Patent Number: 040597695
Section: description

For a better understanding of the present invention, the following are specific Examples illustrating the method of preparing the radiation source according to the invention. EXAMPLE 1 A weighed portion of 165 mg of ground Te.sup.124 was placed into a 100 ml beaker and mixed with 3 ml of a 5N solution of KOH. The mixture was heated to a temperature of 60 to 70.degree. C and a 30% solution of H.sub.2 O.sub.2 was added thereto under stirring. Therewith, an intensive oxidation of the tellurium occurred with the formation of K.sub.2 H.sub.4 TeO.sub.6 which is completed after 10-15 minutes; the excess of hydrogen peroxide is then decomposed by heating at reflux. The potassium tellurate solution was diluted with distilled water to 50 ml and gradually mixed with a solution of 1.63 g of magnesium sulphate (MgSO.sub.4.7 H.sub.2 O) in 30 ml of water. In doing so, a mixture of magnesium tellurate with magnesium hydroxide precipitated. To minimize the adsorption of impurities and enlargening of the precipitate particles, the mixture was boiled, right after precipitation, for 10-15 minutes and the residue, without allowing the mixture to be cooled, was separated on a dense paper filter under suction. The residue was washed with several portions of hot water till no SO.sub.4.sup.= ions were detected. Then, the residue was washed with 10 ml of absolute ethanol and 40-50 ml of diethyl ether, whereafter air was purged therethrough for 5-10 minutes. The residue was dried at a temperature of from 120.degree. to 140.degree. C, placed into a corundum crucible and calcined for 2 hours at a temperature within the range of from 900.degree. to 1,000.degree. C. The calcined residue of 5MgO.Te.sup.124 O.sub.3 was ground, sealed into a quartz ampule and irradiated for 360 hours in a reactor with a flux of 3 to 10.sup.13 thermal neutrons/cm.sup. 2 sec. The resulting 5MgO.Te.sup.125m O.sub.3 was annealed at a temperature within the range of from 900 to 1,000.degree. C for 6 hours, whereafter it was gradually cooled to room temperature. As a result, a radiation source was obtained with an activity of 100 mC and with a natural width of the emission line. EXAMPLE 2 A weighed portion of 500 mg of ground Te.sup.124 was taken for the experiment. Further operations were performed in accordance with the procedure of Example 1, excluding the manufacture of the source 5MgO.Te.sup.125m O.sub.3 per se. To this end, a weighed portion of 100 mg of 5MgO.Te.sup.124 O.sub.3 was placed into a quartz ampule. Irradiation was effected in the reactor with a flux of thermal neutrons of 8.multidot.10.sup.4 thermal neutrons/cm.sup. 2 sec for 500 hours. Annealing of the resulting 5MgO.Te.sup.125m O.sub.3 was conducted at a temperature of 800.degree. C for 7 hours. Further operations were similar to those of Example 1. Two sources were prepared from the thus-prepared active compound: the former with an activity of 1C for experiments of nuclear coherent dissipation on tellurium single cyrstals and the latter with an activity of 200 mC for experiments on resonance absorption. EXAMPLE 3 The experiments in this Example performed in accordance with the procedure of Example 1, with the only difference that annealing of 5MgO.Te.sup.125m O.sub.3 was conducted at a temperature of 600.degree. C for 10 hours. As a result, a radiation source was obtained with activity of 100 mC and with a width of the emission line slightly more than the natural one: 2 .GAMMA. = 6 mm/sec.