Search

We study charged lepton flavor violation associated with a light leptophilic axion-like particle (ALP), $X$, at the $B$-factory experiment Belle II. We focus on production of the ALP in the tau decays $\tau \to X l$ with $l=e,\mu$, followed by its decay via $X\to l^- l^+$. The ALP can be either promptly decaying or long-lived. We perform Monte-Carlo simulations, recasting a prompt search at Belle for lepton-flavor-violating $\tau$ decays, and propose a displaced-vertex (DV) search. For both types of searches, we derive the Belle~II sensitivity reaches in both the product of branching fractions and the ALP coupling constants, as functions of the ALP mass and lifetime. The results show that the DV search exceeds the sensitivity reach of the prompt search to the relevant branching fractions by up to about a factor of 40 in the long decay length regime., Comment: v1, 27 pages, 9 figures, 3 tables; v2, minor changes, mainly updated beam-dump and lepton-flavor-universality constraints, accepted for publication in JHEP

Self-consistent theory for concentrated electrolytes is developed. Oscillatory decay of the charge–charge correlation function with the decay length that shows perfect agreement with the experimentally discovered and so far unexplained scaling is obtained. For the density–density correlations, monotonic asymptotic decay with the decay length comparable with the decay length of the charge correlations is found. We show that the correlation lengths in concentrated electrolytes depend crucially on the local variance of the charge density.

Josephson junctions containing ferromagnetic materials are generating interest for use in superconducting electronics and cryogenic memory. Optimizing the performance of such junctions is an ongoing effort, requiring exploration of a broad range of magnetic systems. Here we study supercurrent transmission through Ni/Ru/Ni synthetic antiferromagnets, with the idea that their magnetic properties may be superior to those of isolated Ni layers. We find that the decay of the supercurrent as a function of Ni thickness is very slow, with a decay length of 7.5 $\pm$ 0.8 nm. We also characterize the magnetic properties of the synthetic antiferromagnets as a function of Ni and Ru thicknesses.

In this Chapter, the data samples used in this thesis are introduced and the general strategy adopted to measure \(\mathrm { D^+}\) and \(\mathrm { D_s^+}\) mesons and their antiparticles in the central rapidity region of the ALICE detector is presented. The \(\mathrm { D^+}\) (\(\mathrm { D_s^+}\)) mesons, composed by a charm quark and a down (strange) antiquark, cannot be directly revealed because of their mean proper decay length of few hundred microns that prevents them to reach the detector. Hence, they are measured via the exclusive reconstruction of their hadronic decays. In particular, the decay channels \(\mathrm { D^{+}\rightarrow K^-\pi ^+\pi ^+}\) and \(\mathrm { D_s^{+}\rightarrow \phi \pi ^+\rightarrow K^-K^+\pi ^+}\) and their charge conjugates are considered in this thesis. The spatial resolution of the ALICE detector [1, 2] allows the separation of the secondary decay vertices of D mesons from the primary interaction vertex, therefore the analysis is based on the reconstruction and selection of secondary-vertex topologies with relatively large separation from the primary interaction vertex. The PID capabilities are also exploited to improve the selection of the \(\mathrm { D_s^+}\) and \(\mathrm { D^+}\) decay products and thus to reduce the background.

Funder: China Scholarship Council (CSC); doi: https://doi.org/10.13039/501100004543, Funder: Fundacja na rzecz Nauki Polskiej (Foundation for Polish Science); doi: https://doi.org/10.13039/501100001870, Graphene on hexagonal boron nitride (hBN) can exhibit a topological phase via mutual crystallographic alignment. Recent measurements of nonlocal resistance (Rnl) near the secondary Dirac point (SDP) in ballistic graphene/hBN superlattices have been interpreted as arising due to the quantum valley Hall state. We report hBN/graphene/hBN superlattices in which Rnl at SDP is negligible, but below 60 K approaches the value of h/2e2 in zero magnetic field at the primary Dirac point with a characteristic decay length of 2 μm. Furthermore, nonlocal transport transmission probabilities based on the Landauer-Büttiker formalism show evidence for spin-degenerate ballistic valley-helical edge modes, which are key for the development of valleytronics.

