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HK: Physik der Hadronen und Kerne
HK 16: Postersitzung / Kernphysik
HK 16.27: Poster
Donnerstag, 23. März 2000, 10:15–12:45, B 69
Precise spectral measurement of the energy distribution of 7Li produced in ternary fission — •S Oberstedt1, D Rochman1, A Oberstedt2, and M Mutterer3 — 1Institut Laue-Langevin, F-38042 Grenoble — 2ITN, SE-70182 Oerebro — 3IKDA, D-64287 Darmstadt
Energy distributions and yields of ternary particles (TP) up to A=34 were
measured
with the recoil mass-separator LOHENGRIN in the past for a large number of
fissioning
systems. For the lighter elements like He, Li and Be, it was observed that
some
isotopes (e.g. 4He, 7Li, and 9Be) have considerably wider energy
distributions compared to their neighbouring isotopes, with a higher yield
especially
at low kinetic energies compared to a Gaussian shape.
From a recent work on neutron-TP angular distributions in the case
of 252Cf(sf) this observation has been confirmed, and it became clear
that
spectra of some TPs can be influenced by a secondary effect. TPs of mass
A+1, which
are neutron-unstable in their groundstates [5He, 7He] or their
excited states
[8Li*, 10Be*], are formed in ternary fission, may undergo
neutron decay
and eventually are detected as an TP with mass A. This would qualitatively
explain the
additional low-energy component in the observed kinetic-energy
distributions .
For attaining a quantitative picture spectral measurements of the above
isotope with
LOHENGRIN have been performed. For the first time absorber foils were used
for the
investigation of the high-energy part.
The measurement technique as well as first experimental results will be
presented.