a proton (he called it a hydrogen atom) was emitted from alpha bombardment experiments but he had no information about the residual nucleus. Blackett's 1921-1924 experiments provided the first experimental evidence of an artificial nuclear transmutation reaction. Blackett correctly identified the underlying integration process and the identity of the residual nucleus. In 1932, a fully artificial nuclear reaction and nuclear transmutation was achieved by Rutherford's colleagues John Cockcroft and Ernest Walton, who used artificially accelerated protons against lithium-7 to split the nucleus into two alpha particles. The feat was popularly known as "splitting the atom," although it was not the modern nuclear fission reaction discovered in 1938 by Otto Hahn, Lise Meitner and their assistant Fritz Strassmann in heavy elements.
   In a standard thermonuclear design, a small fission bomb is placed close to a larger mass of thermonuclear fuel. The two components are then placed within a thick radiation case, usually made from uranium, lead or steel. The case traps the energy from the fission bomb for a brief period, allowing it to heat and compress the main thermonuclear fuel. The case is normally made of depleted uranium or natural uranium metal, because the thermonuclear reactions give off massive numbers of high-energy neutrons that can cause fission reactions in the casing material. These can add considerable energy to the reaction; in a typical design as much as 50% of the total energy comes from fission events in the casing. For this reason, these weapons are technically known as fission-fusion-fission designs.
   In the initial collision which begins the reaction, the particles must approach closely enough so that the short range strong force can affect them. As most common nuclear particles are positively charged, this means they must overcome considerable electrostatic repulsion before the reaction can begin. Even if the target nucleus is part of a neutral atom, the other particle must penetrate well beyond the electron cloud and closely approach the nucleus, which is positively charged. Thus, such particles must be first accelerated to high energy, for example by:
  
  BULLET::::- particle accelerators;
   BULLET::::- 1924 – Writing for "The Pall Mall Gazette", Winston Churchill speculates "Might a bomb no bigger than an orange be found to possess a secret power to destroy a whole block of buildings – nay to concentrate the force of a thousand tons of cordite and blast a township at a stroke?"
  
  Section::::1930–1940.
  
  BULLET::::- 1932 – James Chadwick discovers the neutron, leading to experiments in which elements are bombarded with the new particle.
   Thermonuclear bombs work by using the energy of a fission bomb to compress and heat fusion fuel. In the Teller-Ulam design, which accounts for all multi-megaton yield hydrogen bombs, this is accomplished by placing a fission bomb and fusion fuel (tritium, deuterium, or lithium deuteride) in proximity within a special, radiation-reflecting container. When the fission bomb is detonated, gamma rays and X-rays emitted first compress the fusion fuel, then heat it to thermonuclear temperatures. The ensuing fusion reaction creates enormous numbers of high-speed neutrons, which can then induce fission in materials not normally prone to it, such as depleted uranium. Each of these components is known as a "stage", with the fission bomb as the "primary" and the fusion capsule as the "secondary". In large, megaton-range hydrogen bombs, about half of the yield comes from the final fissioning of depleted uranium.
  