New designs of optical multilayer filters for extending the detection of the highest-energy cosmic rays by atmospheric fluorescence optical telescopes in the presence of crescent moonlight

摘要

This work is aimed at the modeling of optical noise (background radiation) and designing of new optical filters for the detection of atmospheric fluorescence, induced by an ultra-high-energy cosmic ray particle via the extensive air shower effect. The characteristics of optical noise, in the presence of a crescent moon in the spectral region of atmospheric nitrogen fluorescence, in the ultraviolet region are first presented. Then, it is studied how to reduce this noise by notch optical filters, which reject the optical noise emitted in the range between the main peaks of the N2 atmospheric fluorescence, in the UV region. Optical multilayer filters for this purpose have been designed, using the Monte Carlo simulated annealing method, and their performance is presented in this work. There are cases where radioactivity due to alpha particles, emitted for example in radon decays, or radioactivity due to electron accelerator beams could be measured by the technique of air or nitrogen fluorescence. Devices based on this technique can use multilayer optical filters designed and constructed specifically to reject the irrelevant optical noise.