Chemical vapor deposited diamond radiation detectors for ultrahigh radiation dose-rate measurements: Response to subnanosecond, 16-MeV electron pulses

Conductivity modulated devices, similar to photoconductors in operation, for use as radiation detectors were fabricated from polycrystalline chemical vapor deposited diamond films. These detectors were designed to operate under extremely high radiation fields with a large dynamic range in both response and speed. Two types of detectors were studied: a parallel-plate device and a surface device (SDT). The radiation used to excite these detectors was minimum ionizing electrons with an energy of 16 MeV and a nominal pulse width of less than 25 ps. The response time of all detectors was less than 45 ps. The sensitivity of the detectors was in the range 10(-5)-10(-6) A/W. Over the operating range of the detectors, signal saturation was not observed because to the signal size was small in comparison to the applied bias voltage. The detectors appeared to be linear with dose and dose rate over two orders of magnitude, and for dose rates up to 10(13) rad/s. Long-lived signal decay tails contributed to much less than 1% of the signal. The response of a SDT detector appeared to be independent of the orientation of the detector to the incident beam direction when the excitation source is minimum ionizing. It appears that the dose-rate linearity may be extended to a range greater than 10(13) rad/s. (C) 1995 American Institute of Physics.