Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-05-20
Abstract： Electron beam irradiation has become an important part of the nuclear application industry. Low energy electron beam has been increasingly used in waste water treatment and food preservation, and the measurement parameters of irradiation are crucial to the irradiation quality. Since the relevant standards of electron beam dosimetry below 300keV have not been established, the parameter measurements are traced to the 10MeV electron linear accelerator, and the inconsistency of the measurement objects brings systematic bias. In this paper, for the low energy electrons below 300keV, the method of electron beam energy measurement is studied by combining test and simulation calculation, and the absorption dose measuring device based on calorimetry is developed. The relationship between absorbed dose and beam intensity, displacement velocity and other parameters is investigated. The results show that the energy parameters of low energy electrons are measured by the step stacking dose experiment combined with the energy deposition curve simulation, and the absorbed dose parameters of low energy electrons are measured by calorimetry. The measurement uncertainty is 11% (k=2). This study provides a reliable measurement guarantee for low-energy electron beam irradiation technology.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-04-20
Abstract： After decades of research, the problems and behavior of the corrosion of reactor alloy materials are well known. However, some problems in corrosion of reactor materials have not been clarified, including the critical corrosion process of the reactor materials under operational conditions, the role of a single factor in the corrosion process, and the prediction of corrosion behaviors of new materials in extreme environments. The density functional theory, which is based on quantum mechanics, can accurately predict the motion process of atoms and the change in the relevant energy within a very short period. The density functional theory has become an important auxiliary method for investigating the corrosion process of reactor alloy materials in recent years and can help solve the above problems. In this paper, two parts are reviewed. The first part introduces the density functional theory and includes the theoretical basis, development process, and mainstream computing software. In the second part, the research status of the density functional theory in the corrosion of reactor alloy materials is reviewed, including the adsorption, separation, combination, and internal diffusion of the reactor alloy material surfaces in the environments of water-cooled reactor, liquid-metal-cooled reactor, and molten salt reactor.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-11
Abstract： Fusion triple product represents a crucial parameter for evaluating the potential of self-sustained fusion nuclear reactions. It employs the product of three physical properties: the fuel nuclei number density ($n$), plasma confinement time ($τ_ mathrm{E}$) and fuel temperature ($T$) to establish a condition for assessing the feasibility of achieving self-sustained nuclear fusion. This study considers a fusion reaction system using $^{6}$Li-D as nuclear fuel, neglects cyclotron radiation, incorporates the impact of relativistic effects on bremsstrahlung radiation and the impact of recycled energy on the energy gain factor $Q$. Based on this foundation, the minimum triple product ($n_ mathrm{i}Tτ_ mathrm{E}$= SI{4.9e23}{ per cubic meter kilo electronvolt second}) is calculated for the $^{6}$Li-D reaction to yield energy gain of Q=1. These results show that although the $^{6}$Li-D fusion reaction can achieve a positive energy gain but the condition required for the $^6$Li-D fusion reaction is more difficult than the D-T fusion reaction.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-16
LIU Yinshen
YANG Xiaofei
ZHANG Peng
HU Hanrui
BAI Shiwei
WANG Shujing
LIU Yongchao
GUO Yangfan
LIN Zheyang
YAN Zhou
MEI Wencon
CHEN Shaojie
NI Xinyue
XIE Bingqi
YE Yanlin
LI Qite
LI Hongwei
HE Chuangye
YANG Jie
LIU Zuoye
