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Gerstein–Greiner–Zeldovich Effect: Induced Charge Density and Vacuum Energy 格斯坦-格里纳-泽尔多维奇效应:诱导电荷密度和真空能量
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-04-09 DOI: 10.1134/s1547477124020067
P. A. Grashin, K. A. Sveshnikov

Abstract

The Gerstein–Greiner–Zeldovich effect—the spontaneous emission of vacuum positrons under conditions of Coulomb supercriticality—has been studied in detail based on the first principles of quantum electrodynamics within the framework of an essentially nonperturbative approach based on a special combination of analytical methods, computer algebra, and numerical calculations. Particular attention is paid to the vacuum energy ({kern 1pt} {{mathcal{E}}_{{{text{VP}}}}}), considered a function of the parameters of the external Coulomb source: charge (Z) and radius (R). The specific contribution to ({kern 1pt} {{mathcal{E}}_{{{text{VP}}}}}) arising due to the direct Coulomb interaction of the vacuum charge densities ({{varrho }_{{{text{VP}}}}}(vec {r})) has been studied in detail. It is shown that, with correct renormalization, this contribution becomes negative after the first discrete levels descend into the lower continuum. Therefore, it is a purely quantum effect, not observed in classical electrodynamics. The problem of lepton number conservation during spontaneous emission is also discussed.

摘要根据量子电动力学的第一原理,在一种基于分析方法、计算机代数和数值计算特殊组合的基本非扰动方法框架内,对格斯坦-格里纳-泽尔多维奇效应--库仑超临界条件下真空正电子的自发发射--进行了详细研究。特别关注的是({kern 1pt} {{mathcal{E}}_{{text/{VP}}}}}) 的真空能,它被认为是外部库仑源参数的函数:电荷(Z) 和半径(R)。我们详细研究了由于真空电荷密度的直接库仑相互作用而产生的对({varrho }_{{text/{VP}}}}}(vec {r}))的具体贡献。研究表明,在正确的重正化条件下,当第一个离散级下降到低连续体之后,这个贡献就会变成负值。因此,这是一种纯量子效应,在经典电动力学中观察不到。此外,还讨论了自发发射过程中的轻子数目守恒问题。
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引用次数: 0
Method for Studying Characteristics of Light Readout Systems in Liquid Argon 研究液氩中光读出系统特性的方法
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010114
A. S. Selyunin, N. V. Anfimov, K. I. Kuznetsova, A. V. Rybnikov, D. V. Fedoseev, O. B. Samoylov, S. A. Sokolov, A. V. Chetverikov

Abstract

A method for studying the components of the light detection system of the Liquid Argon Time-Projection Chamber (LArTPC) of the Near Detector of the DUNE experiment (DUNE ND) in liquid argon is presented. As part of the methodology, comparative tests of a full-scale light collection module for a liquid argon time-projection chamber and a shortened module were carried out using a cryogenic stand. The light detection efficiency of the full-scale module observed in the study is ~5% less than that of the shortened module. The full-scale module is shown to be suitable for designing the LArTPC Near Detector for the DUNE experiment.

摘要 介绍了研究 DUNE 实验近探测器(DUNE ND)液氩时间投射室(LArTPC)光探测系统在液氩中的组件的方法。作为研究方法的一部分,使用低温台对液氩时间投射室的全尺寸光收集模块和缩短模块进行了对比测试。研究中观察到的全尺寸模块的光探测效率比缩短模块低 ~5%。结果表明,全尺寸模块适用于为 DUNE 实验设计 LArTPC 近探测器。
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引用次数: 0
Concept of the High-Temperature Superconductor Magnetic System of the New Nuclotron Synchrotron 新核子同步加速器的高温超导体磁系统构想
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010060
H. G. Khodzhibagiyan, M. S. Novikov, E. Z. Fisher, A. V. Shemchuk

Abstract

This work is carried out within the Mega-Science project of the new NICA accelerator–collider complex at the Joint Institute for Nuclear Research (JINR) in Dubna. The existing superconducting synchrotron has been operating since 1993 and requires modernization. The New Nuclotron is planned to be built using magnets made of the second-generation high-temperature superconductor (HTS) material produced by Moscow-based S-Innovations. The magnets will be cooled to 30 K with a flow of two-phase neon inside channels of the winding cable, or to 50–65 K with a flow of helium gas, using the next-generation HTS material. The magnet cooling scheme and design are presented.

