Neutron capture in s-wave resonances of nickel-64

Journal Article · Tue May 01 04:00:00 EDT 1984 · Nucl. Sci. Eng.; (United States)

OSTI ID:6302952

Wisshak, K; Fabbri, F; Kappeler, F; Macklin, R L; Reffo, G

The neutron capture widths of the s-wave resonances at 13.9 and 33.8 keV in /sup 64/Ni have been determined using a setup with extremely low neutron sensitivity completely different from all previous experiments on this isotope. This feature is important because these resonances exhibit a very large scattering-to-capture ratio. A pulsed 3-MV Van de Graaff accelerator and a kinematically collimated neutron beam, produced via the /sup 7/Li(p,n) reaction, was used in the experiments. Capture gamma rays were observed by three Moxon-Rae detectors with a graphite, a bismuth-graphite, and a bismuth converter, respectively. The samples were positioned at a neutron flight path of only 6 to 8 cm. Thus, events due to capture of resonance-scattered neutrons in the detectors or in surrounding materials are completely discriminated by their additional time of flight. The short flight path and the high neutron flux at the sample position allowed for a signal-to-background ratio of approximately unity even for the broad resonance at 33.8 keV. The data obtained with the individual detectors were corrected for the efficiency of the different converter materials. For that purpose, detailed theoretical calculations of the capture gamma-ray spectra of the measured isotope and of gold, which was used as a standard, were performed. The final radiative widths are GAMMA..gamma.. (13.9 keV) = 1.01 + or - 0.07 eV and GAMMA..gamma.. (33.8 keV) = 1.16 + or - 0.08 eV, considerably smaller than the rough estimates obtained in previous work.

• Research Organization: Kernforschungszentrum Karlsruhe, Institut fur Kernphysik III, Karlsruhe
• OSTI ID: 6302952
• Journal Information: Nucl. Sci. Eng.; (United States), Journal Name: Nucl. Sci. Eng.; (United States) Vol. 87:1; ISSN NSENA
• Country of Publication: United States
• Language: English

Related Subjects

651625* -- Nuclear Properties & Reactions
A=59-89
Experimental-- Nuclear Reactions & Scattering-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON REACTIONS
CAPTURE
CHARGED-PARTICLE REACTIONS
ENERGY RANGE
GAMMA SPECTRA
HADRON REACTIONS
HEAVY ION REACTIONS
KEV RANGE
KEV RANGE 10-100
LEVEL WIDTHS
LITHIUM 7 REACTIONS
NEUTRON FLUX
NEUTRON REACTIONS
NICKEL 64 TARGET
NUCLEAR REACTIONS
NUCLEON REACTIONS
PARTIAL WAVES
RADIATION FLUX
RESONANCE
S WAVES
SCATTERING
SPECTRA
TARGETS