Possible isotope separation by a process of nuclear excitation by electron transition

This report deals with isotope separation based on a process of nuclear excitation which accompanies transition of an orbital electron. This phenomenon is theoretically predicted in 1982, published in 1973 and designated as NEET (nuclear excitation by electron transition) by the present author. This process is triggered by an energy accumulated in the cloud of orbital electrons which is offerred to the atomic nucleus under certain conditions, resulting in an excited state in the nucleus. Recently the phenomenon has been demonstrated experimentally in some nuclides, including 189Os, 237Np, 235U and 197Au. The NEET process depends on the nuclear-level structures of atoms. For the same element, therefore, it can take place in an isotope while it cannot in another. For example, nuclear excitation occurs in 235U by a NEET process while it is completely impossible in 238U. This indicates that isotope separation of uranium can be performed by taking advantage of this difference. In the first part of the report it is insisted that mass analysis (or isotope identification) can be carried out by using the NEET process without determining the difference in mass. Then, the theory for the NEET process is described, and the required conditions for the process is discussed. Details of the process are described for 189Os, 237Np, 235U and 197Au. Some observations are also shown. (Nogami, K.)