By using the relative measurement method

the number of 10B nuclei in the thin film sample was measured.The experiment was performed at the 4.5 MV Van de Graaff accelerator of Peking University.Neutrons were produced through the D(d

n)reaction and the fast neutrons were moderated by the thick paraffine layer.A 6LiF sample with definite number of 6Li nuclei was used as thereference

and a twin gridded ionization chamber was used to detect the tritons from the 6Li(nth

t)4 He reaction and the alpha particles from the 10B(nth

α)7 Li reaction.