We assess the current coverage and the future discovery potential of LHC searches for heavy Higgs bosons decaying into long-lived particles (LLPs), focusing primarily on the production of pairs of LLPs with hadronic final states. These signatures are generic in dark sectors where a heavy scalar decays into pairs of lighter states which subsequently mix with the Standard Model Higgs. We show that a handful of existing analyses provide broad coverage of LLP decay lengths ranging from millimeters to tens of meters, and explore the complementarity between searches for displaced and prompt final states in several simplified models. For both heavy singlet and heavy doublet scalars, LLP searches typically provide the leading sensitivity in current data and exhibit the strongest discovery potential in future LHC runs. We further translate the impact of these searches into the parameter space of various Twin Higgs models, demonstrating that LLP searches are a promising avenue for discovering a Twin Higgs with displaced decays. Finally, we propose a variety of additional search channels that would improve coverage of the second Higgs at the lifetime frontier., Comment: 37 pages, 12 figures. Matches version published in JHEP

Boundary-driven oscillations were numerically predicted to exist in a reaction-diffusion-advection system, namely in the signaling population of social amoeba D. discoideum. If deprived of nutrients, D. discoideum aggregates by producing cAMP waves at precisely timed intervals. In the presence of an advecting flow, holding the upstream boundary to a zero concentration of cAMP produces an instability that sends periodic wave trains downstream. This instability is expected to exist at lower degradation rates of cAMP and thus provides a mechanism for wave creation in phosphodiesterase deficient systems, such as PdsA- cells. Degradation of extracellular cAMP by the enzyme phosphodiesterase PdsA is fundamental to successfully producing waves, regulating the external cAMP gradient field and preventing the accumulation of cAMP. Using a flow-through microfluidic setup filled with PdsA- cells, we confirm experimentally that boundary-driven oscillations indeed exist. Above a minimum flow velocity, decaying waves are induced, with a decay length that increases with the imposed flow velocity. We performed extensive numerical simulations and showed that these waves have a boundary-driven origin, where the lack of cAMP in the upstream flow destabilizes the system. We explored the properties of these waves and the parameter region where they exist, finding good agreement with our experimental observations. These results provide experimental confirmation of the destabilizing effect of the upstream boundary in an otherwise stable reaction-diffusion system. We expect this mechanism to be relevant for wave creation in other oscillatory or excitable systems that are incapable of wave generation in the absence of flow.

We have developed a low-temperature surface forces apparatus (SFA) using a thermoelectric Peltier module inserted below the bottom surface of the lower sample holder, giving easy access to the samples and allowing quick temperature changes. In air, the temperature can be decreased to ca. -20 °C. To demonstrate the performance of the apparatus, we measured the interactions between ice and a silica surface at -11.5 ± 0.5 °C. An exponentially decaying repulsion of the decay length, 11.2 ± 1.0 nm, was observed, and attributed to the electric double layer (EDL) repulsion. The surface potential of the ice was calculated to be -35 mV by fitting the data to the EDL model.

The feasibility of the carrier decay length extraction from scanning photocurrent profiles in ultra-thin silicon nanowire ohmic-contact devices is theoretically studied. Accurate carrier decay length can be extracted with a typical diffraction-limited excitation spot size of 500 nm for silicon nanowires with diameter down to 20 nm.

Researchers aim to corroborate experimental evidence of long-range decay with theory and simulations of primitive model electrolytes.

We present a surface potential based analytical model for double gate tunnel field effect transistor (DGTFET) for the current, terminal charges, and terminal capacitances. The model accounts for the effect of the mobile charge in the channel and captures the device physics in depletion as well as in the strong inversion regime. The narrowing of the tunnel barrier in the presence of mobile charges in the channel is incorporated via modeling of the inverse decay length, which is constant under channel depletion condition and bias dependent under inversion condition. To capture the ambipolar current behavior in the model, tunneling at the drain junction is also included. The proposed model is validated against TCAD simulation data and it shows close match with the simulation data.

