Gravitational wave detectors: New eyes for physics and astronomy

Several interferometric gravitational wave detectors around the world are now starting to achieve better sensitivity to gravitational waves than ever before. We describe the prospects these detectors offer for physics and astronomy and review the rapid progress and the present status of the detectors’ sensitivities. We also report the progress made by the LIGO Scientific Collaboration in analysing the data produced by the LIGO and GEO detectors during the Collaboration’s Science Runs.     

Dynamical study and control of drift waves in a magnetized laboratory plasma

The various dynamical regimes of collisional drift waves in a magnetized plasma column are experimentally studied. These unstable low-frequency electrostatic waves are related with strong modulations of the ion and electron density. The angular velocity of the rotating plasma column is the control parameter of the dynamics: regular, chaotic and turbulent regimes are obtained. The spatial extension of the system allows for the occurrence of spatiotemporal chaos. The time-delay auto-synchronization method of controlling chaos [K. Pyragas, Phys. Lett. A 170, 421 (1992)] though purely temporal is successfully applied. A numerical study using coupled nonlinear oscillators exhibiting chaos is compared to the experimental results. The control method is tested on this model.     

国外光学薄膜的应用和真空镀膜工艺

本文概述了国外光学薄膜的典型应用和光学薄膜制造工艺的发展，着重阐述了国外的现代真空镀膜工艺。     

Time-amplitude characteristics of thin-walled drift tubes (straws) for gas mixtures ArCO2 with CF4 and O2 additives

Results of the investigation of time-amplitude characteristics of thin-walled drift tubes (straws) of different diameters for gas mixtures ArCO₂ with CF₄ and O₂ additives are described. An essential reduction of the sensitivity time of the straw for CF₄ additive is shown, especially with increase the straw diameter. O₂ additive influences the time parameters of the straw insignificantly. CF₄ or O₂ additives with the so-called cleaning properties are of interest for optimization of parameters of detectors with small sensitivity time under the condition of high loadings.     

Application of quartz glass tubes as the track detectors for chemical identification of short-lived isotopes of elements 104, 105 and 106

The quartz glass open chromatographic columns with thermal gradient, which usually were used for the investigation of chemical properties of short-lived Z104 nuclides, were first used as the track detectors of spontaneously fissioning isotopes of elements 104, 105 and 106. The recoil nuclei of these elements were captured by the flow of gaseous chlorides then go to the quartz tube with reducing thermal gradient 400°C-100°C. The quartz tube was etched in 40% HF. The tracks due to spontaneous fission of isotopes ²⁵⁹104, ²⁶²105 and ²⁶³106 which were etched at the internal wall of quartz tubes were counted under optical microscope.     

Modern technology in artwork conservation: a laser-based approach for process control and evaluation

The present work includes a laser-based methodology for the cleaning of artworks, with emphasis on the preservation of their structural integrity and identity. Modern laser-based techniques and instrumentation offer new tools in the field of artwork and antiquities conservation, aiming to alleviate the traditionally applied methods from existing weaknesses. Although in several cases the use of lasers may give rise to superior results, there are still problems to be resolved in relation to the optimization of procedures for safeguarding from potential damage. Furthermore, several operational parameters have to be simultaneously controlled and the long-term effects induced by laser irradiation must be assessed in detail before a full exploitation of the new methods is established. The control of material removal during laser cleaning is achieved by using laser-induced breakdown spectroscopy (LIBS). This control relies on the collection of spectroscopic data by LIBS, which correspond to the in-depth compositional profile of the artifact. This technique may be combined with structural analysis by holographic interferometry. The latter is important for assessing structural changes, which may be induced during laser ablation. Selected examples of this type of applications in a carefully considered methodology are presented.     

Black hole in an asymmetric electromagnetic field: New ponderomotive effects — Spin precession and drift

Two new ponderomotive effects in black hole physics are indicated: (i) the precession of the rotation axis of a charged black hole in an external magnetic field, (ii) the drift of a non-charged rotating hole in an asymmetric homogeneous electromagnetic field posessing a non-zero Poynting vector. The precession time for a black hole of solar mass with Q = 10^?5M in a magnetic field B ～ 10¹²G is about a year.     

Dynamics control of geometric quantum discord for two coupling qubits in a squeezed vacuum reservoir

We investigate the dynamics of geometric quantum discord of coupled qubits in a squeezed vacuum reservoir. The results show that there is distinct difference between the dynamics of geometric quantum discord and that of quantum entanglement near (or away from) the decoherence free subspace. We also find that the squeezed vacuum reservoir with high squeezed amplitude is more suitable for geometric quantum discord to survive. The robustness of geometric quantum discord is stronger than that of quantum entanglement.     

Production of an electron-positron pair and a photon from the vacuum in a radiation-dominated universe

A study is made of the production of an electron-positron pair and a photon from the vacuum in a Robertson-Walker space with metric ds²=a²()(d²–dx²–dy²–dx²). In Minkowski space, this process is forbidden by the conservation laws. The differential probability of the process is calculated, and its behavior in various kinematic regions is investigated. The probability of the process is estimated numerically for times close to the electron Compton time, and the probability of production of a pair and photon from the vacuum is compared with the probability of pair production in the absence of radiative coupling.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 61–66, February, 1991.     

