Laith Ahmed Najam

This study aimed to evaluate the radiological impacts in Khanaqin, located in the Diyala Governorate, Iraq. The specific activities of natural radionuclides of ²³⁸U, ²³²Th, and ⁴⁰K in soil samples were investigated by collecting thirty composite soil samples from different locations in the area. Measurements were performed using a NaI(Tl) gamma-ray spectrometry system to acquire the data and analyses were conducted using the UCS-20 program. From the results, the average specific activities of ²³⁸U, ²³²Th, and ⁴⁰K were 25.15 ± 3.65 Bq kg⁻¹, 12.27 ± 2.28 Bq kg⁻¹, and 300.09 ± 14.50 Bq kg⁻¹, respectively. These results were lower than the global average recommended by UNSCEAR. The radiological risk criteria were estimated based on the specific activities of radionuclides to assess any radiological risks that may be associated with the soil of the study area under investigation. The radiological risk criteria included radium equivalent activity (Ra_eq), absorbed dose rate (D_R), annual effective dose (AEDE), annual gonadal equivalent dose (AGDE), excess lifetime cancer risk (ELCR), external hazard index (H_ex), internal hazard index (H_in), representative gamma index (I _γ ) and effective dose rate to different body organs (D_organ). They were compared with the international safe limits. Overall, all the radiological risk criteria had values lower than the worldwide average recommended by UNSCEAR. This work employed statistical techniques to understand and explain the statistical characteristics of measured radionuclide-specific activities and the associated radiological risk criteria , including skewness, kurtosis, correlation coefficients, and K-means cluster analysis.

The current study investigates the presence ²²²Rn in tap water, natural spring water, and well water from various locations in Er-Rachidia, Morocco, to assess the potential radiological risks posed to the local community. Radon, a radioactive gas produced by the decay of uranium and thorium in rocks and soil, poses significant radiation hazards. Using a Nuclear Track Detector (LR-115), researchers investigated the presence of radon in water from wells, dams, and rivers. The highest radon concentrations are found in well water, with an average of 1.92 Bq/L. The concentration of river water is the lowest, coming in at 0.53 Bq/L, while the average concentration of dam water is 0.84 Bq/L. On average, the annual effective dosage for well water is 4.57 ms per year. The water dosages from dams range from 1.74 to 2.44 μSv/y, with 1.98 being the average. River water ranges from 0.51 to 1.69 mSv/y, averaging 1.24 µSv/y. The excess lifetime cancer risk varies significantly across water sources: 1.27 × 10−3 to 1.84 × 10−3 (average 1.60 × 10−3) for well water, 0.61 × 10−3 to 0.85 × 10−3 (average 0.69 × 10−3) for dam water, and 0.18 × 10−3 to 0.59 × 10−3 (average 0.43 × 10−3) for river water. The results dispel fears of significant radioactive dangers to the locals by suggesting that the measured radon concentrations are within the limits set by international organizations.

Cadmium Selenide CdSe thin films were deposited on (7.5×1.3×0.1 cm3) glass substrates and (1×1 cm2) p-type silicon substrates using pulsed laser deposition technique (Nd: YAG laser beam with 80 mJ energy, λ = 1064 nm). Then, they were annealed at 300 °C for 1 h to get diodes as visible light detectors. Some of these samples (diodes) were exposed to different intervals (5, 7, 9, 12) days of neutron radiation using (241Am -10Be) source with a flux of 3×105 n/cm2.s and energy of 5.71 MeV. For comparison purposes, the other diodes were kept without any irradiation The morphological and electrical properties of these samples were studied by XRD, FE-SEM and I-V measurements. Results have shown all these thin films exhibit a hexagonal structure. However, there is a slight shift in the preferred orientation (100) for the irradiated films. Also, there was a new (102 - SiO2) peak that appeared in the irradiated thin film pattern. The crystallite size of pristine and (5, 7, 9, 12) days irradiated CdSe thin films were (26.9, 18.3, 24.9, 20.3 and 24.5) nm respectively, whereas, the mean particle size of the pristine film was 37 nm whereas for the irradiated films 53, 64, 73 and 92 nm. Results also show that the band gap of these samples increased from 2.17 eV for pristine thin films to 2.3, 2.48, 2.25, and 2.3 eV for the irradiated thin films. On the other hand, the results of I-V characteristics show the dark/light current. The current under illumination increases when exposed to small values of neutron radiation then it decreases with higher values of exposure. In contrast, the dark current decreases significantly with the irradiation. The effect of the irradiation was clear on the response/recovery period for all devices. Nevertheless, it was more profound in the response/recovery time of pristine devices. Also, the photo-responsivity of the pristine device was larger than the other devices and it was decreased with increasing absorbed doses. HIGHLIGHTS Hexagonal Structure: All CdSe thin films (both pristine and irradiated) exhibit a hexagonal structure, with a slight shift in orientation due to neutron irradiation. Neutron Radiation Impact: Neutron radiation causes a significant shift in crystallite size, decreasing the size for irradiated films. Additionally, a new (102 SiO2) peak emerges in irradiated samples, indicating radiation-induced changes. Band Gap Increase: The optical band gap of the CdSe films increased with neutron irradiation, starting from 2.17 eV in pristine films to values as high as 2.48 eV after irradiation. Morphological Changes: Irradiated films showed increased grain sizes, with neutron exposure leading to the enlargement of mean particle sizes from 37 nm in pristine samples to 92 nm in the most heavily irradiated samples. Electrical Behavior: Neutron irradiation impacted the photodetectors' electrical properties. The light current initially increased with small neutron doses but decreased with higher doses, while dark current consistently decreased after irradiation. GRAPHICAL ABSTRACT

The objectives of the current study are to carry out soil gas radon (Rn) measurements, to evaluate the total inhalation effective dose, to determine risk levels over the lithological formations of the study area. The behavior investigation of Rn activity concentration distributions in dwellings and soils, and soil Rn mapping were also conducted. Soil gas Rn measurements were made at 102 sampling points by Markus 10 instrument. This data was combined with previously reported results from 140 indoor Rn RADTRAK dosimeters to determine the total inhalation effective dose and to conduct a statistical analysis. Overall, the Rn activity concentrations in soil and dwellings range from 4 to 66 kBq m⁻³ and from 15 to 140 Bq m⁻³, with averages of 31 ± 15 kBq m⁻³ and 41 ± 24 Bq m⁻³ respectively. The corresponding total inhalation effective dose ranges from 0.35 to 3.53 mSv y⁻¹, with a mean value of 1.37 ± 0.58 mSv y⁻¹. For soil gas Rn, the chlorite schist lithology showed the highest average concentration level. Which could be justified by the possible presence, within chlorite minerals, highly emitting zones of alpha particles, leading to the formation of radioactive halos. Normal and high‐risk level of Rn were found for about 82% and 11% of the total area surveyed respectively. These findings highlight the need for preventive measure against Rn exposure in homes within the investigated areas. This study contributes valuable insights into Rn distribution patterns and risk assessment, offering a basis for targeted interventions in the region.