A system for activation analysis at small research reactors

Abstract

A simple but highly effective rabbit system is made from an aluminum in-core part, inexpensive plastic tubing and an industrial compressed air generator. Large sample containers have a volume of 25 ml. Smaller containers of 5 ml automatically separate from a transport capsule. A transport time of below 0.5 second enables fast neutron activation analysis (FNAA). A software implementation of a Loss-Free Counting multi-channel analyzer, storing immediately into the multi-megabyte memory of a low-cost 486 or Pentium type PC, enables the real-time control of a rabbit system as well as the collection of up to 1000 pairs of simultaneously recorded loss-corrected and non-corrected spectra of 16 k channels each, in a true sequence without time gaps in between, at throughput rates of up to 200 kc/s. By automatically adapting the noise filtering time to individual pulse intervals, the Preloaded Digital Filter (PLDF) combines low- to medium-rate resolutions comparable to those of high-quality Gaussian amplifiers with throughput rates of up to 100 kc/s, and high-rate resolutions superior to those of state-of-the-art gated integrator systems. The combination of rabbit system, PLDF and software based multi-channel analyzer provides a low-cost but powerful solution for NAA at Triga reactors in developing countries.