Development of a regenerated Beryllium target and a thermal test facility for Compact Accelerator-based Neutron Sources

Abstract

Recently, the possibility to use compact accelerators coupled to high current ion sources for the production of intense low energy proton or deuteron beams has motivated many research laboratories to develop accelerator based neutrons sources for several purposes, including Neutron Capture Therapy (NCT). The NCT needs a high flux, about 10 9 n.cm-2.s-1, of thermal neutrons (E<10 keV) at the tumour site. Up to now, the NCT required neutron flux was mainly delivered by nuclear reactors. However, the production of such neutron flux is now possible using proton or deuteron beams on specific targets able to stand a high pow er (~15- 30 kW) on a small area (~10 cm2). This specific target design, materials and supports, has to cope with extreme physical constraints . The LPSC team has conceived an original solution formed by a thin (8 μm) rotating beryllium target depos ited on a graphite wheel and coupled with a beryllium sputtering device for periodic 9Be layer restoration. By means of 9Be (d,n) 10B nuclear reaction, this target irradiated by a 10- -20 mA deuteron beam (1.45 MeV) should produce the required neutron flux. In order to validate the target design of the neutron flux production and the beryllium target thermal capabilities, we built a 30 cm diameter rotating Beryllium target prototype and a compact electron beam line able to deliver a power density of 3kW/cm2.