Ratio Of Energy Loss Research Articles

Effects of swift heavy ion irradiation on the electrical characteristics of Au/n-GaAs Schottky diodes

Metal-semiconductor diode of Au/n-GaAs is studied under the irradiation of swift heavy ion (SHI) beam (80 MeV 16O 6+), using in situ current–voltage characterization technique. The diode parameters like ideality factor, barrier height, and leakage current are observed to vary with irradiation fluence. Significantly, the diode performance improves at a high fluence of 2 × 10 13 ions cm −2 with a large decrease of reverse leakage current in comparison to the original as deposited sample. The Schottky barrier height (SBH) also increases with fluence. At a high irradiation fluence of 5 × 10 13 ions cm −2 the SBH (0.62 ± 0.01 eV) is much larger than that of the as deposited sample (0.55 ± 0.01 eV). The diode parameters remain stable over a large range of irradiation up to fluence of 8 × 10 13 ions cm −2. A prominent annealing effect of the swift ion beam owing to moderate electronic excitation and high ratio of electronic energy loss to the nuclear loss is found to be responsible for the improvement in diode characteristics.

Energy dissipation during normal impact of elastic and elastic–plastic spheres

In this paper, the energy dissipation during the normal impact of an elastic spherical particle with a substrate, which is assumed to be elastic or elastic–plastic, is investigated using the finite element method (FEM). For the elastic impact, the effect of the size of the substrate (which is assumed to be homogeneous) on the impact behaviour is investigated. By changing the substrate size, the number of reflections of stress wave propagation within the contact duration altered. It is found that the energy dissipation due to stress wave propagation is negligible (<1% of the total kinetic energy) if there is more than one reflection during the contact. If there is no reflection at all within the contact duration, a significant amount of kinetic energy is dissipated due to stress wave propagation. The energy loss ratio λ (the ratio of kinetic energy dissipated to the initial total kinetic energy) is proportional to the impact velocity V i with a power law of 3/5, which is consistent with the analysis of Hunter [Hunter SC. J Mech Phys Solids 1957;8:162–71]. For the plastic impact, the energy loss due to stress wave propagation becomes negligible and kinetic energy is mainly dissipated due to plastic deformation. Two distinct regimes of plastic impacts are distinguished by a critical impact velocity, V i * [Wu CY, Li LY, Thornton C. Int J Impact Eng 2003;28:929–46]: elastoplastic impact and finite-plastic-deformation impact. The kinetic energy dissipation behaviour for these two regimes is discussed. It is shown that a sharper decrease of the coefficient of restitution with an increasing normalised impact velocity V i / V y ( V y is the yield velocity) is observed for finite-plastic-deformation impacts than for elastoplastic impacts.

Estimating the energy of an ice-covered flow

Energy balance of an ice-covered flow in a constant-slope reach of a regulated river is considered. The ratio of energy losses for viscous friction to the total flow energy is evaluated. The turbulence intensities of an open and ice-covered flows are compared.

Flow regimes and energy loss on chutes with upward inclined steps

This paper presents new experimental data on water flow on stepped chutes with upward inclined steps. The slopes of the chutes are 30°, 45°, and 60° whereas the upward angles of the inclined steps are 10°, 20°, and 30°, respectively. Classifications of flow patterns by empirical correlations are presented. Based on dimensional analysis, the important parameters are analyzed, and the relevant dimensionless parameters are established. The energy loss and outlet velocity are strongly influenced by the Drop number and the slope of the stepped chutes. As the Drop number increases, the energy loss ratio decreases. At identical Drop numbers the energy loss ratio on the more moderate slope is greater than on the steeper. The adverse slope of the inclined steps increases the energy loss ratio and decreases the outlet velocity by less than 10%. To estimate the kinetic energy ratio, an empirical equation is proposed.Key words: stepped chutes, inclined step, energy dissipation, skimming flow, spillways.

