A compact neutron detector for the geology application

A compact neutron detector has been designed and built for a geology experiment. The detector had to fit inside a 1.5-in-diameter borehole in a large block of concrete. A gas-filled, 1-in-diameter /sup 3/He tube was attached to a 1-in-diameter electronics preamplifier package. The electronics package consists of a cylindrically shaped, high-voltage section and a single-channel analyzer with a buffered output. The low-voltage components are mounted on a printed-circuit board. The circuit board and the high-voltage section are attached to a semicylindrical base. The outputs consist of a light-emitting diode for visual observations and a fixed-width, TTL (transistor transistor logic)-compatible pulse for a counter. This internal assembly is equipped with coaxial connectors and slips into a thin-walled tube that serves as the preamplifier housing. Power for the detector is supplied by an external, high-voltage supply and a 5-VDC supply.<
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