RADIOMETRIC METHOD FOR DETERMINING CONCENTRATION OF NATURALLY OCCURRING ISOTOPES AND DEVICE THEREFOR

摘要

RADIOMETRIC METHOD FOR DETERMINING CONCENTRATION OF NATURALLY OCCURRING ISOTOPES AND DEVICE THEREFOR The proposed method essentially consists in that a sample of a substance is placed between two scintillators in immediate contact therewith whereupon said sample is hermetically sealed. Arranged in close proximitiy to each scintillator is a photomultiplier tube recording ionizing .alpha.- and .beta.-radiation. A selector is utilized to select pulses corresponding to .alpha.- and .beta.-particles, and delayed coincidence circuits of a recording element separate and record .beta.-.alpha. and .alpha.-.alpha. cascade pairs of delayed coincidences of RaC, ThC, and AcA radionuclides. Flows are measured twice at a predetermined time interval to account for emanation build-up tendency and concentration of isotopes of radium is determined from the formula < IMG > , where < IMG > = concentration of a given isotope of radium; .epsilon.A = isotope-of-radium concentration unit sensitivity of measuring equipment; < IMG > - number of pulses corresponding to cascade pairs for a given radionuclide measured immediately after sealing and after a preset time interval thereafter; .lambda.A= decay constant for radionuclide emanation; T = preset time interval equal to emanation build -up time.