Full‐energy peak efficiency of Si drift and Si(Li) detectors for photons with energies above the Si K binding energy

We studied the full‐energy peak efficiency of a Si drift detector (SDD) and a Si(Li) detector (SLD) using the formalisms proposed by Seltzer [Nucl. Instrum. Meth. 188 (1981) 133] and O'Meara and Campbell [X‐Ray Spectrom. 33 (2004) 146]. The respective adjustable parameters were fitted to full‐energy peak efficiencies measured with certified point radioactive sources. Seltzer's model was able to reproduce the experimental data for the SDD and the SLD in the 6–40 keV and 6–100 keV energy ranges, respectively. In turn, O'Meara and Campbell's formula also performed well for the SDD between 6 and 40 keV and proved to fit satisfactorily in the energy interval 6–60 keV for the SLD. Copyright © 2016 John Wiley & Sons, Ltd.     

A framework for quality control and parameter optimization in diffusion tensor imaging: theoretical analysis and validation

In this communication, a theoretical framework for quality control and parameter optimization in diffusion tensor imaging (DTI) is presented and validated. The approach is based on the analytical error propagation of the mean diffusivity (D(av)) obtained directly from the diffusion-weighted data acquired using rotationally invariant and uniformly distributed icosahedral encoding schemes. The error propagation of a recently described and validated cylindrical tensor model is further extrapolated to the spherical tensor case (diffusion anisotropy approximately 0) to relate analytically the precision error in fractional tensor anisotropy (FA) with the mean diffusion-to-noise ratio (DNR). The approach provided simple analytical and empirical quality control measures for optimization of diffusion parameter space in an isotropic medium that can be tested using widely available water phantoms.     

Interferometric measurement of displacements and displacement velocities for nondestructive quality control

It is shown that the interferometric measurement of small displacements and small-displacement velocities can be used to determine internal stresses or the stresses induced by an applied load in solids and to control structural changes in them. The interferometric method based on the measurement of the reaction of a solid to a small perturbation in its state of stress is applied to determine stresses from the deviation of the reaction to perturbations from that in the standard stress-free case. For structural control, this method is employed to study the specific features of the characteristics of microplastic deformation that appear after material treatment or operation and manifest themselves in the temperature and force dependences of the rate of a small inelastic strain.     

Preparation and control of atomic optimal entropy squeezing states for a moving two-level atom under control of the two-mode squeezing vacuum fields

From the viewpoint of quantum information,this paper studies preparation and control of atomic optimal entropy squeezing states(AOESS) for a moving two-level atom under control of the two-mode squeezing vacuum fields.Necessary conditions of preparation of the AOESS are analysed,and numerical verification of the AOESS is finished.It shows that the AOESS can be prepared by controlling the time of the atom interaction with the field,cutting the entanglement between the atom and field,and adjusting squeezing factor of the field.An atomic optimal entropy squeezing sudden generation in different components can alternately be realized by controlling the field-mode structure parameter.     

Hopping and drift mechanisms of photoconductivity in ZnO:Li films

The mechanisms of dark- and photoconductivity in ZnO:Li films are investigated. The obtained results are interpreted on the basis of hopping mechanism of charge carriers transport for the dark conductivity and the hopping or drift mechanism for the photoconductivity depending on the energy of an exciting photon. For photons with the energy more than the forbidden band gap the drift mechanism of carriers transport takes place, while for photons with the energy less than the forbidden band gap the hopping mechanism takes place.     

The detection mechanism of LiTaO3 type II pyroelectric detectors.: I. The primary and secondary pyroelectric effects

The contributions of the primary and secondary pyroelectric effects in LiTaO₃ type II pyroelectric detectors are discussed in terms of theories of thermoconductivity and electromagnetic field, and formulas for signal voltage and responsivity are given.     

New role for nonlinear dynamics and chaos in integrated semiconductor laser technology

Using an integrated colliding-pulse mode-locked semiconductor laser, we demonstrate the existence of nonlinear dynamics and chaos in photonic integrated circuits (PICs) by demonstrating a period-doubling transition into chaos. Unlike their stand-alone counterparts, the dynamics of PICs are more stable over the lifetime of the system, reproducible from batch to batch and on faster time scales due to the small sizes of PICs.     

Pump efficiency and beam quality control in an end-pumped Cr:LiSAF laser

The laser radiation production in an end-pumped laser requires taking into consideration the following: (a) the optical pumping system, (b) the thermal and spectroscopic characteristics of the gain medium, (c) the mode overlap, and (d) the interaction with the optical resonator. The correlation between the previous four factors is needed to guide the design and evaluation of such a laser system. This suggestion is a better methodology than focusing the discussion on only one factor of the system ignoring interactions. Here, we use these arguments to supervise the complete process with a one-watt pump-diode laser largely astigmatic and a Cr:LiSAF gain medium highlighting the importance between interactions.     

Thin CdTe detectors mounted in back-to-back configuration: spectroscopic performance for low-energy X- and gamma-rays

Thin CdTe detectors (3×5 mm² electrode area and 0.5 mm thick) mounted in a back-to-back configuration with a common anode, have been characterized. The goal was to determine the dimensions of the detector region offering good spectroscopic performance. The detector size was chosen on the basis of previous studies performed on various detectors which have shown that the width of this “best spectroscopy region” assumes a constant value of about 0.4 mm in the device thickness range 1.0–2.5 mm, while it is largely reduced when using a smaller electrode area (2×2 mm²) and 0.5 mm thick devices. The tests were performed by irradiating the detectors with a well collimated E_X=122 keV photon beam. The results show that the edge effects observed in smaller detectors with the same configurations are significantly reduced, giving a better energy resolution, but not a wider region with good spectroscopic performance; at lower energies the effects of larger electrodes (increased electric capacitance and leakage current) result in a higher noise and an increased detection threshold.