1 - IAEA Nuclear Data Services

?. (n,y) ~ Spectroscopy
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W. Michaelis, U. Fanger, G. Markus, H. Ottmar, H. Schmidt
2.1. Introduction
At the Karlsruhe research reactor FR-2 the excited states of several
nuclei have been investigated by thermal neutron capture using a
5-crystal Ge (Li) pair spectrometer £ 1 _7 , a Ge (Li) anti-Compton
device C 2,3-7 , a Ge (Li) - Nal (TI) coincidence system C 1 D and
an angular correlation .spectrometer. Studies were made both in the
region of nearly spherical nuclei and in the region of strongly de­
formed nuclei. A summary of the experimental results has been pre­
sented at the Tokyo conference on nuclear structure Eh J.
2.2. Level Structure of Fe and Ni
57 o1
Since the isotopic abundance of Fe and Ni is low in the natural
elements (2.19 % a nd 1.19 %, respectively), highly enriched samples
of 90.73 % ?•«• and 92.11 % Hi were used as a target.
Level energies for Fe and Ni are summarized in Table II, The
transition diagrams are shown in Figs.10 and Tl9, respectively. Large
dots indicate experimentally established coincidence relationships.
Gamma rays entering a level and dotted at their arrowheads have been
shown to be in coincidence with at least one gamma, ray leaving the
same level and dotted at its origin.
58
The first excited level at 810.5 keV in Fe is the well known one-
phonon vibrational state. A new level with spin and parity 0
has been introduced at 2256.6 keV. This level together with the 2
state at 167^.6 keV belongs to the two-phonon triplet.