Energy Loss Rate Research Articles

Model To Determine a Distinct Rate Constant for Carrier Multiplication from Experiments.

Carrier multiplication (CM) is the process in which multiple electron–hole pairs are created upon absorption of a single photon in a semiconductor. CM by an initially hot charge carrier occurs in competition with cooling by phonon emission, with the respective rates determining the CM efficiency. Up until now, CM rates have only been calculated theoretically. We show for the first time how to extract a distinct CM rate constant from experimental data of the relaxation time of hot charge carriers and the yield of CM. We illustrate this method for PbSe quantum dots. Additionally, we provide a simplified method using an estimated energy loss rate to estimate the CM rate constant just above the onset of CM, when detailed experimental data of the relaxation time is missing.

An estimate of the antineutrino energy loss by beta decay on strongly screening iron group nuclei in presupernova

The research on supernovae explosions is one of the most exciting fields in astrophysics. Recent studies show that the electron capture and beta decay play key roles in supernovae explosions. In this paper, the half-lives of some iron group nuclei by β−-decay are investigated due to shell effect, pair effect, and the changes of the decay energy. We also discuss the influence of strong electron screening (SES) on the electron energy, beta decay threshold energy, and the antineutrino energy loss rates (AELR) in β− decay. The AELR increases, and the screening enhancement factor can get to 4.684 in SES due to Q-value correction, shell and pairing effect. The AELR can be suppressed at lower density and higher temperature environment (e.g., 0.1 < ρ7 < 800, T9 > 30). The screening enhancement factor decreases about 14.10% (e.g., for 56Ni).

The Comparison of the shares of stopping power in a soft tissue-equivalent material

Introduction: Proton therapy is a type of radiation treatment that it uses protons to treat cancer. Because of the protons’ unique ability to distribute the radiation dose more directly to the tumor, it minimizes the damage to nearby healthy tissues. The rate of energy loss by the ion in the target is called stopping power. The total stopping power is sum nuclear and electronic stopping power. Electronic stopping power refers to the slowing down of a projectile ion due to the inelastic collisions between bound electrons in the medium and the ion moving through it. Nuclear stopping power refers to the elastic collisions between the projectile ion and atoms in the target. Materials and Methods: It should be noted that soft tissue-equivalent material denotes a substance, with absorbing and scattering properties for a given radiation that sufficiently match those of a certain biological tissue. The soft tissue-equivalent material usually consists of four elements of hydrogen, oxygen, carbon and nitrogen. By using the SRIM code, we calculated the total stopping power in each element for 10-MeV proton beam. Then, using Bragg's rule, we got the total stopping power for these elements. Also, using the same code, we obtained the total stopping power for the compound. Also, we obtained the contribution of nuclear and electronic stopping power to the total stopping power in this material. Results: By comparing, we observed that the peak height of stopping power using Bragg's rule is more than 20% higher than the SRIM code. This is due to the core and bond (CAB) corrections at low energies in the SRIM code. Also, we observed that total stopping power is due to the electronic stopping power in high energies. By reducing energy, the electronic stopping power is slowly reduced, and the share of nuclear stopping power slowly increases, and the intersection of these is at 50eV energy. Then the contribution of the nuclear stopping power is greater. Conclusion: The proton therapy to treat cancerous tumors is a major technological advance. In low- energies CAB corrections must be taken into account for stopping power of the compound, and therefore, the peak height of the stopping power is reduced. In soft tissue equivalent material for proton beam the contribution of the nuclear stopping power at energies of less than 50 eV is greater than the electronic stopping power. In other energies, the electron- stopping power share is dominant.

Case Study on Application of the Step with Non-Uniform Heights at the Bottom Using a Numerical and Experimental Model

