您选择的条件: 2023
  • Measurement of the high energy γ-rays from heavy ion reactions using ˇ Cerenkov detector

    分类: 物理学 >> 核物理学 提交时间: 2023-12-29

    摘要: The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as asensitive probe to the short range correlation in atomic nuclei. The energy of the -rays can be measuredby collecting theˇCerenkov light in medium induced by the fast electrons generated in Compton scattering orelectromagnetic shower of the incident ray. Two types of detectors, based on pure water and lead glass asthe sensitive material respectively, are designed for the above purpose. The response and optical photonpropagation in detectors have been simulated based on the electromagnetic and optical processes in Geant4.The inherent energy resolution of 0.022(4) + 0.51(2)/E 1/2 for water and 0.0026(3) + 0.446(3)/E 1/2 forlead glass are obtained. The geometry size of lead glass and water are optimized at 30 30 30 cm3 and60 60 120 cm3 , respectively, for detecting high energy -rays at 160 MeV. Hough transform method hasbeen applied to reconstruct the direction of the incident -rays, giving the ability to distinguish experimentallythe high-energy rays produced in the reactions on the target from the random background cosmic ray muons.

  • Milestone progress of the HEPS booster commissioning

    分类: 物理学 >> 核物理学 提交时间: 2023-12-28

    摘要: The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron light source building in China. Its injector consists of a Linac and a full energy booster. The booster captures the electron beam from the Linac and further increases its energy to the same as that required by the storage ring. The full-energy beam could be injected to the storage ring directly or after high-energy accumulation. On November 17, 2023, it was demonstrated that key parameters of the booster successfully reached corresponding target values. These milestone results were accomplished based on many contributions, including nearly a decade of physics design, years of development and installation of equipment, as well as months of beam commissioning. As measured at the extraction energy of 6 GeV, the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm.rad with a single-bunch charge of 5.58 nC, compared with the corresponding target values of 6.6 mA and 35 nm.rad, respectively. This paper presents the physics design, equipment development and installation, and commissioning process of the HEPS booster.

  • α decay in extreme laser fields within a deformed Gamow-like model

    分类: 物理学 >> 核物理学 提交时间: 2023-12-28

    摘要: In this study, the effect of extreme laser fields on the decay process of ground-state eveneven nuclei was investigated. Using the deformed Gamow-like model, we found that state-of-the-art lasers can cause a slight change in the decay penetration probability of most nuclei. In addition, we studied the correlation between the rate of change of the decay penetration probability and angle between the directions of the laser electric field and particle emission for different nuclei. Based on this correlation, the average effect of extreme laser fields on the half-life of many nuclei with arbitrary particle emission angles was calculated. The calculations show that the laser suppression and promotion effects on the decay penetration probability of the nuclei population with completely random particle-emission directions are not completely canceled. The remainder led to a change in the average penetration probability of the nuclei. Furthermore, the possibility of achieving a higher average rate of change by altering the spatial shape of the laser is explored. We conclude that circularly polarized lasers may be helpful in future experiments to achieve a more significant average rate of change of the decay half-life of the nuclei population.

  • 核物质和中子星物质的相对论第一性原理研究

    分类: 物理学 >> 核物理学 分类: 天文学 >> 天体物理学 提交时间: 2023-12-28

    摘要: 相对论 Brueckner-Hartree-Fock (RBHF) 理论是相对论框架下重要的第一性原理方法,仅包含两体力即可以满意描述核物质的饱和性质。在完备的 Dirac 空间中自洽求解核物质 RBHF 方程,唯一确定了单粒子势的标量和矢量分量,避免了已有工作中由于忽略负能态所导致的不确定性,解决了 40 多年来 RBHF 计算中不能唯一确定单粒子势的问题。文章简要回顾 RBHF 理论的发展历史,阐述包含负能态做 RBHF 计算的必要性,介绍利用完备 Dirac 空间的 RBHF 理论,研究核物质性质和中子星物质性质的最新进展,包括有效质量、纯中子物质的每核子结合能、对称和纯中子物质的压强、中子星物质的粒子分数和状态方程、中子星的质量半径关系和潮汐形变等。文章还展望了完备 Dirac 空间的RBHF 理论在确定密度泛函理论参数、描述核子原子核弹性散射和研究中子星内部强子夸克相变等方面的可能应用。

