The Measurement of Short-Lived Delayed Photoneutrons from Fission-Fragment Gamma Rays of 235U in Heavy Water
- 1 April 1968
- journal article
- research article
- Published by Taylor & Francis in Nuclear Science and Engineering
- Vol. 32 (1) , 49-55
- https://doi.org/10.13182/nse68-a18823
Abstract
The kinetic equations for a heavy-water-moderated reactor have terms describing the production of neutrons in the photodisintegration of deuterons. A technique has been developed for the measurement of these short-lived delayed-photoneutron groups. A 235U target was placed in the center of a sphere of D2O and a chopped neutron beam from the VPI reactor was allowed to impinge on the target. The time for a revolution of the chopper varied from 86.4 to 0.463 sec in six steps and there are two pulses per revolution. The ratio of “beam-on” target time to “beam-off” target time is 1 to 16.5. During the beam-off time interval, the production rate of delayed neutron and delayed photoneutrons as a function of time was stored in a time base multichannel analyzer. The half-lives of two new delayed-photoneutron groups were determined to be 7.39 × 10−2 and 4.02 × 10−3 sec with relative abundances of 0.0292 and 0.170, respectively. The relative abundances represent the fractions of the delayed-neutron and delayed-photoneutron groups.Keywords
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