Luminescence of Polymethyl Methacrylate Excited by a Runaway Electron Beam and by a KrCl Excilamp
This paper reports an experimental study of luminescence excited in polymethyl methacrylate (PMMA) by a runaway electron beam and by a KrCl excilamp with a wavelength of 222 nm. It is shown that the major contributor to the luminescence of PMMA in both cases is a luminescence band with a maximum intensity at ~490 nm. Based on experiments with the excilamp, it is supposed that Cherenkov radiation with a wavelength shorter than 300 nm is bound to increase the intensity of this band. The luminescence intensity at ~490 nm varies proportionally with the number of beam electrons, allowing the use of this radiation to determine the number of high-energy electrons in electron beams. In PMMA with high absorption at 300–400 nm, one more luminescence band with a maximum intensity at ~400 nm is observed. It is confirmed that in gas diodes at a pressure of 760 torr, the intensity of Cherenkov radiation against the background of luminescence is low and undetectable.