The development culminated in the high-flux reactor of the Institut Laue-Langevin (in operation since 1972) that achieved the highest neutron flux to this date. Besides a few high-flux sources, there were some twenty medium-flux reactor sources at universities and other research institutes. Starting in the 1980s, many of these medium-flux sources were shut down, and research concentrated at a few world-leading high-flux sources. Today, most neutron scattering experiments are performed by research scientists who apply for beamtime at neutron sources through a formal proposal procedure. Because of the low count rates involved in neutron scattering experiments, relatively long periods of beam time (on the order of days) are usually required to get good data. Proposals are assessed for feasibility and scientific interest. Walter B. Gibson  Walter Brown Gibson (September 12, 1897 – December 6, 1985) was an American author and professional magician, best known for his work on the pulp fiction character "The Shadow". Gibson, under the pen-name Maxwell Grant, wrote "more than 300 novel-length" "Shadow" stories, writing up to "10,000 words a day" to satisfy public demand during the character's golden age in the 1930s and 1940s. He authored several novels in the Biff Brewster juvenile series of the 1960s. He was married to Litzka R. Gibson, also a writer, and the couple lived in New York state. Walter Brown Gibson was born on September 12, 1897, in the Germantown neighborhood of Philadelphia, Pennsylvania, to Alfred Cornelius Gibson (1849–1931) and May Morrell Whidden Gibson (1863–1941). Gibson graduated from Colgate University in 1920 where he was a brother of Delta Kappa Epsilon, and began working "for newspapers in his native Philadelphia as a reporter and crossword-puzzle writer," specifically for "The North American", and later "The Evening Ledger". In 1928 Gibson was asked by Macfadden Publications to edit "True Strange Stories"; he did, for a time, identified as Walter Scofield, commuting back and forth to New York. In 1931, after submitting some crime stories for "Detective Story Magazine", he was asked by publishers Street & Smith to produce the first print adventure of The Shadow, who at that stage was merely a voice, the mysterious narrator of the Street & Smith-sponsored "Detective Stories" radio drama. It was Gibson who created all the mythos and characterization of The Shadow, including his alter ego of wealthy playboy Lamont Cranston.