摘要--这项工作是在杜布纳联合核研究所(JINR)新的 NICA 加速器-对撞机综合体巨型科学项目范围内进行的。现有的超导同步加速器自 1993 年以来一直在运行,需要进行现代化改造。新同步加速器计划使用由总部位于莫斯科的 S-Innovations 公司生产的第二代高温超导体(HTS)材料制成的磁铁。磁体将通过绕组电缆通道内的两相氖流冷却到 30 K,或通过下一代 HTS 材料的氦气流冷却到 50-65 K。本文介绍了磁体冷却方案和设计。
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引用次数: 0
Vacuum Integration: UV- and IR-Divergencies 真空集成:紫外线和红外线分歧
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010023
I. V. Anikin

Abstract

In this note we present the important details regarding the massless vacuum integrations which are not outlined in the literature. In particular, it has been shown how the delta-function represents either UV‑regime or IR-regime. In the case of vacuum integration, we advocate the use of sequential approach to the singular generated functions (distributions). The sequential approach is extremely useful for many practical applications, in particular, in the effective potential method.

摘要 在这篇论文中,我们介绍了有关无质量真空积分的重要细节,这些细节在文献中没有概述。特别是,我们已经证明了 delta 函数是如何代表紫外区(UV-regime)或红外区(IR-regime)的。在真空积分的情况下,我们主张对奇异生成的函数(分布)使用序列方法。顺序法在许多实际应用中都非常有用,特别是在有效势法中。
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引用次数: 0
Exploring Stopping Power Models for Efficient Ignition Condition in Inertial Confinement Fusion Driven by Fast Ignition Method 探索快速点火法驱动的惯性约束聚变中高效点火条件的停止功率模型
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010102
S. Nouri, B. Khanbabaei

Abstract

Fast ignition, a pivotal concept in inertial confinement fusion, presents a departure from conventional methods by implementing a two-stage process for fuel compression and ignition. This novel approach minimizes driver requirements and enhances energy efficiency. Among the primary solutions for initiating fast ignition, the utilization of light ion beams, specifically protons, generated through the interaction of high-power lasers with convertor foils, emerges as a prominent strategy. Investigation into the transport of alpha particles produced by the deuterium-tritium fusion reaction plays a vital role in the formation of a hot spot within the fast ignition framework. The self-heating effect caused by the energy deposition of alpha particles triggers ignition in the fusion fuel. Thus, this study focuses on exploring the impact of modern stopping power models, specifically BPS and MD, on the ignition criteria and hot spot formation of pre-compressed DT fuel using a two-temperature model in a non-equilibrium state. These new models are compared and contrasted with previous ones. For this investigation, a DT equimolar fuel with a density of 300 g cm–3 and an incident proton beam featuring an average energy of 4 MeV and a Maxwellian energy distribution are employed. Our calculations demonstrate that the newer BPS and MD stopping power models slightly shift the ignition criterion towards higher ρR values. Furthermore, the thermal efficiency reduction of alpha particles in these stopping power models leads to a significant decrease in hot spot temperature when compared to older models.

