A novel method to estimate the dead layer of HPGe detector for Monte Carlo FEPE computation.

In this study, a novel method to determine the surface and lateral dead layers of p-type HPGe detector is proposed to compute the full energy peak efficiency (FEPE). The method employed standard radioactive point sources 241Am, 133Ba and FEPE measurement at low energies to estimate the thickness of frontal and lateral dead layers. The method is simple to apply, requires only two standard radioactive sources to estimate the optimum thickness of frontal and lateral dead layers. The proposed method is validated by measuring the efficiency of various point sources and a volume source in the energy range from 59 to 1408 keV. The measured efficiencies agree to simulation with relative deviation less than 4.0% at each energy. The proposed detector model enables to calibrate the detector for environmental radioactivity measurement without standard volume sources.

Health risk assessment of radioactive footprints of the urban soils in the residents of Dera Ghazi Khan, Pakistan.

The aim of the study was to evaluate the radiation levels, radiological doses and excess lifetime cancer risk possessed by the urban soils that were collected from the vicinity of the exclusive mining and excavation centers of Dera Ghazi Khan. The high purity germanium detector was utilized for assessment of naturally occurring radionuclides (NORMs) in soil and results showed that the average activity concentrations of 226Ra, 232Th, and 40K (37 Bq/kg, 43.07 Bq/kg, 737 Bq/kg respectively) surpassed the world's average documented values (35 Bq/kg, 30 Bq/kg, and 400 Bq/kg respectively). Moreover, the average values of radiological hazards assessment like radium equivalent, internal and external hazard indices, absorbed dose rate, annual gonadal dose equivalent and excess lifetime cancer risk were 155.70 (Bq/kg), 0.4, 0.5, 73.96 (nGy/h) 90.73 (µSv/y), 476.24 (µSv/y) and 0.31(10-3) respectively. The data acquired was analyzed using descriptive statistics, cluster analysis and principal component analysis. ArcGIS (10.5) software was utilized for developing maps of radionuclide's concentration for the study area. Results of the study may serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.

Transfer of radioactivity from soil to vegetation in Rechna Doab, Pakistan.

In Rechna Doab, samples of the most common vegetation, perennial grass Desmostachya bipinnata (dab), were collected along with soil samples from 29 sites. Natural radioactivity of ²²6Ra, ²³²Th/²²8Ac and 4°K was measured by using high purity germanium-based gamma ray spectrometer. Activity concentration levels of ²²6Ra, ²³²Th/²²8Ac and 4°K in soil were found to be 46.8 ± 6.2 (36.0-57.6), 61.4 ± 5.9 (48.2-73.2) and 644.8 ± 73.9 (537.7-868.4) Bq kg⁻¹ (dry mass), respectively, and those in vegetation were 2.74 ± 1.70 (1.00-6.39), 2.24 ± 0.59 (1.56-2.61) and 172.72±113.37 (53.14-469.24) Bq kg⁻¹ (dry mass), respectively. The measured values of the activity concentration in vegetation are comparable with some other international data. Calculated soil to vegetation transfer factors of ²²6Ra, ²²8Ac and 4°K were 0.06 ± 0.03 (0.02-0.14), 0.04 ± 0.01 (0.03-0.04) and 0.26 ± 0.16 (0.09-0.69). The mean outdoor absorbed dose rate in air for the area under study was determined as 8.22 nGy h⁻¹ and the mean indoor absorbed dose rate in air was 11.52 nGy h⁻¹. The total annual effective dose to the general public from the vegetation was found to be (0.02-0.16) mSv, which is below the recommended limit value of 1 mSv y⁻¹ for the general public. The dab vegetation under study was found to be radiologically safe for the population and environment.