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TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN, ĐẠI HỌC QUỐC GIA THÀNH PHỐ HỒ CHÍ MINH

KHOA VẬT LÝ - VẬT LÝ KỸ THUẬT

BỘ MÔN VẬT LÝ HẠT NHÂN - NGÀNH KỸ THUẬT HẠT NHÂN - NGÀNH VẬT LÝ Y KHOA

Vu Ngoc Ba,  Le Thi Ha Giang, Bui Ngoc Thien, Truong Thi Hong Loan, Ngo Quang Huy

Applied Radiation and Isotopes 163 (2020) 109229

Abstract:

In this work, the physical dimensions and the actual position of germanium crystal within a detector housing, the homogeneity of the crystal surface and outer dead layer thickness for a p-type HPGe detector were con rmed by the scan method using the collimated low energy photon beams combined with Monte Carlo simulation. The length and the diameter of the crystal were found to match with the values supplied by the manufacturer in discrepancy of about 3%. Only one mounting strap (Typical) for holding the crystal inside the mounting cup instead of two which is indicated in the detector drawing supplied by manufacturer was revealed by scanning along the lateral face of detector. Scanning on the front surface and around the lateral face of detector by the collimated 59.5 keV photon beam veri ed the outer dead layer thicknesses at the front surface and lateral face of the crystal averagely increases about 6.5% and 12% respectively. Adjusting the detector parameters for MCNP simulation by these veri ed values, the simulated peak ef ciencies for different photon energies become being in accordance with the experimental peak ef ciencies.

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Van‐Chung Cao, Thi Ly Nguyen, Thi Thu Hong Pham, Thi The Doan, Han‐Tuong Luc, Nhut‐Huan Phan, Giang T. T. Phan,  Trung H. Duong,  Hoai‐Nam Tran

Journal of Radioanalytical and Nuclear Chemistry

Abstract:

A treatment of dose nonuniformity inside Lo Ren and purple star apples irradiated by 10 MeV electron beam accelerator has been proposed by using medium density berboards (MDF). The dose uniformity ratios (DURs) inside the Lo Ren and purple star apples were estimated as 2.47–2.48 and 2.18–2.22, respectively. To reduce the DURs, the arrangement and the thickness of the MDF boards were determined by Monte Carlo simulations. Measurements of the absorbed doses have been conducted to compare with the simulations. The DURs were reduced to 1.36–1.39 and 1.44–1.46 for the Lo Ren and purple star apples, respectively.

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Nguyen Tri Toan Phuc, Kazuki Yoshida, Kazuyuki Ogatta,

Phys.Rev. C100,064604 - Published 6 December 2019

ABSTRACT:

Background: Proton-induced nucleon knockout (p,pN) reactions have been successfully used to study the single-particle nature of stable nuclei in normal kinematics with the distorted-wave impulse approximation (DWIA) framework. Recently, these reactions have been applied to rare-isotope beams at intermediate energies in inverse kinematics to study the quenching of spectroscopic factors.

Purpose: Our goal is to investigate the effects of various corrections and uncertainties within the standard DWIA formalism on the (p, pN) cross sections. The consistency of the extracted reduction factors between DWIA and other methods is also evaluated.
Method: We analyze the ( p, 2 p) and ( p, pn) reaction data measured at the R3 B-LAND setup at GSI for carbon, nitrogen, and oxygen isotopes in the incident energy range of 300–450 MeV/u. Cross sections and reduction factors are calculated by using the DWIA method. The transverse momentum distribution of the 12C(p,2p)11B reaction is also investigated.

Results: We have found that including the nonlocality corrections and the Møller factor affects the cross sections considerably. The proton-neutron asymmetry dependence of reduction factors extracted by the DWIA calculation is very weak and consistent with those given by other reaction methods and ab initio structure calculations.

Conclusions: The results found in this work provide a detailed investigation of the DWIA method for ( p, pN ) reactions at intermediate energies. They also suggest that some higher-order effects, which is essential for an accurate cross-section description at large recoil momentum, is missing in the current DWIA and other reaction models.

