Saclay and Argonne see nuclear quartet states

If you bombard $Fe56$ with $O16$ ions, you can observe $C12$ ions being emitted, which means that an alpha particle (really two protons and two neutrons whose relative motions are probably correlated as they are in an alpha particle) has been incorporated in the residual nucleus—in this case $Ni60.$ The spectrum shows certain selected states and not others. That is, at certain specific energies the alpha particles find an easy way to get in—the system appears to resonate. Such experiments with alpha‐particle transfer reactions are exciting great interest among nuclear physicists.