Alpha half-life

Diamond, H., and R.F. Barnes Alpha half-life of Pu244 Physic. Rev. 101,... 

Absorption/Distribution - The mean alpha half-life of mitoxantrone is 6 to 12 minutes, the mean beta half-life is 1.1 to 3.1 hours, and the mean gamma... 

Lounsbury, M., and Durham, R. W., 1971, The alpha half-life of in Proc. Inti. Conf. Chem. Nucl. Data, Measurement and Applications. Canterbury, M. L. Hurrell, ed., Inst. Civil Engineers, London, pp. 215-219. 

Sargramostim s indications are shown in Table 6.4. Cellular division, maturation, and activation are induced through the binding of GM-CSF to specific receptors expressed on the surface of target cells. On 2-hour intravenous infusion, the alpha half-life is 12 to 17 minutes, followed by a slower decrease (beta half-life) of 2 hours. The manufacturer s label should be consulted for precautions. Additional indications for GM-CSF under study are as an adjuvant to chemotherapy and an adjuvant to AIDS therapy. 

The empirical Taagepera-Nurmia formula (O Eq. (2.61), Chap. 2) describes the alpha half-life as the function of alpha-energy and the atomic number of the daughter nucleus. O Figure 2.34 in Chap. 2 illustrates the relationship. 

For basic studies on weighable quantities of californium, the Cf isotope is used. Its alpha half-life of 351 4 years [2,3] makes it suitable for chemical/physical experiments, where weighable quantities of californium are required. The Cf isotope is available as an isotopically pure material from the decay of Bk (beta emitter, half-life of 320 days), the latter being the major berkelium isotope obtained from reactors ( Bk is also formed, but it has a 3.5 h half-life). To obtain Cf free of other californium isotopes, it is first necessary to separate berkelium chemically from the californium produced in a reactor, and then permit the Bk to decay to Cf, which can subsequently be chemically separated from the berkelium. Currently, up to 60 mg per year of Bk are produced in the HFIR at ORNL, which is sufBdent to provide multi-milligram amounts of Cf [4]. The only other known production of Bk, and hence isotopically pure Cf (excluding the use of a mass separator), is in the USSR. The quantity of these materials available in the USSR is believed to be less than that produced by the HFIR. 

Polonium-210 is a low-melting, fairly volatile metal, 50% of which is vaporized in air in 45 hours at 55C. It is an alpha emitter with a half-life of 138.39 days. A milligram emits as many alpha particles as 5 g of radium. 

Twenty five isotopes of polonium are known, with atomic masses ranging from 194 to 218. Polonium-210 is the most readily available. Isotopes of mass 209 (half-life 103 years) and mass 208 (half-life 2.9 years) can be prepared by alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron, but these are expensive to produce. 

Twenty isotopes are known. Radon-22, from radium, has a half-life of 3.823 days and is an alpha emitter Radon-220, emanating naturally from thorium and called thoron, has a half-life of 55.6 s and is also an alpha emitter. Radon-219 emanates from actinium and is called actinon. It has a half-life of 3.96 s and is also an alpha emitter. It is estimated that every square mile of soil to a depth of 6 inches contains about 1 g of radium, which releases radon in tiny amounts into the atmosphere. Radon is present in some spring waters, such as those at Hot Springs, Arkansas. 

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. 

Element 259-104 is formed by the merging of a 13C nuclei with 249Cf, followed by emission of three neutrons. This isotope has a half-life of 3 to 4 s, and decays by emitting an alpha particle into 255No, which has a half-life of 185 s. 

Element 106 was created by the reaction 249Gf(180,4N)263X, which decayed by alpha emission to rutherfordium, and then by alpha emission to nobelium, which in turn further decayed by alpha between daughter and granddaughter. The element so identified had alpha energies of 9.06 and 9.25 MeV with a half-life of 0.9 +/- 0.2 s. 

The acceptance of the name was premature because both Russian and American efforts now completely rule out the possibility of any isotope of Element 102 having a half-life of 10 min in the vicinity of 8.5 MeV. Early work in 1957 on the search for this element, in Russia at the Kurchatov Institute, was marred by the assignment of 8.9 +/- 0.4 MeV alpha radiation with a half-life of 2 to 40 sec, which was too indefinite to support discovery claims. 

