分类： 物理学 >> 核物理学 提交时间： 2024-05-08
摘要： 互补型金属氧化物半导体（Complementary Metal Oxide Semiconductor, CMOS）图像传感器有着体积小，质量轻，功耗低，高集成度等特点正逐步取代CCD图像传感器，在空间辐射环境中有着质子，重粒子，γ射线，电子等大量的高能粒子，CMOS图像传感器会受到重离子的辐射效应并对其有着永久损伤的影响。本文主要是针对CMV4000在重离子辐照下的永久损伤机制。CMV4000在经过重离子辐照过后其图像有着明显的热像素（暗电流尖峰高于其他像素暗电流尖峰数倍通常表现为该像素的灰度值是其他正常像素的数倍），在下一帧图像以及后续图像中热像素也并不会消失，因此热像素并不是暂时的。本文还将考虑 CMOS图像传感器在辐照前后各像参数的对比并揭示各项参数的退化机理。
分类： 工程与技术科学 >> 物理学相关工程与技术 分类： 工程与技术科学 >> 仪器仪表技术 分类： 电子与通信技术 >> 电子技术 分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间： 2024-05-06
摘要： 本文提出了一种用于低温扫描隧道显微镜(CryoSTM)的跨阻放大器(TIA)设计方案。在CryoSTM中带有尖端样品成分的TIA称为CryoSTM-TIA。该CryoSTM-TIA的跨阻增益在1Gohm，而其带宽大于300kHz。所提出的CryoSTM-TIA的独特特点是其前置放大器由单个低温高电子迁移率晶体管(HEMT)制成，因此在100kHz时仪器等效输入噪声电流功率谱密度低于4(fA)2/Hz。此外，应用“偏置冷却法”可用于原位控制HEMT掺杂区冻结DX-中心的密度，改变其结构以降低器件噪声。利用该仪器，可以进行高能量分辨率的快速扫描隧道光谱测量。并且，它能够测量各种量子系统在原子尺度上的扫描隧道散粒噪声谱(STSNS)，即使散粒噪声非常低。它为通过测量STSNS来研究新的量子态提供了一个强大的工具，例如检测拓扑量子系统中马约拉纳束缚态的存在。
分类： 电子与通信技术 >> 电子技术 分类： 工程与技术科学 >> 仪器仪表技术 分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 分类： 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间： 2024-05-06
摘要： In this work, we design and fabricate the transimpedance Amplifier (TIA) following the design mentioned in Ref. cite{Liang2024}. In the TIA, the preamplifier (Pre-Amp) is made of a junction field effect transistor (JFET) that can work at 77 K. The post-amplifier is made of an operational amplifier (OPA). Cascade Pre-Amp and Post-Amp to form the inverting-amplifier (Inv-Amp). The gain-bandwidth product of Inv-Amp with the gain about 50,000 is higher than 10 GHz. With a 1.13 Gohm feedback network, the gain of TIA is 1.13 Gohm and its bandwidth is about 97 kHz. The equivalent input noise voltage power spectral density of TIA is not more than 9 (nV)2/Hz at 10 kHz and 4 (nV)2/Hz at 50kHz, and its equivalent input noise current power spectral density is about 26 (fA)2/Hz at 10 kHz and 240(fA)2/Hz at 50 kHz. The measured transport performances and noise performances of TIA are consistent with the simulations and calculations, verifying the feasibility for the design of low-noise large-bandwidth TIA proposed in Ref. 1 . And, TIA with various performances that meet various needs can be designed according to the design methods in Ref. 1,2 . With the same gain, the bandwidth of the TIA in this work is much larger than the present TIA and its noises are much lower than those of present ones. The TIA in this work is perfect for the cryogenic STM working at 77 K (i.e. liquid nitrogen temperature).
