分类： 核科学技术 >> 辐射物理与技术 分类： 物理学 >> 核物理学 提交时间： 2026-04-28
摘要： During the measurement of low- and intermediate-level radioactive waste (LILW), various factors can obscure weak peaks in low-count gamma spectra to different extents. Hence, before the gamma spectra of LILW are analyzed, these factors should be eliminated through effective smoothing. This study aimed to address the loss of weak peak information in gamma spectra due to the low energy resolution of LaBr3(Ce) detectors during smoothing. For the first time, this study integrated the discrete wavelet transform (a transform that decomposes a given signal into a number of sets), Nyquist sampling rate (the lowest sampling rate that permits accurate reconstruction of a sampled analog signal), and fast Fourier transform (an algorithm that computes the discrete Fourier transform of a sequence). Through this integration, this study established an optimal criterion for the decomposition level, an adaptive threshold correction model, and a novel threshold function tailored to smoothing low-count gamma spectra. Experimental results demonstrated that the proposed method enhances the signal-to-noise ratio of an original gamma spectrum by 2.51 times. Compared with traditional methods, the novel method substantially reduced the root mean square error between the smoothed and original spectra by 87.1%, achieving this with a lower smoothness value. Furthermore, it mitigated channel distortions in the full-width at tenth-maximum for the characteristic peaks of the low-count spectrum by 75.0% to 96.9%. Under different peak distances, the peak-to-valley ratio of the overlapping peaks smoothed by the novel method increased by up to 7.4% compared with other methods. This method removes noise efficiently, preserves the original data of low-count spectra, and optimizes the peak-to-valley ratio of overlapping peaks. The results of this researchbroaden the potential application scenarios of the LaBr3(Ce) detector in LILW measurements, as well as in other fields, such as regional geophysical exploration, radiation environment monitoring, nuclear medicine, and astrophysical measurements. It substantially reduces the cost of establishing measurement systems for low-activity radioactive materials in complex environments.
分类： 核科学技术 >> 核科学与技术 提交时间： 2026-04-27
摘要： CsI(Tl) 探测器因其可靠的脉冲形状鉴别（PSD）能力，在核物理实验中被广泛用于带电粒子识别（PID）。为克服现有数字化 PID 方法数据量大、计算复杂及实时性不足的局限性，本文提出一种基于电荷-数字转换矩阵（QDC-Matrix）的算法。本算法基于 CsI (Tl) 信号的三指数衰减模型，三个指数项分别对应信号快成分、慢成分与电子学响应成分。通过对信号波形进行多段分段积分，利用各段积分与三指数函数的时间关联特性构建线性方程组，求解快、慢成分幅度，并依据快、慢成分幅度比与粒子属性的关联，实现带电粒子的快速鉴别。该方法无需完整波形数据，大幅降低传输与存储开销，通过蒙特卡洛优化积分区间，保证鉴别精度与全波形拟合相当。实验验证表明，在典型熔合蒸发反应数据中，QDC-Matrix 算法性能优于电荷比较法，与拟合相当。该算法为 CsI(Tl) 阵列在核物理实验中的高效 PID 提供了新方案。
分类： 核科学技术 >> 粒子加速器 提交时间： 2026-04-26
PengBo, Chen
ShaoYi, Wang
WenBo, Zhang
RongWei, Zha
Bin, Sun
JiaXing, Wen
Cheng, Lei
ZongQing, Zhao
Du, Wang
摘要： Dielectric laser accelerators (DLAs) can achieve acceleration gradients exceeding those of conventional radio-frequency accelerators by one to two orders of magnitude. Existing DLA design approaches rely heavily on empirical parameter tuning and single-variable optimization, which fundamentally constrains performance enhancement. Here, a new optimization strategy for DLA structures is proposed based on the Gated Adaptive Network for Deep Automated Learning of Features (GANDALF). This framework integrates key parameters such as geometric configurations, material properties, and optical field characteristics into a comprehensive analysis. By accurately predicting particle energy gain, the structural parameters are optimized, significantly improving DLA performance. The proposed approach outperforms traditional computational methods, particularly for nonperiodic structures, enabling continuous particle acceleration. The GANDALF model demonstrates high accuracy, robustness,and adaptability, yielding an average acceleration gradient of 2.8 GV/m (Y2O3), enabling sustained acceleration in the majority of the acceleration channel, with a beam spot radius of 3.13 µm. Additionally, a cascaded DLA design concept is introduced and validated, paving the way for extended acceleration lengths on photonic chips.
