您选择的条件: 辐射物理与技术
  • Shuffler中子质询系统核材料质量测量的基体校正新方法

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-07-08

    摘要: 废物桶中基体材料的存在限制了主动质询系统对核材料质量测量的准确性,确保核保障测量结果不受基体材料的影响至关重要。因此,基于通量监测器响应,本文在传统校正方法的基础上开发了一种新的基体校正方法。为了验证新方法的有效性,利用Geant4工具包构建了WM3210 PAN Shuffler系统模型以及常见的基体材料,并开展了模拟研究。结果表明,对于不同富集度以及分布状态的U3O8材料,传统校正方法与新校正方法均可以有效的降低基体材料对核材料质量测量的影响,但相较于传统方法,新方法表现出更好的校正能力。对于U3O8材料位于基体中心的情况,新校正方法得到的235U质量平均相对偏差为13.6%,而对于U3O8材料均匀弥散在基体中的情况,新校正方法得到的235U质量平均相对偏差为7.78%。

  • Robustness of the octupole collectivity in 144Ba within the cranking covariant density functional theory in 3D lattice

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-07-04

    摘要: The octupole deformation and collectivity in octupole double-magic nucleus144Ba are investigated using theCranking covariant density functional theory in a three-dimensional lattice space. The reducedB(E3)transi#2;tion probability is implemented for the first time in semiclassical approximation based on the microscopicallycalculated electric octupole moments. The available data, including theI–ωrelation and electric transitionalprobabilitiesB(E2)andB(E3)are well reproduced. Furthermore, it is shown that the ground state of144Baexhibits axial octupole and quadrupole deformations that persist up to high spins (I≈24ℏ).

  • Systematic analysis and modeling of the FLASH sparing effect as a function of dose and dose rate

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-07-03

    摘要: Ultrahigh-dose rate radiotherapy (FLASH-RT) is a revolutionary radiotherapy technology that can spare normal tissues without compromising tumor control. Although qualitative experimental results have been reported, quantitative and systematic analysis of data is necessary. Particularly, the FLASH effect response model to the dose or dose rate is still unclear. This study investigated the relationships between the FLASH effect and experimental parameters, such as dose, dose rate, and other factors by analyzing published in vivo experimental data from animal models. The data were modeled based on logistic regression analysis using the sigmoid function. The model was evaluated using prediction accuracy, receiver operating characteristic (ROC) curve, and area under the ROC curve. Results showed that the FLASH effect was closely related to the dose, mean dose rate, tissue type, and corresponding biological endpoints. The dose rate corresponding to a 50% probability of triggering cognitive protection in the brain was 45Gy s−1. The dose rate corresponding to a 50% probability of triggering intestinal crypt survival and regeneration was 140Gy s−1. For the skin toxicity effect, the dose corresponding to a 50% probability of triggering the FLASH effect was 24Gy. This study helps to characterize the conditions underlying the FLASH effect and provides important information for optimizing experiments.

  • SiC基辐射伏特电池研制及性能优化

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-27

    摘要: 为提升辐射伏特电池的总转换效率和输出功率,综合考虑耗尽区宽度、扩散长度及电极结构等因素对电荷收集效率、总转换效率及输出功率的影响,通过优化换能器件及电极结构,成功制备出总转换效率及输出功率较高的63Ni-SiC基PIN结换能器件。所制备的辐伏电池的短路电流、开路电压、输出功率及总转换效率分别达到了10.29 – 13.43 nA/cm2、1.32 – 1.44 V、11.66 – 14.69 nW/cm2及2.24% –2.82%。与团队之前的工作相比,开路电压、FF因子及总转换效率分别平均提高了127.50%、114.47%及512.10%,且总转换效率高于文献报道的结果(0.5% – 1.99%)。结果表明,通过采用具有“浓度梯度层I层”的PIN结构、优化结区宽度和掺杂浓度,以及优化电极材料和结构,可显著提升辐伏电池的总转换效率和输出功率,为辐伏电池的设计与制备提供了重要的理论参考和实验依据。

