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2.
We present a neutron polarimetric experiment where two kinds of spinor precessions are observed: one is induced by different total energy of neutrons (zero-field precession) and the other is induced by a stationary guide field (Larmor precession). A characteristic of the former is the dependence of the energy-difference, which is in practice tuned by the frequency of the interacting oscillating magnetic field ωR. In contrast the latter completely depends on the strength of the guide field, namely Larmor frequency ωL. Our neutron-polarimetric experiment exhibits individual tuning as well as specific properties of each spinor precession, which assures the use of both spin precessions for multi-entangled spinor manipulation. 相似文献
3.
The idea of a Larmor clock is reexamined in the relativistic regime. We propose a concept of proper time for quantum theoretical particles. The Larmor clock can measure, under some relevant conditions, the proper time that passes while the particle stays in a space region. Our approach to Larmor clock is different than those of other researchers in the following two aspects: our concept of Larmor clock does not distinguish whether the particle is transmitted or reflected at the end of its stay, and pointer of our Larmor clock is not the spin but the total angular momentum. 相似文献
4.
The nutation accompanying the well-known Larmor precession discussed with respect to an inertial frame in an earlier paper
is now considered in the rotating Larmor frame where the precession is absent and the nutation is therefore fully emphasized.
It is shown that, in this frame, the nutating vector generates, in general, what may be called interpenetrating partial cones, the two parts of which merge into a single cone traced twice over, when the orbit of the charged particle changes to a circle
— giving an immediate explanation of the discontinuous jump in the nutation frequency to twice its value as the orbit changes
continuously from an ellipse to a circle. 相似文献
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We modulated the intensity of a neutron beam using Larmor precession techniques. We simulated triangular coils by using magnetised foils in electromagnets with rectangular pole shoes. Reversing the orientation of two of the magnetised foils in the spin-echo small-angle neutron scattering (SESANS)-instrument in Delft and changing the field settings was sufficient to obtain a modulation with a period in the order of 1 mm. We expect to be able to go to a modulation with a period of .This technique can be used to measure small-angle neutron scattering, analogous to the method used in SESANS, but with the advantage that all the manipulation of the neutron spin occurs before the sample. This means that the technique is insensitive to magnetic perturbations at the sample position. By positioning several of these devices after each other it will be possible to obtain a sharper modulation, or a modulation in two directions. 相似文献
7.
Resonant tunneling quantum structures consist of asymmetric wells and barriers have been investigated to find their optimized geometrical parameters and potential profile by the numerical calculations. The results show that the widths and the depths of the asymmetric wells have a significant effect on the transmission coefficient and the dwell time. The properties exhibited in this work may establish guidance to the device applications. 相似文献
8.
A. Fraenkel E. Finkman G. Bahir A. Brandel G. Livescu M.T. Asom 《Superlattices and Microstructures》1992,12(4)
The transport of hot electrons in the AlxGa1−xAs barriers above the wells in a multiple quantum well (MQW) structure is investigated. The structures that are studied are asymmetric quantum well infrared detectors. The transport of the hot electrons normal to the layers is strongly dependent on both voltage and well shape. It is suggested that the key parameter which affects the transport properties is the dwell time of the electrons in the continuum, above the well region. This is most readily seen in asymmetric MQW structures, in which the dwell time under an applied bias depends very strongly on bias polarity. Calculations of electron transmission coefficient and dwell time show that the electron mean free path in asymmetric wells is much larger in positive bias than in a negative one. Employing this model, we achieve a very good fit to experimental data. 相似文献
9.
We investigate the ratio of spin precession frequency to orbital frequency for a spinning charged particle confined to circular
orbit in the equatorial plane of a compact object, with a uniform magnetic field, as described by the Wald and the Ernst potentials.