分类： 物理学 >> 核物理学 提交时间： 2026-04-25
摘要： The high density fuels, including uranium monocarbide UC, UN, and the uranium carbonitride U(CN) that results from carbon impurities following UN fabrication, have recently attracted attention for light-water reactor (LWR) applications because of their facilitation on increased 235 U loading at a fixed enrichment, high thermal conductivity and high melting temperatures. Despite these favorable properties, numerous performance aspects must be evaluated before any lesser-studied uranium compounds become viable LWR fuel forms. This study is first to perform thermodynamic calculation to evaluate thermal stability pure UC and UN in a closed system mimicking Pressure-water reactor (PWR) coolant, based on which UN or UC is not thermodynamically stable in any aqueous electrochemical system during a cladding breach. Then the potential interactions between UN and UCN with Zr or SiC cladding were systematically evaluated using a thermodynamic database of U-Zr-Si-C-N was developed in this work using the CALPHAD approach and validated with available literature data. The interfacial stability of UN/Zr, UC/Zr, UN/SiC and UC/SiC were assessed by calculating the isothermal sections U-Zr-N, U-Zr-C, U-Si-C, U-Si-C-N at 1500,1000 and 500 C, as well as the isopleth sections of U(C 0.3 N 0.7 )-Zr. The results predict that a complex reaction pathway between UN and Zr will produce multiple layers including phases of bcc(U,Zr), UZr2, hcp(Zr,N) and fcc(U,Zr)N. This response is more complicated than that between UC and Zr where a single ZrC layer is predicted. Improved thermodynamic stability is predicted when compatability with SiC cladding is considered. Both UN and UC are in equilibrium with SiC when modeled under the same temperature conditions. Potential carbon impurities present in UN as a result of the fabrication process were not found to contribute detrimentally to fuel-cladding contact for either Zr or SiC cladding under conditions evaluated here.
分类： 物理学 >> 核物理学 提交时间： 2026-04-24
摘要： Shape quantum phase transition is an important and hot topic in nuclear structure. In this paper, we begin tostudy the finite-N shape quantum phase transition in the SU3-IBM. In this new proposed model, new spherical-like γ-soft spectra was found to resolve the spherical nucleus puzzle, which is a new γ-soft rotational mode.In this paper, the shape phase transition along the new γ-soft line is first discussed, and then the neighbouringcase at the prolate side is also studied. Some key quantities are discussed. We find that double shape phasetransitions occur along a single parameter path. The new γ-softness is really a shape phase and the shape phasetransition from the new γ-soft phase to the prolate shape is found. The experimental supports are also foundand108Pd may be the critical nucleus.
分类： 物理学 >> 核物理学 提交时间： 2026-04-24
Zhu, Ms. Songxian
Jia, Dr. Huiming
Lin, Dr. Chengjian (Nuclear physics)
feng, Prof. jing
Qiu, Dr. Yijia
Liu, Prof. shilong
yang, Dr. yi
Yang, Dr. Lei
Ma, Dr. Nanru
Yang, Dr. Feng
Wen, Mr. Peiwei
Luo, Mr. Tianpeng
chang, Mr. Chang
Duan, Ms. Hairui
Zhang, Dr. Huanqiao
摘要： To further study the heavy-ion nuclear reaction mechanisms and fission of actinide nuclides by using the surrogate reaction method, a compact and efficient hybrid detector array for coincidence measurements of the beam-like particles and fission fragments has been developed and tested online. This detector array consists of four silicon strip detector telescopes and two parallel-plate avalanche counters. For the near-barrier \(^{7}\mathrm{Li} + ^{238}\mathrm{U}\) reaction, the fission fragments correlated with the beam-like \(^{6}\mathrm{He}\) particles originating from the transfer reaction were confirmed by analyzing the folding angle. The fission barrier height for the short-lived actinide nucleus \(^{239}\mathrm{Np}\), produced in the \(1p\) stripping channel, was extracted from its fission probability. The deduced value shows a good agreement with the existing literature data.
