On the classical-trajectory eikonal approximation for electron capture into multicharged ions

The eikonal approach to electron capture developed in earlier publications is analyzed with respect to its physical content using the Born series as a reference expansion. In the language of perturbation theory, the eikonal approach describes a close collision between electron and projectile followed by multiple distant collisions between electron and target nucleus. The distant encounters have a large weight in phase space and therefore dominate capture at intermediate energies. The post-prior discrepancy is shown to be fairly small for nonresonant 1s-1s capture.     

Atomic capture ratios for muons in oxides

Using the lifetime technique, atomic capture ratios of negative muons have been measured in 41 oxides. The results, though a little different from the earlier TRIUMF findings, are consistent with the mesic X-ray measurements. It has been noticed that the atomic capture ratios have an approximately linear dependence on density, whereas the Z-dependence is periodic.     

A measurement of the muon capture rate in liquid deuterium by the lifetime technique

The lifetime technique has been used to measure the muon capture rate in ultra pure liquid deuterium in conditions where the μd spin state is known. The experimental method avoids the earlier difficulties due to the fusion neutrons. The following result has been obtained for the capture rate in the μd doublet total spin state: λ_c^D = 470 ± 29 s⁻¹.     

Mass number dependence of activation capture cross sections for 14 MeV neutrons

Radiative capture cross sections of 14.5 MeV neutrons have been measured for several nuclei with an essentially improved activation method. The results agree with those from the spectrum method, which confirms that “shell effects” exhibited by earlier activation data are due to experimental errors.     

Ortho-para transition rate in mu-molecular hydrogen and the proton's induced pseudoscalar coupling gp

We report a measurement of the ortho-para transition rate in the p mu p molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate Lambda op = (11.1 +/- 1.7 +/-(0.9)(0.6)) x 10(4) s(-1), which is substantially larger than the earlier result of Bardin et al. The result has striking implications for the proton's induced pseudoscalar coupling g(p), changing the value of g(p) obtained from the most precise ordinary muon capture measurement from 10.6 +/- 2.7 to 0.8 +/- 2.8, and from the sole radiative muon capture measurement from 12.2 +/- 1.1 to 10.6 +/- 1.2, bringing the latter result closer to theoretical predictions.     

Internal bremsstrahlung and double internal bremsstrahlung in initial p-state electron capture

Internal bremsstrahlung (IB) and double internal bremsstrahlung (DIB) have been studied for initial p-state electron capture. In the case of IB the relative contributions of discrete and continuum intermediate states have been calculated and, in contrast to IB in initial Is state capture, it has been found that the contributions from the discrete intermediate states are dominant. Calculations for DIB have been extended and some approximations used in earlier calculations are shown to be reasonable. Predictions are made for DIB in the EC decay of SU55 Fe and ¹³¹Cs, nuclei which may be suitable for experimental investigations.     

Weave States in Loop Quantum Gravity

Weaves are eigenstates of geometrical operators in nonperturbative quantum gravity, which approximate flat space (or other smooth geometries) at large scales. We describe two such states, which diagonalize the area as well as the volume operators. The existence of such states shows that some earlier worries about the difficulty of realizing kinematical states with non-vanishing volume can be overcome. We also show that the Q operator used in earlier work for extracting geometrical information from quantum states does not capture more information than the area and volume operators.     

Relativistic invariant approach to the parity violation in np→dγ capture

It is shown that the consistent relativistic invariant approach to the parity violation in np→dγ capture of thermal neutrons leads to results which differ essentially from those of the nonrelativistic approach. In particular the isospin selection rule established earlier for the photon circular polarization is charged due to the contribution of “relativistic” parity violating components of the deuteron and np-scattering wave function.     

Charge relaxation in conducting dielectric films with shallow and deep traps

A nonsteady-state boundary-value problem of the relaxation of a charge injected into a dielectric film is solved analytically with allowance for the film conductivity and capture of charge carriers by traps having a finite emptying rate. The one-and two-zone modes of charge relaxation are considered. The obtained general expressions reduce to earlier published formulas derived in particular cases. Numerical calculations and an analysis of the experimental data available in the literature on the electret state of oxide films deposited on metal substrates confirm the applicability of the proposed model of dielectric relaxation.     

Image denoising exploiting inter- and intra-scale dependency in complex wavelet domain

A new locally adaptive image denoising method, which exploits the intra-scale and inter-scale dependency in the dual-tree complex wavelet domain, is presented. Firstly, a recently emerged bivariate shrinkage rule is extended to a complex coefficient and its neighborhood, the corresponding nonlinear threshold functions are derived from the models using Bayesian estimation theory. Secondly, an adaptive weight, which is able to capture the inter-scale dependency of the complex wavelet coefficients, is combined to the obtained bishrink threshold. The experimental results demonstrate an improved denoising performance over related earlier techniques both in peak signal-to-noise ratio (PSNR) and visual effect.     

Correlation between biological activity and energies of electronic transitions in benzodiazepines. Negative ion mass spectrometry and ultraviolet absorption spectroscopy study of some derivatives

A correlation between the energies of electronic singlet transitions in benzodiazepines and their biological activity, which was revealed earlier by means of negative ion mass spectrometry with resonance electron capture, has been verified with a UV absorption spectroscopy investigation. Also, it has been noted that the energies of electronic singlet transitions in benzodiazepines are close in value to the ionization energies of atoms Cs, Rb, K, Na, Li and Tl, the cations of which are known to play an important role in nerve cell excitation processes. Copyright 1999 John Wiley & Sons, Ltd.     

