Prompt gamma

Because of the increasing emphasis on monitoring of environmental cadmium the detemiination of extremely low concentrations of cadmium ion has been developed. Table 2 Hsts the most prevalent analytical techniques and the detection limits. In general, for soluble cadmium species, atomic absorption is the method of choice for detection of very low concentrations. Mobile prompt gamma in vivo activation analysis has been developed for the nondestmctive sampling of cadmium in biological samples (18). 

This can result in a radioactive product from the A(n, t)A reaction where A is the stable element, n is a thermal neutron, A is the radioactive product of one atomic mass unit greater than A, and y is the prompt gamma ray resulting from the reaction. A is usually a beta and/or gamma emitter of reasonably long half-life. Where access to a nuclear reactor has been convenient, thermal neutron activation analysis has proven to be an extremely valuable nondestructive analytical tool and in many cases, the only method for performing specific analyses at high sensitivities... 

Of these neutron interactions, those that produce prompt-7 rays were evaluated as the most feasible for mine detection. As discussed in the Introduction, we define a prompt 7-ray as one which is produced as a direct result of the primary neutron interaction, usually within nanoseconds of that initial event. Such reactions are obviously attractive because they can best satisfy the desired rapid sweep rate over a minefield. The three specific neutron-prompt gamma reactions that were intensively investigated by the US Army are listed below ... 

Lindstrom RM (1998) Reference material certification by prompt-gamma activation analysis. Fresenius J Anal Chem 360 322-324. 

Z.B. Alfassi and C. Chung (eds), Prompt Gamma Neutron Activation Analysis, CRC Press, Boca Raton, FL (1995). 

Figure 2.13 Schematic diagram of the nuclear processes involved in neutron activation analysis. Prompt gamma neutron activation analysis (PGNAA) occurs within the reactor delayed gamma NAA (DGNAA) occurs at some remote site. (After Glascock, 1994 Fig. 1. John Wiley Sons Limited. Reproduced with permission.)...

The y particle is emitted virtually instantaneously on the capture of the neutron, and is known as a prompt y - it can be used analytically, in a technique known as prompt gamma neutron activation analysis (PGNAA), but only if such y s can be measured in the reactor during irradiation. Under the conditions normally used it would be lost within the nuclear reactor. In this reaction, no other prompt particle is emitted. The isotope of sodium formed (24Na) is radioactively unstable, decaying by beta emission to the element magnesium (the product nucleus in Figure 2.13), as follows ... 

Prompt gamma neutron activation analysis (PGNAA)... 

Glascock, M.D., Spalding, T. G., Biers, J. C., and Corman, M.F. (1984). Analysis of copper-based metallic artefacts by prompt gamma-ray neutron activation analysis. Archaeometry 26 96-103. 

Ouri, Y., Shirari, N. and Ebihara, M. (2003) Chemical composition of Yamato (Y)980459 and Y000749 Neutron-induced prompt gamma-ray analysis study. Antarctic Meteorite Research, 16, 80—93. 

Revay, Zs., Molnar, G.L., Standardisation of the prompt gamma activation analysis method, Radiochim. Acta, 91, 2003, 361-369. 

The prompt gamma-rays emitted following neutron or charged particle interactions with the target nuclide may be used as a basis for non-destructive analyses. The important advantage of this technique is that the determination does not depend in any manner on the half-life of a product radionuclide. In fact, using this technique, the product nuclide need not even be radioactive. Many conventional activation determinations are limited in their sensitivities by short half-life product radionuclides, or the fact that the most abundant or highest cross section isotope of the element to be determined leads to a stable product on irradiation. 

Pierce, T. B., P. F. Peck, and W. M. Henry Determination of Carbon in Steels by Measurement of the Prompt Gamma-Radiation Emitted During Proton Bombardment. Nature 204, 571 (1964). 

Layer charges can be calculated from mineral and chemical composition. Mineral composition can be determined by the comparison of x-ray diffraction and thermal analytical and surface area studies. Chemical composition is determined by a total chemical analysis of the sample. In the classical method, chemical analysis is made after acidic dissolution (Ross and Hendricks 1945). Nowadays, nondestructive analytical methods (e.g., electron microscopy, prompt gamma activation analysis, etc.) are also applied. Chemical composition is usually given as oxides (e.g., Si02, A1203, etc.). The cations are divided into three groups ... 

Molnar, G. L., and R. M. Lindstrom. 1998. Nuclear reaction prompt gamma-ray analysis. In Nuclear methods in mineralogy and geology Techniques and applications. Ed. A. Vertes, S. Nagy, and K. Stivegh. 145-164. New York Plenum. 

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