Deconvolution of gamma-ray spectra obtained with NAI(Tl) detector in a water tank.

Maximum-likelihood fitting by the expectation maximization deconvolution method is presented to analyse gamma-ray spectra recorded using an NaI(Tl) detector for a water monitoring system. The applicability of the method was tested by deconvolving measured spectra taken using an industry standard 3'' x 3'' cylindrical NaI(Tl) detector in a model water tank with several calibration sources. The results show significant removal of the Compton continuum counts and efficient transfer of the counts into the corresponding photo-peaks. The peak-to-total count ratio and the number of counts in the photo-peaks in the deconvolved spectra increased approximately 4.67 and 5.29 times, respectively, compared with those of measured spectra taken using an NaI(Tl) scintillation detector in the case of (137)Cs.

Body radioactivity and radiation dose from 40K in Bangladeshi subjects measured with a whole-body counter.

A group of subjects of Bangladeshi adults from both sexes were studied for internal radioactivity and effective dose by measuring the whole-body activity of naturally occurring 40K using a whole-body counter. The mean activity concentration in the whole body and effective dose due to naturally occurring 40K for the average male were found to be 2.0 +/- 0.4 Bq x g(-1) and 100 +/- 26 microSv x y(-1), respectively and those for the average female were 1.7 +/- 0.3 Bq x g(-1) and 100 +/- 20 microSv x y(-1), respectively. The mean activity concentration in the whole body and effective dose for both sexes were 1.9 +/- 0.4 Bq x g(-1) and 100 +/- 25 microSv x y(-1), respectively. The effective dose from 40K for subjects is below the value reported by the UNSCEAR.