A possible underground accelerator in the Dresden Felsenkeller

Due to the suppression by the Coulomb barrier, the cross sections of astrophysically relevant nuclear reactions are very low at the stellar energy. Therefore they can only be directly measured in a low-background environment. For more than a decade, the LUNA collaboration has pursued this approach with a 0.4\,MV accelerator in the Gran Sasso underground laboratory in Italy. It was highly successful in studying the nuclear physics of the Sun and of the Big Bang. However, the energy range of LUNA is not sufficient to address the nuclear reactions of stellar helium burning and the neutron source reactions for the astrophysical s-process. Therefore, in the NuPECC 2010 long range plan it is recommended to install one or more accelerators with higher energy underground. A comparison of the background at LUNA (1400\,m rock cover) and the Dresden Felsenkeller (45\,m) has shown that with an anti-muon veto the background counting rates in a $\gamma$-detector differ only by a factor of three. The feasibility of installing a 2-3\,MV accelerator for intense $\alpha$-beams in Felsenkeller will be discussed.