Wyatt W. Givens

CYCLIC ACTIVATION ANALYSIS.

Abstract Cyclic activation analysis is a technique which utilizes very efficiently a low-output, pulsed source of neutrons and short-lived radioactivities for analytical purposes. With this technique radioactivities having half lives of a few minutes to as short as a few milliseconds can readily be used as a basis for elemental analysis. This paper presents a mathematical analysis of cyclic activation, some experimental studies verifying the mathematical predictions, application of the technique to a specific analysis problem, and some suggested areas where cyclic activation could possibly be used to good advantage.

Uranium assay logging using a pulsed 14-Mev neutron source and detection of delayed fission neutrons

An in‐situ uranium assay logging system has been developed that measures directly and quantitatively the uranium concentration in the formation surrounding a drill hole. System operation is based on the DFN (delayed fission neutron) method which involves (1) bombarding a formation with short duration bursts of neutrons from a pulsed‐neutron generator to induced fission in any uranium present; (2) separating delayed fission neutrons, from source and prompt fission neutrons, by waiting a few milliseconds after each neutron burst before activating the neutron counter system; (3) deactivating the neutron counter system before the beginning of the next neutron burst; and (4) repeating this bombard‐wait‐count cycle a sufficient number of times to accumulate a statistically acceptable number of the delayed neutron counts. The DFN logging method has been used routinely in our field operations for several years, and it has successfully overcome one of the most perplexing problems encountered in uranium exploration...