Bombardment with protons

In the discussion that followed, Rutherford added information about the work he was carrying on, in collaboration with Oliphant, on various reactions produced in lithium by bombardment with protons and deuterons,43 and Ernst Lawrence described in more detail the cyclotron he had invented and first constructed with a few collaborators in 1932.44... 

Nuclear reactions induced by bombardment with protons and by deuterons are illustrated by the following examples ... 

This misuse of the word radioactivity causes many people to incorrectly think of radioactivity as something one can get by being near radioactive materials. There is only one process which behaves anything like that, and it is called artificially induced radioactivity, a process mainly carried out in research laboratories. When some materials are bombarded with protons, neutrons, or other nuclear particles of appropriate energy, their nuclei may be transmuted, creating unstable isotopes which are radioactive. 

Why does bombardment with protons usually require higher energies than bombardment with neutrons ... 

Notes The nuclear reactions for the production of Iodine Isotopes are listed. For i23Te(p, n) STe Is the target nuclide, (p, n) Is nuclear reaction which Indicates bombarding with proton, with a emitting of neutron, and 23 is produced. In the nuclear reactions, p Is proton n Is neutron 2n means two neutrons, d Is deuterium, a Is alpha particle, Is gamma rays, f Is fission products. EC means decay by electron capture, and (P ) means decay by beta emission. 

It is also possible to prepare artificial isotopes by bombardment with protons, neutrons, a-particles, etc. These isotopes are radioactive and after varying lengths of time they undergo transmutation accompanied by the emission of electrons. The determination of stable isotopes is carried out with the mass spectrometer and radioactive isotopes are determined by measuring their degree of radioactivity. 

Numerous nuclear transformations have been induced by processes in which atoms have been bombarded with neutrons, protons, deuterium, carbon atoms and ions. 

The nucleus of an atom consists of protons and neutrons that are bound together by a nuclear force. Neutrons and protons are rearranged in a nuclear reaction in a manner somewhat akin to rearrang ing atoms in a chemical reaction. The nuclear reaction liberating energy in a nuclear power plant is called nuclear fission. The word fission is derived from fissure, which means a crack or a separation. A nucleus is separated (fissioned) into two major parts by bombardment with a neutron. 

The number of protons in an element s atomic nucleus is called the atomic number, Z, of that element. For example, hydrogen has Z = 1 and so we know that the nucleus of a hydrogen atom has one proton helium has Z = 2, and so its nucleus contains two protons. Henry Moseley, a young British scientist, was the first to determine atomic numbers unambiguously, shortly before he was killed in action in World War I. Moseley knew that when elements are bombarded with rapidly moving electrons they emit x-rays. He found that the properties of the x-rays emitted by an element depend on its atomic number and, by studying the x-rays of many elements, he was able to determine the values of Z for them. Scientists have since determined the atomic numbers of all the known elements (see the list of elements inside the back cover). 

C22-0054. Identify the compound nucleus and final product resulting from each of the following nuclear reactions (a) carbon-12 captures a neutron and then emits a proton (b) the nuclide with eight protons and eight neutrons captures an a particle and emits a y ray and (c) curium-247 is bombarded with boron-11, and the product loses three neutrons. 

Activation—The process of making a material radioactive by bombardment with neutrons or protons. 

Francium occurs as a result of the disintegration of actinium. Francium is found in uranium minerals, and can be made artificially by bombarding thorium with protons. It is the most unstable of the first 101 elements. 

Two methods to secure very small samples of francium for examination use the decay processes of other radioactive elements. One is to bombard thorium with protons. The second is to start with radium in an accelerator, where, through a series of decay processes, the radium is converted to actinium, which in turn rapidly decays into thorium, and finally, thorium decays naturally into francium. Following is a schematic of the decay process used for the production of small amounts of Fr-223 which, in turn, after several more decay processes ends up as stable lead (Pb) ... 

Rutherford and Chadwick knew that if the Joliots realized that their conclusions were erroneous, they might discover the neutron first. So Chadwick immediately went to work performing new experiments. He soon found that if beryllium was bombarded with alpha particles, a kind of radiation consisting of particles with a mass close to that of the proton were produced. He ruled out the possibility that the radiation consisted of gamma rays by showing that, if it did, the gamma rays would have insufficient energy to produce the effects that were observed. Chadwick had discovered Rutherford s neutron. 

The experiments went on, however, and in 1968 experiments at the Stanford Linear Accelerator Laboratory showed that quarks were indeed real. When protons were bombarded with high-energy electrons, pointlike charges were discovered inside the proton. These charges could only be charged particles, in other words, quarks. 

For example, uranium-238 when bombarded with fluorine-19 produced Md-252. Also, certain nuclear reactions carried out by heavy ion projectiles involve stripping reactions in which some protons and neutrons may transfer from the projectiles onto the target nucleus, but the latter might not capture the projectile heavy ion. 

Technetium isotopes are prepared by bombardment of molybdenum with protons and neutrons. A few nuclear reactions are shown for the three long-... 

Gamma-ray from disintegration of beryllium by Deuterons and Protons) 3) K. Lark-Horowitz et al, PhysRev 48, 100(1935) (Gamma rays from nitrogen bombarded with Deuterons) 4) R.G. Herb et al, PhysRev 51, 691—98(1937) (Gamma rays from light... 

---