Rays, alpha

Gr. aktis, aktinos, beam or ray). Discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902. Occurs naturally in association with uranium minerals. Actinium-227, a decay product of uranium-235, is a beta emitter with a 21.6-year half-life. Its principal decay products are thorium-227 (18.5-day half-life), radium-223 (11.4-day half-life), and a number of short-lived products including radon, bismuth, polonium, and lead isotopes. In equilibrium with its decay products, it is a powerful source of alpha rays. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300-degrees G. The chemical behavior of actinium is similar to that of the rare earths, particularly lanthanum. Purified actinium comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.6-year half-life. It is about 150 times as active as radium, making it of value in the production of neutrons. 

Alpha-gras, n. alfa grass, esparto, -milchsaure, /. (,o -)lactic acid, -naphtol, n. alpha naphthol, a-naphthol (l-naphthol). -strahlen, m.pl. alpha rays, -zellstoff, m. alpha cellulose. Alpranken, f.pl. bittersweet (Solanum dulcamara). 

The half-lives of the elements vary widely, as shown in Table 3.2. Some isotopes, nitrogen-14 for example, are stable and experience no natural radioactive decay. However, bombarding even a stable element with energetic alpha rays can cause transmutation. Rutherford discovered the proton when he created hydrogen from a stable isotope of nitrogen. 

Light-silver-colored element generated from a plutonium isotope (241Pu) by beta decay. Never detected in nature. Chemically similar to Europium. A few tons have been produced throughout the world through regeneration of fuel rods. Americium is a good source of alpha rays. Hence it is suitable to measure thicknesses, as a detector in smoke alarms, and for the activation analysis of the tiniest amounts of substances. 

A stream of alpha particles is sometimes called an alpha ray. A stream of beta particles is called a beta ray. A gamma ray is composed of a stream of gamma particles. 

Preliminary studies, already, resulted in a dose response curve which rises sharply up to about 0.5 mGy/month and then flattens into a plateau (Figure 1). In the dose range up to 0.3 mGy/month only a small part (about 0.014 mGy/month) was due to internal alpha exposure, whereas at higher doses more and more the exposure to alpha rays were dominant. 

It is unknown whether and to what amount these substances would induce chromosome aberrations according to their toxicity without the effect of irradiation. Therefore the knowledge of the effect of the alpha rays of radon and daughters on chromosomes is still missing. 

In the blood cultures Pb-214 and Bi-214 decay completely within four hours. The dose due to their disintegrations can be calculated according to the following equations. Only the alpha rays of Bi-214/Po-214 have to be taken into consideration, because the doses due to beta and gamma rays are neglectible. 

No calculation of the RBE of the alpha rays at this very low dose range can be made, as no in vitro study was carried out with x- or gamma rays at such low dose levels. The lowest dose of x-rays with which a chromosome aberration study has been carried out was 4 mGy (Pohl-Riiling et al.t 1983) A very rough estimation of the RBE at doses between 2 and 4 mGy yield a value between 2 and 3 ... 

Walling, has discovered processes for releasing atomic energy, bombarding beryllium with alpha rays, and imagines an array of idealistic and even spiritual results of atomic energy that were much the same as those elaborated by Soddy in the Interpretation of Radium twenty-five years earlier ... 

Allyltin compounds, reaction with hexa-fluoroacetone, 30 232-233 Al NMR spectroscopy, 36 433-436 Alpha rays, kinetic data on, 3 202-203 Alumina... 

Beginning in 1922 she published a long series of excellent researches on polonium, in which she determined the velocity of its alpha-rays and the distribution of their lengths, and observed their ionizing power, the oscillations in their paths, and the homogeneity of their initial velocity. In 1923 she used an original method to determine the range in air of its alpha-particles. 

Mile. Curie s doctor s dissertation in 1925 was entitled Investigation regarding the alpha rays of polonium. With the help of various collaborators, including F. Behounek, Mile. Chamte, J. d Espine, G. Fournier,... 

Their joint papers on The numbers of ions produced by alpha rays of radium C in air were published in the Comptes rendus in 1928. In the following year they investigated the nature of the absorbable radiation which accompanies the alpha-rays from polonium. In 1930 M. Joliot presented his thesis for the doctorate, which was entitled The electrochemistry of the radio-elements, and Mme. Joliot continued her study of polonium (123). 

M. and Mme. Joliot showed that boron and lithium, when they are bombarded with alpha-rays from polonium, also emit penetrating radiations (126). Their work gave early evidence of the probable existence of the neutron, a hypothesis which has since been fully verified by the researches of Professor James Chadwick, the 1935 Nobel laureate in physics (127). 

Since the alpha-ray impacts shattered only a minute proportion of the total number of atoms of boron, aluminum, or magnesium, the chemical identification of the products was extremely difficult. These indefatigable workers, however, accomplished even this. Although it would have been impossible to identify the products simply by ordinary chemical means, the Joliots were able to take advantage of the radioactive nature of the products formed. Since they had good reason to believe that the boron atom had captured a helion and ejected a neutron and that the new element was therefore probably an isotope of nitrogen, they heated some bombarded boron nitride with caustic soda and found that the liberated... 

Curie, I., F. Joliot, and P. Savel, Radiations excited by alpha rays in light... 

Note Beta rays consist of a stream of negatively charged particles (electrons) emitted from radioactive substances with the velocity of light (186000 miles/sec or 2.99 10 °cm/sec). There are also alpha rays, which consist of a stream of positively charged particles emitted from radioactive substances with a speed of 20,000 miles/sec (1.922x10 cm/sec)... 

Acetylene Condensation and Polymerization Products may be obtained by subjecting acetylene to the action of heat, light electrons, alpha-rays, elec discharge, etc with or without catalysts (Ref 1, i892-3ll One such products is cuprene(qv), which is a condensation product of acetylene and not a polymer as it is usually called. The real polymerization product of acetylene is... 

The three most common forms of radiation coming from a radioactive substance are called by the first three letters of the Greek alphabet, OC, (5, J-—alpha, beta, and gamma. In a magnetic field, alpha rays bend one way, beta rays bend the other way, and gamma rays do not bend at all. Note that the alpha rays bend less than do the beta rays. This happens because the alpha particles have more inertia (because they have more mass) than the beta particles. JThe source of all three radiations is a radioactive material placed at the bottom of a hole drilled in a lead block. 

Alpha and beta rays are deflected in opposite directions in a magnetic field because they are oppositely chaiged—alpha rays are positive and beta rays are negative. Gamma rays have no electric charge and are therefore undeflected. 

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