Proton Recoil Telescope Based on Diamond Detectors for the Measurement of Fusion Neutrons

Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactors because of their proven radiation hardness. In comparison to the standard neutron diagnostics currently used (i.e., fission chambers, silicon based detectors, scintillators) CVD diamonds are less sensitive to y rays, which represents a huge background in fusion devices. Furthermore, their low leakage current provides a high energy resolution. A CVD diamond based detector has been proposed for the measurement of the 14 MeV neutrons from DT fusion reaction. The prototype was arranged in a proton recoil telescope configuration, featuring a plastic converter in front of the sensitive volume, in order to induce the (n, n) reactions which generate the recoil protons. The segmentation of the sensitive volume, achieved using two crystals with two dedicated electronic readouts, allowed to perform measurements in coincidence, which suppressed the neutron-carbon elastic scattering background. A preliminary prototype was assembled and tested at FNG (Frascati Neutron Generator), showing promising results regarding efficiency and energy resolution.