A pulsed-neutron activation analysis system capable of handling and analyzing short-lived radioisotopes with half-lives as short as 1 to 2 sec was developed. Since a single reactor pulse will induce more activity for short-lived neutron reaction products than continuous irradiation to saturation at a normal reactor power level, experimental procedures were formulated to analyze quantitatively a few important fast neutron reactions with short-lived products and to establish limits of detection for these reactions using this system. To augment the fast neutron reactions, a cadmium-lined in-core terminus was utilized to reduce (n,γ) interference reactions.

The reactions analyzed were 16O(n,ρ)l6N,19F(n,α)16N, 19F(n,γ)20F, 23Na(n,ρ)23Ne, 23Na(n,α)20F,34S(n,ρ)34P, and 31P(n,α)28Al. The detection limits which were attained for these reactions utilizing this system were: 54.8 µg for 16O, 0.23 and 0.19 µg for 19F, 1.8 and 8.0µg for 23Na, 150 µg for 34S, and 2.6 µg for 31P. Most of these limits are an order of magnitude or more lower than those reported by users of the Cockroft-Walton neutron generators usually employed for these analyses.