COLOUR CENTRES IN DOPED ALKALI HALIDES.THE ROLE OF OXYGEN AND TITANIUM IN THE LUMINESCENCE OF LiF : Mg : Ti M.C. WINTERSGILL, P.D. TOWNSEND et F. CUSSO-PEREZ J. Phys. Colloques, 37 C7 (1976) C7-123-C7-126 DOI: 10.1051/jphyscol:1976724