Steps effectively dissipate the energy of water along a path and reduce the size of the stilling basin but are rarely used in curved spillways. The shore spillway of a reservoir, which is restricted by topography, must be arranged in a curved shape. At high flow velocity and low water depth, some areas of the base plate of the curved spillway were not covered by the water. The water flow into the stilling basin did not form a submerged hydraulic jump. It was proposed that a step with bottom non-uniform heights be placed in the smooth base plate of the curved spillway to improve these undesirable hydraulic phenomena. A physical model experiment with a length scale of 1:40 verified the feasibility of the curved stepped spillway in engineering. Based on the k-ε model and volume-of-fluid (VOF) method, a three-dimensional numerical model was established, and the reliability of the numerical model was verified by measured data. The main flow region, velocity field, cavitation on a step, and the energy loss rate of steps were discussed. The comparison between a curved spillway with and without steps shows that the steps balance the partial centrifugal force in the curved section, making the water depth of the cross-section evenly distributed, and the base plate was no longer covered by water. The flow pattern on the steps was skimming flow, and the velocity of the flow into the stilling basin was greatly reduced. The elevation of the concave bank of the base plate was raised, resulting in the formation of transverse flow, which in turn constituted a three-dimensional energy dissipation pattern with the longitudinal flow. The energy loss was significantly higher than that of the smooth curved spillway. However, the triangular region near to the concave bank on the base plate experienced negative pressure, and an aeration device in front of the steps was needed.

Horndeski gravity without screening in binary pulsars

We test the subclasses of Horndeski gravity without Vainshtein mechanism in the strong field regime of binary pulsars. We find the rate of energy losses via the gravitational radiation predicted by such theories and compare our results with observational data from quasi-circular binaries PSR J1738+0333, PSR J0737-3039, PSR J1012+5307. In addition, we consider few specific cases: the hybrid metric-Palatini f(R)-gravity and massive Brans-Dicke theory.

Electron single flexural phonon relaxation, energy loss and thermopower in single and bilayer graphene in the Bloch–Gruneisen regime

The flexural phonons serve as one of the important modes of interaction in graphene that can inhibit carrier mobility. For the estimation of scattering due to flexural phonons a two-phonon scattering process had been in place, as due to symmetry constraints out-of-plane deformations modulate electron hopping only in the second order. But recently it has been shown that electrostatic gating can break the planar mirror symmetry and activate single flexural phonon scattering processes (Gunst et al 2017 Phys. Rev. Lett. 118 046601). Motivated by this we perform single flexural phonon mechanism based analytical and numerical calculations of the electron phonon relaxation rate, energy loss rate and thermopower in single and bilayer graphene and obtain the power exponents of these quantities in the Bloch Gruneisen regime using the non-equilibrium Boltzmann transport equation. We find that the scattering by flexural phonons substantially changes the temperature dependencies from that observed due to in-plane phonons but the carrier concentration dependencies remain the same as of the in-plane phonons for all the three investigated quantities.

Energy loss in nano-dimensional wire structures due to piezoelectric interaction at low temperatures

The theory of energy loss rate of non-equilibrium electrons due to inelastic interaction with intravalley piezoelectric phonons in a nano-dimensional semiconductor wire has been developed under the condition of low lattice temperatures, without recourse to the standard approximations which are usually made when developing theories at relatively higher temperatures. Such approximations are hardly valid when the lattice temperature is low. As expected, compared to the well-known earlier results, the theory here, reveals a complex and altogether different dependence of the energy loss rate upon the carrier energy and the lattice temperature. The numerical results have been obtained for narrow channel wires of GaAs and GaN. On comparison with other available results, it is revealed that the finite energy of piezoelectric phonons and the full form of the phonon distribution bring about quite significant changes in the energy loss characteristics at low temperatures.

Interaction of infalling solid bodies with primordial atmospheres of disk-embedded planets

Context. Planets that form early enough to be embedded in the circumstellar gas disk accumulate thick atmospheres of nebular gas. Models of these atmospheres need to specify the surface luminosity (i.e. energy loss rate) of the planet. This luminosity is usually associated with a continuous inflow of solid bodies, where the gravitational energy released from these bodies is the source of energy. However, if these bodies release energy in the atmosphere instead of at the surface, this assumption might not be justified. Aims. Our aim is to explore the interactions of infalling planetesimals with primordial atmospheres at an embedded phase of evolution. We investigate effects of atmospheric interaction on the planetesimals (mass loss) and the atmosphere (heating/cooling). Methods. We used atmospheric parameters from a snapshot of time-dependent evolution simulations for embedded atmospheres and simulated purely radial, infall events of siliceous planetesimals in a 1D, explicit code. We implemented energy transfer between friction, radiation transfer by the atmosphere and the body, and thermal ablation; this gives us the possibility to examine the effects on the planetesimals and the atmosphere. Results. We find that a significant amount of gravitational energy is indeed dissipated into the atmosphere, especially for larger planetary cores, which consequently cannot contribute to the atmospheric planetary luminosity. Furthermore, we examine that planetesimal infall events for cores, MC &gt; 2M⊕, which actually result in a local cooling of the atmosphere; this is totally in contradiction with the classical model.