  • Conceptual Design of a 714-MHz RFQ for Compact Proton Injectors and Development of a New Tuning Algorithm on its Aluminium Prototype

    分类: 物理学 >> 核物理学 提交时间: 2023-12-28

    摘要: Radio frequency quadrupoles (RFQs), which are crucial components of proton injectors, significantly affect the performance of proton accelerator facilities. An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medical applications is designed in this study. The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization. To develop an advanced RFQ, challenging techniques, including fabrication and tuning method, must be evaluated and verified using a prototype. An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance, fabrication procedure, and feasibility of the tuning algorithm. Eventually, a new tuning algorithm based on the response matrix and least-squares method is developed, which yields favorable results based on the prototype, i.e., the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations. Benefiting from the conceptual design and techniques obtained from the prototype, the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.

  • 178Hf同核异能态激发与退激路径研究

    分类: 物理学 >> 核物理学 提交时间: 2023-12-24

    摘要: 具有长寿命高激发态的同核异能素在国家战略安全和储能领域有重要的意义,其关键技术在于掌握人工诱发同核异能素快速退激到基态。近些年该项技术研究遇到了瓶颈,需从原子核结构研究的角度出发,通过对同核异能素的形成、受激激发和退激机制的深入研究,突破遇到的瓶颈,进而掌握诱发同核异能素快速退激到基态的关键技术。本工作是在实验技术方面利用白光中子束流轰击 Hf 靶,创新性地建立了由氟化钡探测器阵列进行全能量测量与高纯锗探测器进行特征伽马射线测量相结合,再结合白光中子飞行时间开窗组成三重符合测量的系统,通过对实验数据的分析发现了 178Hf 同核异能态激发到过渡能级并快速释放的迹象。

  • 夸克物质对称能与夸克星潮汐形变的研究

    分类: 物理学 >> 核物理学 分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2023-12-22

    摘要: 近十年的研究表明,夸克物质对称能对夸克物质的状态方程有重要影响。在本研究中,我们通过采用等效质量模型并在夸克质量标度中引入同位旋依赖项来研究夸克物质的稳定窗口。研究结果表明,足够大的同位旋强度依赖参数$C_I$可以显著地增大奇异夸克物质的稳定窗口,从而使计算结果可以同时满足天文观测数据PSR J1614-2230具有$1.928 pm 0.017$倍太阳质量和双中子星并合事件GW170817中得到的潮汐形变$70 le Lambda_{1.4} le 580$的约束。与奇异夸克物质的情况相反,~u-d~夸克物质的稳定窗口会随着同位旋强度依赖参数的增大而减小,从而使~u-d~夸克星无法支持相应的天文观测数据。最后,我们发现奇异夸克物质的对称能远大于 ~u-d~夸克物质的对称能,并且夸克间的单胶子交换相互作用会导致奇异夸克物质的对称能变软。

  • Infrared Microspectroscopy Beamline BL06B at SSRF

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2023-12-22

    摘要: The infrared microspectroscopy beamline (BL06B) is a phase II beamline project at the Shanghai Synchrotron Radiation Facility (SSRF). The construction and optical alignment of BL06B were completed by the end of 2020. By 2021, it became accessible to users. The synchrotron radiation infrared (SRIR) source included edge radiation (ER) and bending-magnet radiation (BMR). The extracted angles in the horizontal and vertical directions were 40 and 20 mrad, respectively. The photon flux, spectral resolution, and focused spot size were measured at the BL06B end station, and the experimental results were consistent with theoretical calculations. SRIR light has a small divergence angle, high brightness, and a wide wavelength range. As a source of IR microscopy, it can easily focus on a diffraction-limited spatial resolution with a high signal-to-noise ratio (SNR). The BL06B end station can be applied in a wide range of research fields, including materials, chemistry, biology, geophysics, and pharmacology.

