Resonant ddμ formation in condensed deuterium -: art. no. 052705

The rate of dd mu muonic-molecule resonant formation in d mu atom collisions with a condensed deuterium target is expressed in terms of a single-particle response function. In particular, dd mu formation in solid deuterium at low pressures is considered. Numerical calculations of the rate in the case of fee polycrystalline deuterium at 3 K have been performed using the isotropic Debye model of a solid. It is shown that the energy-dependent dd mu formation rates in the solid differ strongly from those obtained for D-2 gaseous targets, even at high d mu kinetic energies. Monte Carlo neutron spectra from dd fusion in dd mu molecules have been obtained for solid targets with different concentrations of orthodeuterium and paradeuterium. The recent experimental results performed in low-pressure solid targets (statistical mixture of ortho-D-2 and para-D-2) are explained by the presence of strong recoil-less resonance peaks in the vicinity of 2 meV and very slow deceleration of d mu atoms below 10 meV. Good agreement between the calculated and experimental spectra is achieved when a broadening of D-2 rotational and vibrational levels in solid deuterium is taken into account. It has been shown that resonant dd mu formation with simultaneous phonon creation in the solid gives only about 10%, contribution to the fusion neutron yield. The neutron time spectra calculated for pure ortho-D-2 and paraD(2) targets are very similar. A practically constant value of the mean dd mu formation rate, observed for different experimental conditions, is ascribed to the fact that all the recent measurements have been performed at temperatures T less than or similar to 19 K. much lower than the target Debye temperature Theta (D) approximate to 110 K. In result, the formation rate, obtained in the limit T/Theta (D)much less than1, depends weakly on the temperature.