分类： 物理学 >> 核物理学 分类： 生物学 >> 放射生物学 提交时间： 2024-05-06
摘要： 我国载人航天和核技术应用正处于快速发展阶段，辐射与核安全仍将长期成为国家重大需求，持续开发新的辐射防护分子靶标和相关药物具有重要价值。先前的研究已发现电离辐射暴露后小鼠血液中的胰岛素样生长因子结合蛋白3（IGFBP-3）的水平显著上升，但是，IGFBP-3蛋白的功能及其血液水平的变化对小鼠辐射损伤的影响仍不清楚。本研究在小鼠肝脏巨噬细胞（Kupffer细胞，MKC）中建立了Igfbp3基因过表达和敲低细胞模型，利用CCK-8、EdU掺入、克隆形成和微球吞噬实验对碳离子照射后不同细胞模型的增殖活力、DNA复制活性和吞噬能力进行检测；在小鼠模型中，通过在照射前2小时尾静脉注射重组IGFBP-3蛋白提前升高血液IGFBP-3蛋白水平，检测致死剂量（5 Gy）碳离子全身照射后小鼠的生存曲线。结果显示，过表达IGFBP-3蛋白显著提高了MKC细胞在辐射暴露后的DNA复制活性、细胞活力、克隆形成率和对微球的吞噬能力，相反地，敲低IGFBP-3蛋白表达则降低了以上检测指标。碳离子辐射暴露前尾静脉注射IGFBP-3蛋白可以显著延缓急性放射损伤小鼠的死亡时间。以上结果从细胞和动物水平表明了IGFBP-3蛋白具有减轻辐射损伤的作用和作为辐射防护药靶的巨大潜力。通过增强小鼠体内Kupffer细胞的辐射抗性和吞噬能力来降低辐射暴露后的感染风险可能是IGFBP-3蛋白发挥辐射防护作用的机制之一。
分类： 物理学 >> 核物理学 提交时间： 2024-04-28
摘要： The high-intensity heavy-ion accelerator facility (HIAF) is a scientific research facility complex composed ofmultiple cascade accelerators of different types, which pose a scheduling problem for devices distributed overa certain range of 2 km, involving over a hundred devices. The White Rabbit (WR), a technology-enhancingGigabit Ethernet, has shown the capability of scheduling distributed timing devices but still faces the challengeof obtaining real-time synchronization calibration parameters with high precision. This study presents a calibra#2;tion system based on a time-to-digital converter implemented on an ARM-based System-on-Chip (SoC). Thesystem consists of four multi-sample delay lines, a bubble-proof encoder, an edge controller for managing datafrom different channels, and a highly effective calibration module that benefits from the SoC architecture. Theperformance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0to 24000 ps with 120000 data for every test. The design presented in this study refines the calibration precisionof the HIAF timing system. This eliminates the errors caused by manual calibration without efficiency loss andprovides data support for fault diagnosis. It can also be easily tailored or ported to other devices for specificapplications and provides more space for developing timing systems for particle accelerators, such as whiterabbits on HIAF.
分类： 物理学 >> 核物理学 提交时间： 2024-04-28
摘要： The Shanghai Laser Electron Gamma Source (SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility (SSRF) is a laser Compton scattering (LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ-rays of 0.25–21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10^7 photons/s at the target at 21.7 MeV, with a 3-mm diameter beam. The beamline was equipped with four types of spectrometers for experiments in (γ,γ’), (γ,n), and (γ,p α). At present, nuclear resonance fluorescence (NRF) spectrometry, flat efficiency neutron detector (FED) spectrometry, neutron time-of-flight (TOF) spectrometry, and light-charged particle (LCP) spectrometry methods have been developed.
分类： 物理学 >> 核物理学 分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-04-28
摘要： A charged particle array, named MATE-PA, which serves as an auxiliary detec#2;tor system to the Multi-purpose Active-target Time projection chamber for nuclear astrophysical and exotic beam Experiments (MATE) has been con#2;structed. The array is composed of twenty single-sided strip-silicon detectors, covering around 10% of the solid angle. It is dedicated for the detection of reaction-induced charged particles which penetrate the MATE active volume. The performance of MATE-PA has been experimentally studied using an alpha source, and a 36-MeV 14N beam injected into the chamber of MATE, filled with a mixture gas of 95% 4He and 5% CO2 under the pressure of 500 mbar, at the Radioactive Ion Beam Line in Lanzhou (RIBLL). The results demonstrate good separation of light charged particles with the forward double-layer silicon detectors of MATE-PA. The energy resolution of the Si detectors was deduced to be about 1% (σ) for an energy loss of about 10 MeV by the α particles. The inclusion of MATE-PA helps improve particle identification, and increases the dynamic range for the kinetic energy of charged particles, in particular that of α particles up to about 15 MeV.