Interlayer exchange coupling (IEC) between GaMnAs layers in GaMnAs/InGaAs/GaMnAs tri-layers was studied by magnetization measurements. Minor hysteresis loops are observed to shift in a direction indicating the presence of ferromagnetic (FM) IEC in the structures. The strength of the FM IEC clearly exhibits an exponential decrease with respect to nonmagnetic InGaAs spacer thickness. The fitting of the spacer thickness dependence of the FM IEC to an exponential decay function provides a decay length of 3.3±0.3 nm, which is relatively large compared to metallic multilayers, indicating a long ranged IEC in systems based on GaMnAs.

Spatiotemporal dynamics of short- and long-time structural relaxation are measured experimentally as a function of packing fraction, ϕ, in quasi-two-dimensional colloidal supercooled liquids and glasses. The relaxation times associated with long-time dynamic heterogeneity and short-time intracage motion are found to be strongly correlated and to grow by orders of magnitude with increasing ϕ toward dynamic arrest. We find that clusters of fast particles on the two timescales often overlap, and, interestingly, the distribution of minimum-spatial-separation between closest nonoverlapping clusters across the two timescales is revealed to be exponential with a decay length that increases with ϕ. In total, the experimental observations suggest short-time relaxation events are very often precursors to heterogeneous relaxation at longer timescales in glassy materials.

Researchers propose a simple physical mechanism that suggests strongly correlated structures lead to shifts in screening length.

This study proposes a method for evaluating the axial decay length of the plasma pressure in detached helium plasmas with a fixed-point laser Thomson scattering and spectroscopic measurements in the linear divertor plasma simulator NAGDIS-II. By controlling the neutral gas pressure, the highly volume-recombining region called the “recombination front” was moved along the magnetic field. The differential terms for the electron pressure and the recombination-front position with respect to the neutral pressure were obtained. By using these two terms, the decay length of the plasma pressure was qualitatively calculated. In addition, from the movable Langmuir probe measurement, difference between the locally estimated decay length around the recombination front and the decay lengths over a wide axial range was discussed. The proposed method can be applied even in the huge heat flux condition where direct-contact measurements such as the Langmuir probe are not available.

The defect detection sensitivity of magnetic nanoemulsions (MNEs) stabilized with different functional moieties such as anionic surfactant, co-polymer and a weak polyelectrolyte is reported here. The visually discernible colour contrast over the defective regions and the corresponding Bragg’s reflection, originating from the linear chain-like structures formed by the leakage magnetic flux are experimentally measured and compared with the theoretically obtained profiles. The linear chain-like structures, formed by the MNEs, are also visualized using atomic force and optical phase contrast microscopy studies. Defect detection studies are carried out on carbon steel samples with artificially made defects (rectangular slots) and the variations in defect detection sensitivity (colour contrast) are assessed under different stabilizing moieties. It is found that the electrostatically stabilized MNEs exhibited superior defect detection sensitivity, as compared to the polymeric stabilizers. The microscopic origin for sensitivity variations, is studied by measuring the inter-droplet forces and hydrodynamic diameter. The inter-droplet force measurements show that the lower decay length is better for improving the defect detection sensitivity. Through image processing and intensity profiling, the defect widths are accurately estimated, which are in good agreements with the actual defect dimensions. The intensity profiles are found to vary linearly with the defect depth for the shallower defects. These results are useful to tailor MNEs with superior defect detection sensitivity and long-term stability towards development of MNE-based thin film sensors for automated and superior defect detection strategies.

