Source Effects

Two source effects are discussed in this section absorption of particles in the source, and the effect of the backing material that supports the source. Both effects are always important in measurements of charged particles. In some cases, however, they may also be significant in X-ray or thermal-neutron measurements. [Pg.277]

Radioactive substances are deposited on a backing material in thin deposits. But no matter how thin, the deposit has a finite thickness and may cause absorption of some particles emitted by the source. Consider the source of thickness t shown in Fig. 8.13. Particle 1 traverses the source deposit and enters the detector. Particle 2 is absorbed inside the source so that it will not be counted. Therefore, source self-absorption will produce a decrease of the counting rate r. [Pg.277]

Source self-absorption may be reduced to an insignificant amount but it cannot be eliminated completely. It is always important for charged particles and generally more crucial for heavier particles ip, a, d, heavy ions) than for electrons. [Pg.277]

An approximate correction for self-absorption can be obtained if the source emits particles following a known attenuation law. As an example, consider a source with thickness / (Fig. 8.14) that has a uniform deposit of a radioisotope emitting /3 particles. Assume that the source gives S betas per second in the direction of the positive x axis. If self-absorption is absent, 5 betas per second [Pg.277]

Example 8.2 Assume that Cs was deposited on a certain material. The thickness of the deposit is 1 = 0.1 mm. Cs emits betas with = 0.514 MeV. What is the value of / for such a source The density of cesium is [Pg.278]

J. R. Gumming and L. H. Weinstein, Nitrogen. sources effects on A1 toxicity in nonmycorrhizal and mycorrhizal pitch pine (Pinus rigida). seedlings 1. Growth and nutrition. Can. J. Bot. 6S 2644 (1990). [Pg.295]

UNSCEAR. 1988. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources, effects and risks of ionization radiation. New York United Nations. [Pg.315]

A charge-transfer complex of diethyl chlorophosphate with DMF as the one-carbon source effects the cyclization of thiohydrazides into thiadiazoles 142 (Equation 50) <2004S17>. [Pg.593]

Figure 32.6 Chernobyl air plume behavior and reported initial arrival times of detectable radioactivity. Plume A originated from Chernobyl on April 26, 1986 Plume B on April 27-28 and Plume C on April 29-30. The numbers indicate initial arrival times 1, April 26 2, April 27 3, April 28 4, April 29 5, April 30 6, May 1 7, May 2 and 8, May 3. (From United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). 1988. Sources, Effects and Risks of Ionizing Radiation. United Nations, New York. 647 pp.)... [Pg.1683]

Data from United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). 1988. Sources, Effects and Risks of Ionizing Radiation. United Nations, New York. 647 pp. Aarkrog, A. 1990. Environmental radiation and radiation releases. Inter. Jour. Radiation Biol. 57 619-631. [Pg.1683]

Frewer, LJ. and Shepherd, R. 1994. Attributing information to different sources Effects on the perceived qualities of information, on the perceived relevance of information, and on attitude formation. Public Understand. Sci. 3, 385-401. [Pg.149]

Kumar, V., Rock, D.A., Warren, C.J., Tracy, T.S. and Wahlstrom, J.L. (2006) Enzyme source effects on CYP2C9 kinetics and inhibition. Drug... [Pg.246]

Philpot, R.M. et al. in "Sources, Effects and Sinks of Hydrocarbons in the Aquatic Environment" American Institute of Biological Sciences, 576 p., Washington, D.C., 1976. [Pg.76]

One of the central problems in air pollution research and control is to determine the quantitative relationship between ambient air quality and emission of pollutants from sources. Effective strategies to control pollutants can not be devised without this information. This question has been mainly addressed in the past with source-oriented techniques such as emission inventories and predictive diffusion models with which one traces pollutants from source to receptor. More recently, much effort has been directed toward developing receptor-oriented models that start with the receptor and reconstruct the source contributions. As is the case with much of air pollutant research, improvements in pollutant chemical analysis techniques have greatly enhanced the results of receptor modeling. [Pg.364]

External source (destructive physical injury e.g., motor vehicle accident) Internal source (effects of high blood pressure on arterial walls)... [Pg.187]

Ignition of Double-Base Propellants. II. Pre ignition Events and Source Effects , AIAAJoum 14 (8), 1111-17 (1976) CA 85, 162869... [Pg.523]

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