摘要快速点火是惯性约束聚变中的一个关键概念,它通过实施燃料压缩和点火两阶段过程,实现了对传统方法的突破。这种新方法最大限度地降低了对驱动器的要求,提高了能源效率。在启动快速点火的主要解决方案中,利用高功率激光器与转换器箔片相互作用产生的轻离子束(特别是质子)是一个突出的策略。对氘氚聚变反应产生的α粒子的传输进行研究,对快速点火框架内热点的形成起着至关重要的作用。α粒子的能量沉积所产生的自加热效应会引发聚变燃料的点燃。因此,本研究利用非平衡态下的双温模型,重点探索现代停止力模型(特别是 BPS 和 MD)对预压缩 DT 燃料的点火标准和热点形成的影响。这些新模型与之前的模型进行了比较和对比。在这项研究中,采用了密度为 300 g cm-3 的 DT 等摩尔燃料和平均能量为 4 MeV、能量分布为 Maxwellian 的入射质子束。我们的计算结果表明,较新的 BPS 和 MD 停止功率模型略微将点火标准转向了较高的ρR 值。此外,与旧模型相比,这些停止功率模型中α粒子热效率的降低导致热点温度显著下降。
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引用次数: 0
System of Cryogenic Physical Targets for the ACCULINNA-2 Facility 用于 ACCULINNA-2 设施的低温物理目标系统
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010084
S. A. Krupko, A. V. Gorshkov, A. A. Bezbakh, A. S. Fomichev, G. M. Ter-Akopian

Abstract

To carry out the experiments with radioactive beams at the ACCULINNA-2 fragment separator in the Flerov Laboratory of Nuclear Reactions, a complex of cryogenic thin physical targets with isotopes H2, D2, T2, 3He, and 4He is being created for the gas, liquid, and solid phase (for hydrogen). One of the three types of cryotargets created for nonhazardous gases in any phase at a temperature of 11–30 K is described. Requirements to the targets are formulated. A variety of available cells are presented, a concept of safe operation with the solid phase of hydrogen is given, and the gas–vacuum test bench for its implementation is described.

摘要 为了在弗列罗夫核反应实验室的 ACCULINNA-2 碎片分离器上进行放射性束实验,正在为气相、液相和固相(氢)制造同位素 H2、D2、T2、3He 和 4He 的低温薄物理靶。本文介绍了为温度为 11-30 K 的任何相中的非危险气体而制造的三种低温靶中的一种。提出了对目标的要求。介绍了各种可用的电池,给出了氢固相安全运行的概念,并描述了实施该概念的气体-真空试验台。
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引用次数: 0
Neutrino Mixing Matrix in Terms of Neutrino Mass Matrix and Its Frobenius Covariants 以中微子质量矩阵及其弗罗贝尼斯协变量表示的中微子混合矩阵
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010072
M. I. Krivoruchenko, F. Šimkovic

Abstract

An explicit expression is derived for the mixing matrix of Majorana neutrinos in terms of the mass matrix and its Frobenius covariants. Illustrative scenarios are taken as examples where the suggested formula is used to obtain the mixing matrix from the mass matrix.

摘要 用质量矩阵及其弗罗贝尼斯协变量推导出了马约拉纳中微子混合矩阵的明确表达式。以示例情况为例,说明了如何利用所提出的公式从质量矩阵得到混合矩阵。
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引用次数: 0
Food Recognition for Smart Restaurants and Self-Service Cafes 智能餐厅和自助咖啡厅的食物识别功能
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010059
M. Gerasimchuk, A. Uzhinskiy

Abstract

In recent years, deep learning has been applied to different tasks in the food recognition field. Some promising solutions have been proposed. Due to the complexity of background food, the problem of pattern recognition on a limited dataset is still challenging. Experiments were conducted on a self-collected dataset with canteen trays, containing images of various dishes depending on the day of the week. The main objective of this work is to compare the effectiveness of modern object detection architectures, namely, YOLO_v5, YOLO_v6, YOLO_v7, and YOLO_v5, with a custom classifier. The experimental results showed that the custom classifier was needed to effectively distinguish dishes with high performance.

摘要 近年来,深度学习已被应用于食品识别领域的不同任务。人们提出了一些很有前景的解决方案。由于背景食物的复杂性,在有限的数据集上进行模式识别仍然是一个具有挑战性的问题。我们在食堂托盘的自收集数据集上进行了实验,该数据集根据一周的不同日期包含各种菜肴的图像。这项工作的主要目的是比较现代物体检测架构(即 YOLO_v5、YOLO_v6、YOLO_v7 和 YOLO_v5)与自定义分类器的有效性。实验结果表明,需要定制分类器才能以高性能有效区分餐具。
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引用次数: 0
Use of Bremsstrahlung of a Linear Electron Accelerator for Processing Large Objects 利用线性电子加速器的轫致辐射处理大型物体
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010047
G. O. Buyanov

