Abstract
A single crystal diamond (SCD) detector and a polycrystalline diamond (PCD) detector have been designed and fabricated using electronic grade CVD diamond. The fabricated detectors were tested for their dark current and X-ray photocurrent. It was found that the SCD and PCD detectors have superb signal to noise ratios (SNR) under X-ray irradiation from an Ag target with 10kV and 40kV accelerating voltage, 2000 and 7000 respectively for the SCD detector and 550 and 2000 for the PCD detector. The performance of these detectors using an 241Am α source was tested under different bias voltages and the results were benchmarked against a commercial SCD detector. The typical rise time of an α event in both of the fabricated detectors are about 1.2ns. The fabricated SCD detector has a 3.7% net energy resolution while that of the commercial detector is about 3.9%. The pulse height spectra are integrated and fitted to obtain the charge collection efficiency. For the fabricated SCD detector, this value is above 97% at bias 200V or beyond, which is 1-2% higher than that of the commercial detector at the same voltage. Finally, the fabricated PCD detector can also detect the presence of α particle although it only has a continuous and decreasing energy spectrum under α radiation. These results fully reveal that the fabricated SCD detector has good performance as a multifunctional detector for both X-ray and α radiation, and show great potential as neutron spectrometer as well.
Highlights
Due to the tremendous energy released during nuclear fusion, controlled thermonuclear fusion has been extensively and intensively studied for decades.1 The long history of magnetic confinement fusion research indicates that the Tokamak-Type is one of the most promising candidates for future controlled fusion devices
It is seen that the dark current is linear with the applied field for the fabricated single crystal diamond (SCD) detector but the polycrystalline diamond (PCD) detector is nonlinear over the whole voltage range measured and becomes approximately linear for the larger applied fields
When we connected the signal from the pre-amplifier directly to the oscilloscope and set it to trigger mode to scan for events continuously, it was observed that the pulse amplitudes of the recorded events from the fabricated SCD detector barely changes, while the amplitudes of the recorded events from PCD detector change constantly in time and most are low energy ones
Summary
Due to the tremendous energy released during nuclear fusion, controlled thermonuclear fusion has been extensively and intensively studied for decades. The long history of magnetic confinement fusion research indicates that the Tokamak-Type is one of the most promising candidates for future controlled fusion devices. The high quality of electronic grade SCD diamonds give further advantage for fabricating detectors, e.g. priming is not apparent and largely unnecessary, and polarization effects can be avoided. Detectors based on these diamonds are stable under the extreme environment of strong magnetic fields, high voltages or high temperatures. In the XRD spectrum of the SCD film, a single sharp peak at 119.5 degree corresponding to the diamond characteristic diffraction planes of (400) was observed. The PCD film diffraction peaks at 43.9 and 91.5 degrees, corresponding to the (111) and (311) planes and their intensities have a ratio 1/2.24. The FWHM of all peaks in both the SCD and PCD are less than 0.1 degree showing that both are well crystallized
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