Gamma spectrometry measurement of

Gamma spectrometry Measurement of gamma particles emitted by radioactive substances. 

On top of these linearity limitations, all of the electronic components of the pulse handling and measurement chain will be subject to time and temperature effects. Gamma spectrometry measurements of environmental samples can... 

Routine estimation of Ra is readily achieved by gamma spectrometry measurement of its short-lived daughter, Ac, which can be verified by values for other Th chain nuclides ( Pb, Bi and T1) obtained at the same time. Deriving values for Ra should be similarly straightforward however, there are several potential sources of error that can make accurate determination problematic. 

Bees themselves have also proved to be efficient indicators of environmental contamination gamma spectrometry measurements show a higher correlation, compared to honey, between Cs radioactivity in the bee matrix and ground deposition R = 0.95) (Figure 11.24). 

Gamma spectrometry measurements cannot, however, give a direct estimate of the Th activity unless equilibrium is assured or the sample history is known. 

In addition to instrumental improvements, various approaches have been used to improve the purity or geometry of sources of natural samples for gamma spectrometric measurement. For example, improvements in source preparation for " Th measurement in water and sediment samples by gamma spectrometry are discussed in Cochran and Masque (2003). It should be emphasized that one of the main advantages of gamma spectrometry is ease of use, since in many cases samples may be analyzed directly or with significantly reduced sample preparation compared to alpha, beta, or mass spectrometric techniques. 

Although not a very recent development, measurement of U-series isotopes by gamma spectrometry is worth a mention here because of its increasing application to the dating of bones. About 50 mg, or less, of bone is required for a TIMS U-series measurement, although a bone section is required if profiles are to be measured for the application of the D-A model. Understandably, museum curators are reluctant to allow the most valuable specimens to be cut or drilled, so the non-destructive measurement of a U-series date is extremely advantageous. 

In terms of atomic spectrometry, NAA is a method combining excitation by nuclear reaction with delayed de-excitation of the radioactive atoms produced by emission of ionising radiation (fi, y, X-ray). Measurement of delayed particles or radiations from the decay of a radioactive product of a neutron-induced nuclear reaction is known as simple or delayed-gamma NAA, and may be purely instrumental (INAA). The y-ray energies are characteristic of specific indicator radionuclides, and their intensities are proportional to the amounts of the various target nuclides in the sample. NAA can thus... 

Two sets of experiments were conducted using six radioactive tracers simultaneously. Starting concentrations are given in Table III. Radionuclides were eluted from the cells with ground-water solutions using a peristaltic pump. Effluent was collected at 90-min intervals by means of a fraction collector connected to the cell with small-bore Teflon tubing. Concentrations of the various isotopes in the effluent were measured by gamma spectrometry. 

After both sets of experiments were completed, the ground-water was drained from the cells and selective chemical extractions of the granite cell walls were performed. The cells were filled with 0.5 mol/L CaCl solution and stirred continuously for 72 h to displace exchangeable radionuclides. After a rinse with demineralized water to remove residual CaCl- solution, the cells were filled with KTOX solution and stirred ror 24 h to remove radionuclides associated with oxyhydroxides. All solutions were analyzed by gamma spectrometry to determine the amounts of radionuclides extracted. Residual activity was measured by direct gamma counting of the cells. 

Conventional decay-schemes studies do not seem appropriate, because of the complexity of the decay schemes, the errors to which they are subject (cf. the discussion of 8 Br above) and the large amount of time needed to carry them out. Direct measurement of the p-strength functions themselves, utilizing total-absorption y spectrometry and, where relevant, delayed-neutron-gamma coincidence techniques, promises to provide a means of producing the necessary information in a reasonable time. 

The measurement of natural gamma rays from rocks and minerals requires basically the same equipment as 7-ray spectrometry in neutron activation, the only difference being that large crystal or semiconductor detectors in a more sophisticated arrangement are necessary to record the low natural activity (Adams and Gasparini, 1970). 

Of the five stable Isotopes of zinc, only three ( Zn, Zn, and Zn) can be measured with (delayed gamma) Neutron Activation Analysis and hlgh-resolutlon gamma spectrometry. The required methodology for the measurement of Zn is the most stringent of the three isotopes and the necessary Radiochemical Neutron Activation Analysis has been developed and described in detail elsewhere (.8), The salient features of neutron activation of these three Isotopes are tabulated in Table li and from these, two points emerge First, with the availahility of thermal neutron... 

Nondestructive method (EMAA instrumental neutron activation analysis) based on the measurement of radioactivity of samples analyzed by high-resolution gamma spectrometry using the differentials of the rate of decay of the radionuclides analyzed in time [15]. NAA has several important advantages [15] ... 

NAA is preferred for the analysis of unique samples such as meteorite, the certification of reference materials, and quality assurance in analytical chemistry [21]. Definitive methods are based on the activation of samples, selective separation of analyzed radionuclides by column (ion-exchange) chromatography, and measurement by gamma spectrometry [15, 16, 19]. In definitive methods, radiochemical separation, co-precipitation, extraction, and ionic exchange guarantee the... 

K is transformed by emission to Ca. (89.05 %) and by electron capture to " °Ar (10.95 %) [24]. The measurement of activity can be analyzed in environmental samples, after drying and homogenizing, by gamma spectrometry with the use of energy spectrum of 1461 keV. In natural water samples, is measured using the Cherenkov counting technique [25, 26]. Thermal ionization mass spec-... 

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