Thirty years ago there was considerable excitement over the first report of a long-ranged “hydrophobic force” between solids that were not wet by water (Israelachvili and Pashley, Nature 1982, 300 , 341–342). Many of the subsequent measurements have been reexamined and found not to support the existence of a long-range hydrophobic force. The principal difficulty was that hydrophobic solids frequently experience other forces, which obscured or were mistaken for a hydrophobic force. In this paper, we review the surviving evidence for a long-range hydrophobic force and find that there is only supporting evidence in a total of two papers, one old and one new, where net attractive forces were measured at separations greater than about 5–6 nm. Thus the evidence is scarce. In contrast there are new experiments showing no such force, thereby arguing against the universality of a measureable hydrophobic force beyond about 6 nm. Since solvent water is common to the experiments, such evidence makes it difficult to describe a universal mechanism for a long-ranged hydrophobic force based on water structure. There are also new measurements that are consistent with a hydrophobic force with a decay length in the range 0.3–1.0 nm. In particular, attractive forces have been measured on small radius surfaces (8–50 nm) consistent with a hydrophobic force with a decay length of 0.5–0.6 nm, and a variety of net repulsive measurements are consistent with an attractive hydrophobic force that has a decay length of 0.3–1.0 nm. We also discuss some new measurements, which are consistent with cavitation, and not a surface force that acts at a distance.

Groundwater level in coastal aquifers is usually affected by tidal waves and rainfall recharge. Therefore, the objective of this study is to present a mathematical model to account for the effects of tidal waves and rainfall recharge simultaneously. The model is based on the Dupuit&ndash, Forchheimer assumptions and is separated into a tidal waves component and rainfall recharge component. A new more general analytical solution for the recharge component is acquired by the generalized integral transform technique. The beach slope, the inclination of an impermeable base of an aquifer, and any randomly distributed rainfall recharge are taken into account in the model. A new finding is that the highest fluctuation in groundwater levels might occur when the range of rainfall recharge is larger than the decay length.

In this report, we describe improvement of image resolution in surface plasmon resonance microscopy (SPRM) which suffers from poor quality due to severe surface plasmon (SP) propagation. Our approach takes two-channel momentum sampling by switched light incidence followed by minimum filtering to implement spatially switched SPRM (ssSPRM). The performance evaluated with periodic wires in comparison with conventional SPRM and bright-field microscopy shows that the effect of SP propagation can be circumvented and the effective decay length of SPRM is calculated to increase by only 7% compared to that of bright-field images.

The narrow scrape-off layer power component observed in COMPASS inner wall limiter circular discharges by means of IR thermography is investigated by Langmuir probes embedded in the limiter. The power flux profiles are in good agreement with IR observations and can be described by a double-exponential decay with a short decay length (

Dispersion stability, ligand structure and conformation, and SERS activities of 1-alkanethiol (CnH2n+1SH, n = 2–14) functionalized gold and silver nanoparticles (AuNPs and AgNPs) were studied as a function of alkanethiol carbon chain length and nanoparticle (NP) type and size. The dispersion stability of alkanethiol functionalized NPs in water increases with increasing alkanethiol chain length and NP size, and the stabilities of the alkanethiol-containing AuNPs are higher than their AgNP counterparts. C3H7SH and longer alkanethiols are highly ordered on AgNPs but disordered on AuNPs. The SERS intensity of the C–S stretch band for the model alkanethiols on AgNPs and AuNPs decays exponentially (I = I0 exp(−Nc/N0)) with increasing number of carbon atoms (Nc). The empirical decay length N0, in terms of the number of the carbon atoms, is 1.29, 0.53, and 0.10 for AgNPs with diameters of 50, 30, and 10 nm, respectively. This decay length is less than 1 for AuNPs of difference sizes. These results show that chang...

Quartz resonators have become a promising tool in bioanalytical sensing during the past decades. They allow for detecting oscillation changes (motional impedance and resonance frequency) arising from changes of the mechanical properties at the sensor interface, or more precisely within the decay length of the acoustic wave (∼250 nm in water).

In theory of shell, decay length is defined as the distance affected by localized external (applied loads) or internal (edge effect, discontinuity) forces and moments, beyond which the effect of these loads becomes negligible. The concept of decay length becomes relevant when assessing the interaction effects caused by adjacent discontinuities. In this paper, the decay lengths for several shells geometries, specifically cylindrical, spherical and conical shells, are reviewed. The available expressions for decay lengths in the literature are listed and are compared with finite element analysis to demonstrate the accuracy of some of the solutions.

