The SOCIAL project: measurement of the $$^{14}$$N(p,$$\gamma )^{15}$$O cross section

Abstract Solar neutrinos play a significant role in constraining the physical conditions in the interior of the Sun and are a unique tool to investigate its core composition. The $$^{14}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>14</mml:mn> </mml:mmultiscripts> </mml:math> N(p, $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> </mml:math> ) $$^{15}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>15</mml:mn> </mml:mmultiscripts> </mml:math> O cross section is the dominant nuclear uncertainty on CNO neutrino flux predictions. At Solar energies (15–50 keV) such a cross-section is too low to be measured directly, therefore current estimates are based on extrapolations of higher energy data. The SOCIAL (SOlar Composition Investigated At LUNA) project aims at determining the $$^{14}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>14</mml:mn> </mml:mmultiscripts> </mml:math> N(p, $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> </mml:math> ) $$^{15}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>15</mml:mn> </mml:mmultiscripts> </mml:math> O reaction rate at astrophysical energies with 5% precision, as requested by Solar models. We take advantage of the much suppressed $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> </mml:math> -ray background achievable in the underground Gran Sasso laboratory to measure $$^{14}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>14</mml:mn> </mml:mmultiscripts> </mml:math> N(p, $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> </mml:math> ) $$^{15}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>15</mml:mn> </mml:mmultiscripts> </mml:math> O partial cross-section in the 100–370 keV energy range. We deliver an intense proton beam from the LUNA accelerator to a solid nitrogen target. $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> </mml:math> -rays are detected with a high-efficiency 4 $$\pi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>π</mml:mi> </mml:math> -BGO detector composed of 6 independent segments. The data analysis technique will lead to determine the total and the partial cross-sections for individual gamma transitions. An overview of the experimental setup and the analysis technique are presented.