Resonance strengths in the O-17,O-18(p, alpha)N-14,N-15 reactions and background suppression underground Commissioning of a new setup for charged-particle detection at LUNA

We report on measurements of resonance strengths and energies for the and 193 keV resonances in the O-18(p,)N-15 and O-17(p,)N-14 reactions, respectively, obtained during commissioning of a new setup for alpha-particle detection studies at the LUNA underground laboratory. Our values, meV and meV, are in excellent agreement with those reported in the literature. New values of resonance energies are keV and keV, respectively, this latter with the highest precision to date. Comparative background measurements in silicon detectors overground and underground were also carried out, yielding up to a factor of 15 in background suppression at LUNA at energies around 200keV. This clearly demonstrates the usefulness of underground measurements in charged-particles experiments, especially at low detection energies.