  • 合肥国产超导质子回旋加速器主真空控制系统的设计与实现

    分类: 核科学技术 >> 粒子加速器 提交时间: 2023-12-21

    摘要: 超导质子回旋加速器是我国自主研发最先进的医学放疗装置之一。真空系统作为加速器的关键子系统,它为加速粒子提供了必要的运行环境。本研究旨在设计加速器的真空控制系统,以维持稳定的高真空环境。本文基于加速器的真空设计需求,采用西门子可编程逻辑控制器 (PLC) 硬件系统和实验物理及工业控制系统 (EPICS)软件框架完成了真空控制系统的设计。内容包括控制系统整体结构、系统运行逻辑、用户界面设计以及安全联锁等,结果表明,该系统在长期运行中,能使得真空系统保持高真空度,控制性能与稳定性满足设计要求,保障了加速器稳定运行。

  • Digital data acquisition system for complex nuclear reaction experiments

    分类: 物理学 >> 核物理学 提交时间: 2023-12-20

  • The SU(3) Dynamics in the Identical Fermion and Boson Systems

    分类: 物理学 >> 核物理学 提交时间: 2023-12-19

    摘要: 基于群代数理论,本文描述了如何构建s, d两轨道能级下的全同费米子体系与全同玻色子体系四极-四极相互作用动力学,据此探讨了全同性原理对核多体系统动力学结构的影响。结果表明,给定粒子数情况下全同费米子体系中低自旋态的空间维数的要比全同玻色子系统中同样自旋态的空间维数大的多,意味着同等条件下前者包含更多更丰富的转动带结构。本文分析展示了一个基于SU(3)群代数理论分析核结构模型的简单实例。

  • Application of a microscopic optical potential of chiral effective field theory in (p, d) transfer reactions

    分类: 物理学 >> 核物理学 提交时间: 2023-12-19

    摘要: The microscopic global nucleonnucleus optical model potential (OMP) proposed by Whitehead, Lim, and Holt, the WLH potential 1 , which was constructed in the framework of many-body perturbation theory with state-of-the-art nuclear interactions from chiral effective field theory (EFT), was tested with (p, d) transfer re#2;actions calculated using adiabatic wave approximation. The target nuclei included both stable and unstable nuclei and the incident energies reached 200 MeV. The results were compared with experimental data and pre#2;dictions using the phenomenological global optical potential of A. J. Koning and J. P. Delaroche, the KD02 potential. Overall, we found that the microscopic WLH potential described the (p, d) reaction angular distri#2;butions similarly to the phenomenological KD02 potential; however, the former was slightly better than the latter for radioactive targets. On average, the obtained spectroscopic factors (SFs) using both microscopic and phenomenological potentials were similar when the incident energies were below approximately 120 MeV. However, their difference tended to increase at higher incident energies, which was particularly apparent for the doubly magic target nucleus 40Ca.

  • 质子辐照嬗变掺杂制备p型氧化镓的仿真分析

    分类: 核科学技术 >> 核科学与技术 提交时间: 2023-12-18

    摘要: 超宽禁带半导体氧化镓是当前半导体领域研究的热点材料,但采用常规的掺杂工艺尚未在大块晶体上实现其p型掺杂,这阻碍了其应用。质子辐照嬗变掺杂是利用高能质子与靶材料核反应所产生的嬗变产物来实现掺杂。多种嬗变产物具有不同的掺杂效果,有望通过多种掺杂元素的库伦耦合效应实现氧化镓的p型掺杂。本文利用带电离子反应的蒙特卡洛软件FLUKA对100MeV质子辐照氧化镓嬗变掺杂开展仿真分析。结果表明,辐照后冷却100天后,活化活度下降约四个数量级,嬗变产物元素浓度趋于稳定。分析不同掺杂类型的嬗变产物元素浓度,表明质子辐照嬗变能形成净p型掺杂。在靶材料不同深度处的净p型掺杂浓度有所差异,在深度0.6-0.9cm处净p型掺杂浓度最大,每1016cm-2辐照注量下可达4.261014cm-3。与40MeV质子辐照和中子辐照嬗变的掺杂相比,100MeV质子辐照嬗变掺杂效率更高。