  • 氚源集成化4H-SiC辐射伏特电池制备研究

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-27

    摘要: 为提升辐射伏特电池性能,研究了耗尽区宽度、扩散长度及电极结构等因素对输出功率的影响,并通过放射源厚度、换能器件结构、电极等方面的设计优化和工艺改进,制备获得了放射源与换能器件集成化的氚化钛-SiC基辐射伏特电池。与未集成化的氚化钛-SiC基电池的测试结果相比,氚化钛与换能器件集成化的方式显著提升了辐射伏特电池的输出性能,其中最大输出功率达到了21.4 nW,在已公开报道的同类型辐射伏特电池中处于较高水平。本工作为制备高性能辐射伏特电池提供了有价值的参考。

  • Shuffler中子质询系统核材料质量测量的基体校正新方法

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-27

    摘要: 废物桶中基体材料的存在限制了主动质询系统对核材料质量测量的准确性,确保核保障测量结果不受基体材料的影响至关重要。因此,基于通量监测器响应,本文在传统校正方法的基础上开发了一种新的基体校正方法。为了验证新方法的有效性,利用Geant4工具包构建了WM3210 PAN Shuffler系统模型以及常见的基体材料,并开展了模拟研究。结果表明,对于不同富集度以及分布状态的U3O8材料,传统校正方法与新校正方法均可以有效的降低基体材料对核材料质量测量的影响,但相较于传统方法,新方法表现出更好的校正能力。对于U3O8材料位于基体中心的情况,新校正方法得到的235U质量平均相对偏差为13.6%,而对于U3O8材料均匀弥散在基体中的情况,新校正方法得到的235U质量平均相对偏差为7.78%。

  • 电子束辐照降解水中链霉素的研究-修改稿

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-27

    摘要: 电子束辐照作为一种高级氧化法,利用其产生的具有强氧化性和强还原性的活性自由基对水中有机物进行处理已经受到广泛研究。目前缺乏利用高级氧化法降解链霉素的研究。因此,采用电子束辐照作为一种新的途径,来探究链霉素降解的可行性。实验结果表明,在1MeV电子束能量和10kGy辐照剂量的条件下,5mg/L的链霉素得到了完全降解。通过DFT预测反应位点,并结合质谱数据分析链霉素降解产物的结构,得到了4种电子束辐照下链霉素的降解产物。同时根据不同辐照剂量下降解产物的成分和含量对降解路径进行合理推测。

  • Application of a neural network model with multimodel fusion for fluorescence spectroscopy

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-19

    摘要: In energy-dispersive X-ray fluorescence spectroscopy, the estimation of the pulse amplitude determines the accuracy of the spectrum measurement. The error generated by the amplitude estimation of the pulse output distorted by the measurement system leads to false peaks in the measured spectrum. To eliminate these false peaks and achieve an accurate estimation of the distorted pulse amplitude, a composite neural network model is proposed, which embeds long and short-term memory (LSTM) into the UNet structure. The UNet network realizes the fusion of pulse sequence features and the LSTM model realizes pulse amplitude estimation. The model is trained using simulated pulse datasets with different amplitudes and distortion times. For the pulse height estimation, the average relative error of the trained model on the test set was approximately 0.64%, which is 27.37% lower than that of the traditional trapezoidal shaping algorithm. Offline processing of a standard iron source further validated the pulse height estimation performance of the UNet-LSTM model. After estimating the amplitude of the distorted pulses using the model, the false-peak area was reduced by approximately 91% over the full spectrum and was corrected to the characteristic peak region of interest (ROI). The corrected peak area accounted for approximately 1.32% of the characteristic peak ROI area. The results indicate that the model can accurately estimate the height of distorted pulses and has substantial corrective effects on false peaks.

