Abstract
Recent improved measurements of threshold excitation and polarization of radiation from helium excited by electrons have led to the conclusion that previously reported "anomalies" are of experimental origin. Helium lines, $\ensuremath{\lambda}=4922,4388, \mathrm{and} 5016$ \AA{}, exhibit polarization energy dependencies similar to that previously reported for $\ensuremath{\lambda}=3889$ \AA{}. Helium lines $\ensuremath{\lambda}=4922 \mathrm{and} 4388$ \AA{} have excitation probability energy dependencies through limited energy ranges as predicted by theory. A tentative explanation of earlier results involves the contribution to both the excitation probability and the polarization of radiation caused by radially directed electrons elastically scattered from the electron beam. Attempts to reduce the radial travel of electrons have resulted in threshold and near-threshold polarization measurements which approach expected magnitudes.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