We theoretically study a tunneling effect in a two-dimensional Dirac semimetal with two Dirac points protected by non-symmorphic symmetries. The tunnel barrier can be arranged by a magnetic exchange potential which opens a gap at the Dirac points which can be induced by a magnetic proximity effect of a ferromagnetic insulator. We found that the tunnel decay length increases with a decrease in the strength of the spin-orbit coupling, and moreover the dependence is attributed to the correlation of sublattice and spin degree of freedoms which lead to symmetry-protected Dirac points. The tunnel probability is quite different in two Dirac points, and thus the tunnel effect can be applied to the highly-selective valley filter., Comment: 5 pages

In this paper, the effective interaction between charged colloids has been studied based on the standard Mayer function perturbation theory. With the formalism developed in this paper, the effective interaction as a function of Mayer functions and the correlation functions of the homogeneous microions is obtained. The asymptotic behaviour of the effective interaction at large distance is analysed in detail. It is found that at large distance the effective interaction is Yukawa like, provided the bare charge is replaced by the renormalised one. Exact expressions for the renormalised charge and the decay length as functions of the short-range part of the Mayer function and that of the correlation function of the homogeneous microions are obtained. With perturbation methods, it is easy to see how the effective interaction at large distance is affected by microion correlations and nonlinearity.

We studied electronic properties of atomic-scale dangling bond (DB) and DB wires on Si(100)-2 × 1:H surfaces using a ultrahigh vacuum scanning tunneling microscope (UHV-STM). The decay of the near-midgap DB-states induced by an unpaired DB depends on the crystalline orientation of the Si(100) surface. The decay length of the DB-states of an unpaired DB wire can be ~ 2.5 nm along the dimer row direction. The perturbation from an unpaired DB to an adjacent paired DB is also demonstrated. The results are in good agreement with density functional calculations.

A core-shell nanosensor was fabricated by molecular self-assemble and evaporation technique in this paper. The optical property of that was measured based on the detection system of LSPR. The sensitivity of this core-shell nanosensor is 300nm/RIU and the decay length is 26nm based LSPR detection system. The results show that this nansensor can reach high sensitivity and be applied for the small molecule or low concentration detection.

It is known that the use of Bi surfactant (unlike Sb) upon the growth of Ge layers on Si(111) increases the contrast between Ge and Si atoms in a scanning tunneling microscope. This makes it possible to distinguish the Ge and Si surfaces. This effect is studied using computer simulation based on the density functional theory. To explain the observed difference between the Ge and Si layers, both structural and electronic effects are considered. The local density of electronic states, as well as the corresponding decay length to vacuum, has been calculated for each of the surfaces. The simulation results have been compared to the previous scanning tunneling microscopy data.

We study a simplified model of the SM Higgs boson decaying to a degenerate pair of scalars which travel a macroscopic distance before decaying to SM particles. This is the leading signal for many well-motivated solutions to the hierarchy problem that do not propose additional light colored particles. Bounds for displaced Higgs decays below $10$ cm are found by recasting existing tracker searches from Run I. New tracker search strategies, sensitive to the characteristics of these models and similar decays, are proposed with sensitivities projected for Run II at $\sqrt{s} = 13 $ TeV. With 20 fb$^{-1}$ of data, we find that Higgs branching ratios down to $7 \times 10^{-4}$ can be probed for centimeter decay lengths.

cited By 26; International audience; We perform a theoretical investigation of individual and coupled gold nanorods as plasmonic nanosensors using the finite-difference time-domain method. Key features of single-nanorod sensors are discussed. The sensitivity distribution of an individual nanorod is anisotropic. The characteristic sensitivity decay length of a single-nanorod sensor is comparable to its diameter. Plasmonic sensing abilities are additive, so analyte-detection sensitivity is not affected by substrates or surface treatments; shifts caused by analytes are only determined by their positions relative to the sensor. Coupled nanorods enhance and concentrate plasmonic sensitivities, and the sensitivity within the gap can be over an order of magnitude higher than that at the nanorod cylinder. The sensitivities of coupled nanorods are only higher than those of individual nanorods when the analytes are anchored within the gaps between nanorods. The calculations show that a single biological molecule can be detected by optimizing nanostructure design and surface treatments to anchor analytes locally on high-sensitivity areas of the sensor surface. Our simulation results assist the design and optimization of plasmonic nanosensors, using single or coupled nanorods. © 2011 American Chemical Society.

