Efficient Bulk Search for Fractional Charge with Multiplexed Millikan Chambers

We outline the design of a fully automated Millikan droplet .apparatus that could detect a single free fractional charge in several hundred grams of matter even without the use of a prefilter. This would constitute an improvement over current limits by about five orders of magnitude. The experiment achieves high material throughput and high background rejection through online processing which allows for a feedback system that can concentrate the measurement effort on anomalous droplets. The task is simplified by generating a monodisperse stream of droplets which will be preprocessed to let only a very narrow range of charges enter the Millikan chamber. Because the droplets can act as carriers of finely dispersed materials it is also possible to search for fractional charge in matter which has not undergone extensive refinement that may have excluded fractionally charged atoms from the sample. In a large refinery style operation many such Millikan chambers could be multiplexed to achieve extremely large material throughput. Submitted for Publication *Work supported in part by the Depar.tment of Energy contract DE-AC03-76SF00515 (SLAC), W-7405-ENG-48 (LLL), and W-7405-ENG-36 (LANL).