DOI: 10.1103/PhysRevC.100.064604

Huynh Nguyen Phong Thu, Nguyen Van Thang, Le Cong Hao

Journal of Environmental Radioactivity 216 (2020) 106189

Abstract:

The effects of moisture content, grain size, temperature, major elemental composition, and the pH of soils on the radon emanation and diffusion coefficients were evaluated in this study. The emanation and diffusion coefficients are strongly influenced by moisture content and grain size. The radon emanation coefficient increased and the diffusion coefficient decreased with decreasing particle size. However, for soils with large particle sizes, the radon emanation and diffusion coefficient remain almost unchanged with variation in grain size. Comparing five different sized soil particles, the emanation coefficient increased and the diffusion coefficient decreased with moisture content. The radon emanation coefficient reached a constant value with different moisture contents depending on the range of grain sizes. The saturation emanation coefficient for less than 0.1, 0.1–0.2, 0.2–0.3, 0.3–0.5, and more than 0.5 mm sized soil grain ranges are 0.47, 0.42, 0.35, 0.26 and 0.23, respectively, with saturation moisture contents of 16%, 14%, 10%, 6% and 4%, respectively. A drastic increase in radon emanation is found at smaller grain sizes with increasing moisture content. Based on the content of major elements and pH of the soils, the multiple regression indicates that the radon emanation coefficient appears to be significantly dependent on iron content and pH. Effective diffusion coefficient values calculated in our study agree with the results calculated by a previous model. Experimental values show that the temperature dependence of the radon diffusion coefficient follows Arrhenius behavior.

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Suppression of the nuclear rainbow in the inelasticnucleus–nucleus scattering

Nguyen Hoang Phuc, Dao T. Khoa, Nguyen Tri Toan Phuc, Do Cong Cuong

Eur. Phys. J. A (2021) 57:75

Abstract:

The nuclear rainbow observed in the elasticα-nucleus and light heavy-ion scattering is proven to be due tothe refraction of the scattering wave by a deep, attractive realoptical potential. The nuclear rainbow pattern, established asa broad oscillation of the Airy minima in the elastic cross sec-tion, originates from an interference of the refracted far-sidescattering amplitudes. It is natural to expect a similar rainbowpattern also in the inelastic scattering of a nucleus–nucleussystem that exhibits a pronounced rainbow pattern in theelastic channel. Although some feature of the nuclear rain-bow in the inelastic nucleus–nucleus scattering was observedin experiment, the measured inelastic cross sections exhibitmuch weaker rainbow pattern, where the Airy oscillationis suppressed and smeared out. To investigate this effect, anovel method of the near-far decomposition of the inelasticscattering amplitude is proposed to explicitly reveal the cou-pled partial-wave contributions to the inelastic cross section.Using the new decomposition method, our coupled channelanalysis of the elastic and inelastic12C+12C and16O+12C scattering at the refractive energies shows unambigu-ously that the suppression of the nuclear rainbow pattern inthe inelastic scattering cross section is caused by a destruc-tive interference of the partial waves of different multipoles.However, the inelastic scattering remains strongly refractivein these cases, where the far-side scattering is dominant atmedium and large angles like that observed in the elasticscattering.

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Nguyễn Duy Thông

Tạp chí Khoa học Trường Đại học Cần Thơ, Tập 56, Số chuyên đề: Khoa học tự nhiên (2020)(1):134-140

Tóm tắt:

Tán xạ nhiều lần được xem là nguyên nhân chính dẫn đến các sai số trong việc xác định vị trí của các hạt tới trong thực nghiệm. Hàm phân bố mật độ xác suất của góc tán xạ nhiều lần đóng vai trò quan trọng trong quá trình làm khớp các số liệu thực nghiệm. Hiện nay, nhiều công trình vẫn đang sử dụng hàm phân bố mật độ xác suất của góc tán xạ nhiều lần tuân theo phân bố Gauss. Điều này dẫn đến các sai số trong quá trình làm khớp. Để xác định hàm phân bố mật độ xác suất của góc tán xạ nhiều lần, trong bài báo này, mô phỏng tương tác của hạt tới để đạt được phân bố của góc tán xạ bằng chương trình g4beamline đã được tiến hành và dựa vào các tính toán  chi2 và hệ số Kullback-Leibler để xác định số hàm Gauss có thể được áp dụng để miêu tả hàm mật độ xác suất.

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