The isotope produced was the 20-hour 255Fm. During 1953 and early 1954, while discovery of elements 99 and 100 was withheld from publication for security reasons, a group from the Nobel Institute of Physics in Stockholm bombarded 238U with 160 ions, and isolated a 30-min alpha-emitter, which they ascribed to 250-100, without claiming discovery of the element. This isotope has since been identified positively, and the 30-min half-life confirmed. 

Ernest O. Lawrence, inventor of the cyclotron) This member of the 5f transition elements (actinide series) was discovered in March 1961 by A. Ghiorso, T. Sikkeland, A.E. Larsh, and R.M. Latimer. A 3-Mg californium target, consisting of a mixture of isotopes of mass number 249, 250, 251, and 252, was bombarded with either lOB or IIB. The electrically charged transmutation nuclei recoiled with an atmosphere of helium and were collected on a thin copper conveyor tape which was then moved to place collected atoms in front of a series of solid-state detectors. The isotope of element 103 produced in this way decayed by emitting an 8.6 MeV alpha particle with a half-life of 8 s. 

In 1967, Flerov and associates at the Dubna Laboratory reported their inability to detect an alpha emitter with a half-life of 8 s which was assigned by the Berkeley group to 257-103. This assignment has been changed to 258Lr or 259Lr. 

Plutonium has a much shorter half-life than uranium (24.000 years for Pu-239 6,500 years for Pu-240). Plutonium is most toxic if it is inhaled. The radioactive decay that plutonium undergoes (alpha decay) is of little external consequence, since the alpha particles are blocked by human skin and travel only a few inches. If inhaled, however, the soft tissue of the lungs will suffer an internal dose of radiation. Particles may also enter the blood stream and irradiate other parts of the body. The safest way to handle plutonium is in its plutonium dioxide (PuOj) form because PuOj is virtually insoluble inside the human body, gi eatly reducing the risk of internal contamination. 

Polonium-210 decays to Pb-206 by alpha emission. Its half-life is 138 days. What volume of helium at 25°C and 1.20 atm would be obtained from a 25.00-g sample of Po-210 left to decay for 75 hours ... 

Half-life is the time taken to decrease the concentration of a drug to one-half its original value. There may be several phases in the elimination, and the most common is the so-called beta-phase. Alpha-phase is a distribution phase and gamma-phase is the terminal phase when the drug is finally leaving the tissues. 

From the alpha-activity remaining in the supernatant liquid after the final precipitation as a fluoride, it can be calculated, using 30,000 years as the half-life of 94239, that this salt of 94 has a solubility of the order of magnitude of 10 mg of the element per liter of 6 N HF solution. This value is necessarily somewhat tentative. 

All reactor-produced plutonium contains a mixture of several plutonium isotopes. The continuous decay of 241pu (14.8 year half-life) is the source of 241/. jhis isotope decays by alpha emission with the simultaneous emission of 60 kilovolt gamma rays in 80% abundance. In order to minimize personnel exposure, this element is removed from the metal prior to fabrication. 

Pyrethroids can also persist in sediments. In one study, alpha-cypermethrin was applied to a pond as an emulsifiable concentrate (Environmental Health Criteria 142). After 16 days of application, 5% of the applied dose was still present in sediment, falling to 3% after a further 17 days. This suggests a half-life of the order of 20-25 days—comparable in magnitude to half-lives measured in temperate soils. 

Th, Th and Po, all decay by alpha emission and are thus measurable by isotope dilution and alpha spectrometry (Ivanovich and Murray 1992). However, " Th is produced by the alpha decay of and in turn decays by beta emission to via the short-lived intermediate " Pa (half-life 1.18 m) ... 

There are two main sources of Rn to the ocean, (1) the decay of sediment-bound Ra and (2) decay of dissolved Ra in the water column. Radon can enter the sediment pore water through alpha recoil during decay events (see discussion in Porcelli and Swarzenski 2003). Since radon is chemically inert, it readily diffuses from bottom sediments into overlying waters. The diffusion of radon from sediments to the water column gives rise to disequilibrium between Rn and Ra, with ratios of ( Rn/ Ra) >1 due to the addition of excess Rn. This excess Rn is unsupported and so is rapidly diminished by decay. Therefore, the excess Rn signal is only resolvable where significant transport of Rn away from the sediment can occur over timescales that do not significantly exceed the half-life of Rn. 

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