Browsing by Author "Shoeib, M. Y"

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Assessment of natural radiation exposure and radon exhalation rate in various samples of Egyptian building materials
(TAYLOR & FRANCIS LTD, 2014-04) Thabayneh, K. M; Shoeib, M. Y
The aim of this investigation was to determine the amount of gamma-decay of several building materials used in Egypt, in terms of Bq kg(-1), and to calculate the radiological effect caused by this radioactivity. Activity concentrations of Ra-226, Th-232 and K-40 in 30 samples of manufactured building materials were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. The activity concentrations for 226Ra, 232Th, and 40K, from the selected building materials, ranged from (8.15 +/- 2.81 to 288.5 +/- 17.49 Bq kg(-1)), (3.59 +/- 1.36 to 77.77 +/- 15.61 Bq kg-1) and (4.09 +/- 4.72 to 1314 +/- 15.30 Bq kg(-1)), respectively. Radium equivalent activities, absorbed dose rate, Excess lifetime cancer risk and the values of hazard indexes were calculated for the measured samples to assess the radiation hazards arising from using those materials in the construction of dwellings. These results show that annual dose absorbed by inhabitants from construction materials used in Egypt (except cement bricks) are below 1.0 mSv y(-1). Therefore, the types used in the current study are quite safe to be used as building materials, except the cement brick, granite and ceramic samples which are critical points for safety in construction. Finally, the so-called can technique has been used to measure radium content and exhalation rates of radon in these building materials samples. Positive correlation was found between radium concentration and radon exhalation rates. Copyright (C) 2014, The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V. All rights reserved.
The Induced Changes in the Bulk Etch Rate and the Thermal Stability of PADC by the Effect of Long Storing Time at Room Temperature and Heat Treatment
(EGYPTIAN SOC NUCLEAR SCIENCES & APPLICATIONS, 2019-01) Shoeib, M. Y; Mokhtar, S. M
The samples of poly allyl diglycol carbonate PADC (CR-39) (stored and fresh samples) polymer track detectors have been heated at different annealing temperatures and different annealing times. The thermal stability has been studied for different annealed samples; it was also examined as a function of the storage time. The percentage degree of crystallinity has been studied for different annealed samples and stored samples. The samples were etched in 6 M KOH solution at 70 degrees C for 3 h. The variation of bulk etch rate of isochronal annealed samples has been studied. The results indicate an improvement in the thermal stability of Poly allyl diglycol carbonate PADC; where the bulk etch rate increases with the increase in the annealing temperature and annealing time. The storage time has no noticeable effect on the bulk etch rate of un-annealed samples, though the thermal stability of PADC improved with increasing the storage time.