Gadolinium isotopes

The 58-0-keV resonance in Tb suffers from the disadvantage of a very large natural linewidth (36 mm s ). Initial measurements in 1966 used both the Gd and Dy parents (see Fig. 17.14) in the form of the respective sesquioxides, the gadolinium isotope giving the better results (88]. A resonance was found in Tb407, Tb2(C03)3, and Tb metal at 80 K. However, as... 

In a second aliquot of the same sample, the concentrations of the burnup monitor Nd and of the gadolinium isotopes in irradiated UO2—Gd20j fuel can also be determined. In this procedure, the rare earth elements are first separated from uranium, plutonium and the fission products by anion exchange from hydrochloric acid solution by addition of known amounts of Nd and Gd spikes to the sample solution, correction for losses of both rare earth elements during the separation process can be made. In the second step, the neodymium and gadolinium fractions are isolated from the other rare earth elements by cation exchange using... 

Zwicky, H.-U., Acme, E. T., Bart, G., Petrik, F., Thomi, H. A. Evaluation of the radial distribution of gadolinium isotopes in nuclear fuel pins by secondary ion mass spectrometry (SIMS). Radiochim. Acta 47, 9-12 (1989)... 

Natural gadolinium is a mixture of seven isotopes, but 17 isotopes of gadolinium are now recognized. Although two of these, 155Gd and 157Gd, have excellent capture characteristics, they are only present naturally in low concentrations. As a result, gadolinium has a very fast burnout rate and has limited use as a nuclear control rod material. 

Silvery, artificial element generated by beta decay from a plutonium isotope (239Pu). Chemically similar to gadolinium. Like Eu and Gd, Am and Cm are difficult to separate. It can be produced in kilogram amounts. The most common isotope is 244Cm with a half-life of 18.1 years. Is used for thermoelectric nuclide batteries in satellites and pacemakers. It is strongly radioactive and hence also suitable for material analysis. 

HPLC-ICP-MS and CE-ICP-MS, are compared with the table values and theoretical results. 155Gd is the most highly abundant nuclide. Compared to the isotope pattern in natural samples more light gadolinium nuclides with a typical isotopic pattern were formed by the irradiation of with high energy protons. 

Table II summarizes the losses we experienced at each step of the target preparation procedure. As the table shows, the most inefficient aspect of our technique is the isotope separation step. Normally, we expect 30% recovery with isotope separation of gadolinium, but this level was obviously not obtained in this particular case. With other rare-earth materials, such as europium and samarium, the expected isotope separation recovery is > 50% and can reach levels as high as 70%. Therefore, allowing for similar chemistry losses, we expect that in those selected cases where isotope separation recoveries are 50%, the amount of initial material required to make a reasonable number of usuable targets can be as low as 100 yg. The amount of intial material required can also be reduced somewhat by paying more attention to increasing the efficiencies of the wet-chemistry yields.

The chemical yields were determined by gamma-counting techniques. The sample contained a number of radioactive isotopes of gadolinium prior to isotope separation. 

Using different membranes and various membrane techniques, isotopes of chlorine [155], carbon [156], lithium in aqueous solutions [157,158], and uranium in CH4 [158,159] were separated. Isotopes of gadolinium and neodymium were separated in hybrid system of nanofiltration/complexation [50]. 

Radioactive isotopes can also be produced artificially when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. Twenty-four artificial radioactive isotopes have been produced. Some of these are used in medicine. For example, gadolinium-153 is used to study the composition of bones. The radiation it gives off acts like X rays, penetrating the bones to reveal the minerals present. 

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