Abstract： The basic properties of atomic nuclei including spins, magnetic moments, electric quadrupole moments and charge radii, are sensitive probes to different aspects of exotic nuclear structure, and are also important to investigate the unrevealed nature of interaction between nucleons. Based on multidiscipline, laser spectroscopy is a unique tool to precisely measure the basic nuclear properties mentioned above in a nuclear-model independent way by measuring the hyperfine structure of atoms, ions, or molecules, which has played an important role in the study of exotic nuclear structures across the different regions of the nuclear chart. Basic principles of laser spectroscopy and various types of experimental devices are expounded after the brief history of the hyperfine structure. Furthermore, advantages of utilizing laser spectroscopy in the study of nuclear structure are briefly introduced by taking the radioactive neutron-deficient Pb region as an illustration. In addition, current condition of collinear laser spectroscopy setup has been systematically reviewed, together with the latest progress on collinear resonance ionization spectroscopy offline devices at Peking University. Finally, the developing status and ongoing plan of laser spectroscopy devices for current and future radioactive ion beam facilities in China have been put forward, and the broad prospects of laser spectroscopy in unstable nuclear properties and the fundamental symmetries based on molecular spectroscopy are interpreted.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-04
Abstract： The nuclear reaction at energies near the Coulomb barrier is an effective way to study the interaction between nuclear structure and dynamics. As more exotic weakly bound nuclei become accessible at new accelerator facilities, it is becoming critically important to understand the influence of weak binding energy on reaction dynamics, including on fusion. At present, a large number of experiments have shown that the complete fusion cross section between stable weakly bound nuclei such as 6,7Li, 9Be and heavy mass target nuclei is suppressed about 30% lower than the fusion cross section calculated by existing theoretical models and the fusion cross section derived from tightly bound nuclear systems. In order to investigate the breakup effect of weakly bound nuclei on the suppression of the complete fusion cross section, studying the breakup reaction and mechanism of weakly bound nuclei has become concerned. This article introduces the recent work on breakup of weakly bound nuclei, including the research of our group.
Subjects: Physics >> Nuclear Physics submitted time 2024-01-12
Abstract： Due to the difficulties of the direct measurement of unstable nuclei neutron capture cross section, the surrogate ratio method had been proved valid in (n, γ) determination. The difference of the spin-parity distribution in compound nuclei that formed by surrogate reaction or neutron capture was discussed in this work. The γ-decay probabilities ratio of 92Zr* and 94Zr* were calculated in various spin-parities up to 8 with TALYS code, and the calculation shows the ratio is insensitive to their spin-parity distribution in high incident neutron energies. The measured γ-decay probabilities ratios of 92Zr* and 94Zr* were compared to the theoretical calculations, it imply that the spin-parity distributions of compound nuclei formed by (18O, 16O) reactions are similar to the one formed by neutron captures.
Subjects: Physics >> Nuclear Physics submitted time 2024-01-09
J. Hu
Z.Y. Han
Y.J. Li
Z.H. Li
G. Lian
Y.P. Shen
S.Q. Yan
S. Zeng
B. Guo
W.P. Liu
Z. Bai
B.L. Jia
S.L. Jin
J.B. Ma
P. Ma
S.B. Ma
S.W. Xu
Y.Y. Yang
N.T. Zhang
X.D. Tang
Abstract： In Orgueil meteorites, an exceptionally high 22Ne/20Ne abundance ratio or even nearly pure 22Ne is ob#2;served, which is the so-called Ne extraordinary problem. Fossil material of extinct 22Na is believed to be the origin of extraordinary 22Ne, these 22Na nuclides were trapped in grains and incorporated into meteorites in stellar explo#2;sive event. Supernovae and neon-rich novae are the primary events, which are responsible for the production of 22Na through the explosive hydrogen burning process. 