1 - IAEA Nuclear Data Services

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ment of the subthreshold fission, cross section with
the aid of a fission neutron detector of Migneco and
Theobald (see 2.2.).
Data on neutron capture in Cu and Nd have been collected.
The analysis of the Cu data between 200 eV
and 16.5 keV is under way.
2.7. Standard Data r157T161T173
2.7.1. Cross Section Ratio B(n,a) to Li(n,a) between 1 keV
and 50 keV
E. Migneco, J. Theobald
The experimental set-up consists of an eight meter
long collimated flight path. The neutron beam is collimated
down to 15 cm by water and boron-carbide and
to 5.5 cm by a sequence of boron-carbide loaded
plastic hollow cylinders. A precisely known sample
of B and Li is to be placed into a sample changer
in the neutron beam. The outcoming particles are detected
by 4 Si surface barrier detectors of 500 mm
each. The different parts of the detection system have
been installed in the flight-path and tested. Up to
now the ^-flash from the linac target induces in the
detectors pulses, which have a time- and amplitude
dependence different from what we have expected. This
limits at the moment our useful energy range to values
lower than the zone of interest.
2.7.2. Shape of the B(na,., ) Cross Section in the Energy
Range 1 to 100 keV
K.H. Bdckhoff
A feasibility study is being prepared about the
measurement of a v( E )/ a ^ v( E ')> where E'=ri E.
n,oti n,oti y
The different energies can be obtained by using
neutrons scattered from the linac beam by a hydrogenous
foil under two different angles. The method