1 - IAEA Nuclear Data Services

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is flux-independent and yields the relative shape of
the B(n,a Y) cross section. This could be normalized
to absolute values at the low energy end where the
capture cross section is known to be /v and by direct
methods at the higher energy end (proton recoil counters).
2.8. Spin Determinations
2.8.1. Spin Measurements of Fissile Nuclei
A.J. Deruytter, C. Wagemans + , C. Furetta ++
A measurement was made of the ratio of binary fission
to ternary fission (two heavy fragments and a longrange
particle) in -^U at the CBNM linac with a flightpath
of 8 meter length. The useful energy-range extends
from 0.18 eV to 21 eV. The time-pf-flight-spectra are
recorded with and without a 20 u thick aluminium absorber
between target and detectors. The target is a
layer of 2 mg/cm , 99.5% ^U on both sides of a thin
aluminium support (0.5 mm thick). On each side a bank
of surface-barrier detectors (Au-Si) detects the fission
fragment (no absorber) or the long-range particles
(absorber in). The ratio of the surfaces of the resonances
in both measurements was taken. Fluctuations
from resonance to resonance are seen. The sign of the
fluctuations is in agreement with the results of
ñichaudon et al. (Saclay).
2.8.2. Spin Assignments of Neutron Resonances of Stable
Nuclides
G. Carraro, C. Cocevat ++ F. Corvi +++ and P. Giacobbe +++
The measurements are carried out by a joint CNEN-CBNM
team. The experimental set-up outlined in the preceding
progress report has been used and measurements
Belgian research fellow NFWO (University of Gent)
++ -i-i
Euratom research fellow
+++ CNEN, Italy