Efficient Determination of Reverberation Chamber Time Constant

Determination of the rate of energy loss in a reverberation chamber is fundamental to many different measurements such as absorption cross section, antenna efficiency, radiated power, and shielding effectiveness. Determination of the energy decay time constant in the time domain by linear fitting the power delay profile, rather than using the frequency-domain quality-factor, has the advantage of being independent of the radiation efficiency of antennas used in the measurement. However, determination of chamber time constant by linear regression suffers from several practical problems, including a requirement for long measurement times. Here, we present a new nonlinear curve fitting technique that can extract the time constant with typically 60% fewer samples of the chamber transfer function for the same measurement uncertainty, which enables faster measurement of chamber time constant by sampling fewer chamber transfer function, and allows for more robust automated data postprocessing. Nonlinear curve fitting could have economic benefits for test houses, and also enables accurate broadband measurements on humans in about 10 min for microwave exposure and medical applications. The accuracy of the nonlinear method is demonstrated by measuring the absorption cross section of several test objects of known properties. The measurement uncertainty of the method is verified using Monte Carlo methods.

Energy loss rate of hot electrons due to polar-optical phonon modes in a semiconductor nanowire under transverse electric field

Within the frame of electron-temperature model we calculate the average energy loss rate due to interface and confined longitudinal optical (LO) phonon emission from a hot-electron gas to a cold lattice in polar semiconductor nanowire surrounded by non-polar material. The system both with and without hot-phonon effect is investigated. The impact of a perpendicular electric field on average energy loss rate is explored. The energy loss rate dependences on electric field strength, wire radius and electron temperature are obtained. It has been shown that the energy loss rate is more sensitive to the electric field when the wire radius is larger. The presented results indicate that the electric field applied perpendicularly to the wire axis can serve as a means to control the energy loss rate. There is an experimental evidence concerning to the increase of energy loss rate with increasing electron temperature as we have obtained.

Forecasting Volcanic Eruptions: Beyond the Failure Forecast Method

Volcano-tectonic seismicity and ground movement are the most reliable precursors to eruptions after extended intervals of repose, as well as to flank eruptions from frequently-active volcanoes. Their behavior is consistent with elastic-brittle failure of the crust before a new pathway is opened to allow magma ascent. A modified physical model shows that precursory time series are governed by a parent relation between faulting and elastic deformation in extension, subject to independent constraints on the rate of crustal loading with time. The results yield deterministic criteria that can be incorporated into existing operational procedures for evaluating the probability of crustal failure and, hence, levels of alert during an emergency. They also suggest that the popular Failure Forecasting Method for forecasting eruptions is a particular form of the parent elastic-brittle model, and that magma transport and crustal fracturing during unrest tend towards conditions for minimizing rates of energy loss.

Evaluating compressive behavior of general fibrous assemblies

General fibrous assemblies are made of loose fibers and air filling in the pores formed by these fibers. An important characteristic of these assemblies is their mechanical behavior under compression and release. In this paper, a unified and systematic experimental investigation was used to quantify and characterize the compressional and recovery behavior of several randomly oriented fibrous assemblies via mechanical and conductive in situ integrated measurement system. An attempt was made to characterize the curves of force, modulus, work and energy loss during compressional and recovery cycles. Considerable hysteresis occurred between the compression and release operations which is an evidence for the existence of fiber slippage and frictional effects. Work, energy loss and recovery rate of work turned out to have a nonlinear exponential relationship with cycles.

Cosmic-ray fermion decay through tau-antitau emission with Lorentz violation

We study CPT and Lorentz violation in the tau-lepton sector of the Standard Model in the context of the Standard-Model Extension, described by a coefficient which is thus far unbounded by experiment. We show that any non-zero value of this coefficient implies that, for sufficiently large energies, standard-model fermions become unstable against decay due to the emission of a pair of tau-antitau leptons. We calculate the induced fermion energy-loss rate and we deduce the first limit on the Lorentz- and CPT-violating coefficient.