A Strong Test of Electroweak Theory Using Pulsating DB White Dwarf Stars as Plasmon Neutrino Detectors

We demonstrate that plasmon neutrinos are the dominant form of energy loss in model white dwarf stars down to Teff ~ 25,000 K, depending on the stellar mass. The lower end of this range overlaps the observed temperatures for the V777 Her star (DBV) instability strip. The evolution of white dwarfs at these temperatures is driven predominantly by cooling, so this directly affects the stellar evolutionary timescale in proportion to the ratio of the neutrino energy loss to the photon energy loss. This evolutionary timescale is observable through the time rate of change of the pulsation periods. Although the unified electroweak theory of lepton interactions that is crucial for understanding neutrino production has been well tested in the high-energy regime, the approach presented here should result in an interesting low-energy test of the theory. We discuss observational strategies to achieve this goal.

Black hole multiplicity at particle colliders (Do black holes radiate mainly on the brane?)

If gravity becomes strong at the TeV scale, we may have the chance to produce black holes at particle colliders. In this Letter we revisit some phenomenological signatures of black hole production in TeV-gravity theories. We show that the bulk-to-brane ratio of black hole energy loss during the Hawking evaporation phase depends crucially on the black hole greybody factors and on the particle degrees of freedom. Since the greybody factors have not yet been calculated in the literature, and the particle content at trans-Planckian energies is not known, it is premature to claim that the black hole emits mainly on the brane. We also revisit the decay time and the multiplicity of the decay products of black hole evaporation. We give general formulae for black hole decay time and multiplicity. We find that the number of particles produced during the evaporation phase may be significantly lower than the average multiplicity which has been used in the past literature.

Enhancement of nuclear energy loss of Al 3 cluster during ion beam mixing

Si films with an embedded Ta marker layer are irradiated by 0.9 MeV Al atoms and 2.7 MeV Al 3 clusters at 200 °C and at dose of 1×10 16 Al atoms/cm 2, respectively. Rutherford backscattering is used to measure the diffusion profiles of Ta marker with and without irradiation. Comparing the profile spreading of Ta marker induced by ion beam mixing of Al atoms and Al 3 cluster, the ratio of the nuclear energy loss of Al 3 cluster to Al atoms as a function of penetration depth of Si surface layer is calculated. The enhancement of nuclear energy loss of Al 3 cluster is clearly indicated in the near surface layer.

Mechanical Properties of Golf Balls under Impact Loading.

The mechanical properties, especially load-deformation relations under quasi-static and impact loading, of golf balls have been investigated. Dynamic compression tests have been conducted by the method that the ball is made to collide with the stress bar at velocities of 20∼65 m/s and the load-deformation curves are obtained by integrating the stress wave histories. The following results have been obtained. The load-deformation curves show non-linearity mainly due to geometrical factor and show hysteresis due to internal friction of the ball both under static and dynamic loading. The ratio of energy loss due to internal friction to input energy increases with the amount of deformation. In collision of the ball with the stress bar, only 70% to 45% of the initial kinetic energy is converted to the rebound kinetic energy. This ratio decreases with increase of the impact velocity. Among the rest of the energy, 25% to 45% is dissipated by internal friction, about 8% is transmitted as elastic wave energy to the stress bar and the rest several % remains in the ball as strain energy and vibration energy.

Instrumented indentation characterisation of mouth-guard materials

Objectives: The aim of the study was to investigate the mechanical properties and energy absorption behavior of mouth-guard materials. Interpretation of indentation force–displacement data has been used to determine these properties. Methods: An ultra micro-indentation system (UMIS) was used to determine near surface properties of mouth-guard materials with nanometer and micro-Newton displacement and force resolution. The measurement procedure was conducted with a small spherical steel indenter ( R=500 μm), with impressions that were equally spaced (250 μm). Measurements of force–displacement response of surfaces at maximum forces of 10, 40 or 50 mN, 10 indentations were made at each of these forces. Tests were undertaken in two different modes to determine the mechanical properties, namely: (a) continuous load to the maximum force and then unload, (b) multiple loading and partially unloading sequence to the maximum load. Results: The force–displacement results were analysed to determine the elastic modulus and contact pressure versus depth of penetration as well as the energy loss. Energy absorption for each material was determined from the ratio of the hysteresis energy loss to the total energy at maximum load and ranged from 10 to 24% among different mouth-guard materials. Energy absorption ratio, elastic modulus and contact pressure were significantly different between different materials with same thickness (FC, GC and C3) ( p<0.01) and significantly different between materials with different thickness (C1 and C3) ( p<0.01). Significance: The present approach provides a simple and efficient method to readily measure the elastic–plastic (hysteretic) response of mouth-guard materials. The indentation technique lends itself to investigate the influence of ageing, heat treatment, sterilisation, moisture etc in a simple systematic manner.

