Can the nuclear matrix elements of neutrinoless double beta decay be measured?

A proposal which allows one in principle to measure the neutrinoless double beta decay Fermi matrix element is briefly described. By making use of the isospin conservation by strong interaction, the Fermi 0 ν β β nuclear matrix element M F 0 ν can be transformed to acquire the form of an energy-weighted double Fermi transition matrix element. This allows one to reconstruct the total M F 0 ν provided that a small isospin-breaking Fermi matrix element between the isobaric analog state in the intermediate nucleus and the ground state of the daughter nucleus could be measured, for example by charge-exchange reactions. Such a measurement could help to discriminate between the different nuclear structure models in which the calculated M F 0 ν may differ by as much as a factor of 5.