Monocular Measurement of the Spectrum of UHE Cosmic Rays by the FADC Detector of the HiRes Experiment

We have measured the spectrum of UHE cosmic rays using the Flash ADC (FADC) detector (called HiRes-II) of the High Resolution Fly’s Eye experiment running in monocular mode. We describe in detail the data analysis, development of the Monte Carlo simulation program, and results. We also describe the results of the HiRes-I detector. We present our measured spectra and compare them with a model incorporating galactic and extragalactic cosmic rays. Our combined spectra provide strong evidence for the existence of the spectral feature known as the ``ankle.‘’