Radiative capture of neutrons in the keV region

Conference · Wed Oct 01 04:00:00 EDT 1975 · Natl. Bur. Stand. (U.S.), Spec. Publ.; (United States)

OSTI ID:7354511

Greenwood, R C ^[1]; Chrien, R E; Rimawi, K

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1. Aerojet Nuclear Co., Idaho Falls, ID

Essentially monoenergetic neutrons with keV energies can be obtained from a reactor by using suitable filters. To date, prompt ..gamma..-ray spectra have been measured using 24-, 2-, and 1-keV neutrons, obtained through Fe + Al + S, Sc + Ti and /sup 6/Li filters, respectively. Two features of these data are of note to reactor shielding. First, the radiative capture spectra from higher Z nuclei usually result from an average over many resonance states. Hence statistical fluctuations in the primary ..gamma..-ray intensities, to which the corresponding thermal neutron capture spectra are subject, are averaged out. Second, such data provide information on the dependence of radiative capture spectra on neutron energy. The data shows that at 24 keV there is a significant p-wave contribution to these spectra, even for those mass regions where the ratio of the p-to-s wave strength function is close to a minima. This occurs because the smallness of the relative penetrability at 24 keV, 0.04 less than (kR)/sup 2/ less than 0.08 for 100 less than A less than 240, is compensated for by the branching ratio GAMMA/sub ..gamma..//GAMMA which is now much larger for p-wave than for s-wave resonances. 6 figures, 1 table (auth)

• OSTI ID: 7354511
• Conference Information: Journal Name: Natl. Bur. Stand. (U.S.), Spec. Publ.; (United States) Journal Volume: 425
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON REACTIONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CAPTURE
ELECTROMAGNETIC RADIATION
EVEN-ODD NUCLEI
GADOLINIUM 154 TARGET
GADOLINIUM 155
GADOLINIUM 156 TARGET
GADOLINIUM 157
GADOLINIUM ISOTOPES
GAMMA RADIATION
HADRON REACTIONS
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
IONIZING RADIATIONS
ISOTOPES
MANGANESE 55 TARGET
MANGANESE 56
MANGANESE ISOTOPES
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
ODD-ODD NUCLEI
RADIATIONS
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
STABLE ISOTOPES
TARGETS