Absorption Of High Energy Electrons Research Articles

Absorption of high energy electrons in liquid nitrogen

The maximum range-energy relation for electrons of 4–32 MeV in liquid nitrogen is obtained by measuring the deposited electrons in the nitrogen with the use of a fine sensitive electrometer, as mentioned previously 1). Applying the previous method to the low temperature liquid absorber, we find that the measured maximum range in liquid nitrogen is rid of the influence from bremsstrahlung photons. By comparing the inclination of the maximum range-energy relation for liquid nitrogen with that for water, it is found that the former is greater than the latter, that is, the energy dissipation for liquid nitrogen is smaller than that for water.

Absorption of high energy electrons in liquid medium

The maximum range-energy relation for high energy electrons penetrating water is obtained based on a physical concept of the range for energetic particles. In this work, the deposited electrons in a liquid are measured with a sensitive electrometer by the charge collecting method. The absorption curve obtained in this method is free from the background due to bremsstrahlung, differing from the ion chamber method. Hence, in the high energy region the extrapolated range of water is shorter than that obtained from the ion chamber method. The maximum range in water in the present experiment agrees well with the theoretical evaluation obtained by the Monte Carlo method. The influence of the bottom of the container holding the absorber is so important that it is discussed experimentally.

The effect of point defects on absorption of high energy electrons passing through crystals

Abstract The effect of substitutional and interstitial atoms on the absorption of high energy electrons is considered. Two mechanisms of absorption are discussed; viz. the contributions due to scattering by the additional scattering centres and due to displacements of the atoms surrounding the point defects. The absorption estimated on these two mechanisms is compared with the results of some experimental measurements on silicon doped with various impurities.

The effects of systematic reflections on measurements of the extinction distance and the absorption of high energy electrons in crystals

Abstract Recent experiments on the energy dependence of the extinction distance and mean absorption coefficient of electrons in magnesium oxide crystals by Dupouy et al. (1965) have shown significant deviations from the relativistic two-beam dynamical theory of electron diffraction. It is shown that if systematic reflections, which are inevitably present in any experiment, are taken into account the experimental results are in accord with many-beam dynamical theory.

The effect of weak bragg reflected beams on the absorption of electrons. II

Abstract The apparent absorption of high energy electrons in crystals due to elastic scattering has been considered by a number of authors, and a numerical estimate of the magnitude of this effect by Hall and Hirsch (1965 a), based upon an approximate theory, suggests that this process makes a negligible contribution to the total. The approximation made in that treatment of considering the scattering kinematically is discussed and its effect upon the predictions of the simple theory investigated by performing some numerical calculations based upon the dynamical theory of diffraction. It appears that the mean apparent absorption due to this cause is overestimated by the simple theory, but that in special cases the apparent absorption can be much larger than the mean value.

Effect of thermal diffuse scattering on propagation of high energy electrons through crystals

A simple theory is developed for calculating the contribution from thermal diffuse scattering to the absorption of high energy electrons passing through crystals. The Einstein model for a vibrating crystal is used and the incident wave is assumed to be a Bloch wave, the thermally diffuse scattered wave to be a plane wave. It is shown that thermal diffuse scattering makes an important contribution to absorption (in agreement with a treatment due to Yoshioka & Kainuma 1962), particularly for elements of high atomic number. The theory also predicts a strong anomalous absorption effect for low order reflexions. The mean and anomalous absorption coefficients are strongly temperature dependent. An improvement of several times the penetration at room temperature is predicted for the penetration at low temperatures, for elements of high atomic number and low Debye temperature 6. In practice the improvement realized is probably limited by another, less temperature-dependent, absorption process due to electronic excitations. Careful experimental measurements of absorption coefficients at low temperatures are needed.

The absorption of high energy electrons in cosmic radiation

Up to now the various calculations based on the cascade-theory of cosmic radiation have not yet considered the problem of the absorption, or of the probability for an electron of given energy of passing through a layer of material, taking into account, that the original electron cannot be distinguished from any of its secondaries. We discuss this problem here assuming the Furry-model; we do not however give this probability itself but the corresponding range of the electron in the material.

The Absorption of High Energy Electrons. IV

The scattering of electrons in lead and in aluminum has been studied, mainly under the conditions used previously for the study of energy loss. The primary object of the investigation was to determine the extent to which the existing energy loss data (up to 13.5 Mev) are affected by multiple scattering. The conclusion reached is that the measurements so far made in lead with electrons below 9 Mev are so much affected by multiple scattering within the absorbing material that they are of very little use as a direct check on the theory for energy loss. In the measurements from 9 to 13.5 Mev the scattering is found to be small enough so that a comparison of the energy losses with the theoretical values is possible. The observed losses are roughly 40 percent in excess of the theoretical. Some measurements on the multiple scattering of 0.9-Mev electrons in thin sheets of aluminum were made, and it was found that the most probable angle of scattering and the average angle of scattering were in good agreement with theoretical predictions.

The Absorption of High Energy Electrons. Part III

The Absorption of High Energy Electrons. Part III

The Absorption of High Energy Electrons, Part II

The Absorption of High Energy Electrons, Part II

The Absorption of High Energy Electrons, Part I

The recoil electrons produced by the 6 Mev gamma-radiation from fluorine bombarded with protons were allowed to pass through 5 mm carbon and 0.5 mm lead absorbers placed across the center of a cloud chamber. The curvatures of the incident and emergent tracks in the magnetic field were measured, the difference giving the loss in passing through the absorber. The losses in carbon are in good agreement with the theoretical losses due to electron collisions alone, and this is satisfactory, since practically no radiative losses are expected in a substance of such low atomic number. In the case of lead, the data show clearly that radiative losses play a large part, and increase with increasing energy of incident particle. The losses in lead are slightly greater than those predicted by theory.