一个高时间分辨的多间隙电阻板室原型

研制了一种多气隙电阻板室原型并建立了相关的测试系统.利用宇宙线测试系统和欧洲核子中心的试验束装置T1?0对其性能进行了测试,给出了初步结果.时间分辨达到70ps,对最小电离粒子的探测效率大于95%.     

On the Traversal Time of Barriers

Fifty years ago Hartman studied the barrier transmission time of wave packets (J Appl Phys 33:3427–3433, 1962). He was inspired by the tunneling experiments across thin insulating layers at that time. For opaque barriers he calculated faster than light propagation and a transmission time independent of barrier length, which is called the Hartman effect. A faster than light (FTL or superluminal) wave packet velocity was deduced in analog tunneling experiments with microwaves and with infrared light thirty years later. Recently, the conjectured zero time of electron tunneling was claimed to have been observed in ionizing helium inside the barrier. The calculated and measured short tunneling time arises at the barrier front. This tunneling time was found to be universal for elastic fields as well as for electromagnetic fields. Remarkable is that the delay time is the same for the reflected and the transmitted waves in the case of symmetric barriers. Several theoretical physicists predicted this strange nature of the tunneling process. However, even with this background many members of the physics community do not accept a FTL signal velocity interpretation of the experimental tunneling results. Instead a luminal front velocity was calculated to explain the FTL experimental results frequently. However, Brillouin stated in his book on wave propagation and group velocity that the front velocity is given by the group velocity of wave packets in the case of physical signals, which have only finite frequency bandwidths. Some studies assumed barriers to be cavities and the observed tunneling time does represent the cavity lifetime. We are going to discus these continuing misleading interpretations, which are found in journals and in textbooks till today.     

Time dependent axially symmetric solutions of the Einstein-Maxwell-Yukawa fields

Extending a technique developed for static fields by Janiset al. [10] to the nonstatic fields two exact solutions in the case of Einstein-Rosen metric for the interacting electromagnetic and zero mass scalar fields have been obtained.     

Time of scattering in the one-dimensional inelastic tunnelling

Summary The various definitions for time of tunnelling across a barrier in one dimension, that have been introduced in the elastic case and discussed by Buttiker and various authors, are here extended allowing for inelastic losses to occur inside the barrier. The framework of a multichannel scattering theory is here used. Their relevance to inelastic tunnelling and resonant tunnelling is critically analysed. Results are reported for the average delay time of eq. (24) in the case of an inelastic point interaction with a harmonic oscillator inside the barrier. To speed up publication, the author of this paper has agreed to not receive the proofs for correction.     

Time development of the light intensity in resonance fluorescence

The time evolution of the fluorescent light emitted by a two-level atom that is driven by an external quantum field close to resonance, has been calculated. Although the treatment lies within the framework of QED, it is found that the answer in no way depends on any quantum properties of the field.     

Time dependence of the luminescence excited by rectangular pulses

The theory of the time dependence of luminescence, during and after excitation by rectangular pulse, is discussed. Some phenomena, which cannot be described as direct excited luminescence, will be mentioned. In order to explain these phenomena, the model for energy transfer between two monomolecular centres has been used. On the basis of this model, the theoretical time dependence of the luminescence is obtained. The theoretical formula describe qualitatively very well the experimental observations in ZnSMn and other compounds.     

On Calculating the Stopping Time of a Cylindrical Body Rotating in a Viscous Continuum and the Time of Entrainment of a Coaxial External Cylinder

The velocity distribution in the vicinity of the surface of an axisymmetric body rotating in a viscous medium at frequency ω directed along its axis is determined. The dissipative function has been calculated and used for deriving the equation of motion, from which an analytic expression for the stopping time of the body (until its complete stoppage) is obtained. The time of entrainment of an external stationary cylinder coaxial with the body is calculated by solving the time-dependent Navier–Stokes equation.     

Time development of quantum lattice systems

The time development of quantum lattice systems is studied with a weaker assumption on the growth of the potential than has been considered previously.Battelle Fellow.     

Time dependence of theJ/Ψ suppression in the quark gluon plasma

The time dependent survival probability of theJ/Ψ, embedded in the medium of quark gluon plasma has been studied. The screening as well as the dissipative effects in the dissolution ofJ/Ψ in QGP have been described through an optical model potential.     

Time evolution of diffusion fringes in the Christiansen effect

When laser radiation is allowed to fall at the diffusion region separating two liquids in a Christiansen filter, a new fringe pattern appears. We termed it as “diffusion fringes”. In the present work, we have studied this interference fringe pattern and its time evolution. It has been observed that there is a definite co-relation between the shape of the fringe pattern and the width of the diffusion region. The time evolution of this fringe patterns indicates that as diffusion region increases the circular fringe becomes elliptical and finally straight. It is believed that a detailed investigation of these diffusion fringes will throw much needed light not only on the theory of the Christiansen effect but also on the rate of diffusion between two molecules.     