In order to see the difference in behaviours for particles with differentg values we consider the cases of electron and proton separately. 相似文献
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The effects of compressibility, finite Larmor radius (FLR) and Hall currents are considered on the thermal instability of
a plasma in the presence of a uniform horizontal magnetic field. For stationary convection, the compressibility has a stabilizing
effect whereas FLR and Hall currents have stabilizing as well as destabilizing effects. For (C
pβ/g)<1, the system is stable. The magnetic field, FLR and Hall currents introduce oscillatory modes in the system for (C
pβ/g)>1. 相似文献
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针对计算机控制光学表面成形中光学表面存在中高频误差的问题,提出了一种基于驻留时间补偿的有效控制方法。分析了抛光误差的形成机理和影响因素,对系统的误差影响因素进行分类和定量描述,构建了抛光过程中磨损影响因子、浓度变化影响因子和系统影响因子。基于各影响因素的影响因子对抛光驻留时间的求解函数进行了修正,提出采用离散最小二乘法对修正的函数求解驻留时间。研究表明:这种补偿方法能提高计算机控制光学表面成形技术中加工模型的精度,减小光学表面的残余误差。 相似文献
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Among all the theories proposed to explain the “anomalous” perihelion precession of Mercury’s orbit first announced in 1859
by Le Verrier, the general theory of relativity proposed by Einstein in November 1915 alone could calculate Mercury’s “anomalous”
precession with the precision demanded by observational accuracy. Since Mercury’s precession was a directly derived result
of the full general theory, it was viewed by Einstein as the most critical test of general relativity from amongst the three
tests he proposed. With the advent of the space age, the level of observational accuracy has improved further and it is now
possible to detect this precession for other planetary orbits of the solar system — viz., Venus and the Earth. This conclusively
proved that the phenomenon of “anomalous” perihelion precession of planetary orbits is a relativistic effect. Our previous
papers presented the mathematical model and the computed value of the relativistic perihelion precession of Mercury’s orbit
using an alternate relativistic gravitational model, which is a remodeled form of Einstein’s relativity theories, and which
retained only experimentally proven principles. In addition this model has the benefit of data from almost a century of relativity
experimentation, including those that have become possible with the advent of the space age. Using this model, we present
in this paper the computed values of the relativistic precession of Venus and the Earth, which compare well with the predictions
of general relativity and are also in agreement with the observed values within the range of uncertainty.
相似文献
16.
Qiong Wang 《Physics letters. A》2010,374(46):4678-3725
Considering finite Larmor radius (FLR) effects, wake effects and stopping power induced by proton projectile in two-component magnetized plasma are investigated within a linear response framework. Numerical results show that, FLR lessens wake effects and stopping power, essentially through excitation of collective plasma electron modes. 相似文献
17.
Quantum motion of particles tunneling a double barrier potential is considered by using stochastic mechanics. Stochastic-mechanical trajectories give us information about complex motion of tunneling particles that is not obtained within the framework of ordinary quantum mechanics. Using such information, we calculate the tunneling times within each of the barriers which depend on the distance between them. It is found that the stochastic-mechanical tunneling time shows better asymptotic behavior than the quantum-mechanical dwell time and presence time. 相似文献
18.
给出一种可有效地演示电子轨道磁矩在外磁场中的进动规律的环电流陀螺,以及演示涡流存在的导体陀螺,并给出了相应分析. 相似文献
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针对磁流变抛光过程中的中频误差的控制,进行了驻留时间与中频误差影响关系的研究。对基于矩阵法得出的驻留时间进行分析,驻留时间矩阵沿抛光头的进给方向的起伏波动性,反映在抛光过程中速度的不连续性,会引入一定的中频误差。提出通过滤波算法使驻留时间沿抛光轮进给方向更加平滑,即相邻两点的速度更加接近,抛光轮只需要很小的加速度和很小的时间内即可完成整个加速过程,从而降低这种速度的波动性带来的误差。通过计算机仿真和实验验证,给驻留时间一个很小的扰动,会使残差的功率谱密度(PSD)曲线发散,而滤波后的驻留时间算法在不失真的情况下,在一定程度上抑制了中频误差。 相似文献