As a rule, starting with He, the heavy isotopes of all elements are delayed neutron emitters:
He-4 stable
He-5 unbound
He-6 β- only 807 ms
He-7 unbound
He-8 β-n 16% of 120 ms
then:
Li-7 stable
Li-8 β- only 839 ms
Li-9 β-n2α 50% of 178 ms
etc... till
Tl-205 stable
Tl-206 (RaE) β- only 252 s...