  Electron-positron angular correlations were measured for the isovector
magnetic dipole 17.6 MeV state ($J^\pi=1^+$, $T=1$) $\rightarrow$ ground state
($J^\pi=0^+$, $T=0$) and the isoscalar magnetic dipole 18.15 MeV ($J^\pi=1^+$,
$T=0$) state $\rightarrow$ ground state transitions in $^{8}$Be. Significant
deviation from the internal pair creation was observed at large angles in the
angular correlation for the isoscalar transition with a confidence level of $>
5\sigma$. This observation might indicate that, in an intermediate step, a
neutral isoscalar particle with a mass of 16.70$\pm0.35 $ (stat)$\pm 0.5 $
(sys) MeV$/c^2$ and $J^\pi = 1^+$ was created.