  • Effects of interstitial cluster mobility on dislocation loops evolution under irradiation of austenitic steel

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-14

    摘要: The evolution of dislocation loops in austenitic steels irradiated with Fe+ is investigated using cluster dynam ics (CD) simulations by developing a CD model. The CD predictions are compared with experimental results in the literature. The number density and average diameter of the dislocation loops obtained from the CD simula tions are in good agreement with the experimental data obtained from transmission electron microscopy (TEM) observations of Fe+-irradiated Solution Annealed 304, Cold Worked 316, and HR3 austenitic steels in the liter ature. The CD simulation results demonstrate that the diffusion of in-cascade interstitial clusters plays a major role in the dislocation loop density and dislocation loop growth; in particular, for the HR3 austenitic steel, the CDmodel has verified the effect of temperature on the density and size of the dislocation loops.

  • Shuffler中子质询系统核材料质量测量的基体校正新方法

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-13

    摘要: 废物桶中基体材料的存在限制了主动质询系统对核材料质量测量的准确性,确保核保障测量结果不受基体材料的影响至关重要。因此,基于通量监测器响应,本文在传统校正方法的基础上开发了一种新的基体校正方法。为了验证新方法的有效性,利用Geant4工具包构建了WM3210 PAN Shuffler系统模型以及常见的基体材料,并开展了模拟研究。结果表明,对于不同富集度以及分布状态的U3O8材料,传统校正方法与新校正方法均可以有效的降低基体材料对核材料质量测量的影响,但相较于传统方法,新方法表现出更好的校正能力。对于U3O8材料位于基体中心的情况,新校正方法得到的235U质量平均相对偏差为13.6%,而对于U3O8材料均匀弥散在基体中的情况,新校正方法得到的235U质量平均相对偏差为7.78%。

  • Comparison of displacement damage effects on the dark signal in CMOS image sensors induced by CSNS back-n and XAPR neutrons

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-10

    摘要: This study investigates the effects of displacement damage on the dark signal of a pinned photodiode CMOS image sensor (CIS) following irradiation with back-streaming white neutrons from white neutron sources at the China Spallation Neutron Source (CSNS) and Xi’an Pulsed Reactor (XAPR). The mean dark signal, dark signal non-uniformity (DSNU), dark signal distribution, and hot pixels of the CIS were compared between the CSNS back-n and XAPR neutron irradiations. The non-ionizing energy loss and energy distribution of primary knock on atoms in silicon, induced by neutrons, were calculated using the open-source package Geant4. An analysis combining experimental and simulation results showed a noticeable proportionality between the increase in the mean dark signal and the displacement damage dose (DDD). Additionally, neutron energies influence DSNU, dark signal distribution, and hot pixels. High neutron energies at the same DDD level may lead to pronounced dark signal non-uniformity and elevated hot pixel values. 

  • Superhydrophobic melamine sponge prepared by radiation induced grafting technology for efficient oil-water separation

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-07

    摘要: 本文介绍了一种超疏水性三聚氰胺(ME)海绵(ME-g-PLMA),该海绵通过高能辐射诱导的原位共价接枝长烷基十二烷基甲基丙烯酸酯(LMA)到ME海绵上,以实现高效的油水分离。所得的ME-g-PLMA海绵具有优良的孔隙结构,具有超疏水性(水接触角为154°)和超亲油性,可吸收高达自身重量66-168倍的各类油脂。所得到的ME-g-PLMA海绵可以通过连接泵连续分离水面上的浮油,或者通过重力驱动装置分离水下的浮油。ME-g-PLMA海绵在长期浸泡在不同的腐蚀性溶液中,多次反复吸油后,也能保持其高疏水性。所得改性ME-g-PLMA海绵具有优异的分离性能,在溢油清理方面具有巨大的潜力。

  • 10B-doped MCP detector developed for neutron resonance imaging at Back-n white neutron source