22Na(p, γ)23Mg and 19Ne(α, p) 22Na are two crucial reactions in the so-called NeNa-MgAl cycle and the rapid-proton process, which lead to the fast nucleosynthesis up to A=100 nuclide region and the outburst of novae and X-ray bursters. Since many proton resonance levels in odd-A compound nucleus 23Mg may be involved at nova temperature, existing measurements can only provide partial effective information on the 22Na(p, γ)23Mg reaction. Large uncertainties still exist in the astrophysical reaction rates of the two reactions at present. Thick target inverse kinematics method is a very effective way to scan the 23Mg proton resonance levels re#2;lated to the 22Na(p, γ)23Mg reaction via the excitation function of 22Na(p, p) elastic scattering, which could be obtained over a large energy range in one-shot measurement with low-intensity radioactive 22Na beam. In the present work, 22Na+p resonance scattering via thick target inverse kinematics was studied at RIBLL1 radioactive beam line in the HIRFL national laboratory at Lanzhou. A high-purity 22Na beam with an intensity of about 2 × 105 pps was produced via the 1H(22Ne,22Na)n reaction with an alcohol-cooled hydrogen gas target. Time-of-Flight by two plastic scintillator detectors and two parallel-plate avalanche counters were used to monitor the 22Na secondary beam before reaching the (CH2 )n target. The timing information is useful for beam particle identification and the position information is essen#2;tial for 22Na(p,p) elastic scattering kinematics reconstruction. Light recoil particles from 22Na+p reaction system were detected by two sets of double-sided silicon strip detector telescopes centered at 𝜃lab = 0° and 14°, respectively, while the heavy recoil particles were stopped in the (CH2 )n thick target. Two-body kinematics reconstruction of 22Na(p,p) elastic scattering is performed on the event-by-event basis, and an excitation function of 22Na(p,p) is obtained in the energy range of 𝐸c.m. = 1.5 to 4 MeV. Obvious proton resonance structure is observed in the 23Mg compound nucleus, which will be further analyzed with R-matrix nuclear theoretical model.
Subjects: Physics >> Nuclear Physics submitted time 2023-12-24
HE Ziyang
WU Xiaoguang
JIANG Wei
LI Congbo
ZHOU Zhenxiang
SUN Qi
GUO Mingwei
WU Hongyi
LI Zhihuan
FAN Ruirui
TANG Jingyu
LI Tianxiao
HU Shouyang
ZHI Yu
SONG Jinxing
LI Peiyu
LUAN Guangyuan
ZHANG Qiwei
WANG Zhaohui
CHEN Xiongjun
Abstract： Isomer with long lifetime and high excitation energy has great significant in the fields of national strategic security and energy storage. Mastering the method of inducing isomer to decay is the key technology. However, this technology has got into trouble in recent years. For mastering the method of inducing isomer to decay, it is beneficial to start the research on the formation, excitation and de-excitation mechanism of isomer from the view of atomic nucleus structure. In terms of experimental technology, we use the white light neutron beams to bombard Hf target. We established a triple coincidence measurement system, whcih consisted of GTAF-II and HPGE, combined with white light neutron time of flight. Through the analysis of experimental data, we found the sign of the $^{178}$Hf isomeric state exciting to the transition level and releasing rapidly.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-12-18
Abstract： Gallium oxide, a wide band gap semiconductor, is a focus material in the semiconductor field at present. However, the conventional doping process has not achieved its p-type doping on bulk crystals, which hinders its application. Proton irradiation transmutation doping is realized by using the transmutation products produced by the nuclear reaction between high-energy protons and target materials. Many transmutation products have different doping effects, and it is expected to achieve P-type doping of gallium oxide based on Coulomb coupling effect of various doping elements. In this paper, the transmutation doping of gallium oxide irradiated by 100MeV protons is simulated and analyzed by using the Monte Carlo software FLUKA of ion reaction. The results show that after 100 cooling days after irradiation, the activation activity decreases by about four orders of magnitude, and the element concentration of transmutation products tends to be stable. The analysis of element concentrations of transmutation products with different doping types shows that proton irradiation transmutation can generate net P-type doping. The net P-type doping concentration is different at different depths of the target material. It is the largest at the depth of 0.6-0.9cm, which can reach 4.26×10^{14}cm^{-3} per 10^{16}cm^{-2} irradiation fluence. Compared with the doping of 40MeV proton irradiation and neutron irradiation, 100MeV proton irradiation transmutation doping efficiency is higher.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2023-12-06