Abstract

The results of a numerical analysis of the dynamics of electrons in a beam injected into air with an energy of several tens of MeV and focused by the field of an accompanying electromagnetic radiation (EMR) wave at a full stopping distance are presented. The main feature is that the electrons travel the main part of the path in a radial focusing field, which provides beam transport. During the motion of an electron beam, multiple collisions occur between the particles of the beam and air molecules. As a result of these collisions, the radius of the electron beam increases. To determine the increase in the beam radius, the external fields under which the electron moves between two neighboring collisions should be taken into account. Since electrons collude with gas molecules randomly, the root-mean-square radial deviation of electrons from the accelerator axis was calculated. Transverse dimension of the electron beam and characteristics of the tracking field are considered. A twofold increase in the permissible root-mean-square deviation is shown to lead to a significant (by a factor of 16) decrease in the required microwave power of the tracking wave. A scheme for obtaining electron beams (and the corresponding bremsstrahlung flow) is theoretically substantiated.

摘要 本文介绍了对注入空气中能量为几十兆电子伏特的电子束中的电子动态进行数值分析的结果,该电子束在完全停止距离处被伴随的电磁辐射(EMR)波场聚焦。其主要特点是电子在径向聚焦场中走完了路径的主要部分,从而实现了电子束的传输。在电子束运动过程中,电子束粒子与空气分子之间会发生多次碰撞。由于这些碰撞,电子束的半径会增大。要确定电子束半径的增加,应考虑到电子在两个相邻碰撞之间移动时所受到的外部场。由于电子与气体分子的碰撞是随机的,因此要计算电子偏离加速器轴线的均方根径向偏差。还考虑了电子束的横向尺寸和跟踪场的特性。结果表明,将允许的均方根偏差提高两倍,可使跟踪波所需的微波功率显著降低(16 倍)。从理论上证实了获得电子束(以及相应的轫致辐射流)的方案。
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引用次数: 0
Coherent Electroproduction of Vector Mesons on Spinless Targets 无自旋靶上矢量介子的相干电致发生
IF 0.5 Q3 Physics and Astronomy Pub Date : 2024-03-12 DOI: 10.1134/s1547477124010096
S. I. Manaenkov

Abstract

It is shown that the amplitude ratios of vector-meson production by heavy photons on spinless targets can be explicitly expressed in terms of the spin-density-matrix elements (SDMEs) only if the lepton beam is longitudinally polarized. Making use of the amplitude ratios as free fit parameters instead of the SDMEs reduces the number of the real parameters in data description from 23 to 8. The exact formula for (R = {{frac{{d{{sigma }_{{text{L}}}}}}{{dt}}} mathord{left/ {vphantom {{frac{{d{{sigma }_{{text{L}}}}}}{{dt}}} {frac{{d{{sigma }_{{text{T}}}}}}{{dt}}}}} right. kern-0em} {frac{{d{{sigma }_{{text{T}}}}}}{{dt}}}}) in terms of the SDMEs is obtained for spinless targets and the new approximate formula for (R) is proposed for nucleon targets.

摘要 研究表明,只有当轻子束纵向偏振时,重光子在无自旋目标上产生矢量介子的振幅比才能用自旋密度矩阵元素(SDMEs)明确表示。利用振幅比作为自由拟合参数而不是自旋密度矩阵元素,可以将数据描述中的实际参数数量从 23 个减少到 8 个。R = {{frac{d{sigma }_{{text/{L}}}}}}{dt}}}的精确公式是mathord{left/ {vphantom {{frac{{d{sigma }_{{text{L}}}}}}{{dt}}}{frac{{d{{sigma }_{{text{T}}}}}}{{dt}}}}}right.kern-0em} {frac{d{sigma }_{{text{T}}}}}}{dt}}}}))在SDMEs方面得到了无自旋目标,并为核子目标提出了(R)的新近似公式。
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引用次数: 0
期刊
Physics of Particles and Nuclei Letters
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