Constraints on light Dark Matter fermions from relic density consideration and Tsallis statistics

The cold dark matter fermions with mass MeV scale, pair produced inside the supernova SN1987A core, can freely stream away from the supernovae and hence contributes to its energy loss rate. Similar type of DM fermions (having similar kind of coupling to the standard model photon), produced from some other sources earlier, could have contributed to the relic density of the Universe. Working in a theory with an effective dark matter-photon coupling (inversely proportional to the scale Λ) in the formalism of Tsallis statistics, we find the dark matter contribution to the relic density and obtain a upper bound on Λ using the experimental bound on the relic density for cold non-baryonic matter i.e. Ωh2 = 0.1186 ± 0.0020. The upper bound obtained from the relic density is shown with the lower bound obtained from the Raffelt’s criterion on the emissibity rate of the supernovae SN1987A energy loss overset{cdot }{varepsilon}left({e}^{+}{e}^{-}to chi overline{chi}right)le {10}^{19} erg g−1s−1 and the optical depth criteria on the free streaming of the dark matter fermion (produced inside the supernovae core). As the deformation parameter q changes from 1.0 (undeformed scenario) to 1.1 (deformed scenario), the relic density bound on Λ is found to vary from ∼ 4.9 × 107 TeV to 1.6 × 108 TeV for a fermion dark matter (χ) of mass mχ = 30 MeV, which is almost10 times more than the lower bound obtained from the SN1987A energy loss rate and the optical depth criteria.

Experimental measurement of the normal coefficient of restitution of micro-particles impacting on plate surface in different humidity

The coefficient of restitution is widely used to characterize the energy loss rate in numerical simulations of discrete element modelling. The accurate input parameters can obtain the accurate simulation results for discrete element modelling. The determination of the coefficient of restitution for the single component particle is the relatively simple process, however, when considering multicomponent particles like fly-ash and humidity environment, the unpredictable property of particle after impact makes the analysis of the coefficient of restitution more complicated. This paper presents an experimental setup to determine normal coefficient of restitution using the high-speed digital camera in different humidity condition. The normal coefficient of restitution was measured for fly-ash micro-particles with different relative velocities and humidity, with a focus on collision velocities below 7 m/s. Therefore, this work focused on the effect of humidity and incident velocity on the normal coefficient of restitution.

Strongly screening corrections to antineutrino energy loss by β − $\beta ^{-}$ -decay of nuclides 53Fe, 54Fe, 55Fe, and 56Fe in supernova

Based on the p-f shell-model, we discuss and calculate $\beta^{-}$ -decay half-lives of neutron-rich nuclei, with a consideration of shell and pair effects, the decay energy, and the nucleon numbers. According to the linear response theory model, we study the effect of electron screening on the electron energy, beta-decay threshold energy, and the antineutrino energy loss rate by $\beta^{-}$ -decay of some iron isotopes. We find that the electron screening antineutrino energy loss rates increase by about two orders of magnitude due to the shell effects and the pairing effect. Beta-decay rates with Q-value corrections due to strong electron screening are higher than those without the Q-value corrections by more than two orders of magnitude. Our conclusions may be helpful for the research on numerical simulations of the cooling of stars.

Gastrointestinal Heat Sink

Measurement of core temperature at the gastrointestinal level with an ingestible telemetric pill (ITP) is increasingly used in research. But, unlike core temperature measured at the rectum via a rectal probe (RP), data contamination due to water or food ingestion remains a limitation of ITP. Rapid creation of a heat sink at the stomach and upper-intestinal level (duodenum to ileum), as can be obtained, for example, following shaved-ice ingestion, could potentially differently impact ITP and RP temperature measurements. In fact, the closer proximity of ITP to the heat sink than RP could result in a more important and faster rate of energy loss for ITP than RP. PURPOSE: To examine the impact of shaved-ice ingestion following exercise-induced increase in core body temperature on the degree of agreement between ITP and RP temperature measurements. METHODS: 8 healthy young men (33 ± 8 yrs, 75 ± 6 kg, 176 ± 5 cm) underwent a passive sitting period of 20 min at 20°C, after which they completed 2 exercise periods (cycling or running) at 75% of estimated maximal heart rate in a hot-dry environment (31.1 ± 1.1°C, 32% RH) with the goal of increasing rectal temperature by 1°C over baseline level. Following each exercise period, subjects passively seated in a 20°C ambient temperature for 45 min while ingesting, over the first 30 min, either 7.5 g of water provided at rectal temperature/kg body mass (after the first exercise) or 7.5 g of shaved-ice provided at -1°C/kg body mass (after the second exercise). Rectal (YSI 401) and gastrointestinal temperatures (HQ Inc.) were measured continuously during the experiments. ITPs were ingested 10 h prior to arrival time at the laboratory. RESULTS: The rate of decrease in RP and ITP temperatures during water ingestion was respectively of 0.017 ± 0.004°C/min and 0.018 ± 0.008°C/min, compared to 0.025 ± 0.006°C/min and 0.026 ± 0.006°C/min for shaved-ice ingestion. Mean biases (RP - ITP) and 95% limits of agreement during the passive sitting period, first exercise period, water ingestion period, second exercise period and shaved-ice ingestion period were respectively of 0.10°C/± 0.35°C, 0.09°C/± 0.31°C, 0.17°C/± 0.66°C, 0.12°C/± 0.38°C and 0.16°C/± 0.64°C. CONCLUSION: The present results indicate that the creation of a heat sink at the stomach and upper-intestinal level does not alter the degree of agreement between RP and ITP.