  • The Energy Response of LaBr3(Ce), LaBr3(Ce,Sr), and NaI(Tl) Crystals for GECAM

    分类: 物理学 >> 核物理学 分类: 天文学 >> 天文仪器与技术 分类: 材料科学 >> 材料科学(综合) 提交时间: 2023-12-15

    摘要: The GECAM series of satellites utilizes LaBr3(Ce), LaBr3(Ce,Sr), and NaI(Tl) crystals as sensitive materials for gamma-ray detectors (GRDs). To investigate the non-linearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship, comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons, radioactive sources, and monoenergetic X-rays. The non-linearity test results of the Compton electrons and X-rays demonstrated substantial differences, with all three crystals presenting a higher non-linearity for X/-rays than for Compton electrons. Despite the LaBr3(Ce) and LaBr3(Ce,Sr) crystals having higher absolute light yields, they exhibited a noticeable non-linear decrease in the light yield, especially at energies below 400 keV. The NaI(Tl) crystal demonstrated an excess light output in the 6200 keV range, reaching a maximum excess of 9.2% at 30 keV in the X-ray testing and up to 15.5% at 14 keV during Compton electron testing, indicating a significant advantage in the detection of low-energy gamma rays. Furthermore, we explored the underlying causes of the observed non-linearity in these crystals. This study not only elucidates the detector responses of GECAM, but also initiates a comprehensive investigation of the non-linearity of domestically produced lanthanum bromide and sodium iodide crystals.

  • Trial application of the envelope method to the potential ambiguity problem

    分类: 物理学 >> 核物理学 提交时间: 2023-12-15

    摘要: The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering data.For a specifi c colliding system, ambiguous potential families can lead to different behaviors in the nearside and farside scattering components.By contrast, the envelope method can decompose the experimental data into two components with negative and positive deflection angles, respectively. Hence, a question arises as to whether the comparison between the calculated nearside (or farside) component and the derived positive-deflection-angle (or negative-deflection-angle) component can help analyze the potential ambiguity problem. In this study, we conducted a trial application of the envelope method to the potential ambiguity problem. The envelope method was improved by including uncertainties in the experimental data.The colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV were considered in the analyses. For each colliding system, the angular distribution experimental data were described nearly equally well by two potential sets, one of which is surface transparent and the other is refractive. The calculated angular distributions were decomposed into nearside and farside scattering components. Using the improved envelope method, the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components, which were then compared with the calculated nearside and farside components. The capability of the envelope method to analyze the potential ambiguities was also discussed.

  • 多丝结构气体探测器研究

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-12-15

    摘要: 多丝结构气体探测器具有耐辐射、响应快、灵敏区大、易于建造等优势而广泛应用于核物理和核技术领域。介绍了多丝结构气体探测器的电场计算理论方法,并利用有限元程序ANSYS及探测器模拟程序GARFIELD进行了多丝结构气体探测器漂移区、雪崩放大区的电场优化设计。此外,结合GEANT4程序进行了宇宙射线入射气体探测器的模拟计算,获得了探测器电流、电压以及输出波形积分电荷的统计结果。在此基础上进行了气体探测器的研制,并用于宇宙射线的测试实验,实验结果与模拟结果基本一致。论文提出的模拟计算方法及实验技术完全可用于多丝结构气体探测器的优化设计及实验评估,为类似探测器及实验提供借鉴。

  • Nondestructive technique for identifying nuclides using neutron resonance transmission analysis at CSNS Back-n

    分类: 物理学 >> 核物理学 提交时间: 2023-12-15

    摘要: Nondestructive and noninvasive neutron assays are essential applications of neutron techniques. Neutron resonance transmission analysis (NRTA) is a powerful nondestructive method for investigating the elemental composition of an object. The back-streaming neutron line (Back-n) is a newly built time-of-flight facility at the China Spallation Neutron Source (CSNS) that provides neutrons in the eV to 300 MeV range. A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments. The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n. This study reveals its potential future applications.

