A jazz band can't get much further under the radar than playing on Sunday afternoon once a month at the Green Mill, but that's the schedule for the Chicago Jazz Composers Collective--which helps explain why its fourth anniversary concert has crept up without much fanfare. Modeled on New York's Jazz Composers Collective, the CJCC presents new works--often terrific, always at least interesting--by two members or guests at each concert, allotting half the show to each composer. But the group's anniversary concerts offer a chance to catch up on the whole clan, with all ten members debuting a piece written for the occasion. (Those ten are trumpeter Jeff Beer, reedist Mitch Paliga, vibist Kathy Kelly, flutist Lloyd Brodnax King, drummer Damon Short, guitarists Dave Onderdonk and Don Tisch, and pianists Kelly Brand, Jo Ann Daugherty, and Fred Simon.) This year I've only had access to Simon's composition in advance, but it seems likely to be the highest-concept entry. His two-part "Fall of America" begins with flutist King reciting Allen Ginsberg's iconic 1956 poem "America" against a moody piano-and-vibes ostinato colored by a small tenor melody; in part two, an instrumental sextet comments on the poem's themes with a spare, measured line that's both wistful and ironic. The piece employs the gentle, carefully cantilevered style Simon has stuck to for most of the past 30 years--you could think of it as Prairie-architecture melody--but this time out he's added some subtle, distinctive harmonic complications that ought to light a fire under the soloists. Sun 11/20, 2 PM, Green Mill, 4802 N. Broadway, 773-878-5552, $5.