We have utilized the discrete dipole approximation to study the localized surface plasmon resonance in infinite, periodic two-dimensional arrays of gold nanospheres with the nanospheres arranged according to the {100} face of an fcc crystal. Specifically, we have performed a systematic study of the sensitivity of both the plasmon resonance wavelength shift and extinction properties considering nanosphere diameters ranging from 20 to 100 nm, and for nanosphere gap distances ranging from 0.5 to 6 times the nanosphere diameter. In doing so, we find that the same universal decay length of the plasmon resonance wavelength shift of about 0.2 units of the nanosphere size that was previously found by Jain et al.(1) for nanoparticle dimers is also operant for two-dimensional arrays. However, we also find that the universality of the plasmon ruler is only valid for arrays with nanospheres smaller than a critical nanosphere diameter of about 70 nm, whereas for larger nanosphere diameters, a decrease in the extinctio...

The distribution of the lengths of force chains in 2D granular assemblies of photoelastic disks was found to decay exponentially, with the decay length a quantitative measure of the way force is applied to the system. A plausibility argument is provided for why this statistic displays an exponential decay.

A Bragg waveguide is analyzed from the viewpoint of obtaining slow light. It is shown that, for this system, a complete mathematical analysis of the pulse propagation with allowance for leakage is possible. Calculations are presented that show that, in a TiO2/SiO2-based Bragg waveguide, one can obtain a group index of ∼1000 with a spatial decay length of ∼3 mm for a nanosecond-scale pulse. Distortion of the pulse due to the group index dispersion proves to be acceptable, in this case, for the pulse propagation length of about 3 mm, which corresponds to the fractional pulse delay ∼10. We also analyze the propagation of the light pulse in the Bragg waveguide with a quantum well inside and show possibility of obtaining a group index of ∼10000.

The results of the study of features of the Ge film transition from two- to three-dimensional growth in different SiGe/Si(001) heterostructures with buried stressed layers are presented. It is shown that deposition of a stressed planar SiGe layer results in a significant decrease in the critical thickness of two-dimensional Ge growth. It was detected that the effect of SiGe layers on Ge film growth is very significant not only in the case of growth directly on the strained SiGe layer, but also if this layer is capped by an unstrained Si layer to thicknesses of ∼3.5 nm. It is shown that the model in which the effect of buried strained SiGe layers is taken into account by introducing the phenomenological parameter “decay length of the effective elastic energy” allows description of experimental result data with good accuracy.

In various models of supersymmetry (SUSY), the lightest superparticle in the minimal SUSY standard model sector, which we call MSSM-LSP, becomes unstable. Then, we may observe the decay of the MSSM-LSP in the detector at the LHC experiment. We show that the discovery of such a decay process (and the determination of the lifetime of the MSSM-LSP) may be possible at the LHC even if the decay length of the MSSM-LSP is much longer than the size of the detector; sizable number of the MSSM-LSPs decay inside the detector if the lifetime is shorter than 0.01-1 millisec. We also discuss the implications of the study of the MSSM-LSP decay for several well-motivated SUSY models., Comment: 13 pages, 4 figures

Temporal characteristics of density bursts in the scrape-off layer of the CASTOR tokamak were investigated. Intermittent positive bursts of density are observed by means of a radial array of Langmuir probes. Globally (comparing the closest and furthermost radial positions with respect to the center of the discharge chamber) we observe a radial decrease of average burst rate together with a radial increase of the average burst duration. Recently, we observed a monotonic radial decrease of average burst rate together with an increase of the average burst duration in the Tore Supra tokamak [1, 2], but the decay length is significantly shorter than in CASTOR. This is most probably due to radially elongated turbulent events (streamers), which govern the radial transport at the edge of the CASTOR tokamak [3] and are responsible for the appearance of density bursts.

