FIELD: physics.;SUBSTANCE: proposed method involves setting accumulation chamber accommodating semiconductor or scintillator alpha-detector. Note here that first measurement is carried out in between interval t1 varying from 6 to 6.1 minutes after accumulation start, while second measurement is performed in between interval t2 varying from 40 to 60 minutes. Then, density of flow of radon qRn and thoron qTn "Бк" m-2, s-1 is defined by the expression , , ;where Nt1 is pulse count rate measured at t1, min. After accumulation start, pulses; s-1; Nt2 is pulse count rate measured at t2, min., after accumulation start, pulses, s-1; KRn(t2) is contribution of radon (222Rn) into total escape of alpha-particles from radon and products of is decay inside accumulation chamber at t2 depending on t2, relative units; φ is count factor that allows for counter efficiency and geometrical factor, pulses s-1 "Бк"-1; S is area of accumulation chamber base , m2; 6.3·10-3 is factor to allows for contribution of radon (222Rn) into total escape of alpha-particles from radon and products of is decay inside accumulation chamber and accumulation of thoron and its radioactive decay for 6 minutes, s-1.;EFFECT: simplified procedure.;1 dwg, 1 tbl
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