{'fraction_non_alphanumeric': 0.0161892901618929, 'fraction_numerical': 0.009962640099626401, 'mean_word_length': 5.28125, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Background of an inversion: the first gas laser

A description of the problems encountered in creating the first continuously oscillating laser (the helium-neon "optical maser") is given, together with some previously unpublished data taken by the author on the excitation transfer process between helium metastables and the upper laser levels in neon. Research on the helium-neon excitation transfer problem is traced back to a little-known paper by Headrick and Duffendack published in 1931. An interesting historical coincidence is noted in that most of the people who did pioneering work in the laser field had some connection with the Physics Department at Columbia University. That probability arose because Columbia was the birthplace of induced resonance experiments in physics during the 1930s.