Polarized Electrons from Photoionization of Polarized Alkali Atoms

Abstract

Figure 6 shows the measured electron densities vs 2 S~density (a quantitative measure of the intensity of the discharge) for He sample pressures of 0. 1 and 0. 22 torr. Under sample conditions closely approximating those employed and analyzed by McCusker et al. (8% absorption of He pumping light on He sample and pressure of 0. 1 torr) in extracting an optimum polarized electron beam, the electron density is approximately 7 &&10cm . However, the error could be as large as a factor of 2, primarily because of uncertainty in the proportionality constant k in Eq. (14), taken here to be 230 cm sec ' appropriate to a uniform electron distribution.fBased on a Master of Arts thesis by J. C. Hill (Rice University, 1969). Phys. Rev. 132, 2561.R. C. Greenhow, Phys. Bev. 136, A660 (1964). 4This relation holds only for P«1, a condition satisfied in the present experiment.The process of photoionization of polarized alkali atoms in an atomic beam has been studied for potassium and lithium. Depolarization processes associated with photoionization of alkali molecules and optically excited atoms were discovered. After eliminating these depolarization mechanisms, the measured photoelectron polarization agreed within an accuracy of 3% with the predicted polarization based on the current theory for this electric dipole process. Using a polarized Li' atomic beam and a pulsed uv light source, we have produced an intense and highly polarized electron beam with 2 x10 electrons in l.5 psec and with a polarization of 0.78, which is a suitable prototype injector source for a high-energy electron accelerator.

Electron spin-polarized alkaline-earth ions produced by multiphoton ionization

“…6 is damage-free since it employs a gas as a target, and the theoretical results show that more than 90% polarization can be achieved when the laser wavelength is properly chosen. Needless to say, as a polarized-electron source, the use of rare gas rather than alkali-metal 7,8 or alkaline-earth vapor is by far preferable from a technical point of view, since rare gas is much easier to handle and higher electron current can be obtained simply by increasing the gas pressure.…”

Photoemission of spin-polarized electrons from GaAs

“…The use of NEA GaAs as a source of polarized electrons has been proposed previously. 4 In Sec. V we describe briefly the criteria for a good source of polarized electrons and discuss NEA GaAs in light of them.…”

Various Researches in Physics

“…Photoionization involved a pulsed high-intensity ultraviolet light source. Eventually a polarized electron beam with a polarization of 0.8 and intensity of 2 × 10 8 e − in a 1.5-µs pulse was produced (38). In 1960 we had the idea to study Mach's principle by looking for the anisotropy of inertial mass in an NMR experiment.…”

“…Our Yale polarized electron source (to be called PEGGY) (38,60), based on photoionization of a polarized 39 K or 6 Li atomic beam, was taken to SLAC. The first polarized electron beam was accelerated to high energy (20 GeV) in 1974 and a polarization of 0.8 was measured by Møller scattering (61).…”