['Similarly', 'to', 'the', 'case', 'of', 'a', 'static', 'tritium', 'source', ',', 'an', 'advantage', 'of', 'the', 'beta', '-', 'beams', 'is', 'that', 'the', 'neutrino', 'fluxes', 'can', 'be', 'very', 'accurately', 'calculated', '.']