分类： 物理学 >> 核物理学 提交时间： 2024-04-28
摘要： Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage, store energy, and decrease power variation. In this study, DC-link capacitors in pulsed power supplies were investigated. By deriving an analytical method for the capacitor current on the H-bridge topology side, the root-mean-square value of the capacitor current was calculated, which helps in selecting the DC-link capacitors. The proposed method solves this problem quickly and with high accuracy. The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement, and the capacitor’s hot spot temperature and temperature rise are calculated using the FFT transform. The test results showed that the error between the calculated and measured temperature increases was within 1.5 ◦C. Finally, the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis. The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2024-04-22
摘要： Electron-diffraction patterns with5-fold rotational symmetry of experimental alloy phases are assumedto be produced by periodic structures. Two three-dimensionalperiodic structures are presented based on regular pentagonal dodecahedrons. These structures can be used as atomic models todescribe the alloy phases. The Fourier-transform patterns of themodels are found to be similar to the correspondingelectron-diffraction patterns of these alloy phases. Details of themotivations and approaches that lead to thesemodels are also discussed.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2024-04-22
摘要： In this paper we followed the idea in Ref. 1 to discuss the Doppler frequency shift of photons and the Compton scattering between photons and electrons, pointing out that followingthe idea we have to modify the usual quantum relation of massless particle. But due to limitedinformation and knowledge, we couldn’t yet determine the specific expression for the correctioncoefficient of the quantum relation of massless particle. However, the phenomenon of spontaneous radiation in a cyclotron maser give us an opportunity to see what the expression for this correctioncoefficient might look like, as the phenomenon of spontaneous radiation in a cyclotron maser canbe explained by the effect of Doppler frequency shift of virtual photons and Compton scatteringbetween virtual photons and electrons. Therefor, under some restrictive conditions, we construct a very concise expression for this correction coefficient by discussing different cases. And then we used this expression to analyze the wavelength of radiation in the cyclotron maser, which tends toa limited value at v→c, rather than to 0 as in the Lorentz model. This paper still inherits the idea inRef. 1 that the energy and momentum of particles cannot be infinite, otherwise it will make some equations meaningless, and this view is also from the idea in some quantum gravity models. This paper also provides us with a possible experimental scheme to determine the value of Qin Ref. 1 , but it still requires extremely high experimental energy.
分类： 天文学 >> 天体力学 分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2024-04-20
摘要： 本文简要介绍新的对称形式的质点动力学方程对天体动力学理论的系统性改进。 首先，对于开放的多体系统，无法找到近似程度非常高的惯性系，在传统理论中不得不引入惯性系的近似，而对称新方程因为可以直接适用于任意的平动参考系而避免了惯性系的近似，从而可以提高理论预言的精度。其次，对于束缚的多体系统，传统理论的动力学应用是先引入质心参考系，在质心参考系中应用牛顿第二定律，然后通过坐标变换再转化到实体参考系，比如太阳系的行星摄动方程。 但是，应用对称新方程则可以一步到位推导得到行星摄动方程。最后，如果进一步考虑行星受到临时推力或者冲击力，甚至为了进一步提高计算精度进而考虑来自束缚系统外的作用力，则一个可以叠加非微扰作用力的行星摄动的修正方程在本文得到了确立。
分类： 物理学 >> 核物理学 提交时间： 2024-04-18
摘要： Based on the dinuclear system model, the calculated evaporation residue cross sections matched well with the current experimental results. The synthesis of superheavy elements Z = 121 was systematically studied through combinations of stable projectiles with Z = 21–30 and targets with half-lives exceeding 50 d. The influence of mass asymmetry and isotopic dependence on the projectile and target nuclei was investigated in detail. The reactions 254Es (46Ti, 3n) 297121 and 252Es (46Ti, 3n) 295121 were found to be experimentally feasible for synthesizing superheavy element Z = 121, with maximal evaporation residue cross sections of 6.619 and 4.123 fb at 219.9 and 223.9 MeV, respectively.
