High-Temperature Diamond Detector for Neutron Generator Output Monitoring in Well Logging Applications

A high-temperature fast neutron detector has been developed for well logging applications. The developed fast neutron detector is based on a single-crystal diamond grown by chemical vapor deposition. Among many other advantages, diamond detectors are rugged, radiation hard, and stable under high temperatures. The diamond detector was evaluated for monitoring the fast neutron intensity of pulsed neutron instruments. Pulsed neutron instruments are employed to deliver formation thermal neutron capture cross section, carbon-to-oxygen ratio, and mineralogy information. The ability to monitor the neutron generator output and correct for fluctuations has a potential for improving the measurement accuracy. Experimental results presented in the article include comparison of spectra acquired in the 25–175 °C temperature range, comparison of spectra acquired in various environments, and normalization of gamma-ray count rates to neutron generator output in a pulsed neutron gamma-ray logging tool. The results clearly show usability of diamond detectors for fast neutron measurements in pulsed neutron instruments.