Deuteron-deuteron fusion by heavy water cluster impact

The impact on deuterated surfaces of singly charged clusters of tens to hundreds of D2O molecules accelerated to 200-600 keV has been found to produce d-d fusion reactions. Detection of the charged reaction products - 3-MeV 1H, 1-MeV 3H, and 0.8-MeV 3He - in a surface barrier detector serve as the signature of d-d fusion. The observed fusion rates are many orders of magnitude higher than can be accounted for on the basis of the very low energies of the individual deuterons in the clusters. Thus a collective mechanism involving energy concentration on a small fraction of the deuteriums appears to be at play. Dependence of fusion yields on cluster size and energy is discussed. Various types of experiments designed to exclude the possibility of artifacts is described. In particular, time-of-flight experiments clearly demonstrate that the observed fusion events are caused by the cluster ions rather than by much faster moving small-ion impurities