A KIND OF SOLUTION FOR DIFFUSION EQUATION WITH SOURE TERM AND THE CONVERSION FORMULAE OF MEASURING RADON WITH TWO FILTER METHOD

The problem of definite solution of diffusion equation of radondaughters in long cylinder is introduced according to the diffusion rule of aero-sol nuclide’s series decay in the velocity field.A kind of solution for uniform-velocity profile is precisely obtained,which makes up the shortage of C.W.Tan’s work.First α-count of radon daughters is measured,then a theoreticalformula calculating radon concentration is infered through dimensionless parame-ter m(μ).When the diffusion coefficient D=0.07cm~2·s~(-1),the theoretical resultis identical well with the result of J.W.Thomas’ experiment.