  The presence of not yet detected intruder states in $^{8}Be$ e.g. a $J=2^{+}$
intruder at 9 $MeV$ excitation would affect the shape of the $\beta ^{\mp
}$-delayed alpha spectra of $^{8}Li$ and $^{8}B$. In order to test the
plausibility of this assumption, shell model calculations with up to $4\hbar
\omega $ excitations in $^{8}Be$ (and up to $2\hbar \omega $ excitations in
$^{10}Be$) were performed. With the above restrictions on the model spaces, the
calculations did not yield any low-lying intruder state in $^{8}Be$. Another
approach -the simple deformed oscillator model with self-consistent frequencies
and volume conservation gives an intruder state in $^{8}Be$ which is lower in
energy than the above shell model results, but its energy is still considerably
higher than 9 $MeV$.
