Abstract The results of background measurements with the prototype of the Borexino detector (CTF) have been used to obtain an upper bound on the neutrino magnetic moment, µ ν . The new upper limit for µ ν from pp and 7 Be solar neutrinos is (5.5 × 10 −10 )µ B (90% c.l.) in the Standard Solar Model scenario. This is the first limit on µ ν obtained using sub-MeV neutrinos. The sensitivity of the prototype to the neutrino charge radius and the neutrino radiative decay are also presented
