ANGULAR DISTRIBUTION FOR 7-LI(N,N')7-LI***(478) BY ANALYZING DOPPLER BROADENED GAMMA LINES
Scattering experiments on 7-Li at higher neutron energies cannot separate the transition to the first excited state (478 keV, 73 fs**0.5) from the ground state transition by time-of-flight. Our knowledge on the angle integrated inelastic (Q = 478 keV) cross section stems from experiments observing the C.M.-isotropic 478 keV gamma line. It is demonstrated that the missing neutron angular distributions can be deduced from the Doppler broadening of this gamma line. The experiment was conducted at 8 MeV neutron energy using a metallic enriched Li sample, a 70 cm**3 Ge(Li)-detector, and conventional electronics for n,gamma event discrimination by time-of-flight. In contrast to earlier experiments the gamma observation angle was varied between 45 degrees and 135 degrees . The observed gamma line changes its position and its shape depending on the observation angle. Its width is about ten times the resolution of the Ge(Li)- detector, which was determined to be 1.7 keV FWHM under realistic conditions. From these observed line shapes the angular distribution in terms of Legendre coefficients is deduced by applying a combination of Monte-Carlo calculations and least squares fitting. The Monte-Carlo code makes allowance for the energy distribution of the primary neutrons, sample size effects, the combined effect of stopping power and half-life, and for the gamma detector resolution.
Bibliographic Reference: NUCLEAR DATA FOR BASIC AND APPLIED SCIENCE, SANTA FE, NEW MEXICO (USA), MAY 13-17, 1985 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32028 ORA
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Record Number: 1989123074200 / Last updated on: 1987-01-01
Available languages: en