Transmission type slow positron beam generating device

摘要

In a slow positron beam generating device comprising a target member (11) having a beta decay radioisotope producing function for producing, when an incident surface (11a) of the target member is irradiated by accelerated particles (10 ), beta + decay radioisotopes due to nuclear reaction within the target member so that the beta + decay radioisotopes emit fast positrons around the decay radioisotopes, a moderator ( 12 ) is disposed nearer beta + to an opposite surface (11b) of the target member than the incident surface and has a fast positron moderating function for moderating into slow positrons the fast positrons emitted from the opposite surface. The opposite surface is opposite to the incident surface. An ejecting electrode (13) ejects the slow positrons as a slow positron beam (14). Use may be made of a different target member having not only the beta + decay radioisotope producing function but also the fast positron moderating function in order to remove the moderator from the device. In this case, the ejecting electrode is disposed nearer to the opposite surface of the different target member than the incident surface of the different target member.