Observation of beta-ray spectra after penetrating absorbing materials

beta-Ray spectra after penetrating absorbing materials of various thicknesses were observed by the use of a scintillation-type beta-ray spectrometer equipped with a flat NE-102 plastic scintillator of 5mm thickness for sources of (60)Co, (90)Sr-(90)Y, (137)Cs, (147)Pm and (204)Tl. Although the spectra changed rapidly with increasing absorber thickness, the average beta-ray energy was kept nearly constant for a wider range. These results are consistent in that the beta-ray absorption curve becomes quasi-linear in a semi-logarithmic plot. Spectra including scattered beta-rays from several materials placed behind the source were also measured for (137)Cs and (204)Tl. It may be concluded that mean energy measurements by the use of beta-ray spectrometer of this kind is useful for the identification of nuclides in radiation protection purposes even in worse source-conditions.