Search for muon catalyzed d3He-fusion

We report on the results of an experiment aimed at observing muon-catalyzed d3He-fusion with a setup previously used for studies of the muon-catalyzed dd-fusion. The basic element of the setup is a high pressure ionization chamber operating as an active target. In this experiment the chamber was filled with an HD + 3He (5.6%) gas mixture at 13.2 bar pressure and 50 K temperature. These conditions were chosen as optimal for formation of the 3Heμd-molecules with a low level of background from the d-μ-d fusion. The chamber was exposed to the negative muon beam at PSI. During a 3-week data-taking period, 9.7 x 108 muon stops have been selected. The analysis of the data was able to determine a new upper limit for the d3He-fusion rate in the 3Heμd-molecule (λf≤ 6x 104 s-1), which is more than three orders of magnitude lower than the previously existed limit