reaction in metal at bombarding energies below 5 keV

In order to study the electron screening effect on low-energy nuclear reactions in metals, the D+D reaction in Ti and Yb was investigated. Yields of protons emitted in the D(d, p)T reactions from the deuteron bombardment of Ti and Yb thick targets with bombarding energies between 2.5 and 7.2 keV were measured. The obtained yields were compared with those predicted by using the parametrization of cross sections at higher energies. It was found that the reaction rates in metals are enhanced over those of the bare nuclei for keV, and the enhancement can be interpreted as caused by the electron screening. The electron screening potentials in Ti and Yb are deduced to be eV and eV, respectively.