Diffusion of helium was characterized in natural monazite. Polished slabs of natural monazite were implanted with 100keV 3He to a dose of 5 x 1015 3He/cm2 and annealed. The 3He distributions were measured using nuclear reaction analysis: 3He(d,p)4He. The diffusion in monazite, normal to (100), was described by:

D(m2/s) = 1.60 x 10-7exp[-150(kJ/mol)/RT]

D.J.Cherniak, E.B.Watson: American Mineralogist, 2013, 98[8-9], 1407-20