LI Yun-qiu
LI Cong-bo
ZHENG Yun
LI Tian-xiao
WU Xiao-guang
HONG Rui
WU Hong-yi
ZHENG Min
ZHAO Zi-hao
HE Zi-yang
LI Jin-ze
LI Guang-shun
GUO Cheng-yu
NI Lei
ZHOU Zhen-xiang
HE Chuang-ye
LIU Fu-long
ZHOU Xiao-hong
LIU Min-liang
ZHANG Yu-hu
Abstract： High spin states of 94Nb have been studied with the 82Se(18O, p5n)94Nb fusion evaporation reaction at anincident beam energy of 82and 88 MeV. The level scheme of 94Nbhas been modified and extended with 15 newγrays. Based on γ-γcoincidence relationships，DCO ratios and linear polarization measurements, the new level structures in 94Nb have been interpreted in terms of the shell model calculations performed in the configuration space π(1f5/2, 2p3/2, 2p1/2, 1g9/2 ) for the protons and ν(2p1/2, 1g9/2, 1g7/2, 2d5/2 ) for the neutrons.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-11-17
Abstract： The diamond-like carbon (DLC) stripper foils with ~5 μg/cm2 in thickness were produced by using the composite technology of the filtered cathodic vacuum arc (FCVA)- alternating current carbon arc (ACCA)-relaxation technique. The uniformity of the DLC foils were measured by the XP2U balance. The results show that the maximum inhomongeneity of DLC foils in the range of Φ100mm is 8.82%. The microstructure of the DLC foils were measured by the scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The SEM images show that the DLC foils are smooth, and contain hardly droplets through the double 90° filters. The Raman spectrum indicates that the DLC foils are amorphous carbon films. The X-ray photoelectron spectrum indicates the sp3 bonds of the DLC foils exceed 70%. The irradiation lifetimes of the DLC stripper foils were tested and compared with the heavy ion beams at the Beijing HI-13 Tandem Accelerator. The results indicate that the lifetime of the DLC stripper foils after relaxation is ~3 times of the DLC stripper foils before relaxation. The lifetime of DLC stripper foil is respectively 4 and 13 times of the carbon stripper foil for the 197Au- and 63Cu- ion beams (~9 Mv, ~1 μA). The lifetime of DLC stripper foil is 2.6-10 times of the carbon stripper foil for the 107Ag-、70Ge-、48Ti-、28Si- and 127I-ion beams. The heavier ions and the stronger beam current, the longer lifetime of DLC stripper foil is compared with that of carbon stripper foil. The lifetime of the DLC stripper foils is related to the substrate bias voltage, and increases at first and then decreases with the increasing of the substrate bias voltage. The lifetime reaches the peak value when the substrate bias voltage is -400 V.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-08-08
Abstract： Abstract：The testing equipment for boron aluminum alloy neutron absorption materials in spent fuel pool grid of nuclear power plant developed by China Institute of Atomic Energy was upgraded and improved, and the integrated data acquisition system, transmission system and control record analysis system were developed. The detection equipment can be used for multi-point measurement of samples of different sizes. The detection device has the characteristics of continuous, fast, and full area detection, with two modes: fixed point detection and mobile detection. Completed 20cm × 30cm hanging sample, 373cm × 19.5cm long board, 6cm × 6cm square template and Φ 5cm × 0.3cm circular sample plate have been tested and the detection results have been analyzed. The neutron absorption performance testing equipment for boron aluminum alloy materials lays the foundation for conducting non-destructive testing research on domestically produced boron containing neutron absorption materials, and provides strong support for critical safety monitoring of spent fuel pools in nuclear power plants.
Subjects: Nuclear Science and Technology >> Reprocessing Technology of Spent Nuclear Fuel submitted time 2022-05-28
Abstract：
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Peer Review Status:Awaiting Review
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