Alpha-particle Detectors for APT Neutron Generators

APSTEC has developed and produced several types of position-sensitive semiconductor detectors for installation into the high static vacuum of the neutron generator.

This technology is protected by the patent of Russian Federation № 2247411 (of 23.04.2004).

Detectors have been tested inside a large NG400 neutron generator at Radium Institute. It remained operational after being subjected to an integral α-particle flux of 10¹⁴, which corresponds to about 5000 hours of work of a portable neutron generator with intensity 10⁸ n/s into 4π.

These detectors have been installed and tested inside a portable DT neutron generators of the NG27 series produced by VNIIA.

Nine-segment α-detector with dimensions
of each segment 1 x 1 cm²

Nine-ring α-detector

36-pixel α-detector and a standard APSTEC preamplifier

All detectors come with a specially designed preamplifiers, which are protected against huge interference from the working neutron generator. Thresholds of individual preamplifiers can be monitored and set remotely. Signals from all preamplifiers are fed into a programmable logic device (PLD), which performs pileup rejection, determines the number of the hit segment, forms the output timing signal, and passes this information to the DAQ in digital form.

have close to 100% intrinsic efficiency to 3 MeV alpha-particles;
produce 10 ns-wide pulses, which correspond to a maximal load of about 10⁷ α/s (with ~10% pileup);
do not affect the sealed vacuum and withstand heating during sealing of the NG vacuum tube;
were tested inside a large NG400 neutron generator at Radium Institute; remained operational after being subjected to an integral α-particle flux of 10¹⁴, which corresponds to about 5000 hours of work of a portable neutron generator with intensity 10⁸ n/s into 4π;
are not sensitive to X-rays. Special measures are taken to make detectors insensitive to light, scattered deuterons and electrons.