半导体深能级瞬态谱中多子脉冲下的少子陷阱响应

在一个Si中掺Aup⁺n结的多子脉冲下深能级瞬态谱(DLTS)中,发现了一个少子峰信号。给出了这一现象的主要实验结果,并做了系统的物理分析。这是p⁺n结中高掺杂一侧的自由少数载流子尾在自建势所张开的空间电荷区中被少子陷阱俘获后,再发射的结果。 关键词：     

Absolute cross section of the3He(α,γ)7Be reaction

The absolute cross section σ(E) of the³He(α, γ)⁷Be reaction has been measured fromE _c.m. =195 to 686 keV. The studies employed both a supersonic jet gas target and an extended gas target, and were carried out by the observation of the prompt capture γ-ray transitions as well as the⁷Be residual nuclei. The absolute cross sections deduced from the capture γ-rays are in good agreement with most previous work and remove a discrepancy with other earlier work. In comparison, the σ(E) values obtained from the⁷Be residual nuclei are systematically higher, suggesting a small production of additional⁷Be by contaminant reactions.     

Effect of interface traps on Debye thickness semiconductor films

The presence of the boundary interface trapping states and their role in determining the properties of Debye thickness thin semiconductor films, are demonstrated experimentally, using PbTe films deposited on mica. These charged states could not be observed earlier and be studied directly, because of the screening by the relatively high carrier density of the ordinary PbTe. Thin, Debye length thickness, PbTe films with a high concentration of interface trapping centers, possess an extraordinary high resistance. In this case the thermostimulated capacitor discharge method can be successfully applied to determine the energy of these levels, their carrier capture cross-sections and their donor- or acceptor-like character. The experimental results and theoretical calculations are discussed.     

Zero-dimensional model for magnetic curvature driven Rayleigh Taylor turbulence simulations

A zero-dimensional nonlinear evolution model is derived from the full set of two-dimensional fluid evolution equations of the curvature driven Rayleigh Taylor instability. Such a model, arrived on heuristic grounds earlier, was found to capture the principal features of the final saturated state of the instability [A. Das, S. Mahajan, P. Kaw, A. Sen, S. Benkadda, A. Verga, Phys. Plasmas 4 (1997) 1018; A. Das, A. Sen, S. Mahajan, P. Kaw, Phys. Plasmas 8 (2001) 5104]. We present a detailed analysis of the linear and nonlinear characteristics of the model and also discuss some of its limitations.     

Influence of an electric field on photostimulated states in NH4BPh4 films

The influence of an electric field on stable photostimulated triplet states of NH₄BPh₄ at a temperature of 77 K have been studied by EPR spectroscopy. It has been established that, on exposure to UV radiation, electron capture by traps in the band gaps takes place with formation of triplet state. After application of an electric field, triplet states are destructed because, with an increase in the applied voltage, a gradual inclination of energy bands takes place and electrons found in traps on different energy levels are released. The assumption that captured electrons are found in traps on different energy levels is confirmed by earlier studies of thermoluminescence spectra.     

Spinbestimmung der angeregten Zustände verschiedener Kerne aus der Gammazirkularpolarisation nach dem Einfang polarisierter Neutronen

The circular polarisation of the gamma radiation following capture of polarized slow neutrons in natural titanium, chromium, nickel, zinc and selenium was investigated by means of a polarimeter using transmission of magnetized iron as polarization sensitive effect. A large Ge-diode was used for measurement of capture gamma spectra. By this way the spin of 55 levels in Ti⁴⁹, Cr⁵¹, Cr⁵³, Cr⁵⁴, Ni⁵⁹, Ni⁶¹, Ni⁶³, Zn⁶⁵, Zn⁶⁷, Zn⁶⁸, Se⁷⁷ and Se⁷⁸ were determined. In 37 cases existing spin determinations were confirmed, in 1 case our results contradicts earlier spin determinations and 17 new spin assignments were made.     

A structural model of market dynamics,and why it matters

In this paper, we explore an approach to understanding price fluctuations within a market via considerations of functional dependencies between asset prices. Interestingly, this approach suggests a class of models of a type used earlier to describe the dynamics of real and artificial neural networks. Statistical physics approaches turn out to be suitable for an analysis of their collective properties. In this paper, we first motivate the basic phenomenology and modelling arguments before moving on to discussing some major issues with inference and empirical verification. In particular, we focus on the natural creation of market states through the inclusion of interactions and how these then interfere with inference. This is primarily addressed in a synthetic setting. Finally we investigate real data to test the ability of our approach to capture some key features of the behaviour of financial markets.     

Formation of higher-order fullerene dianions in collisions with Na atoms

We have measured electron capture cross sections in collisions between higher order fullerene anions C_n ^- (n=76, 78, 82, 84, 86, 90 and 96) and Na atoms. The ions were produced in an electrospray ion source (ESI) and accelerated to an energy of 50 keV. The measured cross section for dianion formation is three times larger for C₉₆ than that for C₆₀. The latter cross section was earlier found to be 36 ?². The dramatic increase of the cross section with fullerene size is explained by means of the curve crossing model for electron transfer.     

Dielectronic recombination rates for the Be sequence

The dielectronic recombination (DR) rate coefficients have been recalculated for the C, Ar, and Fe target ions of the Be-sequence with an improved estimate of the high Rydberg state contribution. The Δn = 0 excitation-capture mode is reexamined in an improved LS coupling scheme and the effect of configuration interaction in the target and in the final (stably, bound) states is considered. The contribution of the 1s (Δn_t ≠ 0) excitation mode is also estimated and found to be on the order of 5% of the total DR capture rate at high electron temperatures. This updates and supersedes our earlier results for this isoelectronic sequence.