分类： 物理学 >> 核物理学 提交时间： 2026-04-23
摘要： Background: The exploration of neutron-rich nuclei far from stability has revealed exotic phenomena like the change of magic numbers, shape coexistence, and halo formation. Neutron-rich magnesium isotopes provide a pivotal testing ground for understanding how shell evolution, deformation, and continuum coupling collectively govern nuclear structure near the drip line. Purpose: This work aims to systematically investigate the ground-state properties and the emergence of deformed neutron halos in even-even magnesium isotopes34−44Mg, with a focus on the microscopic mechanisms driving shell closure quenching, deformation development, and halo formation. Methods: We employ the deformed relativistic mean-field theory combined with the complex momentum representation and BCS pairing (DRMF-CMR-BCS). This framework self-consistently treats deformation, pairing correlations, and continuum coupling, providing a unified description of bound, resonant, and continuum states. Calculations are performed using the NL3 effective interaction. Results: Our calculations reveal the microscopic mechanism for the collapse of the N = 20 and N = 28 shell closures, identifying it as a cooperation of monopole drift in key neutron orbitals (e.g., 1/2−1, 3/2−2) and the stabilization of prolate deformation. In 40,42,44Mg, we predict the universal emergence of deformed halos characterized by a striking shape decoupling: a prolate core coexists with an oblate halo. This halo is predominantly formed by low-angular-momentum orbitals, with the dominant contributor shifting from a narrow resonant state (3/2−2) in 40Mg to a weakly bound orbital (3/2−2) in 42Mg. The anomalous occupancy of narrow resonances underscores the important role of pairing, enhanced continuum coupling. Conclusions: The structure of neutron-rich Mg isotopes is governed by the intricate competition between single-particle energies, deformation, pairing, and the continuum. Our calculations offer clear, testable predictions for future rare-isotope beam experiments.
分类： 物理学 >> 核物理学 提交时间： 2026-04-23
Long, Mr. Yi
Wang, Mr. Yue-Hua
Zhan, Mr. Dong
Li, Prof. Shuang
Deng, Prof. Jun-Gang
Mu, Dr. Lin
Cheng, Dr. Jun-Hao
Zhang, Dr. Hongfei
摘要： Unlike ground-state two-proton ($2p$) radioactivity, excited-state $2p$ emission is typically characterized by high decay energy and angular momentum, making it an important probe for studying the nuclear structure of extremely proton-rich nuclei. However, describing excited-state $2p$ radioactivity half-lives also poses a challenge to theoretical models. To examine whether the generalized liquid drop model (GLDM) with the improved proximity energy (Prox. 77-Set 13), optimized using ground-state $2p$ radioactivity experimental data, can be extended to describe excited-state $2p$ radioactivity, this work calculates the half-lives for $^{14}$O$^{*}$, $^{17}$Ne$^{*}$, $^{18}$Ne$^{*}$, $^{29}$S$^{*}$, and $^{94}$Ag$^{*}$. The present calculations are compared with experimental data and calculations obtained from the effective liquid drop model (ELDM), the unified fission model (UFM), and the Coulomb and proximity potential model (CPPM). The results calculated by this work are in good agreement with both the experimental data and the results of other theoretical models, validating the applicability of the GLDM with improved proximity energy for describing excited-state $2p$ radioactivity. This work also systematically investigates the dependence of excited-state $2p$ radioactivity half-life on decay energy and angular momentum, which will shed new light on the properties of exotic proton-rich nuclei.
