Formation of $^8$He in the $^9$Be$(\pi^-,p)X$ and $^{10}$B$(\pi^-,pp)X$ stopped pion absorption reactions

The structure of levels of the $^8$He heavy helium isotope has been studied in the $^9$Be$(\pi^-,p)X$ and $^{10}$B$(\pi^-,pp)X$ stopped pion absorption reactions. Measurements have been performed with a two-arm multilayer semiconductor spectrometer at the LANL. Indications to the existence of a soft dipole mode at the excitation energy $E_x \approx 3$ MeV have been obtained. A state with a high excitation energy of $12.2(5)$ MeV has been observed for the first time.