Elasto-plastic deformation of glass-like carbons heat-treated at different temperatures

Nano-indentation of glass-like carbons (GCs) heat-treated at different temperatures was carried out with a 3 μm radius spherical tipped indenter. The effect of crystal structure and micro-texture on elastic and elasto-plastic deformation resulting from the indentation was observed. The elastic modulus and yield stress of GCs was found to reduce with elevation of heat treatment temperature (HTT). The power law fitting constant k for the elasto-plastic deformation of the loading stress–strain curves by the indentation and the indentation elasticity index k/ E* reduced with development of the graphitic structure of GC, so that ‘elasticity’ of GC decreased with the elevation of HTT of GCs. Hysteresis loops were observed on the indentation force–displacement curve during the loading–unloading cycle. Hysteresis energy loss, which corresponds to the area of the hysteresis loops, increased with the elevation of HTT for the same terminal load. The indentation ductility index D, the ratio of hysteresis energy loss to total indentation energy, was linearly dependent on indentation elasto-plastic deformation strain ε ep. The indentation elasto-plastic modulus m, which is obtained from the slope of the plots of D versus ε ep, reduced with the elevation of HTT of GCs. From the reduction of m, it was concluded that ‘plasticity’ (or ‘ductility’) of GC increased with the elevation of HTT of GCs.

Composition of Ni–Ta–C thick films using simulated annealing analysis of elastic backscattering spectrometry data

Simulated annealing has been used successfully on elastic backscattering spectrometry data collected from tribological films of NiTa x C y on Si substrates. Manual analysis of the data was possible assuming that the films were well conditioned (homogeneous with depth). However, the C cross-section changes rapidly with beam energy, precluding manual analysis of more complex structures. We show that integrating the non-Rutherford cross-sections in the IBA DataFurnace leads to excellent fits, and analysis of compositional variation becomes trivial. We can demonstrate that the films have a very constant composition throughout their depth, that the precision of the analysis is about 2% and that the accuracy of the C determination approaches 10%. We demonstrate an error in the energy loss database (TRIM95) value of the ratio of Ni and Ta energy loss of 2%.

16S ゴルフボールのインパクト特性(第 2 報) : ボールの動的荷重-変位関係

The mechanical properties, especially load-deformation relations under quasi-static and impact loading, of golf balls have been investigated by experiments and numerical simulations. Dynamic compression tests have been conducted by the method that the ball is made to collide with the stress bar and the load-deformation curves are obtained by integrating the stress wave histories. The following results have been obtained. The load-deformation curves show non-linearity mainly due to geometrical factor and show hysteresis due to internal friction of the ball both under static and dynamic loading. The ratio of energy loss due to intemal friction to input energy increases with the amount of deformation. The energy loss ration due to hysteresis does not strongly depend on strain rate. In collision of the ball with the stress bar, only 65% to 45% of the initial kinetic energy is converted to the rebound kinetic energy. This ratio decreases with increase of the impact velocity. Among the rest of the energy, 25% to 40% is dissipated by internal friction, about 10% is transmitted as elastic wave energy to the stress bar and the rest several % remains in the ball as strain energy and vibration energy.