Improvements in the Sensitivity of Time Resolved Fluorescence Energy Transfer Assays

The effect on fluorescence resonance energy transfer (FRET) of multiple labelling of DNA oligonucleotides with donor lanthanide chelate and acceptor CyDye fluors has been investigated. It is shown that using a multiple donor lanthanide chelate with a single acceptor Cy or Cy5 can increase sensitivity and fluorescence output. The enhanced FRET observed in the multiple donor label system has been utilised in two different DNA based assay formats to demonstrate the advantages over a steady state fluorescence assay and a radiometric assay.     

Time reversal of ocean noise

It has recently been shown [Roux et al., "Extracting coherent wave fronts from acoustic ambient noise in the ocean," J. Acoust. Soc. Am. 116, 1995-2003 (2004)] that the time-averaged correlation of ocean noise between two points yields a deterministic waveguide arrival structure embedded in the time-domain Green's function. By performing a set of these correlations between a vertical receive array and a single receiver, transfer functions necessary for time reversal can be extracted from ocean noise. Theory and simulation demonstrate this process and data of opportunity from the North Pacific Acoustic Laboratory experiment confirm the expected performance of a noise-based time reversal mirror.     

GaN激子跃迁的时间分辨光谱学研究

用时间分辨光谱学方法研究低压有机金属化学汽相沉积生长的ＧａＮ中自由，束缚激子（ＢＸ）的跃迁，讨论了这些跃迁的光致发光谱，复合寿命及其与温度的关系，给出了中性施主束缚激子和自由激子（ＦＸ）的辐射复合寿命分别为０．１２ｎｓ和０．４ｎｓ。     

Time constants for nonstationary arcs

The time constants associated with the initial deviations of an arc column from a static state have been studied analytically. The basic approach is to use a Taylor series expansion in powers of time of the energy balance equation. It is assumed that the arc gas is optically thin and is in local thermal equilibrium. Initially the effects of radial gas flow (which must exist for dynamic arcs) are neglected, but this simplification is later relaxed. The initial conditions are given by the properties of a cylindrically symmetric, wall-stabilized DC positive column. The interrupted (freely decaying) and the step-modulated arcs are considered, and initial time constants for conductance, electric field, and heat flux potential are computed. For numerical results the best available values of thermodynamic and transport properties have been used.     

Voltage Recovery Time of Small Spark Gaps

A two-pulse method is used to determine how fast and to what degree a small spark gap can recover its voltage holdoff capability after breaking down. The first pulse is used to overvolt and break down the gap. The second pulse is used, after a time delay, to determine the voltage recovery of the gap. By varying the time delay to the second pulse, a recovery voltage versus time plot can be obtained. Time delays from 10 ?s to 100 ms have been recorded. The spark gap discharges millijoules of energy with a gap spacing of less than 1 mm. Recovery has been measured at breakdown voltages of up to 10 kV in argon, hydrogen, and a mixture of the 2 gases. The experimental setup, pulse circuits, and data collection methods are described. Percent voltage recovery versus time plots for various parameters (gas species, gap spacing, and pressure) are discussed.     

时间间断式通讯转接器的研制

时间间断式通讯转接器是为在强电磁干扰区进行正常通讯而设计,该通讯转接器的研制,使速调管走廊强电磁干扰区的通讯稳定可靠,从而消除由于外界干扰而造成的通讯错误.     

Time constant measurements of high pressure arc columns

Measurements have been made of the column field strength response to step current disturbances of high pressure arcs for currents 4–40 amps in air, nitrogen, oxygen and argon. The influence of current step amplitude has been taken into account and the results used to derive the conductance time constant values of free recovery. The measured steady state and transient properties agree in general with the properties predicted for an arc column dominated by thermal conduction loss. The results clearly show the development of arc cores with current increase.     

Time Resolved Actinometric Study of Pulsed RF Oxygen Discharge

The dissociation efficiency of a pulsed RF discharge (with duty cycle 1:1 and discharge duration 0.2, 1, 5, and 20 ms) in oxygen at pressures from 1 to 5 torr and effective discharge currents from 50 to 210 mA has been studied. For monitoring of the atomic oxygen density the method of actinometry has been used. In order to evaluate the absolute dissociation degree, a numerical model has been developed and actinometric coefficients were calculated. Maximal degree of the dissociation reached value of 0.05. A saturation of the dissociation degree at higher pressures was observed and discussed.     

Time asymmetry of the Universe

The entropy of the Universe is calculated within the Einstein and Logunov concepts. It is shown that the entropies of the Universe calculated within the foregoing concepts coincide at the Beginning and at the present time.