Sensitivity of secondary particle emission to hadronic physics models in GATE/Geant4 proton therapy simulations at 100 MeV
Pham Thi Cam Lai, Nguyen Tri Toan Phuc, Vo Hong Hai
Science & Technology Development Journal 2023, 26(3):2930-2936
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Ba Ngoc Vu, Thien Ngoc Bui, Phong Thu Nguyen Huynh, Hao Cong Le, Phuong Truc Huynh, Hong Loan Thi Truong
Journal of Radioanalytical and Nuclear Chemistry
Abstract:
In this work, the radon exhalation, annual effective dose and excess lifetime cancer risks due to the exposure of radon released from raw building materials containing fly ash of different fractions were evaluated. The 226Ra and 222Rn concentrations were evaluated by the measurements on HPGe gamma spectrometer, RAD 7 radon detector combined with model calculation of radon exhalation for standard rooms. The results indicated that the emanation fraction for fly ash is lower than the corresponding value for soils and rocks. The surveyed building materials of containing fly ash can result in an indoor radon concentration up to 1.7 Bq m−3 which is below the recommended value of 100 Bq m−3 by WHO, the annual effective dose increases from 0.007 to 0.022 mSv year−1, the excess lifetime cancer risks ranges from 0.027 × 10–3 to 0.085 × 10–3 with the ratio of 3.2 for the additional fly ash content in cement up to 75%. In the meanwhile, it has a down trend and influences inconsiderably on these parameters for sand. The obtained mean annual effective doses are lower than the dose limitation of 10 mSv year−1 recommended for occupational workers.
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Le Dinh Hung, Phan Long Ho*, Vu Tuan Minh, Lam Tran Van Anh, Le Hoang Minh, Le Quang Vuong, Tran Thien Thanh, Chau Van Tao
Environmental Geochemistry and Health (2026) 48:498
Abstract:
The presence of naturally occurring radionuclides in coastal groundwater constitutes a significant public health risk, especially in areas susceptible to hydrological variability. This research applies multivariate statistical methods, including principal component analysis and hierarchical cluster analysis, alongside the PHREEQC thermodynamic model to elucidate the mechanisms governing the mobility of naturally occurring radioactive materials (NORM), specifically gross alpha and beta activity, in a tropical coastal aquifer. Examination of 44 groundwater samples collected over two seasons indicated that more than half exceeded the national guideline for gross alpha activity (0.1 Bq/L). The results indicate that mildly acidic and reducing (anaerobic) conditions facilitate the reductive dissolution of iron and manganese hydroxides. The reductive dissolution of Fe/Mn oxides destabilizes the mineral structures that previously acted as sorptive barriers, thereby releasing trapped radionuclides directly into the groundwater. Additionally, this mobilization is synergistically influenced by competitive ion exchange mechanisms. PHREEQC modeling further identifies a potential iron “lock/release” mechanism: at mildly acidic conditions (mean pH 5.36–5.39), ferrihydrite precipitation is inhibited, maintaining elevated radionuclide mobility. Conversely, as pH increases (up to 7.32), the system approaches supersaturation (saturation index, SI > 0), promoting co-precipitation and resulting in a more than 31-fold decrease in alpha activity during the rainy season (from 0.405 to 0.013 Bq/L). In contrast, beta-emitting radionuclides are less affected by iron-related processes and are predominantly influenced by dilution, with a reduction of approximately threefold (from 0.358 to 0.109 Bq/L). These findings establish a scientific basis for developing cost-effective water treatment approaches, such as aeration combined with pH adjustment, to simultaneously remove heavy metals and alpha radioactivity from tropical coastal aquifer systems.
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N. Tomida, T.N.T.Ngan, et al.
Physical Review Letters 124, 202501 (2020)
Abstract:
We measured missing mass spectrum of the 12C(γ,p) reaction for the first time in coincidence with potential decay products from η' bound nuclei. We tagged an (η + p) pair associated with the η'N → ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observedinthebound-stateregion.An upper limit of the signal cross section in the opening angle cosθηplab < -0.9 was obtained to be 2.2 nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η' production rate. Our results indicate a small branching fraction of the η'N → ηN process and/or a shallow η'-nucleus potential.
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Rapid method for determining elemental composition in oxide powder sample using Rayleigh-COMPTON scattering technique
Le Hoang Minh, Pham Thi Anh Nhung, Huynh Dinh Chuong, Nguyen Thi Truc Linh, Phan Nguyen Hoang Long, Tran Thien Thanh
Radiation Physics and Chemistry, Available online 28 March 2024
Abstract:
This study presents an innovative approach utilizing gamma scattering techniques to precisely determine the composition percentage in a two-component oxide compound. The experiment involved a 241Am gamma-ray source emitting 59.54 keV radiation and a Si(Li) detector to capture Rayleigh and Compton scattering signals from oxide powder samples. These samples were meticulously prepared by blending Pb3O4 and ZnO, with Pb3O4 proportions ranging from 0% to 100%. To ensure accuracy, eleven standard samples were employed to generate standard curves for Rayleigh intensity, Compton intensity, and the Rayleigh-Compton ratio. The key finding of this research was the calculation of composition percentages for the four samples under investigation, derived from experimental data and the standard curve. Validation against reference materials revealed a minimal relative deviation of approximately 1.0% when estimating the Pb3O4 ratio, showcasing the precision and potential applicability of this method in material science and analysis.
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