分类： 物理学 >> 核物理学 提交时间： 2026-04-20
摘要： As critical sensing components in industrial automation and control systems, electronic sensors are prone to performance degradation and drift faults due to harsh operating environments. Among these, minor drift faults are characterized by slow variation and weak early-stage features, making them difficult to detect promptly using conventional methods. Once accumulated to a detectable level, such faults pose serious threats to system safety and operational stability. To address this issue, this paper proposes a sensor drift fault detection and data reconstruction method based on sequence-to-sequence model and principal component analysis (Seq2Seq-PCA). The method first selects auxiliary variables through Spearman correlation analysis to construct the input feature set. A Seq2Seq model with an attention mechanism is then employed for multi-step rolling prediction to capture the dynamic characteristics of the system. Principal component analysis is applied to the prediction residuals to establish a statistical monitoring model, enabling sensitive detection of minor drift faults. Upon fault detection, the multi-step prediction values of the Seq2Seq model are directly used as the reconstructed output, achieving seamless integration of fault detection and data reconstruction. Experimental results on the nuclear power plant simulator demonstrate that the proposed method achieves accurate detection and reliable reconstruction under various drift rates.
分类： 核科学技术 >> 粒子加速器 提交时间： 2026-04-20
摘要： 针对质子-α粒子肿瘤治疗平台对高性能直线注入器的需求，本文开展了工作频率为220 MHz的α粒子射频四极场（RFQ）加速器的束流动力学设计。为了进一步降低ParmteqM软件自带的参数设计程序所得方案的纵向发射度，以满足后续加速结构对纵向发射度的要求，自主开发了基于Mathematica软件的RFQ参数设计程序。采用“两段式成形”设计策略对成形段进行了改进设计，该策略通过分段线性调控成形段的同步相位与调制因子的变化速率，实现了对束团聚束过程的精细控制。动力学模拟结果表明，改进后的设计方案束流传输效率高达98.1%，出口纵向归一化均方根发射度较原方案降低了近50%，显著提升了束流品质。随后利用CST MWS构建了腔体的三维模型并进行了仿真，结果表明腔体Kp因子为1.79，无载品质因数Q0为13225，调谐器频率调谐范围为-1.1MHz~1.5 MHz。通过端部底切与调谐器的联合调控，将象限内的场不平整度严格控制在了±0.5%以内。采用计算得到的三维电磁场，在TraceWin软件中进行多粒子跟踪验证。结果表明基于CST MWS三维电磁场的TraceWin验证结果与ParmteqM的模拟结果基本吻合。
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2026-04-20
Shi-Yu Zhang
Yang-Bo Nie
Yan-Yan Ding
Qi Zhao
Kuo-Zhi Xu
Xin-Yi Pan
Xiao-Yu Wang
Bei-Bo He
Hong-Tao Chen
Qi Sun
Zheng Wei
摘要： Accurate nuclear data for neutron interactions with bismuth are crucial for applications in nuclear technology and radiation protection. This paper presents a comprehensive benchmark analysis that compares experimental data obtained at multiple angles and thicknesses with simulations based on four nuclear-data libraries: CENDL 3.2, ENDF/B-VIII.0, JENDL-5, and JEFF-3.3. The experiments involved neutron-leakage measurements of bis muth at three thicknesses and six angles, along with standard sample validations. Pulse time distributions were reconstructed using the maximum likelihood expectation maximization algorithm, and a silicon-carbide detector was employed to accurately distinguish between deuterium–tritium and deuterium–deuterium reaction products. Simulation models validated using polyethylene-sample results demonstrated calculated-to-experimental (C/E) values of 1 ± 0.03, thus confirming their reliability. The analysis revealed that CENDL-3.2 exhibited the best overall agreement in the elastic scattering region. In the discrete inelastic scattering region, JENDL-5 performed best at larger angles, while JEFF-3.3 was more accurate at smaller angles. In the continuous inelastic scatter ing region, JEFF-3.3 demonstrated the best overall performance, with CENDL-3.2 achieving good agreement at selected angles. In the (n,2n) reaction region, ENDF/B-VIII.0 provided C/E values closest to unity, while JENDL-5 ensured better consistency across the full energy spectrum. These findings highlight the importance of selecting appropriate nuclear-data libraries and emphasize the necessity for ongoing data refinement to im prove modeling accuracy.
