BẢN TIN KHOA HỌC

Background subtraction using the SNIP method enhanced by the Levenberg–Marquardt algorithm

Anh Nhi Le, Thanh Tai Chau, Ngoc Ba Vu, Thien Thanh Tran, Le Hao Cong, Van Tao Chau

Nuclear Instruments and Methods in Physics Research Section a Accelerators Spectrometers Detectors and Associated Equipment, 171544 (2026)

Abstract

In this study, a practical refinement of the SNIP method is proposed for background subtraction in HPGe γ-ray spectra. A single filter width determined from the detector specifications is used in Gaussian convolution to obtain preliminary peak parameters, which are then refined using the Levenberg–Marquardt (LM) algorithm to provide more reliable peak widths for SNIP background subtraction. The resulting method, referred to as LMSNIP, is evaluated using the ¹⁵⁴Eu spectra measured at 25 cm and 5 cm. The reconstructed backgrounds are directly compared with those obtained using the adaptive SNIP approach, while the resulting net peak areas are compared with Genie2K. For the 25 cm spectrum, LMSNIP and adaptive SNIP provide generally similar background estimates. Under the more demanding 5 cm condition, however, LMSNIP yields a smoother and more stable baseline and generally better agreement with Genie2K for most investigated peaks. Additional validation using the ¹³³Ba spectrum measured at 5 cm further shows that LMSNIP remains effective for a reference spectrum with different low-energy characteristics. These results support the applicability of LMSNIP to background reconstruction and net peak-area determination under the investigated close-geometry conditions.

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Background Radiation in some Quarries and Quarry Lakes in Binh Duong Province, Vietnam

Van Thang Nguyen, Nguyen Phong Thu Huynh, Huynh Thi Yen Hong, Truong Huu Ngan Thy, Huynh Truc Phuong, Cong Hao Le

Journal of Radioanalytical and Nuclear Chemistry(2022)

Abstract:

Operation of some quarries can release radioactive materials from the deep soil to other environments that potentially impact human health. The present study investigated concentrations of radon and other radionuclides in surface soil, air, and water around two quarries in the south of Vietnam. Indoor radon concentrations ranged between 6.19 Bq m^-3 and 20.6 Bq m^-3. In surface soil, the average concentrations of ⁴⁰K, ²²⁶Ra, and ²³²Th were 387, 36.5, and 44.5 Bq kg^{− 1}, respectively. In surface soil, the average values of radioactivity found for ⁴⁰K, ²²⁶Ra, ²³⁸U, and ²³²Th were 2.65, 1.23, 1.12, and 1.22 mBq l^-1, respectively. The results show that the radioactive levels in the quarry region are found higher than in the nearby area. However, these levels are not enough for a recommendation for public health.

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Phan Long Ho, Le Dinh Hung,Vu Tuan Minh,Dang Van Chinh, Tran Thien Thanh, Chau Van Tao

Science of The Total Environment, Available online 18 June 2020, 140291

Abstract:

This paper presents information on the concentration of radioactivity and chemicals at 12 water stations that used groundwater as their raw water supply source. The groundwater's radioactivity was higher than the treated, tap, and surface water, but lower than the national and international recommendations. At five stations (41.7%), the gross alpha contents were higher than the levels advised by Vietnam's regulations, but met the WHO and IAEA's recommendations. The mean active (Bq L⁻¹) gross alpha, gross beta, Ra-224, Ra-226, and Ra-228 were 0.093 ± 0.012, 0.221 ± 0.020, 0.031 ± 0.004, 0.028 ± 0.004, and 0.035 ± 0.001, respectively. The contribution of Ra-226 to the gross alpha was in a range of 23%–60% (r = 0.91, p value <.001), and the ratio of Ra-226/Ra-228 ranged from 0.49–1.06. For the treated and tap water, each age groups' annual committed effective dose was lower than the international regulations. The concentration of the total dissolved solids, sulfate, chloride, sodium, barium, and manganese met the national regulations. However, during the rainy season, the surface water in the area was affected by saltwater intrusion, with salinity up to 4.1‰. Discriminant analysis was applied to study the differences among the water groups. As a result, the treated and tap water were separated from the others.

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Assessment of physicochemical properties and radioactivity in groundwater at households living in bac Lieu province, vietnam

Phan Long Ho, Le Dinh Hung, Vu Tuan Minh, Nguyen Tran Bao Thanh, Dang Van Chinh, Le Hoang Minh, Tran Thien Thanh, Chau Van Tao

Environ Geochem Health

Abstract:

This paper presents findings on groundwater physiochemical composition and radioactivity levels in households in Bac Lieu province, Vietnam. Through discriminant analysis, it was observed that groundwater quality exhibits spatial variations corresponding to saline intrusion zones. The paired-samples T-tests revealed significantly different ratios of Ra-224, Ra-226, and Ra-228 isotopes between Na–Cl and Ca–Na–HCO3 water types. All three water types had a ratio of Ra-226/Ra-228 of approximately one, indicating the presence of groundwater aquifers beneath the crust and fluvial marine sediment. Furthermore, strong associations between sulfate and calcium suggest that CO2 enrichment in groundwater aquifers indicates anoxic aquatic environments. Twenty-five of the thirty-three evaluated samples exceeded the national technical regulations for domestic water quality with parameters such as chloride, sulfate, sodium, gross alpha, or total dissolved solids. Fifteen samples exceeded gross alpha's allowable contamination threshold of 0.1 Bq/L. The combination of Ra-226 and Ra-228 did not surpass the U.S. Environmental Protection Agency's recommended limit of 0.185 Bq/L. However, nineteen samples exhibited annual committed effective doses of radium isotopes for infants that exceeded the WHO recommendation of 0.1 mSv/year.

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L. H. Khiem, K. Sera, T. Hosokawa,N. H. Quyet, M. V. Frontasyeva, T. T. M. Trinh, N. T. B. My, N. T. Nghia, T. D. Trung, L. D. Nam, K. T. Hong, N. N. Mai, D. V. Thang, N. A. Son, T. T. Thanh, D. P. T. Tien

Journal of Radioanalytical and Nuclear Chemistry, published online: 21 February 2020

Abstract:

The concentration of 22 metal elements including Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr, Ba and Pb in Barbula Indica moss samples collected in 12 di erent sites in Ha Noi in July of 2018 were determined by Proton Induced X-ray Emission. The obtained results has been used for assessment of heavy metal pollution in the air in Ha Noi region. The factor analysis was applied to the concentration data of 11 interested elements and the possible sources of air pollution have been suggested. The study showed that the PIXE technique is e cient to environmental pollution analysis since it precise, fast and low-cost.

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Assessment of annual effective dose from radium isotopes in groundwater samples in households along the lower Mekong River

Phan Long Ho, Vu Tuan Minh, Le Dinh Hung, Do Quoc Trung, Dang Van Chinh, Tran Thien Thanh, Chau Van Tao

Abstract

In this study, the 224Ra, 226Ra, 228Ra in groundwater samples at Long Phu district were determined by HPGe detector with co- precipitation method. The median concentrations were 0.040 ± 0.005 Bq L−1, 0.039 ± 0.004 Bq L−1, and 0.049 ± 0.004 Bq L−1. Highest MDC values were 0.028 Bq L−1, 0.010 Bq L−1, 0.018 Bq L−1, respectively. It’s a strong relationship between 224Ra, 228Ra versus conductivity, salinity, TDS, SO42−. The annual e ective dose of the age groups was lower than the WHO rec- ommended value except for infants exceeding around 1.5 times. Besides, the 226Ra minimum recovery obtained was 90% with trueness 9.9% and relative percentage di erence 6.1%.