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Lê Quang Vương, Phan Long Hồ, Lê Công Hảo, Trần Thiện Thanh, Châu Văn Tạo

Những tiến bộ trong Vật lý Kỹ thuật và Ứng dụng – CAEP VI

Tóm tắt:

Trong công việc này, phương pháp Monte Carlo với chương trình mô phỏng MCNP-CP và phương pháp tất định sử dụng phần mềm ETNA được áp dụng để tính toán hệ số hiệu chỉnh trùng phùng của nguồn RGU dạng trụ, với các chiều cao mẫu là 0,99 cm, 1,53 cm, 2,01 cm, 2,59 cm, 2,89 cm, 3,69 cm. Các kết quả thể hiện sự phù hợp tốt giữa hai phương pháp với độ sai biệt tương đối nhỏ hơn 2%. Ngoài ra, hệ thực nghiệm với đầu dò HPGe loại p và các nguồn RGU được sử dụng đo phổ gamma và xác định hiệu suất ghi đỉnh năng lượng toàn phần trong khoảng năng lượng từ 46,5 keV đến 2447,9 keV. Đối với nguồn RGU có chiều cao 0,99 cm, ở năng lượng gamma 768,5 keV của đồng vị 214Bi, giá trị hiệu suất ghi đỉnh khi có hiệu chỉnh trùng phùng có độ sai biệt tương đối lớn nhất là 25% so với giá trị không có hiệu chỉnh trùng phùng. Điều đó chứng minh rằng hệ số hiệu chỉnh trùng phùng có đóng góp quan trọng và không thể bỏ qua trong các nghiên cứu về hiệu suất ghi đỉnh sử dụng hệ phổ kế gamma.

Nguyễn Anh Tuấn, Châu Văn Tạo

Tạp chí Phát triển Khoa học và Công nghệ – Khoa học Tự nhiên, 4(4):737-743

Tóm tắt:

Chùm electron năng lượng cao phát ra từ các máy gia tốc ngày càng được ứng dụng rộng rãi trong xử lý thực phẩm, y tế, biến tính vật liệu, đổi màu đá bán quý và xử lý môi trường gồm nước thải, khí thải và bùn thải. Chùm electron phát ra từ máy gia tốc chỉ hữu hiệu trong việc xử lý bề mặt vì khả năng xuyên sâu thấp, do đó khi cần xử lý khối vật liệu có mật độ mặt cao chùm electron được bắn vào bia nặng để chuyển đổi sang tia X theo cơ chế phát bức xạ hãm. Trong báo cáo này, hiệu suất chuyển đổi tia X được xác định bằng thực nghiệm đo liều hấp thụ gây ra bởi chùm electron và chùm photon kết họp mô phỏng MCNP4c2 cho các bia khác nhau, với các mức năng lượng chùm electron tới bia 5 MeV, 7,5 MeV và 10 MeV. Kết quả mô phỏng MCNP4c2 và đo thực nghiệm đo liều bằng liều kế phim cho thấy hiệu suất chuyển đổi phụ thuộc vào vật liệu bia và năng lượng chùm electron tới. Hiệu suất chuyển đổi cao nhất khi sử dụng bia hỗn hợp Ti – H20 – Pb, với kết quả tương ứng với các mức năng lượng 5,0 MeV, 7,5 MeV và 10,0 MeV là 5,57 %, 7,12 % và13,54 %. Bia hỗn hợp Ti – H2O – Pb có tính ứng dụng thực tế cao vì bia được cấu tạo với 3 lớp vật liệu vở bọc Ti có chức năng chịu lực, chịu nhiệt, nước giải nhiệt được luân chuyển giữ lớp Ti và Pb để giải nhiệt cho bia.

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Yuki Fujii, Yu Nakazawa, Ewen Lawson Gillies, Eitaro Hamada, Masahiro Ikeno, MyeongJae Lee, Satoshi Mihara, Yuta Miyazaki, Masayoshi Shoji, Chau Thanh Tai, Tomohisa Uchida and Kazuki Ueno for COMET Collaboration

DOI: 10.1109/NSSMIC.2018.8824619

Abstract:

A COMET Experiment Phase-I is designed to search for a muon to an electron conversion with a 100 times better sensitivity than the current upper limit on its branching ratio in order to investigate the new physics beyond the standard model. To achieve such an unprecedented sensitivity, a high intensity muon beam is mandatory. In consequence, an extremely high hit rate is predicted and it can cause a high trigger rate more than tens of kHz dominated by the background events. Then the high trigger rate would lead to the severe dead-time in the data acquisition. Therefore it is essential for a success of the experiment to reduce the trigger rate down to a few kHz within a processing time shorter than 5 μs while maintaining the signal efficiency high enough. We are developing an event classification algorithm utilising a CDC hit information and a dedicated fast online trigger system to accomplish this aim. The event classification based on a boosted decision tree shows 3.8 kHz of trigger rate, which almost satisfies the rate requirement, with a good compatibility to the trigger electronics. The total processing time to generate the trigger decision is estimated to be ~3 μs which also fulfils the timing requirement.