Effects of crystal defects on the stopping powers for channeled ions in ion implanted single crystals

The ion beam channeling method is used in the study of impurity distribution and implantation damage in crystalline materials. This technique requires knowledge of the stopping power of a channeled ion. Although the stopping powers for non-channeled ions are well established, the energy loss of channeled ions has been studied only in perfect crystals. The energy-loss measurements have been made for 2.2 MeV protons in different damaged Si crystals. The defects were created by multiple energy implantation of noble gas ions (He and Xe). The total implantation dose was varied to produce different types and concentrations of defects. The average ratio of channeled and non-channeled energy loss of ions has been measured by resonance backscattering. These data have a precision of 3%. The influence of the beam alignment from crystal axis on stopping power ratio has been investigated.

Two-Phase Slug Flow in a Concentric Annulus with a Rotating Inner Cylinder.

Gas-liquid two-phase slug in a concentric annulus with a rotating inner cylinder has been experimentally investigated. The flow patterns identified on the basis of visual observations are classified into four categories, i.e., slug flow, spiral-slug flow, peripherally elongated slug flow and ring-form slug flow. Such a flow regime map is expressed as a function of the total volumetric flux and the rotational speed. The rising velocity of a large bubble approximately coincides with Nicklin et al.'s correlation at relatively low rotational speed, while the rising velocity is lower than that of Nicklin et al.'s correlation at high rotational speed. This is closely related to the void fraction distribution along the radial direction in the annulus. The ratio of the kinetic energy loss to the potential one in the slug flow regime is well correlated by a linear function of the volumetric flux ratio of two phases as in the case of a bubbly flow regime. This ratio of energy losses is well expressed using the drift-flux model modified by taking into account the large bubble size in the annulus.

Energy Loss of Gas-Liquid Two-Phase Flow in a Concentric Annulus with a Rotating Inner Cylinder.

Energy loss of gas-liquid two-phase flow in a concentric annulus with a rotating inner cylinder has been experimentally investigated. The energy loss is closely related to the flow pattern and becomes almost constant in the spiral and ring-form flows observed under relatively high rotational speed. The ratio of the kinematic energy loss to the potential one in such flow regimes is well correlated by a linear function of the volumetric flux ratio of two phases. Drift-flux model and the two-phase friction multiplier of Chisholm are successfully applied to the estimation of the energy loss in this complex flow field.

A unified quantitative approach to trophic cascade and bottom-up: top-down hypotheses

A general analytic approach is developed to predict how perturbing one level of a food chain affects the stocks in other levels. (The comparison is between initial and final steady states.) This yields qualitative and quantitative predictions of the trophic cascade hypothesis and the bottom-up: top-down hypothesis, respectively. For a wide range of reasonable ratio-dependent functional relationships between trophic levels in a food chain, the quantitative approach predicts that perturbation effects should propagate up the chain with the same sign and roughly constant strength, but down the chain with alternating sign and diminishing strength. There is less diminishment for the case of trophic levels with a low ratio of energy losses (metabolism, mortality) to input. The trophic cascade model’s prediction of the sign of compartmental stock changes is based on a linear food chain model and does not necessarily hold for food webs. Both points are illustrated by simulating perturbation responses in models of two ecosystems (one representing a chain and one a web). The approach can be used for a wide range of functional responses connecting trophic levels besides ratio dependence.

Studies of a ring phase-conjugate mirror containing a photorefractive crystal with asymmetric transmission

The characteristics of the ring passive phase conjugator with a nonreciprocal transmission photorefractive crystal inside its loop are studied experimentally and theoretically. It is found that the orientation of the photorefractive crystal and the ratio of energy losses in the two sides of the crystal within the loop can combine to influence the phase-conjugate reflectivity of this device.

Detailed in situ study of ion beam-induced amorphization of zircon

Single crystals of zircon (ZrSiO4) cut into (010) thin toils were irradiated with 700 and 1500 keV Kr+, 1500 keV Xe+ and 400 keV He+ ions to investigate the role of electronic or ionization process vs nuclear collision during damage accumulation. The irradiations were conducted at room temperature with in situ transmission electron microscopy (TEM) using the HVEM Tandem Facility at Argonne National Laboratory. The level and ratio of electronic and nuclear energy loss in the sample vary with the mass and energy of the ions. Analysis of 700, 1500 keV Kr + and 1500 keV Xe + irradiations demonstrated that zircon samples were amorphized at ~0.9 dpa (2.0–4.8 × 1014 ions/cm2: assuming displacement energy equals to 15 eV) regardless of the level of total ionization energy deposited. The 400 He+ irradiation, for which there was the highest electronic/nuclear energy loss ratio, was performed to 1× 1016 ions/cm2 at a much higher dose rate and gave no indication of amorphization. Therefore, displacement damage by nuclear collision must be the controlling mechanism in ion beam-induced amorphization of zircon.

