Radiation hardness studies of InGaAs photodiodes at 30, 52, & 98 MeV and fluences to 1010 protons/cm2

We report the effects of radiation damage due to ionizing protons on InGaAs photodiodes. The photodiodes were irradiated at energies of 30, 52, and 98 MeV and fluences up to 10(10) protons/cm(2) in experiments at the Indiana University Cyclotron Facility. The photodiodes were tested for changes in their dark current, their relative responsivity as a function of wavelength from 1000 - 1600 nm, and their absolute responsivity in narrow bandpasses spread throughout the same wavelength region. The measurements were all made with detectors traceable to NIST standards. At these exposures and energies, the most significant effects are seen in the dark current levels.