Underground experimental study finds no evidence of low-energy resonance in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Li</mml:mi><mml:mprescripts/><mml:none/><mml:mn>6</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo>)</mml:mo><mml:mmultiscripts><mml:mi>Be</mml:mi><mml:mprescripts/><mml:none/><mml:mn>7</mml:mn></mml:mmultiscripts></mml:mrow></mml:math>reaction
D. Piatti, T. Chillery, R. Depalo, M. Aliotta, D. Bemmerer, A. Best, A. Boeltzig, C. Broggini, C. G. Bruno, A. Caciolli, F. Cavanna, G. F. Ciani, P. Corvisiero, L. Csedreki, T. Davinson, A. Di Leva, Z. Elekes, F. Ferraro, E. M. Fiore, A. Formicola, Zs. Fülöp, G. Gervino, Alex Gnech, A. Guglielmetti, C. Gustavino, Gy. Gyürky, G. Imbriani, M. Junker, I. Kochanek, Maria Lugaro, L. E. Marcucci, Paola Marigo, E. Masha, R. Menegazzo, V. Mossa, F. R. Pantaleo, V. Paticchio, R. Perrino, P. Prati, L. Schiavulli, K. Stöckel, O. Straniero, T. Szücs, M. P. Takács, S. Zavatarelli
Abstract
The astrophysical $^{6}\mathrm{Li}(p,\ensuremath{\gamma})^{7}\mathrm{Be}$ reaction occurs during Big Bang nucleosynthesis and the pre-main sequence and main sequence phases of stellar evolution. The low-energy trend of its cross section remains uncertain, since different measurements have provided conflicting results. A recent experiment reported a resonancelike structure at center-of-mass energy 195 keV, associated to a positive-parity state of $^{7}\mathrm{Be}$. The existence of such resonance is still a matter of debate. We report a new measurement of the $^{6}\mathrm{Li}(p,\ensuremath{\gamma})^{7}\mathrm{Be}$ cross section performed at the Laboratory for Underground Nuclear Astrophysics, covering the center-of-mass energy range $E=60$--350 keV. Our results rule out the existence of low-energy resonances. The astrophysical $S$-factor varies smoothly with energy, in agreement with theoretical models.