Muon-catalyzed<i>dd</i>fusion between 25 and 150 K: Experiment

Abstract

This paper reports an experimental investigation of muon-catalyzed fusion in pure deuterium by detection of dd fusion neutrons. Target temperatures of 25.5--150 K and gas densities of 2% and 5% liquid-hydrogen density were used. The rates \ensuremath{\lambda}\ifmmode \tilde{}\else \~{}\fi{}F for dd\ensuremath{\mu} formation from both hyperfine states of d\ensuremath{\mu} atoms as well as the hyperfine transition rates \ensuremath{\lambda}\ifmmode \tilde{}\else \~{}\fi{}FF\ensuremath{'} were separated in a kinetic analysis of the observed time spectra. This measurement of the temperature dependence of all important rates in the dd\ensuremath{\mu} catalysis cycle allows a comprehensive and quantitative test of the present theory of resonant molecule formation. In particular, the temperature behavior of dd\ensuremath{\mu} formation from the d\ensuremath{\mu} quadruplet state determines the binding energy \ensuremath{\varepsilon}11=-1966.1(3) meV of the participating dd\ensuremath{\mu} state with unique accuracy. In general, convincing agreement between experiment and theory concerning the dd\ensuremath{\mu} formation process is found, whereas the theoretical hyperfine rates, consisting of nonresonant and resonant contributions, exceed the experimental values by \ensuremath{\sim}40%.