Studies of amorphous silica fibers bombarded with neutral particles indicate that both photons and neutrons have the same mechanism for creating defects, however rate of creation and affected wavelengths pertaining to each type remains unclear. It is difficult to positively attribute defects to one or the other when both are introduced in the sample concurrently. We sought to mitigate this issue in the current experiment by placing lead shielding of various thicknesses in the line of radiation from a nuclear reactor to the Yb-doped fiber, which is then exposed to neutrons and photons from a nuclear reactor source. Reducing photon fluence via various thicknesses of high-Z shielding materials, while maintaining the same neutron fluence, provides for a comparison of defect formation rates in YDF. In comparing neutron dominant and gamma dominant radiation sources for a similar total dose, the absorption spectrum of the 20/400 YDF deconvolves to several Gaussian peaks, with a 0.1 eV shift for the 1-1.5 eV peak and a 0.15 eV shift for the 2-2.5 eV peak (lower energies). Noticeably, the gamma radiation dominant source absorption spectrum shows a peak around 1.6 eV significantly more pronounced than in the neutron radiation dominant source dataset.