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Measurement of indoor Concentrations were performed in Zulfi city of Saudi Arabia, using CR-39 track etch detectors .This investigation focused on the influence of different parameters, namely different locations, school categories, school building types, and room type as well as on the existence of differences in radon concentration at floor levels. We divided the Zulfi city into five regions, keeping in mind their geographical locations between Tuwaiq Mountains and Al-Thuwayrat sands. The measured average radon concentrations for regions 1-5 respectively are: 87.0 ± 14.2 Bq/m 3 , 83.4 ± 6.0 Bq/m 3 , 61.6 ± 6.4 Bq/m 3 , 63.7 ± 5.4 Bq/m 3 and 87.5 ± 6. Bq/m 3 and the minimum concentrations are 28.0 Bq/m 3 , 5.5 Bq/m 3 , 1.1 Bq/m 3 , 1.0 Bq/m 3 and 24 Bq/m 3 respectively. These results are still within normal limits and below the action level of 148 Bqm -3 set by the U.S. Environmental Protection Agency (EPA). A test of significance using Minitab program was applied to investigate if radon levels in regions are significantly different from each other. We tried all combinations, and found the following results. The "within regions" (different location) test yielded, region 2 is not significant versus region" 1" (p=0.783) and versus region "5" (P=0.646) , whereas it is significant versus region "3" ( P=0.0160) and also versus region "4" (p=0.018). We investigated government and rented school's building also and none was found significantly different (p=0.052). Floors of the same building were tested in order to examine the radon concentration as a function of storey level. No significant difference was observed at floor levels (p=0.009). When girl's schools versus Boys and kindergartens schools were tested they were found significantly different. It is believed that this significant difference is due to geographical nature of the area, since most of the girl's schools were selected from regions 2 and 3, these regions are relatively close to the Tuwaiq mountains whereas other regions are near to the Al-Thuwayrat sands.

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We have investigated the influence of Ag doping on zinc oxide thin films. Pure and Ag doped, preferentially oriented transparent zinc oxide thin films were prepared by sol gel technique on a glass substrate using diethyl amine as a stabilizer. The X-ray diffraction analysis revealed that the films with hexagonal wurtzite type structure were polycrystalline in nature with a preferred grain orientation in the 101 direction. The crystallite sizes decreased from 34 nm to 27 nm after silver doping. Both photoluminescence and optical transmission measurements showed that the band gap increased after the Ag doping. The structure and optical characterization studies clearly indicated the incorporation of Ag in ZnO. Hence, the observed increase in the optical band gap and decrease in crystallite size can be directly attributed to the effect of Ag ion incorporation into the ZnO lattice.

Measurement of indoor radon concentration was performed in Najran region in the south west of Saudi Arabia, using CR-39 dosimeter. Despite many previous studies on indoor radon concentrations in Saudi Arabia, the data available are still limited. The objective of this study, which is the first of its kind in the region, is to have preliminary data of radon in this region. Such measurement will contribute towards further studies in this region of Saudi Arabia. The indoor radon concentration was measured in the villages of Fara Al-Jabal and Badr AlJanoob (about 2000 m above sea level), Hadadah and Al-Khanig (about 1700 m above sea level). It was found that radon distribution in these villages is normal skewed to the right, with a range of 9±5 to 163±32 Bqm -3 and an average of 49±2 Bqm -3 . It was also found that the average radon concentration is independent of altitude. Our findings show that the values are below the safe limit of 150 Bqm -3 set by the Environmental Protection Agency (EPA) of the U.S.A.