1 - IAEA Nuclear Data Services

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Precision Measurements of Excitation Functions of
(n,p), (n,g) and (n,2n) Reactions Induced by
13.5 - 14.7 MeV Neutrons.
H.K. Vonach, W.G. Vonach, H. Münzer (Universitât
ñünchen) un'd P. Schrammel (Ges. f. Strahlenforschung,
Neuherberg)
i o
Excitation Functions for the reactions F (n,2n),
24 Mg (n,p), 27 A1 (n,cü, 48 Ti (n,p), 51 V(n,a),
65r. • / o \ 107. / - v 106mA : 115T / 0 v 114mT
•Cu (n,2n), 'Ag (n,2n) Ag,. •'In (n,2n) In,
181 Ta (n,2A) 108m Ta and 197 Au (n,2n) 196 Au were
determined in 30 - 50 EeV steps iii the energy range
13.50 - 14.7 MeV using the activation method. Neutrons
from the D ;- T reactions (deuteron energy 0.12 MeV)
were used to irradiate the samples. The gamma-activities
produced by the reactions were measured with a large
NaJ well crystal (statistical accuracy 0.2 - 0.5 %).
Systematic errors were minimized by use of an accurate
geometry (target sample distance 100 + 0.15 mm) and by
use of an extremely light air-cooled target assembly
minimizing the contribution of elastically scattered
neutrons to the activation of the samples and by the
use high-purity metallic samples. The attenuation of
neutrons in the target and target assembly as well the
intensity of the neutrons scattered elastically by
target and target assembly was calculated as a function
of the neutron emission angle (and corresponding neutron
energy) and appropriate corrections applied. In this
way an overall accuracy of about 1 % could be obtained
for the relative cross-section CT(En)tf(14.7MeV) . Q^
excitation functions are shown in fig. 1 to 8, crosssections
are arbitarily normalized to unity at 14.7 MeV,
the size of the data points corresponds to the statistical
errors. The smooth curves are least square fits
of first or second degree polynomials except for the
24
Mg (n,p) and Al (n,a) were definitely fine structure
is present and the smooth curves were drawn according
to "eye-inspection".