  • 强流质子同步加速器涂抹注入方法研究

    分类: 核科学技术 >> 粒子加速器 提交时间: 2023-12-14

    摘要: 空间电荷效应是强流质子加速器的核心问题之一,在注入和初始加速阶段其影响最大。采用相空间涂抹方法并优化其涂抹过程,可以有效地缓解空间电荷效应对束流注入和加速效率及发射度增长的影响。横向相空间涂抹方法可分为相关涂抹和反相关涂抹。在本文中,首先,我们对强流质子同步加速器的横向相空间涂抹方法进行深入研究,包括不同的涂抹方法和实现方式。其次,基于中国散裂中子源(CSNS)注入系统,对束流注入过程和反相关涂抹设计方案进行详细研究,深入探索实际垂直涂抹范围变小的原因和凸轨磁铁边缘聚焦效应对涂抹效果和束流动力学的影响。同时,简单介绍了在反相关涂抹机械结构基础上实现相关涂抹的方法及其对实现CSNS设计指标起到的关键作用。最后,根据未来加速器对不同涂抹注入方法在线切换的需求,我们提出了一种同时实现相关和反相关涂抹的新注入方案,并对其进行详细地论证、模拟和优化。

  • Total ionizing dose effect modeling method for CMOS digital integrated circuit

    分类: 物理学 >> 核物理学 提交时间: 2023-12-13

    摘要: Simulating the total ionizing dose (TID) of an electrical system using transistor-level models can be difficult and expensive, particularly for digital integrated circuits (ICs). In this study, a method for modeling TID effects in complementary metal-oxide semiconductor (CMOS) digital ICs based on the input/output buffer information specification (IBIS) was proposed. The digital IC was first divided into three parts based on its internal structure: the input buffer, output buffer, and functional area. Each of these three parts was separately modeled. Using the IBIS model, the transistor V-I characteristic curves of the buffers were processed, and the physical parameters were extracted and modeled using VHDL-AMS. In the functional area, logic functions were modeled in VHDL according to the data sheet. A golden digital IC model was developed by combining the input buffer, output buffer, and functional area models. Furthermore, the golden ratio was reconstructed based on TID experimental data, enabling the assessment of TID effects on the threshold voltage, carrier mobility, and time series of the digital IC. TID experiments were conducted using a CMOS noninverting multiplexer, NC7SZ157, and the results were compared with the simulation results, which showed that the relative errors were less than 2% at each dose point. This confirms the practicality and accuracy of the proposed modeling method. The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID, which has potential applications in the design of radiation-hardening tolerance in digital ICs.

  • Simulation study of BESIII with stitched CMOS pixel detector using ACTS

    分类: 物理学 >> 核物理学 提交时间: 2023-12-13

    摘要: The reconstruction of the tracks of charged particles with high precision is crucial for HEP experiments toachieve their physics goals. The BESIII drift chamber, which is used as the tracking detector of the BESIIIexperiment, has suffered from aging effects resulting in degraded tracking performance after operation for ap-proximately 15 years. To preserve and enhance the tracking performance of BESIII, one of the proposals is toadd one layer of a thin cylindrical CMOS pixel sensor based on state-of-the-art stitching technology betweenthe beam pipe and the drift chamber. The improvement in the tracking performance of BESIII with such anadditional pixel detector compared to that with only the existing drift chamber was studied using the moderncommon tracking software ACTS , which provides a set of detector-agnostic and highly performant trackingalgorithms that h

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