Secondary-electron yields from thin foils: A possible probe for the electronic stopping power of heavy ions.

We have measured heavy-ion-induced (${Z}_{P}$=2,10,18,36,54; 15 keV/u\ensuremath{\le}${E}_{P}$/${M}_{P}$\ensuremath{\le}600 keV/u secondary-electron (SE) yields from sputter-cleaned entrance (${\ensuremath{\gamma}}_{B}$) and exit surfaces (${\ensuremath{\gamma}}_{F}$) of thin solid foils (C, Al, Ti, Ni, and Cu; d\ensuremath{\approxeq}1000 A\r{}) in ultrahigh vacuum (p${=10}^{\mathrm{\ensuremath{-}}7}$ Pa). A pronounced increase of the forward to backward SE yield ratio R=${\ensuremath{\gamma}}_{F}$/${\ensuremath{\gamma}}_{B}$ with increasing ${Z}_{P}$ is observed. The SE yield to energy-loss ratio ${\ensuremath{\Lambda}}^{\mathrm{*}}$=\ensuremath{\gamma}/${S}_{e}$ has been found to be smaller for heavy ions (HI) than for light ions (H and He); i.e., ${\ensuremath{\Lambda}}^{\mathrm{*}}$(HI)${\ensuremath{\Lambda}}^{\mathrm{*}}$(He)${\ensuremath{\Lambda}}^{\mathrm{*}}$(H). Also, at low projectile velocities (${v}_{P}^{2}$50 keV/u), the value of ${\ensuremath{\Lambda}}^{\mathrm{*}}$ increases with decreasing ${v}_{P}$. The velocity and projectile dependence of both R and ${\ensuremath{\Lambda}}^{\mathrm{*}}$ can be described within simple extensions of Schou's SE emission transport theory and a semiempirical Sternglass-type model introduced by Koschar and co-workers as caused by nonequilibrium projectile energy losses ${S}_{e}^{\mathrm{*}}$ near the surfaces. The near-surface energy losses are reduced compared to tabulated bulk energy loss values ${S}_{e}$ both for forward and backward emission under the assumption of a proportionality between SE yields and dE/dx. The ${Z}_{P}$-dependent reduction factors, i.e., the ratios ${S}_{e}^{\mathrm{*}}$/${S}_{e}$, as well as material parameters \ensuremath{\Lambda}=\ensuremath{\gamma}/${S}_{e}^{\mathrm{*}}$, are deduced from the SE yield measurements. Nevertheless, a rough overall proportionality \ensuremath{\gamma}\ensuremath{\sim}dE/dx over four decades of both forward and backward secondary-electron yields \ensuremath{\gamma} and electronic energy losses dE/dx in a wide range of projectile velocities (15 keV/u \ensuremath{\le}${E}_{P}$/${M}_{P}$\ensuremath{\le}16 MeV/u) and projectile nuclear charges ${Z}_{P}$ (1\ensuremath{\le}${Z}_{P}$\ensuremath{\le}92) is found.

A new method for determining the rate of energy loss of charged particles in matter

The energy loss of charged particles, of incident energy of the order of MeV, in traversing matter and scattering at 90° is analysed for different target orientations. Computer simulations of the energy loss of alpha particles using the stopping power values according to the currently available tabulations indicate that for moderate film thicknesses the ratio of energy losses along the scattered and the incident trajectories is approximately proportional to the ratio of the thicknesses traversed. Hence the measured energy losses yield, in the first approximation, the ratio of average stopping powers along the two channels.