2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/44248We consider the effect of ambient matter on the Majorana phase of neutrinos. We find that this can lead to an observable signal if a neutrino oscillation experiment could be performed where the source and the detector are at appropriately different matter densities. We illustrate the situation using a beta beam neutrino source as an example and show that a 5 sigma signal for the matter modification of the Majorana phase could be possible in a 5-year run.10 pages, 1 figure, LatexHigh Energy Physics - Phenomenologytext