Study of nonlocality effects in direct capture reactions with Lagrange-mesh R-matrix method
Nguyen Hoang Phuc, Nguyen Tri Toan Phuc, Do Cong Cuong
International Journal of Modern Physics EVol. 30, No. 09, 2150079 (2021)
Abstract:
We apply the Lagrange-mesh 𝑅-matrix method to calculate the 𝑆-factor for the 13C(𝑝,𝛾)14N and 16O(𝑝,𝛾)17F direct radiative capture reactions. By comparing the astrophysical 𝑆-factors calculated with nonlocal and local potentials, we investigate the nonlocality effects coming from the nuclear potentials in the direct capture reactions. Our calculations are in good agreement with the experimental data and indicate a nonnegligible difference in the results of local and nonlocal potentials. The use of small diffuseness narrow potentials also provides a remarkably good fit in the case with multiple broad resonances. Our findings suggest that the nonlocal potential improves the calculated results although the difference between the local and nonlocal potentials is smaller than uncertainties from other sources. We propose the nonlocality potential should be used in the potential model calculation of future astrophysics rates evaluation.
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Tran ThienThanhLe Hoang Minh,Nguyen Quoc Bao Cuong, Huynh Dinh Chuong, Nguyen Duy Thong, Vo Hoang Nguyen, Phan Long Ho, Chau Thanh Tai, Chau Van Tao
Phan Long Ho, Le Dinh Hung, Vu Tuan Minh, Dang Van Chinh, Tran Thien Thanh & Chau Van Tao
Scientific Reports Volume 10, Article number: 4299 (2020)
Abstract:
This paper presents information on the gross alpha and gross beta activity concentrations of two hundred twenty-six groundwater samples collected by gas ow proportional counters in southern Vietnam. The gross alpha results in the water samples ranged from 0.024 to 0.748 Bq L−1 with a mean of 0.183 ± 0.034 Bq L−1, and the gross beta results in the water samples ranged from 0.027–0.632 Bq L−1 with a mean of 0.152 ± 0.015 Bq L−1. The values obtained in this work were compared with those previously published for various regions or countries. Next, untreated and treated groundwater samples were analyzed to assess their in uences on the treatment process. The results showed that there
were di erences in the minimum detection concentrations and the mean activity values between the untreated and treated groundwater samples (The p-value of the mean comparison tests is signi cant with p < 0.05). In both sample groups, there was a strong positive correlation of the gross alpha versus the gross beta results (r > 0.6). This means that among the radionuclides, the major sources of beta radiation are uranium and thorium decay series radionuclides. Finally, the annual e ective dose for adults (>17 years) was calculated based on the assumption that major radionuclides have the highest e ective dose conversion factors. In general, the results for Pb-210, Ra-226, and Ra-228 were observed to be lower than the recommended reference values established by the World Health organization and the International Atomic Energy Agency, except for the value of Po-210.
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Simultaneous correction of the coincidence summing and self‑absorption for radioactivity measurement in solid samples by MCNP‑CP code
Le Quang Vuong, Tran Thien Thanh, Phan Long Ho, Le Cong Hao, Chau Van Tao
Journal of Radioanalytical and Nuclear Chemistry
Abstract:
The present work of this study involves an advanced analytical procedure that allows direct and fast determining the specific activity of 238U and 235U using the gamma-rays of 63.3 keV and 185.7 keV after subtraction of the contribution of overlapping peaks. This procedure also included MCNP-CP code in order to calculate the coincidence summing and the self-absorption correction factor. Validation of the developed procedure was confirmed by the IAEA proficiency test to calculate the activities of radionuclides in various types of samples such as rich thorium, secular equilibrium, and disequilibrium of uranium. The final scores were received “acceptable” for all radionuclides.
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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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