In supersymmetric (SUSY) models with the gravitino being the lightest SUSY particle (LSP), the SUSY breaking scale (i.e., the gravitino mass) could be determined by measuring the lifetime of the next-to-lightest SUSY particle (NLSP). However, for an ultralight gravitino of mass of O(1) eV, which is favored cosmologically, the determination of the SUSY breaking scale, or the gravitino mass, is difficult because the NLSP decay length is too short to be measured directly. Recently we proposed a new determination of the gravitino mass by measuring a branching fraction of two decay modes of sleptons. In this paper, we investigate the prospects for determining the gravitino mass at LHC. For demonstration we take some explicit gauge-mediation models and show that the gravitino mass can be determined with an accuracy of a few 10% for an integrated luminosity 10-100 fb^{-1}., Comment: 16 pages, 10 figures

Taken impurity radiation and momentum loss in the divertor region into consideration, the applicability of Core-SOL-Divertor(CSD) model to the divertor detachment is investigated. Three solutions for the low recycling state, the high recycling state and the detached state can be obtained from the CSD model. The dependence of the ratio of the decay length for the density (Δn) and temperature (ΔT) in the SOL region is also examined, and it is found that Δn/ΔT ∼ T0.5s scaled by the SOL temperature (Ts), which is based on the experimental data, has a good potential to reproduce B2-EIRENE results. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Edge effects in a rock mass near a system of periodic mine workings crossed by a crack (fold fault) are considered. The stress state near the mine workings is determined by solving an elastic problem using the piecewise-homogeneous medium model. The original differential problem is reduced to a discrete problem based on the concept of a base scheme. Methods are proposed to solve the discrete problem, and the issue of optimizing the numerical analysis is discussed. The stress distribution around mine workings is analyzed. The stress isolines that represent the boundaries of edge effect zones and indicate their maximum decay length are plotted

Corrosion is typical of the damage that occurs in ageing pressure vessels and pipelines used in industrial processes as a result of reactive products inside or harsh environmental conditions on the outside. Structural integrity of such components needs to be evaluated periodically to establish the continued suitability of the vessels under operating conditions. The present paper develops a method for Level 2 (as categorized by API 579) fitness-for-service (FFS) evaluation of spherical pressure vessels with localized corrosion. The decay lengths for spherical shells subject to different sizes of corroded areas are calculated based on elastic effects in shells so as to identify the reference volume participating in plastic action. Lower bound “remaining strength factors” of spherical pressure vessels containing corrosion damage are formulated by the application of Mura's variational formulation and the m α -multiplier method. Three alternative design recommendations are given. The effectiveness of the proposed methods is evaluated and demonstrated through illustrative examples and comparison with Level 3 inelastic finite element analyses.

Spherical shapes are used in industry as hemispherical vessel heads or high-pressure storage vessels due to the inherent strength associated with the shape. Structural integrity of such components needs to be evaluated periodically to prevent failure of the vessels under operating conditions. The paper develops a method for Level 2 (as defined by API 579 [(2000). Fitness-for-service, API 579. Washington, DC: American Petroleum Institute]) fitness-for-service estimation of spherical shapes subject to local hot spots where the temperatures are elevated due to local damage. The decay length for spherical shells is determined, and the size of hot spot to be identified as local is proposed. A lower bound “remaining strength factor” (RSF) for spherical pressure vessels containing hot spots is formulated by the application of Mura's variational formulation and the m α -multiplier method. The effectiveness of the proposed Level 2 method is evaluated and demonstrated through an example.

The composition profile at a solid surface in the one-phase region of a binary liquid mixture in the complete wetting regime has been studied with neutron reflectometry. A hexane-rich film adsorbs to an octadecyl-coated silicon surface from a n-hexane-d 14 /perfluoro-n-hexane mixture. Above the critical temperature, T c , of 14.4 °C, there is a comparatively thin (5-20 nm) film with an excess n-hexane content that decays exponentially toward the bulk, with the n-hexane content and decay length increasing as the temperature approaches T c . Below T c , as the coexistence temperature To of 8.9 °C is approached, a very long-range effect on the density profile becomes apparent and the n-hexane content of the film remains greater than that of bulk out to distances z > 100 nm. Although the data are consistent with a z -3 decay of the composition profile, as expected for van der Waals forces, we cannot unambiguously assign a decay to the long-range 80-120 nm region of the film. However, as for van der Waals forces, the n-hexane surface excess, r, increases as (T - T 0 ) -1/3 near coexistence, but more steeply closer to T c .

