Velocity distribution in an atomic beam

Ganghua Mei

I. Estermann, O. C. Simpson, Otto Stern

The free fall of atoms is observed in long molecular beams of potassium and cesium atoms. The measurement of the intensity distribution in a beam deflected by gravity represents the velocity distribution of the beam atoms and permits an accurate determination of this distribution. The results show that the measured values agree in general with those calculated for a modified Maxwellian velocity distribution in the beam. At larger deflections, i.e., for slow atoms, a deficiency of intensity was observed, which increased both with increasing deflection and with increasing pressure in the oven where the beam originates. This deficiency is explained by collisions in the immediate vicinity of the oven slit.

A. D. Gazazyan, Razmik G. Unanyan

Michael Köhl, Anton Öttl, Stephan Ritter +3 more

Richard C. Miller, Polykarp Kusch

A high-resolution, high-intensity, spiral velocity selector has been designed for the study of the velocity distributions of the components of atomic and molecular beams. It has been found possible to design oven slits which closely approximate the ideal aperture of kinetic theory. An analysis has been made of the velocity distributions in beams of potassium and thallium over a range of velocity from 0.3 to 2.5 times the most probable velocity in the oven. The agreement between the observed distribution and that deduced, on the basis of the assumptions that the distribution in the oven is Maxwellian and that the aperture is ideal, is very good.

M. R. Williams, Walter F. Buell, H. Metcalf