分类： 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间： 2024-04-17
Shuqiang He
Yi-Feng Zheng
Guosheng Shi
Yi-Jie Xiang
Meihui Xiao
Qituan Zhang
Yue-Yu Zhang
Haiping Fang
摘要： The identification of new materials with superconducting properties is the pursuit in the realm of superconductivity research. Here, excitedly, we show that the simplest salt daily used can be made a superconductor at normal pressure only by adjusting its stoichiometry of Na and Cl as Na3Cl at normal pressure based on first-principles calculations. This bulk stable abnormal Na-Cl stoichiometric crystal of 3:1, the first ‘magic’ ratio, includes metallic (Na) atoms in the core as well as hybridization of ionic and metallic bonding, facilitating the electron-phonon-coupling for superconductivity with a critical temperature Tc of 0.13 K. The flat bands and van Hove singularities near the Fermi level produce large densities of states, similar to H3S and LaH10, which is beneficial for the emergence of superconductivity. The crystal composed of with abnormal Na-Cl magic stoichiometry is a precisely tunable, purely sodium and chloride-based, three-dimensional bulk superconductor, which is therefore an ideal material for designing and understanding abnormal stoichiometric crystals. The methodology of constructing this bulk abnormal crystal may be general to almost all elements, which could lead to insights into the physics of other conventional superconductors and even high-critical-temperature superconductors.
分类： 物理学 >> 核物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2024-04-15
摘要： 在相对论重离子碰撞中寻找手征磁效应（CME）有助于我们理解强相互作用中的CP对称性破缺和量子色动力学（QCD）真空的拓扑性质。基于CME的背景和信号相对于旁观者平面和参与者平面有不同的相关性，实验上提出了一种双平面方法提取CME信号。利用具有不同强度CME的多相输运模型，我们在质心碰撞能量为200 GeV的同质异位素碰撞中重新探讨了双平面方法，发现相对于两个不同平面的CME信号和背景效应的比值系数是不同的，这与目前实验测量中的假设不一致。这种差异来自于相对于旁观者和参与者平面的CME的退关联，它源于末态的相互作用。我们的发现表明，目前的实验测量可能高估了在相对论性重离子碰撞中观测到的末态CME信号的比例。
分类： 物理学 >> 核物理学 提交时间： 2024-04-12
摘要： 奇$A$核$^{53-65}$Co负宇称晕态能级结构的系统性比较表明，$^{55}$Co存在能级$9/2^-$与$11/2^-$反转，且$^{53,57}$Co可能存在较强的集体效应。基于GXPF1A有效相互作用的壳模型计算较好地再现这些核的晕态能级，及相应的磁矩和电四极矩实验值。壳模型计算结果展示$^{53-65}$Co基态$7/2^-$波函数中质子主要组态成分均为$ pi left(1f_{7/2} right)^7$。$^{55}$Co中激发态$9/2^-$与$11/2^-$中$1f_{7/2}$质子激发和$1f_{7/2}$中子激发之间存在竞争，从而导致两能级反转。此外，利用Constrained Hartree-Fock（CHF）方法研究了$^{53,55,57}$Co四极形变特征，结合壳模型计算得到的平均占据数和组态，分析了$^{55}$Co激发态能量相较于其他Co同位素更高的原因。
分类： 信息科学与系统科学 >> 信息科学与系统科学基础学科 分类： 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 分类： 天文学 >> 天文学 提交时间： 2024-04-11
摘要： The electromagnetic fields of point sources with time varying charges moving in the vacuum are derived using the Liénard-Wiechert potentials. The properties of the propagation velocities and the Doppler effect are discussed based on their far fields. The results show that the velocity of the electromagnetic waves and the velocity of the sources cannot be added like vectors; the velocity of electromagnetic waves of moving sources are anisotropic in the vacuum; the transverse Doppler shift is intrinsically included in the fields of the moving sources and is not a pure relativity effect caused by time dilation. Since the fields are rigorous solutions of the Maxwell’s equations, the findings can help us to abort the long-standing misinterpretations concerning about the classic mechanics and the classic electromagnetic theory. Although it may violate the theory of the special relativity, we show mathematically that, when the sources move faster than the light in the vacuum, the electromagnetic barriers and the electromagnetic shock waves can be clearly predicted using the exact solutions. Since they cannot be detected by observers in the region outside their shock wave zones, an intuitive and reasonable hypothesis can be made that the superluminal sources may be considered as a kind of electromagnetic blackholes.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2024-04-10
