  The stable nucleus $^{15}$N is the mirror of $^{15}$O, the bottleneck in the
hydrogen burning CNO cycle. Most of the $^{15}$N level widths below the proton
emission threshold are known from just one nuclear resonance fluorescence (NRF)
measurement, with limited precision in some cases. A recent experiment with the
AGATA demonstrator array determined level lifetimes using the Doppler Shift
Attenuation Method (DSAM) in $^{15}$O. As a reference and for testing the
method, level lifetimes in $^{15}$N have also been determined in the same
experiment. The latest compilation of $^{15}$N level properties dates back to
1991. The limited precision in some cases in the compilation calls for a new
measurement in order to enable a comparison to the AGATA demonstrator data. The
widths of several $^{15}$N levels have been studied with the NRF method. The
solid nitrogen compounds enriched in $^{15}$N have been irradiated with
bremsstrahlung. The $\gamma$-rays following the deexcitation of the excited
nuclear levels were detected with four HPGe detectors. Integrated
photon-scattering cross sections of ten levels below the proton emission
threshold have been measured. Partial gamma-ray widths of ground-state
transitions were deduced and compared to the literature. The photon scattering
cross sections of two levels above the proton emission threshold, but still
below other particle emission energies have also been measured, and proton
resonance strengths and proton widths were deduced. Gamma and proton widths
consistent with the literature values were obtained, but with greatly improved
precision.
