Thermal noise limit in measuring the gravitational constant G using the angular acceleration method and the dynamic deflection method

A general comparison is made between two methods of measuring the gravitational constant G. The angular acceleration method can avoid the anelasticity effect since the torsion fiber is not twisted. The dynamic deflection method is similar in principle but it does not use feedback, therefore a major noise introduced by the feedback control system in the angular acceleration method can be avoided. Both methods have their advantages and can be performed with the same device. Based on different expressions of G, we have expressed the signal-to-noise ratio and calculated the thermal noise limit for both methods. In order to get a lower thermal noise limit, the dynamic deflection method should avoid resonance.     

Technique of studying thermal diffusivity of metallics in different directions in a field of centrifugal accelerations and forces

Study of the thermal diffusivity of metallics in a field of centrifugal accelerations and forces is essential for aerospace engineering. Characteristics of thermal diffusivity of materials are used in calculations of thermal state of blades and disks of turbine rotors. An original technique and a device on semiconductors have been developed for determination of thermophysical characteristics of materials on an acceleration bench using a vacuum chamber, under centrifugal forces and accelerations. Presented are results on nonstationary heating of heat conductors in the radial and circumferential directions in a field of centrifugal forces and accelerations. Analysis of experimental results shows that the thermal diffusivity of heat conductors grows with rotational speed as compared with a static state without rotation. The thermal diffusivity phenomenon of concern has two components: from centrifugal acceleration and from centrifugal tensile load. From experimental data on the effect of tensile forces it follows that the second component is small. Thus, said thermal diffusivity growth is strongly associated with increase in the velocity of electron drift in ametal under centrifugal acceleration forces.     

Hawking Radiation of Dirac Particles in an Arbitrarily Accelerating Kinnersley Black Hole

Quantum thermal effect of Dirac particles in an arbitrarily accelerating Kinnersley black hole is investigated by using the method of generalized tortoise coordinate transformation. Both the location and the temperature of the event horizon depend on the advanced time and the angles. The Hawking thermal radiation spectrum of Dirac particles contains a new term which represents the interaction between particles with spin and black holes with acceleration. This spin-acceleration coupling effect is absent from the thermal radiation spectrum of scalar particles.     

热等离子体中的尾波加速

通过计算在等离子体温度不太高时尾波中本底等离子体的分布函数,推导出热等离子体中的尾波方程.这个方程对进一步研究如何最大限度地提高热等离子体中的尾波加速效率提供了出发点.讨论了温度对等离子体尾波加速的影响. 关键词：     

Influence of the thermal motion on the line shape and position of resonances in collinear fast beam laser spectroscopy

We derive the spectral line shape for collinear fast beam laser spectroscopy. As initial condition we take a thermally distributed ensemble into account. While the thermal velocity distribution of the fast ensemble has an asymmetric structure due to the acceleration by the electrostatic field, under typical experimental conditions the convolution with the natural line shape preserves the Lorentz profile with negligible broadening. However, the spectral line as a whole experiences a small shift depending on the temperature of the source and the acceleration . PACS 32.70.Jz     

Flame acceleration in a narrow channel with flow compressibility and diverging or converging walls

We study the effects of non-parallel (diverging or converging) channel walls on flame propagation and acceleration in planar and cylindrical narrow channels, closed at the ignition end and open at the other, accounting for thermal expansion in both the zero Mach number and weakly compressible flow limits. For parallel channel walls, previous work has shown that thermal expansion induces an axial flow in the channel, which can significantly increase the propagation speed and acceleration of the flame. In this study, we consider examples of diverging/converging linear walls, although our asymptotic analysis is also valid for curved walls. The slope of the channel walls is chosen so that the magnitude of the thermal-expansion induced flow through the channel obtained for parallel walls is modified at leading-order, thereby influencing the leading-order flame propagation. For zero Mach number flows, the effect of the diverging/converging channel walls is moderate. However, for weakly compressible flows, the non-parallel walls directly affect the rate at which pressure diffuses through the channel, significantly inhibiting flame acceleration for diverging walls, whereas the flame acceleration process is enhanced for converging walls. We consider several values of the compressibility factor and channel wall slopes. We also show that the effect of a cylindrical channel geometry can act to significantly enhance flame acceleration relative to planar channels. The study reveals several new physical insights on how non-parallel channel walls can influence the ability of flames to accelerate by modifying the flow and pressure distribution induced by thermal expansion.     

Fast electrons generation by RF and random fields near the antenna I. One dimensional model and regular fields

Test particle motion and acceleration has been explored in strong radio frequency (RF) fields, for which quasilinear ponderomotive force approximation is not valid. By nonlinear acceleration in spatially varying wave amplitude of RF travelling wave, electrons may be accelerated to time averaged velocities significantly larger than the RF wave phase velocity, and than the boundary plasma thermal velocity, in RF fields of several Volts per centimeter at wave frequency of 7 MHz. It is also demonstrated that even weak spatial gradients, much weaker than those expected in experiments, of the RF wave field amplitude, have significant consequences for the particle motion. Estimates are presented of the total energy transferred from the near antenna RF field to the plasma due to the nonlinear electron acceleration effects.     

