Response of a Diamond detector to Energetic Alpha particles and Protons

Measuring the energy and production rate of charged fusion products such as protons, tritons and alpha particles in a tokamak fusion plasma as a function of time and position provides important information on the energetic particle distribution function. Silicon surface barrier (SSB) detectors have traditionally been used to detect these particle in nuclear physics experiments but their use in tokamaks is limited due to radiation damage and their temperature sensitivity which can strongly affect the energy resolution and the detection efficiency. Diamond based surface barrier could be a valid alternative as diamond is an intrinsic semiconductor with a much larger band-gap than silicon.

We present a comparative study of the detector response of a single crystal chemical vapor deposition diamond detector with an active area of 3.8 mm² and a 120 μm depletion depth and a SSB with an active area of 50 mm² and a depletion depth of up to 300 μm. We measured the energy resolution using a high-resolution ²⁴¹Am source with a rate of 4.2 kBq and varied the detector temperature over a temperature range of 70^o C. Using a 4 MeV proton beam from the John D. Fox Superconducting Linear Accelerator Laboratory at Florida State University we measured the responses of both detectors to protons for particle rates up to 400 kHz. Results will be presented and discussed.