Neutrino electron scattering and electroweak gauge structure: Probing   the masses of a new Z boson
  Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We discuss the use of strong radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO, HELLAZ and LAMA. We display the sensitivity of these detectors in testing the possible existence of extra neutral $E_6$ gauge bosons. 
O. G. Miranda, V. B. Semikoz, and J.W.F. Valle