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-31

    摘要: Neutron resonance imaging (NRI) has recently emerged as an appealing technique for neutron radiography. Its complexity surpasses that of conventional transmission imaging, as it requires a high demand for both a neutron source and detector. Consequently, the progression of NRI technology has been sluggish since its inception in the 1980s, particularly considering the limited studies analyzing the neutron energy range above keV. The white neutron source (Back-n) at the China Spallation Neutron Source (CSNS) provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV. Neutron-sensitive microchannel plates (MCP) have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions, high detection efficiency, and low noise. In this study, we report the development of a 10B-doped MCP detector, along with its associated electronics, data processing system, and NRI experiments at the Back-n. Individual heavy elements such as gold, silver, tungsten, and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1-100 eV energy range; the more difficult medium-weight elements such as iron, copper, and aluminum with resonance peaks in the 1-100 keV energy range can also be identified. In particular, results in the neutron energy range of dozens of keV (Aluminum) are reported here for the first time.

  • Geant4 simulation of fast electron bremsstrahlung imaging at the HL-3 tokamak

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-31

    摘要: To further research on high-parameter plasma, we plan to develop a two-dimensional hard X-ray (HXR) imag#2;ing system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 keV. The application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross section. Therefore, it is suitable for the study of fast-electron physics, such as radio-frequency wave current drives, fast electrons driving instabilities, and plasma disruptions in fusion research. In this study, we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4, in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are considered. The preliminary calculation results indicate that the HXR energy deposition on the detector is symmetrically distributed, even though the plasma distribution is asymmetric owing to the toroidal effect. These simulation results are helpful in constructing the relationship between the energy deposition on the de#2;tector and parameter distribution on the plasma cross section during HL-3 experiments. This is beneficial for the reconstruction of the fast-electron distribution function and for optimizing the design of the HXR-imaging system.

  • Cone-beam computed tomography noise reduction method based on U-Net with convolutional block attention module in proton therapy

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30

    摘要: Cone-beam computed tomography (CBCT) is mostly used for position verification during the treatment pro#2;cess. However, severe image artifacts in CBCT hinder its direct use in dose calculation and adaptive radiationtherapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Netwas proposed for CBCT noise reduction in proton therapy, which is a CBCT denoised U-Net network with con#2;volutional block attention modules. The datasets contained 20 groups of head and neck images. The CT imageswere registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, wastrained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and theoriginal sCTU-Net are called CBAM-SCT and U-Net-SCT images, respectively. The HU accuracies of the CT,CBCT, and SCT images were compared using four metrics: mean absolute error (MAE), root mean square error(RMSE), peak signal-to-noise ratio (PSNR), and structure similarity index measure (SSIM). The mean values ofthe MAE, RMSE, PSNR, and SSIM of CBAM-SCT images were 23.80 HU, 64.63 HU, 52.27 dB, and 0.9919,respectively, which were superior to those of the U-Net-SCT images. To evaluate dosimetric accuracy, the rangeaccuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scannedfield and simple plan were calculated to compare the effects of the noise reduction capabilities of the originalU-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively thansCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reductionin proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed modelprovided relatively explicit information regarding patient tissues. Moreover, it can be used in dose calculationand adaptive treatment planning in the future.

  • Impact of initial fluctuations and nuclear deformations in isobar collisions

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30

    摘要: Relativistic isobar ($^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr) collisions have revealed intricate differences in their nuclear size and shape, inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions. In this study, we investigate the relative differences in the mean multiplicity ($R_{ langle N_{ rm ch} rangle}$) and the second- ($R_{ epsilon_{2}}$) and third-order eccentricity ($R_{ epsilon_{3}}$) between isobar collisions using Optical and Monte Carlo Glauber models. It is found that initial fluctuations and nuclear deformations have negligible effects on $R_{ langle N_{ rm ch} rangle}$ in most central collisions, while both are important for the $R_{ epsilon_{2}}$ and $R_{ epsilon_{3}}$, the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom. These features, compared to real data, may probe the particle production mechanism and the physics underlying nuclear structure.

  • Method for detector description conversion from DD4hep to Filmbox

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30

    摘要: DD4hep serves as a generic detector de Conversely, Filmbox~(FBX) stands out as a widely used 3D modeling file format within the 3D software industry.In this paper, we introduce a novel method that can automatically convert complex HEP detector geometries from DD4hep de The feasibility of this method was demonstrated by its application to the DD4hep de The automatic DD4hep--FBX detector conversion interface provides convenience for further development of applications, such as detector design, simulation, visualization, data monitoring, and outreach, in HEP experiments. 

