Nuclear beta decay

Kirsten, T., Heusser, E., Kaether, D., Oehm, I, Pernicka, E., Richter, H. (1986) New geochemical double beta decay measurements on various selenium ores and remarks concerning tellurium isotopes. In Nuclear Beta Decays and Neutrino, T. Kotani, E. Ejiri, E. Takasugi, Eds., pp. 81-92. Singapore World Scientific. 

Bogumil Jeziorski received his M.S. degree in chemistry from the University of Warsaw in 1969. He conducted his graduate work also in Warsaw under the supervision of W. Kolos. After a postdoctoral position at the University of Utah, he was a research associate at the University of Florida and a Visiting Professor at the University of Waterloo, University of Delaware and University of Nijmegen. Since 1990 he has been a Professor of Chemistry at the University of Warsaw. His research has been mainly on the coupled-cluster theory of electronic correlation and on the perturbation theory of intermolecular forces. His other research interests include chemical effects in nuclear beta decay, theory of muonic molecules and relativistic and radiative effects in molecules. 

In nuclear beta decay the most directly observed experimental quantity is the decay rate... 

H. Behrens and W. Biihring, Electron Radial Wave Functions and Nuclear Beta-Decay (Clarendon, Oxford, 1982). 

Neutrinos are created in nuclear processes and in various elementary particle interactions. The most familiar process is nuclear beta-decay, in which an unstable nucleus simultaneously emits an electron (beta-ray) and a neutrino. This process may be visualized as an unstable nucleus radiating its energy by creating a pair of leptons a neutrino and an electron. It is referred to as beta-minus decay when an electron (e ) is emitted with an antineutrino Ve) or beta-plus decay when a positron (e+) is emitted with a neutrino (Vg). In another beta-decay process, called electron capture, one of the orbital electrons in an atom is absorbed by the nucleus and a neutrino is emitted. Examples of these processes are... 

In the last column of Table 7.1, the most popular radioactive precursor nuclide is given together with the nuclear decay process (EC = electron capture, = beta decay) feeding the Mossbauer excited nuclear level. 

He is present in natural gases with a concentration of MO-7 of that of 4He and 1(T6 of the helium in the atmosphere. The separation is very expensive. Hence 3He is instead obtained as by-product of tritium production in nuclear reactors. Tritium in fact produces, by beta decay (the half life is 12.26 years), 3He the separation of 3He is obtained through a diffusion process. 

Dr. Hafemeister Most isotopes really can be studied just as well or better by beta decay. I can think of only one that can t—Le, potassium-40. This is a strange case because it is an odd-odd nucleus, and there are only about four odd-odd nuclei that are stable. An odd-odd nucleus means that it decays to the neighboring even-even nuclei, and in this case one cannot populate it by beta decay. However, in most cases one does just as well with beta decay, particularly since using a nuclear reaction for direct population is so expensive. It can be done, so there should be a good reason to spend the money. Radiation damage studies by these techniques are feasible and may well be useful. 

It was the first new element to be produced artificially from another element experimentally in a laboratory. Today, all technetium is produced mostly in the nuclear reactors of electrical generation power plants. Molybdenum-98 is bombarded with neutrons, which then becomes molybdenum-99 when it captures a neutron. Since Mo-99 has a short half-life of about 66 hours, it decays into Tc-99 by beta decay. 

Polonium is found only in trace amounts in the Earths crust. In nature it is found in pitchblende (uranium ore) as a decay product of uranium. Because it is so scarce, it is usually artificially produced by bombarding bismuth-209 with neutrons in a nuclear (atomic) reactor, resulting in bismuth-210, which has a half-hfe of five days. Bi-210 subsequently decays into Po-210 through beta decay The reaction for this process is Bi( ) Bi — °Po + (3-. Only small commercial milligram amounts are produced by this procedure. 

Americium does not exist in nature. All of its isotopes are man-made and radioactive. Americium-241 is produced by bombarding plutonium-239 with high-energy neutrons, resulting in the isotope plutonium-240 that again is bombarded with neutrons and results in the formation of plutonium-241, which in turn finally decays into americium-241 by the process of beta decay. Both americium-241 and americium-243 are produced within nuclear reactors. The reaction is as follows Pu + (neutron and X gamma rays) —> " Pu + (neutron and X gamma rays) —> Pu—> Am + beta minus ([ -) followed by " Am—> jNp-237 + Hej (helium nuclei). 

Seventeen radioisotopes have been synthesized in nuclear reactions. Among them Kr-85 and Kr-87 have the longest half-lives of 10 and 6 % years, respectively, both undergoing beta decay. 

Protactinium-233 is produced by the beta decay of the short-lived thorium-233. Thorium-233 is obtained by neutron capture of natural thorium-232. The nuclear reactions are as follows ... 

Again, both mass and charge are conserved. Gamma emission often accompanies both alpha and beta decay, but because gamma emission does not change the parent element it is often emitted when writing nuclear reactions. 

Beta Decay nuclear process in which a beta particle is emitted... 

The Nuclear Force. The nuclear forces and the interactions between pions and nucleons are strong the electron-electron and electron-photon interactions are electromagnetic the beta decay interactions are weak... 

Plutonium is a man-made element, and only infinitesimal traces occur naturally. It melts at 641°C and boils at 3330°C. 239Pu is formed in nuclear reactors by neutron capture in 238U, followed by two successive beta decays (Fig. 5.1). Further neutron captures lead to 240Pu and 241 Pu. 238Pu is formed from 239Pu by (n,2n) reactions, or from 235U by three successive neutron captures and two beta decays. Table 5.1 shows the half-lives, alpha and X-ray energies of the principal Pu isotopes. 

Taken together, these conclusions created serious problems in physical interpretation. How could neutron capture by a single isotope initiate three such different reaction processes How could the capture of just one neutron create such great instability that multiple beta decays were needed to alleviate it Nuclear isomerism was known, but how to explain the triple isomerism of 239U Worst of all, how could one account for the inherited isomerism - for several generations - in the... 

Note that in this equation the net effect of beta decay is to change a neutron into a proton. Although an electron is ejected from the nucleus, it was not part of the nuclear composition. The electron called a beta particle comes into being only when the nucleus tries to become stable, as shown here ... 

Be is not a stable isotope despite its large neutron separation energy, because it can beta decay to the more stable isobar 7Li (see under Mass excess in Glossary). As a resultno 7Be exists on Earth or in the meteorites, except by transient production by cosmic rays, and none has been seen (yet) in stars. But it is stable against breaking up into nuclear particles (as opposed to beta decay) and is an observable isotope in nature in two ways. 

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