分类： 物理学 >> 核物理学 提交时间： 2026-04-20
Yang, Mr. jicong
Li, Dr. Xiaolong
Guo, Prof. Qi
Feng, Mrs. Jie
Zheng, Dr. Qiwen
lin, Mr. wen
Li, Prof. Yudong
摘要： Commercial Off-The-Shelf (COTS) devices are widely used in aerospace electronic systems, but their process design does not meet the application requirements of the space radiation environment, leading to performance degradation risks caused by Total Ionizing Dose (TID) effects. However, traditional sampling-average radiation hardness (RH) assessment methods are costly and time-consuming, and fail to effectively address lot-to-lot and within-lot fluctuations in the RH consistency of COTS devices. This paper proposes a machine learning model based on physical feature enhancement. A high-quality dataset is constructed via irradiation experiments on devices from multiple manufacturers and lots. By introducing electrical parameter responses under multiple electrical stress conditions as enhanced feature parameters, the model realizes non-destructive identification of device manufacturing processes and prediction of total-dose radiation degradation. Results show that the model achieves identification accuracy of approximately 0.965 for device manufacturers and 0.842 for lots; at four specific dose points, the coefficient of determination (R²) for radiation degradation prediction is above 0.838, outperforming the sampling-average prediction method. Incorporating electrical parameter responses under multiple electrical stress conditions improves the model’s performance in manufacturing process identification and TID radiation degradation prediction. This study reveals that differences in the pre-irradiation initial electrical parameters of devices have an implicit correlation with their radiation hardness characteristics. Compared with a single test condition, the responses of device parameters to multiple electrical stresses contain richer RH feature information. In addition, the model is verified to have certain generalization ability on new lot samples not included in the training set. This method provides a new approach for the efficient screening and assessment of the radiation hardness of COTS devices.
分类： 物理学 >> 核物理学 提交时间： 2026-04-20
Li, Dr. Guo
Shi, Prof. Jian-Rong
Zhang, Dr. Suyalatu 张苏雅拉吐
Yan, Prof. Hong-Liang
Chen, Prof. Yong-Shou
摘要： The post-asymptotic giant branch (post-AGB) star IRAS 14325-6428 exhibits a peculiar heavy-element abundance pattern, characterized by a high [Ba/La] ratio and an anomalous odd-isotope Ba ratio (f_odd,ba=0.25±0.08), which is difficult to explain via the classical slow neutron-capture process (s-process). In this work, we theoretically investigate this abundance pattern by considering intermediate neutron-capture process (i-process) nucelosyntheis. We employ a self-consistent computational framework. A stellar model representative of the progenitor (1.5 M_sun, Z = 0.003) is evolved with MESA to the thermally pulsing AGB phase to obtain intershell elemental abundances. These values are then used as input for i-process nucleosynthesis calculations performed with a one-zone network (NucNet Tools) at constant temperature and density. The observed heavy-element abundances are best reproduced by a model with neutron density N_n = 5×10^13 cm^-3 and neutron exposure τ = 1.4 mbarn^-1, followed by dilution with a scaled-solar composition. This model reproduces the high [Ba/La] and [Ba/Ce] ratios and yields a post-dilution odd-isotop fraction f_odd,ba = 0.51, consistent with the observational trend. The abundance pattern arises from the i-process path approaching the neutron magic number N = 82, where the flow slows and the material accumulates at 135I, which subsequently β- decays to 135Ba. This leads to enhanced Ba production and reduced synthesis of heavier species. These results, consistent with the star's multi-element classification as enriched in both s- and r-process elements, provide quantitative support for an i-process origin of the heavy elements in IRAS 14325-6428, likely triggered by a relatively short-lived proton-ingestion episode in its AGB progenitor.
