t+t clustering in He-isotopes.

t+t clustering in He isotopes is investigated by using two theoretical approaches. A role of the t+t cluster component in the ground state is examined with AMD triple-S, allowing the wider configuration space containing simultaneously the "t+t+valence neutrons" structure and "4He+valence neutrons" structure. We understand the importance of the t+t component even for the ground state. Further, t+t resonances are investigated with RGM type approach. We obtained many t+t states as resonances near to t+t threshold. [ABSTRACT FROM AUTHOR]