1 - IAEA Nuclear Data Services

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to the calculation of the scattering curves so that these experimental
curves could he used directly to check the model. Some preliminary
measurements have also been done on the paramagnetic scattering by
UO , KKnP, and Mn S.
During the last quarter, measurements have been stopped' in order to
install 9 evacuated flight paths moving inside a shielded room.
4« Joint Researoh by OES and BCM2J on Fission Cross Sections.
A joint program of research of CEN and BCMN was started in 1966 and has
been pursued in 1967»
The measurements are reported elsewhere in this Report, under the
following heading :
Fission in the Resonanoe Region:
235
2.1. Normalization of relative U fission cross-sections in the
resonance region.
2.2. Ratio of Binary-to-Temary Fission in
235„
u.
5« Properties of " ffl U.
M. HEVE de MEVERGNIES and P. del MARMOL
The possibility of measuring the fission cross section of " m n (l/2 )
?39
has been investigated. This isomeric state is fed by the a-deoay of Pu ,
so a Πsource can be prepared, using a catcher foil to collect the
239
recoils from a thin Pu layer. Preliminary estimates shows that by
subsequent irradiation of such a Ü source, in contact with a Makrofol
fission track detector, in a thermal flux of about 5*10 n/cm s.,
the fission cross section of this isomer could be measured if it is of
the order of or larger than about 50° "b* These measurements are underway.
235
As the isomer decays to the U ground state by a 25 eV-transition fully
converted in the P and Q layers, a study of the chemical or "environmental