  • 基于蒙特卡罗模拟的离子CT图像重建及相对阻止本领误差研究?

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-28

    摘要: 离子束放射治疗(放疗)越来越广泛地被运用于肿瘤治疗,目前使用传统X射线计算机断层扫描(CT)来制定离子放疗治疗计划时存在相对阻止本领(RSP)具有较大误差的问题,理想的方式是直接使用高能离子束对患者成像,生成离子放疗治疗计划设计时所需的医学图像,避免RSP转换从而减小RSP的误差。本研究使用蒙特卡罗程序Geant4/Gate搭建了离子CT模拟平台,设计了理想与现实两种离子CT成像系统探测器,利用最大似然法和ASD-POCS算法实现了图像重建,研究了理想与现实两种设置、多种能量以及不同离子种类对模体内硫、磷、碳和钙四种材料插件重建RSP误差的影响。结果表明,330MeV质子在理想与现实设置两种情况下的RSP相对误差都小于1.547%,理想设置下的RSP相对误差远小于现实设置,现实设置下各材料的RSP重建误差接近理想设置下的三倍;质子的RSP相对误差随着能量的增加而减小,在230MeV时的RSP相对误差最大,在硫、磷、碳和钙四种材料中分别为2.855%、2.468%、1.653%、2.553%。在330MeV时的RSP相对误差达到最小,在硫、磷、碳和钙四种材料中分别为0.181%、0.351%、0.250%和0.245%;在能量330MeV/u下,碳离子在硫、磷、碳和钙四种材料中的RSP相对误差分别为0.060%、0.281%、0.150%、0.082%,误差均在0.281%以内,RSP相对误差小于330MeV的质子。因此,与质子CT相比,碳离子CT能为离子放疗治疗计划设计提供更为精确的RSP数据。

  • Simulation study of the performance of the Very Large Area gamma-ray Space Telescope

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-26

    摘要: The Very Large Area gamma-ray Space Telescope (VLAST) is a mission concept proposed to detect gamma#2;ray photons through both Compton scattering and electron-positron pair production mechanisms, thus enablingthe detection of photons with energies ranging from MeV to TeV. This project aims to conduct a comprehensivesurvey of the gamma-ray sky from a low-Earth orbit using an anti-coincidence detector, a tracker detectorthat also serves as a low-energy calorimeter, and a high-energy imaging calorimeter. We developed a MonteCarlo simulation application of the detector using the GEANT4 toolkit to evaluate the instrument performance,including the effective area, angular resolution, and energy resolution, and explored specific optimizations ofthe detector configuration. Our simulation-based analysis indicates that the current design of the VLAST isphysically feasible, with an acceptance above 10 m2 sr which is four times larger than that of the Fermi-LAT,an energy resolution better than 2% at 10 GeV, and an angular resolution better than 0.2 ◦ at 10 GeV. TheVLAST project promises to make significant contributions to the field of gamma ray astronomy and enhanceour understanding of the cosmos.

  • Machine learning the apparent diffusion coefficient of Se(IV) in compacted bentonite

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-22

    摘要: Light Gradient Boosting Machine (LightGBM) and Random Forest (RF) algorithms were used to predict the apparent diffusion coefficient of Se(IV) in compacted bentonite.Seven instances of Se(IV)were measured using through-diffusion method.LightGBM (R2= 0.98 and RMSE = 0.025) exhibited superior predictive accuracy with a trainingdataset consisting of 956instances and eight input featuresfrom Japan Atomic Energy Agency(JAEA-DDB).Shapley Additive Explanation and Partial Dependence Plots analysesrevealedvaluable insightsinto the diffusion mechanism of adsorbed anion obtained by evaluating the relationshipsbetween the apparent diffusion coefficient and the dependency of each input feature.