Arbitrary Energy Spectrum Research Articles

Calculated initial energies of electrons in Si and SiO2 irradiated by photons with energies up to 2 MeV

Calculated spectra of initial energies are presented to electrons produced in Si and SiO2 irradiated by monoenergetic photons with energies up to 2 MeV and by photons from 60Co. The computations take into account the photoelectric effect, single Compton scattering of an incident photon, and emission of an Auger electron following creation of a K-shell vacancy in a Si or O atom. Pair production is neglected. The tables presented here can be used to calculate initial electron energy spectra for photons with an arbitrary energy spectrum up to 2 MeV.

Monte Carlo calculations of initial energies of electrons in water irradiated by photons with energies up to 1GeV.

Previous calculations of the initial energies of electrons produced in water irradiated by photons are extended to 1 GeV by including pair and triplet production. Calculations were performed with the Monte Carlo computer code PHOEL-3, which replaces the earlier code, PHOEL-2. Tables of initial electron energies are presented for single interactions of monoenergetic photons at a number of energies from 10 keV to 1 GeV. These tables can be used to compute kerma in water irradiated by photons with arbitrary energy spectra to 1 GeV. In addition, separate tables of Compton-and pair-electron spectra are given over this energy range. The code PHOEL-3 is available from the Radiation Shielding Information Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830.

Synchrotron emissivity from mildly relativistic particles

Approximate analytic expressions are presented for evaluation of the frequency and angular dependence of synchrotron emissivity from mildly relativistic particles with arbitrary energy spectrum and pitch angle distribution in a given magnetic field. Results agree with previous expressions for a nonrelativistic Maxwellian particle distribution, and when extrapolated to nonrelativistic and extreme relativistic regimes, they also agree with the previous expressions obtained under those limiting conditions. The results from the analytic expression are compared with results from detailed numerical evaluations. Excellent agreement is found not only at frequencies large compared to the gyro-frequency but also at lower frequencies, in fact, all the way down to the gyro-frequency, where the analytic approximations are expected to be less accurate.

Surface region of the space charge in a semiconductor with an arbitrary energy spectrum of the trapped states

The screening of the electric field in a semiconductor with an arbitrary energy spectrum of the trapped centers is discussed in this paper. Expressions which describe the voltage dependence of the capacitance are derived on the basis of the solution of Poisson's equation. An analysis is performed of the particular cases of a monoenergetic center and a quasicontinuous spectrum of charge localization centers with a constant and an exponential energy distribution density, and the possibility is noted of determining the parameters of this distribution by means of the processing of experimental results according to the formulas derived in this paper.

Analytical approximations in the theory of turbulent diffusion

It is pointed out that numerical and simulational calculations of the Lagrangian decay time τL are easily explained by straightforward analytical approximations. This result demonstrates the usefulness of these approximations for problems of turbulent transport. A calculation is then made of the turbulent diffusion coefficient D in terms of an arbitrary energy spectrum, for homogeneous isotropic turbulence. This relation is compared with previous results.

The Computation of Pion Depth-Dose Curves in Water and Comparison with Experiment

A Monte Carlo program has been written for calculating absorbed dose as a function of position in a water target irradiated by beams of pions (π+ and π-). The incident pions can have an arbitrary energy spectrum, at present limited to 125 MeV, this energy including most beams that have been used in radiobiological experiments. The presence of muons and electrons, which contaminate pion beams in practice, is also included. The incident particles may enter the target at any point and with any direction of travel. Calculations can thus be made for nonparallel, nonuniform beams. The size of cylindrical volumes in the target over which the absorbed energy is averaged can be varied to simulate the use of detectors of various dimensions. The calculations include pion-nucleus interactions, multiple coulomb scattering, pion and muon decay at rest, as well as the transport and further interactions of secondary protons and neutrons. Good agreement is obtained between calculated and measured depth-dose curves with π+...

292. Breakdown mechanism of thin dielectric films: G A Blinov, Fiz Tverd Tela, 12 (8), Aug 1970, 2487–2488 ( inRussian)

We present a simplified theoretical formulation of the thermoelectric power (TP) under magnetic quantization in quantum wells (QWs) of nonlinear optical materials on the basis of a newly formulated magneto-dispersion law. We consider the anisotropies in the effective electron masses and the spin–orbit constants within the framework of k.p formalism by incorporating the influence of the crystal field splitting. The corresponding results for III–V materials form a special case of our generalized analysis under certain limiting conditions. The TP in QWs of Bismuth, II–VI, IV–VI and stressed materials has been studied by formulating appropriate electron magneto-dispersion laws. We also address the fact that the TP exhibits composite oscillations with a varying quantizing magnetic field in QWs of n- Cd3As2, n- CdGeAs2, n-InSb, p-CdS, stressed InSb, PbTe and Bismuth. This reflects the combined signatures of magnetic and spatial quantizations of the carriers in such structures. The TP also decreases with increasing electron statistics and under the condition of non-degeneracy, all the results as derived in this paper get transformed into the well-known classical equation of TP and thus confirming the compatibility test. We have also suggested an experimental method of determining the elastic constants in such systems with arbitrary carrier energy spectra from the known value of the TP.

Energy Loss of High-Energy Cosmic Rays in Pair-Producing Collisions with Ambient Photons

General and essentially exact formulas for the energy-loss process $A+\ensuremath{\gamma}\ensuremath{\rightarrow}A+{e}^{+}+{e}^{\ensuremath{-}}$ are given for high-energy cosmic-ray nuclei traversing an isotropic radiation field of arbitrary energy spectrum. These formulas are obtained by integrating the appropriate differential cross section in the rest frame of the cosmic-ray particle. Results are then given for the case of a Planckian photon distribution at arbitrary temperature. The effect of this energy loss on a universal flux of cosmic rays is then investigated along with the possibility that the observed "knee" at high energies is due to pair production. Finally, the energy-loss formula is applied to quasistellar objects, and it is shown that if these objects are at cosmological distances, they are opaque to particles above a certain energy which depends upon the size of the object.