A polarized atomic hydrogen beam

Abstract

We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the beam at all points along its path. As a subsidiary result, we also present measurements of the relative and absolute efficiencies of the VjG Supavac mass analyzer for masses 1 and 2.

Velocity dependence of simple magnetic devices in atomic physics

“…This time is just the length of the magnets divided by the velocity in the x direction. It is clear that if a suitable model exists for the atomic source a computer program can be run to trace the paths of the various atoms as in [10].…”

“…For finite lengths of the magnets and extended sources a computer model can again be constructed using basic physics to trace the paths of each atomic velocity group in the beam. Reference [10] actually describes such a modelling process for an experiment.…”

“…Typical cross-sectional view of a hexapole magnet[10].atoms in the beam leads to an equation of simple harmonic motion as seen below.F = -VU = -(-// Q V|£|) = (/z Q )Vp:/2)* 2 +/)] (14)where |B| = (K/2)(x 2 +y 2 ) = Kt 2 /2, the magnitude of the field (15) F = (fi a K)(xi + yj) and u = I ---) , the angular frequency (16)…”

Measurement of intensity-dependent rates of above-threshold ionization (ATI) of atomic hydrogen at 248 nm

“…I calculated the dissociation fraction from the change in the H2 pressure at the RGA. There are two common definitions of dissociation fraction (Chan et al 1988). The one used here is the fraction of the total number of atoms and molecules that are atoms:…”

“…The important thing to know about the atomic hydrogen beam was its density. This can be calculated as in Chan et al (1988) from the pressure inside the discharge tube, the estimated conductances of the capillary, the process of effusion at the end of the capillary, and the angular size of the hole in the skimmer.…”