分类： 物理学 >> 核物理学 提交时间： 2026-04-19
Strizhak, Dr. Alexander
Ivashkin, Dr. Aleksandr
Baranov, Mr. Alexander
Musin, Mr. Sultan
Tkachev, Dr. Igor
摘要： The possibility to use the SrI2(Eu) scintillator for detection of tritium neutrino with energy below 20 keV is suggested. SrI2(Eu) scintillator has a record light yield up to 120 photons/keV that in combination with high photon detection efficiency photodetectors would enable the detection threshold below 1 keV. The compact modular setup of SrI2(Eu) scintillation detectors to register sub-keV energy deposition from neutrinos interactions is considered. Each individual detector module comprises four small scintillators with attached SiPM arrays packed together in a light-tight plastic case. The main drawback of SiPM, the high dark current rate (DCR), which is exponentially dependent on temperature, can be suppressed at negative operating temperatures. The experimental tests of SiPMs were performed over a wide temperature range from +20°C to -65°C,that show the DRC reduction for about three orders. To further suppress the effect of DCR, a time coincidences of the signals in each detector module were implemented. The light collection of SrI2(Eu) scintillators with SiPM readout was studied using several γ-ray sources. The optimal operating conditions were examined to provide a minimum energy detection threshold. The normalized light collection achieves 26.3 photoelectron/keV in all range of measured energies. The performed tests with low energy γ-ray sources confirmed that constructed SrI2(Eu) modules are suitable for high-resolution X- and γ-rays spectroscopy.
分类： 物理学 >> 核物理学 提交时间： 2026-04-18
于, Dr. 鸿翔
Zhou, Dr. Chong
Fu, Dr. Yao
yang, Dr. yi-ang
Wang, Mr. Shanwu
Xue, Dr. Shuaiyu
deng, Dr. hui
摘要： Molten salts are efficient heat-transfer and storage media widely used in advanced energy systems, including nuclear and concentrated solar power. Their high melting points, however, can induce transient pipeline freezing, impairing operational economy and compromising flow safety. This study employs an integrated multiscale CFD and lumped-parameter approach to systematically investigate the complex freezing process of molten salt in pipes and to quantify the effect of key boundary conditions. Under pumped-inlet conditions, the characteristic temperature and flow rate exhibit a distinct dynamic: an initial decrease, followed by recovery and stabilization, marking the transition from initial filling to steady flow. Excessively designed cooling systems can drive the heat removal rate beyond a safe threshold. The risk of pipe blockage rises substantially for values of the dimensionless freezing parameter θ ≤ 1. The model's applicability is examined, and a parametric sensitivity analysis assesses the influence of inlet temperature, flow velocity, cooling intensity, pipe length, and wall thickness. This work provides a theoretical basis and safety-design guidelines for freeze-protection in molten salt cooling systems.
分类： 核科学技术 >> 粒子加速器 提交时间： 2026-04-16
摘要： 采用X射线透射分选技术进行矿物分选可以提高目标矿物的含量，从而优化资源利用，提高生产效率，但分选过程中所得到的矿石图像会存在目标粘连及重叠的情况，导致分选紊乱及资源浪费。为了提高矿物资源利用率及分选效率，本文针对具有明显重叠阴影的深度重叠矿石图像提出了一种矿石图像形状及密度值补偿算法，用于修复独立矿石图像的形状并补偿其上重叠区域的密度值，通过区域生长算法提取重叠区域二值图像，将重叠区域二值图与独立矿石二值图进行“或”运算以修复独立矿石图像的形状，通过不同外接圆半径的轮廓线实现对独立矿石图像重叠区域的密度值补偿。试验结果表明，经算法处理后的独立矿石图像具有更接近于实际情况的形状与密度值，与标准对照数据相比，中心坐标准确率相较于未修复图像提升了73.58%，对图像重叠区域的平均密度值补偿效率高达91.35%，被补偿区域与实际情况的相似程度相较于未补偿图像提升了82.71%；本文方法对具有明显重叠阴影的深度重叠矿石图像展现出较强的形状修复及密度值补偿有效性，可大幅提升矿物分选效率。
分类： 物理学 >> 核物理学 提交时间： 2026-04-16
Yu, Miss Jiachen
Li, Mr. Kaihang
Gu, Mr. Jingfan
Cai, Mr. Chang
Chen, Mr. Jiangyu
Dai, Mr. Huayu
Fang, Dr. Rundong
Gao, Mr. Hongrui
Gao, Prof. Fei
Guo, Mr. Xiaoran
Guo, Mr. Jiheng
Jia, Mr. Chengjie
Hao, Mr. Yanzhou
Han, Mr. Xu
Lei, Mr. Yang
Li, Dr. Shenchao
Li, Mr. Siyin
Lin, Prof. Qing
Liu, Dr. Jiajun
Ren, Miss Yuanyuan
摘要： The RELICS (REactor neutrino LIquid xenon Coherent elastic Scattering) experiment employs a dual-phase liquid xenon time projection chamber to search for Coherent Elastic Neutrino-Nucleus Scattering (CEνNS) induced by reactor neutrinos. To detect these sub-keV nuclear recoils and minimize signal attenuation, it is critical to maintain a sufficiently low impurity concentration in the detector. This work presents a comprehensive purity evolution model developed to describe impurity migration inside the detector. Utilizing measured material outgassing rates as input parameters, the model incorporates non-uniform transport mechanisms of the impurities, including circulation, vaporization, and condensation. The model is validated using data from a dedicated prototype detector. Based on this validated model, projections for the purification performance of the upcoming RELICS-10 and RELICS-50 detectors are provided.
