Resonance strengths in the 17,18O(p, α)14,15N reactions and background suppression underground

Resonance strengths in the 17,18O(p, α)14,15N reactions and background suppression underground

Bruno, C. G.; Scott, D. A.; Formicola, A.; Aliotta, M.; Davinson, T.; Anders, M.; Best, A.; Bemmerer, D.; Broggini, C.; Cavanna, A. C. F.; Corvisiero, P.; Depalo, R.; Di Leva, A.; Elekes, Z.; Fülöp, Z.; Gervino, G.; Griffin, C. J.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Menegazzo, R.; Napolitani, E.; Prati, P.; Somorjai, E.; Straniero, O.; Strieder, F.; Szücs, T.; Trezzi, D.

We report on measurements of resonance strengths and energies for the Ep=151 and 193 keV resonances in the18O(p, α )15N and17O(p, α )14N reactions, respectively, obtained during commissioning of a new setup for alpha-particle detection studies at the LUNA underground laboratory. Our values, ωγ(151)=164.2±0.9stat+12.1−11.7syst meV and ωγ(193)=1.68±0.03stat±0.12syst meV, are in excellent agreement with those reported in the literature. New values of resonance energies are Ep=151.2±0.3 keV and Ep=194.8±0.3 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.

Keywords: Nuclear Astrophysics

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