The Energy Distribution of Secondary Electrons from Columbium

Abstract

Energy distribution curves of secondary electrons from an outgassed columbium target have been obtained with the same apparatus as in similar studies on molybdenum. The results from Cb are qualitatively similar to those from Mo. "Discrete loss" and "fixed energy" groups of secondary electrons are observed at energies which are in most cases slightly less than the corresponding ones in the case of Mo. The number of elastically reflected electrons was also studied as a function of primary energy. The curve shows marked similarity to that obtained from Mo, the peaks again being at somewhat lower energies in the case of Cb. It is shown that the lower values of the energies involved in the various phenomena in the present case are to be expected because of the lower atomic number of Cb and because of its larger lattice constant.

Study of Secondary Electron Emission from Niobium at Cryogenic Temperatures

“…Apart from the maxima II peaks Haworth [8] found that in the low energy section of the curve for Nb (on the true secondaries curve region), there appeared fixed energy groups (appearing as humps on the main curve) at energies of 9, 21 and 31 eV. These humps too were characteristic of the metal used and independent of the primary electron energies.…”

“…A spherical retarding grid has the advantage of collecting secondary electrons over all emission angles. The dispersion analyzers, typically of the electrostatic type [26,29,34,42,7,10] and the magnetostatic type, [3,4,45] directly measure the secondary electron emission at a particular energy. These dispersion analyzers preferentially select secondary electrons emitted within a narrow energy band to be detected.…”

“…It must also have its discharge pressure held below 10 -2 by the low vacuum pump during operation. The pump used in this experiment has a blade rotation speed of 75,000 rpm, and is capable of maintaining a base pressure of8 10 Torr with a pumping speed of 60 l/s for nitrogen.…”