Concentration and distribution characteristics of gross alpha, 238U, 234U and 226Ra in freshwater of some rivers and artificial lakes in southeast Vietnam
Minh An Dinh, Nhut Tan Tran, Van Thang Nguyen, Xuan Anh Dao Lam, Truc Phuong Huynh, Cong Hao Le
Applied Radiation and Isotopes 225 (2025) 112064
Abstract:
Rivers and artificial lakes are the major sources that supply freshwater to communities, cities, agriculture, and industry. However, this water type is normally polluted by radionuclides, which are from groundwater discharge, surface soil runoff, or Naturally Occurring Radionuclides (NOR) effluents. In this study, gross alpha and alpha-emitting radionuclides (234U, 238U and 226Ra) were analysed in freshwater samples collected in 31 sites in two rivers and four quarry lakes in Southeast Vietnam. The analyses were conducted in two separate parts of water: suspended matter and filtered water. The mean gross alpha, 234U, 238U and 226Ra activities in unfiltered water were 52.9, 8.2, 7.9, and 6.1 mBq L−1, respectively. These values remain within the recommendations of the United States Environmental Protection Agency (USEPA) and World Health Organization (WHO) for the contamination of radionuclides in drinking water. High activities were found in the water of the Sai Gon River due to the impact of pollutants from the densely populated and industrial zones. Ratios of 234U/238U were found to be slightly >1, while ratios of 226Ra/234U and 226Ra/238U were found to be < 1. Radionuclides 234U, 238U and 226Ra contribute significantly to the gross alpha in both rivers and artificial lakes. Strong linear correlations were found between the activities of alpha-emitting radionuclides and gross alpha in quarry lake water (Pearson correlation coefficient p > 0.7). For two types of freshwater, a significant amount of gross alpha, alpha-emitting radionuclides, was found in the suspended solids of water. The suspended matter/water partition coefficients (Ksw) for two types of water were 1.23 × 105, 1.66 × 104, 1.55 × 104, and 9.7 × 103 L kg−1 for gross alpha, 234U, 238U and 226Ra, respectively. Ksw values of the gross alpha and radionuclides for river water are significantly higher than those in quarry lake water.
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COMPARATIVE STUDY OF SIMULATION AND EXPERIMENT IN DETERMINING 192Ir SOURCE STRENGTH FOR BRACHYTHERAPY QUALITY ASSURANCE
Tran Thi Bao Ngoc, Phan Quoc Uy, Le Quang Vuong, Tran Thien Thanh, Chau Van Tao
Radiation Physics and Chemistry
Abstract:
This research is of paramount importance as it combines experimental measurements and Monte Carlo simulation to determine the air kerma strength of the 192Ir source, which plays a crucial role in dose calculations for brachytherapy treatment planning. The air kerma strength represents the source strength value, directly influencing the accuracy of dose calculations in cancer treatments. Verifying the source strength during each source exchange is essential to the quality assurance process.
In this study, the 192Ir Gammamed Plus source, provided by Varian, was used to calculate the air kerma strength through experimental measurements and Monte Carlo simulation. The measurements were conducted on a brachytherapy system with an HDR 1000 Plus well-type ionization chamber and source tube 70010 from Standard Imaging. Using the MCNP6 code, we constructed a model equivalent to the experimental system, consisting of the source geometry, source tube, and well-type chamber, with source self-absorption also considered.
The air kerma strength measurements differed from the certified value by less than 2%, within the allowable range according to the AAPM TG40 recommendations. The experimental and simulation methods showed strong agreement, with less than 4.1% discrepancies. Considering source self-absorption, the air kerma strength calculation for the 192Ir source was consistent across both methods. The findings of this study validate that we successfully built an experimental system model using the Monte Carlo simulation with the MCNP6 code. This model can be further developed for future research.
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Le Hoang Chien, Dao T. Khoa, Nguyen Hoang Phuc, Doan Thi Loan, Nguyen Tri Toan Phuc
PHYSICAL REVIEW C 114, 014614 (2026)
Abstract:
A density dependent nucleon-nucleon interaction (CDM3YR) has been parametrized based on the original M3Y-Reid interaction, to properly reproduce the saturation properties of symmetric nuclear matter (NM) in the nonrelativistic Hartree-Fock calculation with the energy of NM in a good agreement with the microscopic ab initio results over densities up to three times the saturation density. The real optical potential (OP) of symmetric12C + 12C and 16O + 16O systems is then calculated within the double-folding model (DFM) using the realistic densities of 12C and 16O nuclei and CDM3YR interaction, for the optical model analysis of elastic scattering at low energies and determination of the astrophysical 𝑆 factor of 12C + 12C and 16O + 16O fusion in the barrier penetration model. The DFM calculation of the real OP for these two symmetric systems was also done using the original (density independent) M3Y-Reid interaction, and that added by a repulsive core suggested by Esbensen et al. [Phys. Rev. C 77, 054608 (2008); Phys. Rev. C 84, 064613 (2011)], to explore the impact of medium effects that are effectively encoded in the density dependence of the CDM3YR interaction.
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The COMET Collaboration
Abstract:
The Technical Design for the COMET Phase-I experiment is presented in this paper. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into electrons in the field of an aluminum nucleus (μ–e conversion, μ−N → e−N); a lepton flavor- violating process. The experimental sensitivity goal for this process in the Phase-I experiment is 3.1 × 10−15, or 90% upper limit of a branching ratio of 7 × 10−15, which is a factor of 100 improvement over the existing limit. The expected number of background events is 0.032. To achieve the target sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will be used. Two types of detectors, CyDet and StrECAL, will be used for detecting the μ–e conversion events, and for measuring the beam-related background events in view of the Phase-II experiment, respectively. Results from simulation on signal and background estimations are also described.
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Combination of experimental and simulation methods for determination of effective atomic number by Rayleigh-Compton scattering technique
Le Hoang Minh, Van Thi Thu Trang, Tran Thien Thanh
JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 2025
Abstract:
This paper presents the gamma scattering technique to determine substance' component concentrations. The experimental and simulated R/C ratios of binary oxide samples (Fe2O3and SiO2) were measured. The concentration of each element were interpolated, with a bias relative less than 5% for the elements in the reference samples. The elements' experimental and theoretical Rayleigh-Compton ratio values had a robust relationship in the equation RexpR/C=1.03×RtheoR/C (n = 11; r = 0.99; p-value < 0.01). The Zeff interpolation results and the calculation results from the theoretical formulas have good agreement with an average difference of 5%.
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