Parity and the Polarization of Electrons from Co60 AND Parity and Electron Polarization: Møller Scattering.

In " THE PHYSICAL REVIEW ", Second Series, Vol. 106, N. 2 pp. 386-7 and Vol. 107, N. 2, pp. 643-4, two entire issues in original printed wrappers. Very fine copies, ownership inscriptions. FIRST EDITIONS. " The first measurement of longitudinal polarization in decay was made by Frauenfelder et al. in a very difficult measurement using Mott scattering of the electrons from 60 Co Beta decay. These measurements clearly showed parity violation, and gave a result for longitudinal polarization consistent with, though smaller thanP = -v/c. This original Mott scattering experiment was difficult for a number of reasons. Since Mottscattering only measures transverse polarization, it is necessary to electrostatically rotate the longitudinal polarization from Beta Decay. Such an electrostatic rotation generates very short focal length electron optics, and is generally astigmatic as well. Furthermore, the rotation is correct for only one energy, while Beta Decay gives a broad energy spectrum. Only the scattered electron is detected, making rejection of backgrounds very difficult, as there are often γ’s associated with Beta Decay as well as electrons and γ’s from beam striking the apparatus walls, rotator electrodes and beam dump. Plural and multiple scattering effects in the very thinnest of foils degrade the asymmetry, and this effect is not a menable to analytic calculation. Finally, Mott scattering does not work for positrons, removing the possibility of checking many Beta decays.These realities led Frauenfelder et al. to switchto Møller scattering for electron polarimetry, and they soon published (in the same volume of Physical Review as their earlier Mott measurements!) Møller scattering measurements of longitudinal polarization." (Overview of electron polarimetry Charles K. Sinclair. https://pos.sissa.it/archive/conferences/182/033/PSTP2013_033.pdf ). EZHELA, pag 156.