Intense beams of radioactive nuclei

Most research reactors, for example, IBR-2, IBR-30 (Dubna), and BR-10 (Obninsk), have more than ten channels. It is shown theoretically and experimentally that one of these channels can be used as a source of heavy radioactive ions. This substantially extends the range of applications of these reactors in physical investigations. A method based on the electrostatic extraction of ions is considered. This method makes it possible to obtain isotopically pure beams of radioactive nuclei with an intensity of about 10{sup 10} nuclei/s and higher by exposing gaseous and solid targets to reactor neutrons. Following neutron capture by a nucleus, the atom is ionized with a certain probability as the result of conversion of a photon produced in the reaction (n, {gamma}) on an electron or as the result of ensuing K capture or {beta} decay of the nucleus that captured the neutron. The radioactive ions produced are extracted from the volume by an electric field and are then accelerated or deposited on an appropriate electrode. It is shown experimentally that, for a proper choice of the target geometry, the collection coefficient of {sup 125}I ions for a gaseous target containing {sup 124}Xe and for a solid target (containing, for example,more » {sup 181}Ta) amounts to about 50%. 14 refs., 2 figs.« less