Optimization of 178m2Hf Isomer Production in Spallation Reactions

摘要

After successful observation of gamma-emission from the 31-yr isomer of 176Hf induced by x-ray irradiation. the scientific interest for the triggering of long-lived nuclear spin isomers has greatly increased. We observed great efficiency of the triggering with low-energy (<20 keV) x-rays inducing the decay of 178m2Hf isomers that stresses all models. which might have been able to predict such an effect. Thus, there is a necessity to produce research lab-sized quantities of 178m2Hf isomers and in such a manner that the isomer samples could be used in research experiment as soon as possible. Since the production of 176m2Hf isomers will obviously be very expensive, careful and detailed analysis for the optimization of such production must be performed. The objective of this proposal is to find the most effective way of 178m2Hf isomer production for research uses and define the main parameters of nuclear facilities needed for that. Such research must minimize the risk of non-optimal production of 178m2Hf and can lead to significant cost savings. As a result of such research, two or three spallation reactions, which would happen to be the most promising for effective production of small quantities of the 178m2Hf isomers, shall be chosen. For each of them all advantages and disadvantages will be listed. So one would be able to select, taking into account the available nuclear facilities and the accepted costs, the most suitable nuclear reaction needed to produce these small quantities of the 178m2Hf isomer. All the results of our research will be presented and discussed at scientific conferences and workshops and published in 0pen scientific periodicals.