Particle-in-cell studies of fast-ion slowing-down rates in cool tenuous magnetized plasma

We report on 3D-3V particle-in-cell simulations of fast-ion energy-loss rates in a cold, weakly-magnetized, weakly-coupled plasma where the electron gyroradius, ρe, is comparable to or less than the Debye length, λDe, and the fast-ion velocity exceeds the electron thermal velocity, a regime in which the electron response may be impeded. These simulations use explicit algorithms, spatially resolve ρe and λDe, and temporally resolve the electron cyclotron and plasma frequencies. For mono-energetic dilute fast ions with isotropic velocity distributions, these scaling studies of the slowing-down time, τs, versus fast-ion charge are in agreement with unmagnetized slowing-down theory; with an applied magnetic field, no consistent anisotropy between τs in the cross-field and field-parallel directions could be resolved. Scaling the fast-ion charge is confirmed as a viable way to reduce the required computational time for each simulation. The implications of these slowing down processes are described for one magnetic-confinement fusion concept, the small, advanced-fuel, field-reversed configuration device.

DRFM hybrid model to optimize energy performance of pre-treatment depth filters in desalination facilities

Rapid depth filtration is the dominant pre-treatment technology in seawater desalination industry today. Optimizing the pre-treatment filter’s energy performance provides economies of scale in the total energy usage of desalination facilities on a broader sense. However, this objective remains difficult to achieve by far. In this study, we develop a numerical algorithm, termed as Dynamical Rapid Filtration Model (DRFM), to simulate the effective clogging dynamics occurring inside a depth filter which depends on a multitude of controlled and non-controlled operating parameters. DRFM quantifies the filtration kinetics with a modified Yao’s model to represent the particle removal mechanisms occurring within the simulated filter. A unique length scale is also introduced to account for the particle size effect on the filter’s energy loss rate incurred, i.e. its energy performance, during its effective filtration stage. Concurrently, we performed an experimental study with a lab-scale depth filter to develop a model equation for measuring its total contaminant mass removal rate (Rc) due to effective clogging conditions. For a predicted Rc transient profile, good agreement is obtained between the experimental results and predicted values from DRFM. We then extensively discuss on a novel DRFM hybrid model to optimize the filter’s energy performance which subsequently affects the filter’s optimized backwashing timing for achieving economies of scale. The simulation results from the hybrid model demonstrates on how various filter configurations can result in lower energy cost to effectively pre-treat each unit volume of intake seawater as compared to the current industrial average of 0.39kWh/m3. Finally, we include a cost analysis to demonstrate on how the obtained economies of scale alleviates a portion of the total energy cost for each unit volume of desalinated water.

Relativistic effects in the energy loss of a fast charged particle moving parallel to a two-dimensional electron gas

Abstract We present a fully relativistic formulation for the energy loss rate of a charged particle moving parallel to a sheet containing two-dimensional electron gas, allowing that its in-plane polarization may be described by different longitudinal and transverse conductivities. We apply our formulation to the case of a doped graphene layer in the terahertz range of frequencies, where excitation of the Dirac plasmon polariton (DPP) in graphene plays a major role. By using the Drude model with zero damping we evaluate the energy loss rate due to excitation of the DPP, and show that the retardation effects are important when the incident particle speed and its distance from graphene both increase. Interestingly, the retarded energy loss rate obtained in this manner may be both larger and smaller than its non-retarded counterpart for different combinations of the particle speed and distance.