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Huynh Dinh Chuong, Nguyen Thi Hai Yen, Nguyen Thi My Le, Hoang Duc Tam

Applied Radiation and Isotopes Available online 29 April 2020, 109197

Abstract:

This study proposes an approach to determine the density of a liquid based on the gamma scattering method. The liquids used to determine density were poured in a cylindrical tube. This approach requires that the ratio R (the ratio of area under a single scattering peak for a liquid to that for water) increase linearly with an increase in the density of the liquid. In a certain range of density, a linear relationship was obtained between the ratio R and density, as described by a linear calibration curve with coefficients of slope and intercept, for the investigated tube diameters. In particular, the values of the slope and intercept could be expressed as mathematical functions of the diameter of the tube. For a given tube, the coefficients of slope and intercept of the linear calibration curve were obtained based on these functions, which helped determine the density of the liquid. The reliability of the proposed approach was evaluated by using it to calculate the densities of five liquids—n-hexane, diethyl ether, acetonitrile, toluene, and glycerol—using tubes with inner diameters of 1.8 cm, 2.25 cm, and 2.68 cm. The results show that the maximum relative deviation between the reference and the measured densities was 4.3%.

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Huynh Truc Phuong, Tran Pham Ngoc Trinh, Dinh Thanh Binh, Nguyen Thi Truc Linh, Truong Thi Hong Loan, Tran Tuan Anh, Ho Manh Dung, Nguyen Van Dong

Science & Technology Development Journal, 22(4):370-377

Abstract:

Introduction: Breast cancer is the most common type of cancer resulting in death. Trace elements of Fe, Se and Zn can play a key role in the onset and prevention of breast cancer. Trace elements in the fingernails may be used as bioindicators for breast cancer diagnosis. The purpose of this work is to determine the concentrations of Fe, Se, and Zn in the fingernails of women with breast cancer and healthy women, which used to find the difference and correlation of these elements in the fingernail.

Methods: This research was approved by the Ethics Committee of Dong Nai General Hospital. The fingernail collected from 29 women with breast cancer and 30 healthy women, who are the same age and living in Dong Nai province, Vietnam. The concentrations of Fe, Se, and Zn in the fingernails were determined using the k0-INAA method. The analytical data were evaluated using some statistical analysis for the correlation of trace elements in the fingernails of both groups.

Results: As a result, the mean concentrations of Fe, Se and Zn in fingernails of women with breast cancer were 102.87 ug/g, 0.75 ug/g and 65.49 ug/g, respectively, while those of healthy women were 69.74 ug/g, 0.78 ug/g and 107.75 ug/g. The assessment of these elements in fingernails for both two sample groups, including t-test and correlation coefficients, was also carried out in this study. As a result, the significant difference (p < 0.05) was found for the Fe and Zn in fingernails of women with breast cancer, while those of Se was not found. The correlation between Se and Zn was found in both groups. The correlation between Fe and Zn was found in fingernails of healthy women, but it disappears in the women with breast cancer.

Conclusions: From our finding, it can be concluded that Fe and Zn significantly associated with the risk of breast cancer, while Se is not associated.

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Determination of some elements in the nails in patients with colon cancer using total reflection X-ray fluorescence

Huynh Truc Phuong, Nguyen An Son, Nguyen Thi Nguyet Ha, Nguyen Thi Minh Sang, Nguyen Thi Truc Linh, Dinh Thanh Binh, Truong Thi Hong Loan, Ho Manh Dung, Tran Tuan Anh, Nguyen Van Dong

Spectrochimica Acta Part B: Atomic Spectroscopy 182 (2021) 106234

Abstract:

Sixty-two subjects (31 men with colon cancer) participated in this study. The analysis of elements in the nails was performed by total reflection X-ray fluorescence (TXRF) technique. The results showed that fifteen elements were quantifed, including the following: S, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, and Br. We have found that there were significant differences in the concentrations of elements Ca, Cr, Fe, Cu, Zn, As, and Se between normal subjects and men with colon cancer (p < 0.05). We conclude that TXRF is a technique suitable for elemental analysis in human nail samples. The concentration of elements Ca, Cr, Fe, Cu, Zn, As, and Se could be among the factors used for the diagnosis of colon cancer risk in men.

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FACULTY OF PHYSICS & ENGINEERING PHYSICS

DEPARTMENT OF NUCLEAR PHYSICS - NUCLEAR ENGINEERING - MEDICAL PHYSICS

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