摘要： 本文考虑一种量子化的参考系理论，考虑这种时空参考系在量子二阶矩涨落下的Ricci流理论及其蕴含的引力理论。由于该理论中非平凡的时空二阶量子涨落，我们讨论了宇宙加速膨胀(宇宙学常数)问题、星系尺度的径向加速度反常问题，极早期暴涨等问题，及其时空熵的起源问题。最后我们也给出该理论的一些可能预言。
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2024-04-10
摘要： Artificial Neural Network (ANN) has become a powerful tool in the field of scientific research with its powerful information encapsulation ability and convenient variational optimization method. In particular, there have been many recent advances in computational physics to solve variational problems. Deep neural network (DNN) is used to represent the wave function to solve quantum many-body problems using variational optimization. In this work we used a new Physics-Informed Neural Network (PINN) to represent the Cumulative Distribution Function (CDF) of some classical problems in quantum mechanics and to obtain their ground state wave function and ground state energy through the CDF. By benchmarking against the exact solution, the error of the results can be controlled at a very low level. This new network architecture and optimization method can provide a new choice for solving quantum many- body problems.
分类： 信息科学与系统科学 >> 信息科学与系统科学基础学科 分类： 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 分类： 电子与通信技术 >> 光电子学与激光技术 分类： 物理学 >> 地球物理学、天文学和天体物理学 分类： 物理学 >> 基本粒子与场物理学 提交时间： 2024-04-08
摘要： The Einstein’s theory of special relativity is based on his two postulates. The first is that the laws of physics are the same in all inertial reference frames. The second is that the velocity of light in the vacuum is the same in all inertial frames. The theory of special relativity is considered to be supported by a large number of experiments. This paper revisits the two postulates according to the new interpretations to the exact solutions of moving sources in the laboratory frame. The exact solutions are obtained using the classic Maxwell’s theory, which clearly show that the propagation velocity of the electromagnetic waves of moving sources in the vacuum is not isotropic; the propagation velocity of the electromagnetic waves and the moving velocity of the sources cannot be added like vectors; the transverse Doppler effect is intrinsically included in the fields of the moving sources. The electromagnetic sources are subject to the Newtonian mechanics, while the electromagnetic fields are subject to the Maxwell’s theory. We argue that since their behaviors are quite different, it is not a best choice to try to bind them together and force them to undergo the same coordinate transformations as a whole, like that in the Lorentz transformations. Furthermore, the Maxwell’s theory does not impose any limitations on the velocity of the electromagnetic waves. To assume that all objects cannot move faster than the light in the vacuum need more examinations. We have carefully checked the main experiment results that were considered as supporting the special relativity. Unfortunately, we found that the experimental results may have been misinterpreted. We here propose a Galilean-Newtonian-Maxwellian relativity, which can give the same or even better explanations to those experimental results.
分类： 物理学 >> 核物理学 提交时间： 2024-04-08
摘要： 原子核同位旋标量巨单极共振的研究是约束核物质不可压缩系数 $K_ infty$ 的重要途径，对理解核天体物理现象提供了重要的信息。目前巨单极共振研究中存在的主要问题是 Pb 和 Sn 中巨单极共振不能够同时描述的矛盾，它阻碍了核物质不可压缩系数的精确约束。本文综述了准粒子无规相位近似理论和准粒子振动耦合理论对该问题的研究进展。
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