Rindler effect for a nonuniformly accelerating observer

Both the Klein-Gordon equation and the Dirac equation are dealt with in the generalized Rindler space-time of a nonuniformly accelerating observer. Making use of a new method and introducing a tortoise-type coordinate transformation, it is proved that there exist an event horizon and thermal radiation depending on time in the space-time. The Hawking-Unruh temperature is proportional to the variable acceleration.     

The surfatron acceleration of cosmic rays in the galactic plasma

The optimum conditions for a prolonged holding of charged particles resonantly trapped from the galactic plasma by nonlinear waves and for the acceleration of these particles to high energies by the surfatron mechanism are established. The density of particles trapped by the plasma waves of large amplitude and by the quasitransverse magnetosonic shock waves is estimated. Various reasons leading to possible breakage of the process of surfatron acceleration of cosmic rays in the Galaxy are considered. Within the framework of the surfatron acceleration mechanism, galactic cosmic rays originate predominantly from the interstellar plasma and their energy spectrum is formed in two stages. In the first stage, some of the galactic plasma particles are accelerated from thermal energies to 10¹⁵ eV/nucleon; in the second stage, the cosmic rays may continue gaining energy up to 10¹⁹ eV/nucleon and above.     

Generalized Uncertainty Relation of One-Dimensional Rindler Oscillator

General Minkowski vacuum state is seen to be equivalent to a thermal bath for a Rindler uniformly accelerated observer. This paper calculates the generalized uncertainty relation of one-dimensional Rindler oscillator in the coordinate representation. The calculations show that for a Rindler uniformly accelerated observer there is not only general quantum fluctuation but also thermal fluctuation related to his acceleration.     

Beschleunigungsreaktionen von Neutronen

Acceleration of neutrons by isomeric nuclei. The inelastic neutron acceleration (INNA) by long living isomeric nuclei is studied. The theoretical estimates of the INNA cross-sections for thermal neutrons for a number of isomers give the values in the range 0.1 - 10²b. Inelastic acceleration of thermal neutrons was observed by ^152mEu and ^180mHf, and confirmed the high value of the INNA cross-sections. As a result of the high probability of acceleration some isomeric nuclei ^113mIn, ^115mIn, are not usual moderators but accelerators of neutrons. The use of the INNA reaction for the study of high excited levels and the nature of various nuclear hindrances are discussed.     

Possible causes for the acceleration of diffusion during thermal cycling of heterogeneous systems

We analyze a possible mechanism for the acceleration of diffusion in heterogeneous systems during thermal cycling resulting from the redistribution of the excess concentration of the components.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 22–25, February, 1972.     

Spontaneous excitation of a circularly accelerated atom coupled with vacuum Dirac field fluctuations

We study the spontaneous excitation of a circularly accelerated atom coupled with vacuum Dirac field fluctuations by separately calculating the contribution to the excitation rate of vacuum fluctuations and a cross term which involves both vacuum fluctuations and radiation reaction, and demonstrate that although the spontaneous excitation for the atom in its ground state would occur in vacuum, such atoms in circular motion do not perceive a pure thermal radiation as their counterparts in linear acceleration do since the transition rates of the atom do not contain the Planckian factor characterizing a thermal bath. We also find that the contribution of the cross term that plays the same role as that of radiation reaction in the scalar and electromagnetic fields cases differs for atoms in circular motion from those in linear acceleration. This suggests that the conclusion drawn for atoms coupled with the scalar and electromagnetic fields that the contribution of radiation reaction to the mean rate of change of atomic energy does not vary as the trajectory of the atom changes from linear acceleration to circular motion is not a general trait that applies to the Dirac field where the role of radiation reaction is played by the cross term.     

High precision thermal modeling of complex systems with application to the flyby and Pioneer anomaly

Thermal modeling of complex systems faces the problems of an effective digitalization of the detailed geometry and properties of the system, calculation of the thermal flows and temperature maps, treatment of the thermal radiation including possible multiple reflections, inclusion of additional external influences, extraction of the radiation pressure from calculated surface data as well as computational effectiveness. In previous publications [1, 2] the solution to these problems have been outlined and a first application to the Pioneer spacecraft have been shown. Here we like to present the application of our thermal modeling to the Rosetta flyby anomaly as well as to the Pioneer anomaly. The analysis outlines that thermal recoil pressure is not the cause of the Rosetta flyby anomaly but likely resolves the anomalous acceleration observed for Pioneer 10.     

