Positron beams from small accelerators and status of a novel positron storage project

16th International Conference on Positron Annihilation

Weber, M.H.^1 ; Riley, B.D.^1 ; Baker, C.J.^1 ; Lynn, K.G.^1

Center for Materials Research, Dana Hall 102, Washington State University, Pullman, WA 99164-2711, United States^1

关键词: CVD Diamond;    Defect generation;    Deuteron energies;    Direct current;    Intense beams;    Positron beams;    Positron emitters;    Rapid-heating;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/443/1/012081/pdf
DOI  :  10.1088/1742-6596/443/1/012081

来源: IOP

【 摘 要 】

Positrons are generated by an intense beam of deuterons. Deuterons with energies up to 3 MeV and 300 μA intensity or 1000 W power are guided onto a carbon target. The (d,n) reaction converts12C into the positron emitter13N. In one version a CVD diamond target is rotated behind a W foil moderator after irradiation. Rapid heating of the diamond and defect generation limits this method to deuteron power 13N molecules are released had must be condensed behind a moderator. Graphite is employed for higher power doses. External direct current or e-beam heating are used to reach temperatures in excess of 2000 K when nitrogen is released from graphite. Efforts to maximize the release of13N containing molecules as well as the goal to accumulate positrons in a novel trap design are discussed. Up to 75% of the activity was released at 2 MeV. This decreases with deuteron energy.