1 - IAEA Nuclear Data Services

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6.4* Method for measurement of in-pile neutron angular distributions and
check of the differential neutron cross sections of the Li(n^t) He
reaction relative to a narrow neutron energy group»
G. and S. DE LEEUW
A method for the measurement of the neutron angular distribution in-pile
has been described in paper SM 101-45 of the " Symposium on Fast Reactor
Physics and Related Safety Problems" at Karlsruhe in november 1967*
In an isotropic neutron flux, this method based on the simultaneous
measurement, "by means of solid state detectors, of the E, and E + E.
TJ OC t
spectra relative to the collimated particles, allows also the determina­
tion of the differential neutron oross sections. The cross section is
deduced from the measured monoenergetic triton distribution. The
definition of the neutron energy, selected in the E + E spectrum by
means of a single channel, depends on the window width of the channel
and the resolution of the spectrometer.
The optimal resolution obtainable till now being 60 keV (FWHM of the
thermal peak) the determination of the angular differential neutron
oross section is only possible in the high energy region (above about
500 keV), below only a check of the existing ones makes sense.