In R-parity conserving supersymmetric (SUSY) models the lightest SUSY particle (LSP) is stable and a candidate for dark matter. Depending on the coupling and mass of this particle the life time of the next-to-lightest SUSY particle (NLSP) may be large compared to experimental time scales. In particular, if the NLSP is a charged particle and its decay length is of the order of the Earth's diameter Cherenkov telescopes might observe parallel muon-like tracks of NLSP pairs produced in neutrino-nucleon interactions in the Earth's interior. We have investigated two SUSY scenarios with a long-lived stau NLSP and a gravitino LSP in view of the observability at the IceCube detector., 4 pages, 4 figures, talk given at TeV Particle Astrophysics II (Madison WI), to be published in J. Phys. Conf. Ser

AES sputter depth profiles of multilayers with constituents of very different backscattering factors show characteristic distortions in the shape of the intensity–depth profiles. These distortions are quantified by introducing an extension of the local effective backscattering factor concept developed in an earlier paper in the mixing-roughness-information depth (MRI) model for profile quantification. The extension is based on a linear superposition of two newly defined parameters, the effective backscattering factors for each interface that are diminished with distance from the respective interface by another characteristic parameter, the mean effective backscattering decay length. As shown for a Ni/C multilayer structure of six alternating layers of Ni (38 nm) and C (25 nm) on a Si substrate, AES intensity depth profiles calculated with the presented modification of the MRI model, yield an excellent agreement with the measured profile after some adjustment of the initial mean effective backscattering decay lengths and, sometimes, after a slight change of the backscattering factors given by the Ichimura–Shimizu relations. The backscattering effect is studied as a function of the single layer thickness. A critical layer thickness can be determined, below which the backscattering influence becomes negligible for typical AES depth profiling results. Copyright © 2007 John Wiley & Sons, Ltd.

We performed a thorough micromagnetic investigation of spin waves propagation in extended ferromagnetic films and in arrays of either single- or bi-component ferromagnetic stripes, encompassing both the dipolar-dominated and the exchange-dominated regions. The considered nanostructures represent one-dimensional magnonic crystals where allowed and forbidden frequency intervals appear due to the artificial periodicity. It is shown that both the bandwidth and the decay length of propagating spin modes depend on the geometrical characteristics of the artificial structures. The results of the present “virtual experiments” can be exploited to design miniaturized and tunable magnonic filters for microwave applications.

We report a systematic study of spin transport in antiferromagnetic (AF) insulators having a wide range of ordering temperatures. Spin current is dynamically injected from Y3Fe5O12 (YIG) into various AF insulators in Pt/insulator/YIG trilayers. Robust, long-distance spin transport in the AF insulators is observed, which shows strong correlation with the AF ordering temperatures. We find a striking linear relationship between the spin decay length in the AFs and the damping enhancement in YIG, suggesting the critical role of magnetic correlations in the AF insulators as well as at the AF/YIG interfaces for spin transport in magnetic insulators., 16 pages, 4 figures

The possible role of growing static order in the dynamical slowing down toward the glass transition has recently attracted considerable attention. On the basis of random first-order transition theory, a new method to measure the static correlation length of amorphous order, called "point-to-set" (PTS) length, has been proposed and used to show that the dynamic length grows much faster than the static length. Here, we study the nature of the PTS length, using a polydisperse hard-disk system, which is a model that is known to exhibit a growing hexatic order upon densification. We show that the PTS correlation length is decoupled from the steeper increase of the correlation length of hexatic order and dynamic heterogeneity, while closely mirroring the decay length of two-body density correlations. Our results thus provide a clear example that other forms of order can play an important role in the slowing down of the dynamics, casting a serious doubt on the order-agnostic nature of the PTS length and its relevance to slow dynamics, provided that a polydisperse hard-disk system is a typical glass former.