Double beta decay experiment using /sup 100/Mo

We have started a search for double beta decay of /sup 100/Mo using lithium drifted silicon Si(Li) detectors and thin molybdenum (Mo) foils. The experiment is located in the Consolidated Silver mine at Osburn, Idaho. We present preliminary results comparing a prototype array above ground to the array below ground, both without Mo foils. We also present data from an underground run with /sup 100/Mo foils which gives a half-life limit for the Majoron decay mode of /sup 100/Mo greater than 5 x 10/sup 19/ years (68% confidence level) equivalent to 8 x 10/sup 20/ years for /sup 76/Ge. 4 refs., 8 figs.