Response of a diamond detector sandwich to 14MeV neutrons

Abstract

In this paper we present the measurement of the response of 50 µm thin diamond detectors to 14 MeV neutrons. Such neutrons are produced in fusion reactors and are of particular interest for ITER neutron diagnostics. Among semiconductor detectors diamond has properties most appropriate for harsh radiation and temperature conditions of a fusion reactor. However, 300-500 µm thick diamond detectors suffer significant radiation damage already at neutron fluences of the order of 10 14 n/cm 2 . It is expected that a 50 µm thick diamond will withstand a fluence of > 10 16 n/cm 2 . We tested two 50 µm thick single crystal CVD diamonds, stacked to form a "sandwich" detector for coincidence measurements. The detector measured the conversion of 14 MeV neutrons, impinging on one diamond, into α particles which were detected in the second diamond in coincidence with nuclear recoil. For 12 C(n, α) 9 Be reaction the total energy deposited in the detector gives access to the initial neutron energy value. The measured 14 MeV neutron detection sensitivity through this reaction by a detector of effective area 3×3 mm 2 was 5 × 10counts cm 2 /n. This value is in good agreement with Geant4 simulations. The intrinsic energy resolution of the detector was found to be 240 keV FWHM which adds only 10% to ITER's 14 MeV neutron energy spread.

High‐Pressure High‐Temperature Single‐Crystal Diamond Type IIa Characterization for Particle Detectors

“…For example, for spectrometric charged particle detectors on alternating current (AC) single‐crystal CVD diamond, an energy resolution of 0.27% has been achieved at the 5.489 MeV Am α‐line . Today, based on CVD diamond, the high‐efficiency thermal and fast neutron detectors are produced based on CVD diamond; microstrip, pixel, and 3D detectors for high‐energy physics and other fields are also being actively developed …”

Experimental characterisation of diamond-based neutron spectrometer

“…The comparison result is shown in figure 10. The differences in the compared pulse-height distributions can be explained by the inaccurate accounting of the neutron scattering processes and by the neglecting of the charge collection processes in the Geant4 model (as in the similar works [11,16,17]). The pulse-height scale and the energy resolution evaluated from the experiment with the DT-neutrons did not correspond to the same characteristics evaluated from experiment with the alpha-particles.…”

“…For such a distribution, the dependence of the right edge position on the neutron energy is non-linear. For its accurate determination, the modelling of the pulse-height distribution from diamond detector was performed using the Geant4 toolkit [14][15][16][17].…”

New neutron detections

“…Chemical Vapor Deposition (CVD) technique allowed to reduce dramatically the amount of B and N impurities (down to 10 −9 ) as well as crystal defects. This permits to build detectors with a large charge collection distance, resistant to very high neutron fluences [15].…”