We report on a new measurement of the ^ { 14 } N ( p, \gamma ) ^ { 15 } O capture cross section at E _ { p } = 140 to 400 keV using the 400 kV LUNA accelerator facility at the Laboratori Nazionali del Gran Sasso ( LNGS ) .
The uncertainties have been reduced with respect to previous measurements and their analysis .
We have analyzed the data using the R-matrix method and we find that the ground state transition accounts for about 15 % of the total S-factor .
The main contribution to the S-factor is given by the transition to the 6.79 MeV state .
We find a total S ( 0 ) = 1.7 \pm 0.2 keV b , in agreement with recent extrapolations .
The result has important consequences for the solar neutrino spectrum as well as for the age of globular clusters .