Le Thi Ngoc Trang, Huynh Dinh Chuong, Tran Thien Thanh
Journal of Radioanalytical and Nuclear Chemistry (2020)
Abstract:
In this study, the optimization of the p-type HPGe detector model has been performed to improve the accuracy of Monte Carlo simulation in calculating full energy peak efficiency. The optimized detector model was validated by comparison of simulated efficiencies with experimental efficiencies for measurement configurations of point-like sources at various distances from the detector surface and cylindrical sources on the detector surface. The obtained results showed an excellent agreement between the simulated and experimental efficiencies with relative deviations of less than 4% in the energy range from 53 to 1847 keV.
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Onset of collectivity for argon isotopes close to N=32
Phys. Rev. C 109, 034312
Abstract:
The shell closure at N=32 has been investigated by a first spectroscopy of the N=31 nucleus 49Ar at the Radioactive Isotope Beam Factory. Using the 50Ar(p,pn) reaction channel in inverse kinematics, 50Ar projectiles at 217 MeV/nucleon impinged on a 150 mm long liquid hydrogen target, part of the MINOS device. Prompt deexcitation γ rays were measured with the NaI(Tl) array DALI2+. Reaction products were analyzed with the SAMURAI spectrometer, which allowed the measurement of the momentum distributions and angular momentum transfer. Data were compared to state-of-the-art theoretical predictions, including shell-model, energy-density functional, and ab initio calculations. An onset of collectivity is suggested besides the spherical configuration typical of a closed shell nucleus, such as for 52Ca.
On the Bohr-Sommerfeld quantization condition and assault frequency in a semiclassical model for α decay
Le Hoang Chien, Nguyen Tri Toan Phuc
Nuclear Physics A 1018 (2022) 122373
Abstract:
We study the impacts of the Bohr-Sommerfeld quantization condition and the assault frequency on the α decay half-life within the semiclassical model. The potential between the α particle and daughter nucleus is calculated by the double-folding model using the CDM3Y3 density-dependent nucleon-nucleon interaction with a finite-range exchange term. We show that the proper implementation of the Bohr-Sommerfeld condition leads to a considerable change of the calculated α decay half-life with certain forms of potential. We also propose an alternative treatment for the assault frequency based on the generalized oscillator potential. This description of assault frequency considerably improves the agreement between the calculated α decay half-lives and the experimental data.
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Nuclear rainbow of the symmetric nucleus-nucleus system: Interchange of the nearside and farside scattering
Phys. Rev. C 109, 064606 – Published 4 June 2024
Abstract:
Extensive elastic scattering data measured at energies around 10 to 20 MeV/nucleon for some light identical systems, like 12C+12C and 16O+16O, were shown to exhibit the nuclear rainbow pattern of broad Airy oscillations of the elastic scattering cross section at medium and large angles. Because of the identity of the scattered projectile and recoiled target, the smooth rainbow pattern at angles around and beyond 𝜃c.m.≈90∘ is strongly deteriorated by the boson exchange in the 12C+12C and 16O+16O systems at low energies. The exchange symmetry of two identical nuclei implies the Mott interference of the direct and exchange scattering amplitudes, which destroys the nuclear rainbow pattern. The nuclear rainbow features in the elastic scattering of two identical nuclei have been discussed so far based on the nearside-farside (NF) decomposition of the scattering amplitude given by an optical model calculation neglecting the projectile-target exchange symmetry. Moreover, the NF decomposition method was developed in the 1970s by Fuller for nonidentical dinuclear systems only, and the details of how the exchange symmetry of an identical system affects the evolution of nuclear rainbow remain unexplored. For this purpose, the Fuller method is generalized in the present work for the elastic scattering of two identical (spin-zero) nuclei, with the projectile-target exchange symmetry taken explicitly into account. The results obtained for elastic 12C+12C and 16O+16O scattering at low energies show that the exchange symmetry results in a symmetric interchange of the nearside and farside scattering patterns at angles passing through 𝜃c.m.=90∘, which requires a more subtle interpretation of nuclear rainbow. We found further that a similar NF interchange also occurs in a nonidentical nucleus-nucleus system with the core-core symmetry at low energies, where the elastic cross section at backward angles is due mainly to the elastic transfer of cluster or nucleon between two identical cores. This interesting effect is illustrated in the elastic 16O+12C scattering at low energies where the elastic 𝛼 transfer between two 12C cores has been proven to enhance the elastic cross section at backward angles.
Non-destructive evaluation of thickness of material plates through Compton back-scattering technique using Si(Li) detector
Huynh Dinh Chuong, Nguyen Duy Thong, Vo Hoang Nguyen,Le Hoang Minh, Nguyen Thi Truc Linh, Phan Long Ho, Tran Thien Thanh, Chau Van Tao
Radiation Physics and Chemistry (2022), 109978
Abstract:
This study aims to develop the system for the non-destructive evaluation of the thickness of material plates based on the Compton back-scattering technique using a Si(Li) detector and 241Am radioactive sources. The calibration curve is constructed based on the areas under the Compton scattering peak obtained from the measurements of reference samples. This calibration curve is used to determine the saturation thickness, the maximum measurable thickness (MMT) with the desired accuracy, and the unknown thickness of a sample. To validate the reliability of the system, we have performed thickness measurements for seventeen aluminum samples with different thicknesses in the range of 4.40–21.07 mm. The samples are measured seven times, except for two samples with thicknesses of 11.52 mm and 14.98 mm up to twenty times. The Pearson's correlation coefficient between the reference and measured thicknesses presented a strong positive correlation. The average relative deviation between the reference and measured thicknesses is less than 1%.
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NGHIÊN CỨU PHƯƠNG PHÁP ĐÁNH GIÁ HOẠT ĐỘ RADON TRONG NHÀ SỬ DỤNG HỆ PHỔ KẾ GAMMA
Lê Quang Vương, Nguyễn Huỳnh Khánh Duyên, Huỳnh Đình Chương, Hoàng Đức Tâm, Trần Thiện Thanh, Châu Văn Tạo
TẠP CHÍ KHOA HỌC TRƯỜNG ĐẠI HỌC SƯ PHẠM TP HỒ CHÍ MINH, Tập 20, Số 12 (2023): 2081-2094
TÓM TẮT
Theo Tổ chức Y tế thế giới (WHO), khí radon trong nhà là một trong những nguyên nhân gây ung thư phổi và cần được giám sát. Trong nghiên cứu này, chúng tôi trình bày một phương pháp đánh giá hoạt độ radon (222Rn) trong nhà dựa trên phép đo phổ gamma của đồng vị 214Bi, là sản phẩm phân rã của 222Rn trong chuỗi 238U. Đầu tiên, hoạt độ 222Rn trong năm căn phòng có kích thước khác nhau được đo bằng hệ thiết bị RAD7. Tiếp theo, hoạt độ 214Bi được xác định bằng hệ phổ kế gamma sử dụng đầu dò NaI(Tl) kết hợp với mô phỏng MCNP6. Hàm làm khớp tuyến tính thể hiện mối tương quan tốt giữa kết quả hoạt độ 214Bi và 222Rn (R2 = 0,998). Phương pháp này có thể cho kết quả dự đoán nhanh chóng hoạt độ 222Rn trong nhà, hỗ trợ điều tra giám sát các khu vực có hàm lượng 222Rn bất thường.