Spontaneous excitation of a detector in circular motion coupled to massless Rarita–Schwinger fields in vacuum

We study the spontaneous excitation of a detector (modeled by a two-level atom) in circular motion coupled nonlinearly to vacuum massless Rarita–Schwinger fields in the ultrarelativistic limit and demonstrate that the spontaneous excitation occurs for ground-state atoms in circular motion in vacuum but the excitation rate is not of a pure thermal form as that of the atoms in linear uniform acceleration. An interesting feature is that terms of odd powers in acceleration appear in the excitation rate whereas in the linear acceleration case there are only terms of even powers present. On the other hand, what makes the present case unique in comparison to the atom’s coupling to other fields that are previously studied is the appearance of the terms proportional to the seventh and ninth powers of acceleration in the mean rate of change of atomic energy which are absent in the scalar, electromagnetic and Dirac field cases.     

城市典型地物的热辐射特性研究

运用热红外技术监测地表温度已获得成熟的发展,城市化进程的加快使得城市热岛效应日益显现,有关城市典型地物热辐射特性的研究对于分析城市热岛现象的成因和分布具有重要意义。本文通过对保定市地面实测数据的研究发现,地物类型、观测时间和墙面朝向是影响城市典型地物热辐射亮度温度的主要因素。结果显示,地物类型的不同显著影响其亮度温度,但仍存在同谱异物现象;不同时间观测到的地物热辐射强度不同,且在很大程度上影响其在各通道上的亮温差异;不同朝向墙面的亮温也有差异,且这种差异随观测时间而改变。对城市典型地物热辐射特性的研究具有理论和实践意义,为热红外遥感监测城市热岛效应提供了依据。     

双中子星并合的中微子信号

2017年8月17日,LIGO/Virgo首次探测到了双中子星并合事件的引力波信号,随后多波段的跟进观测获得了GW170817事件的多波段“全息”图像并确认源头在40 Mpc外的NGC4993星系,但颇为遗憾的是(尽管与理论预期符合)当时全球运行中的中微子探测器都没有探测到与GW170817相关联的中微子。普遍认为,热中微子在双星引力潮汐撕裂绕行阶段就会产生,在并合事件后的十几毫秒内达到峰值;若并合中心产物为伽马射线暴或者稳定的磁星,还会在并合的即刻至数天内产生超高能中微子。因此,中微子信号不仅可以辅助研究并合后的产物环境,还可以在天文尺度上研究中微子的基本性质和寻找粒子物理标准模型之外的新物理。即使只探测到一个热中微子事件,也可以获得热中微子的能谱标度信息和诊断并合后十几毫秒内星体本身和周围环境的物理参数。另外,因为引力波以光速传播,通过热中微子信号相对引力波信号的时延,可限制中微子的绝对质量。若探测到延迟的高能中微子信号,除了可以清楚地证明双中子星并合的中心产物是磁星,还可以研究并合产物附近的磁场环境和宇宙射线加速机制。     

Catalysis of the Back Thermal cis–trans Isomerization Reaction of Stilbazolium Betaine by Metmyoglobin

The catalytic effect of metmyoglobin on the back thermal cis trans isomerization reaction of stilbazolium betaine M is reported. This reaction shows substantial acceleration in the presence of metmyoglobin in comparison to the same reaction without the protein or in the presence of metmyoglobin cyanide. It is suggested that the observed thermal reaction acceleration may arise from the coordination of the protonated stilbazolium betaine molecule to the sixth ligand position of the heme iron and subsequent chromophore deprotonation or from the low polarity of the heme pocket microenvironment.     

Macroparticle acceleration by a laser-plasma stream

A physical model is proposed for macroparticle acceleration in an expanding laser plasma. Two acceleration mechanisms are considered, based on absolutely inelastic interaction of the laser-plasma ions with the macroparticle surface: acceleration due to the ion momentum and reactive acceleration due to evaporation of the surface layer. The processes are mathematically described with the aid of the gasdynamics equations with thermal conductivity. Approximate analytic expressions are obtained and permit an estimate of the laser-plasma energy as well as of the quasiparticle momentum as functions of the parameters of the laser pulse, of the target, and of the macroparticle. The analytic solutions are compared with numerical computations using the RAPID program; the comparison confirms that the results agree qualitatively and quantitatively.Quantum Radiophysics Division, Lebedev Physics Institute. Translated from Preprint No. 209 of the Lebedev Physics Institute, Academy of Sciences USSR, Moscow, 1990.     

Quantum field theory,horizons and thermodynamics

The aim of the article is to obtain an intuitive understanding of the recently explored deep connections between thermal physics, quantum field theory and general relativity. A special case in which a detector moves with constant acceleration through a quantum vacuum is examined to clarify the fact that such a detector becomes thermally excited, with a temperature proportional to its acceleration. An elementary physical explanation of this fundamental result is provided. The uniformly accelerated observer finds his space-time manifold bounded by an event horizon and so realizes a ‘model’ black hole. Real black holes also have thermal properties when quantum effects are taken into account; these are described and the correspondences with the accelerated case are pointed out. In particular, an elementary account is given of the thermal Hawking radiation emitted by the black holes formed by collapsed stars.