分类： 物理学 >> 核物理学 提交时间： 2026-04-16
摘要： We study the generation and space-time evolution of fluid acceleration in heavy-ion collisions using AMPT and UrQMD transport models combined with a Gaussian smearing method. The peak proper acceleration reaches several hundred MeV, with mild model dependence. Transverse acceleration points outward and is strongest at the fireball boundary due to steep pressure gradients and low enthalpy density—a persistent feature even at early times and low energies. Longitudinal acceleration shows strong collision-energy dependence: low-energy collisions exhibit early deceleration from nuclear stopping, while ultra-relativistic collisions produce sharp acceleration pulses from passing nuclei. The volume-averaged acceleration is nearly centrality independent, as extreme acceleration localizes at boundaries. These strong acceleration fields may have important implications for QGP physics, including the Unruh effect mimicking a thermal bath, potential influences on the chiral phase transition and deconfinement, and contributions to spin polarization beyond vorticity.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2026-04-16
摘要： 合肥先进光源（HALF）储存环120台二极磁铁全部采用电磁型变气隙纵向梯度二极磁铁，其积分场及均匀性的精确测量，是保证束流品质的重要环节之一。为满足大批量磁铁高效、高精度的测量需求，HALF研制了一套平移长线圈磁场测量系统。该系统设计了独特的双层测量线圈，可在单次扫描中同步获取磁铁孔径内两个高度平面的积分场及其均匀性信息。开发了自动测量功能，该系统可实现磁铁自动标准化励磁循环及自动加载励磁电流并进行磁场测试。测试结果表明，积分场测量重复精度优于1×10-4，积分场均匀性重复精度优于5×10-5，优于霍尔点测法通常达到的10-4量级重复精度。该系统的成功研制为HALF二极磁铁的批量检测提供了可靠的技术手段，具有重要的工程应用价值。
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2026-04-16
摘要： 为满足中国电子—离子对撞机电子冷却系统对电子束源的大电荷量、高重复频率、长脉冲、低发射度与低能散要求，提出一套基于能量回收直线加速器的前端物理设计方案，并围绕强空间电荷效应与高阶非线性耦合两大核心问题开展束流动力学模拟与优化研究。注入器采用162.5 MHz四分之一波长超导射频光阴极电子枪、650 MHz聚束腔、单腔增强段及1.95 GHz三次谐波腔协同构型，通过遗传算法对激光光斑尺寸、脉冲长度、腔体相位与梯度、螺线管磁场等参数进行全局优化。并束段对比评估了四种典型结构，揭示了二阶路径长度系数与纵向电荷密度梯度协同导致发射度在并束段增长的物理机制。主加速段采用三腔模组化设计，每个腔包含两个加速单元，返航束线中180°弯转段采用对称多磁铁构型抑制高阶像差，路径调节段仅用于相位匹配。结果表明，注入器出口处束流能量3.5 MeV，归一化发射度1.4 mm·mrad，相对能散0.46‰；并束段中多磁铁小偏转角构型发射度增长最小；主加速段出口能量10.4 MeV，发射度2.5 mm·mrad，能散0.47‰；返航相位调节实现理论能量回收效率接近100%。全局模拟显示，冷却段入口束流参数达到设计目标。本研究验证了大电荷量长束团参数下能量回收直线加速器物理设计的可行性，为未来中国电子—离子对撞机电子冷却ERL提供参考。
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