Understanding the propagation processes of cosmic rays is critical to interpreting features in the cosmic-ray spectrum. HELIX (High Energy Light Isotope eXperiment) seeks to improve this understanding by measuring the chemical and isotopic abundances of light cosmic ray nuclei. HELIX is optimized to measure the abundances of the propagation clock isotope Be-10 and stable isotope Be-9 at energies between 0.2 and 3 GeV/n, an essential dataset for understanding the propagation history of cosmic rays. In addition, HELIX will measure the fluxes of all the light isotopes between protons (Z=1) and neon (Z=10). The HELIX instrument is a magnet spectrometer, designed to fly on a long duration balloon, and consists of a 1 Tesla superconducting magnet with a high-resolution drift-chamber tracker for measuring the particle rigidity, a time of flight detector for measuring charge and velocities at lower energies, and a ring-imaging Cherenkov detector (RICH) for measuring particle velocities at higher energies. Although containing contributions to many elements of HELIX's payload, the majority of this thesis project concerns the design, construction, and calibration of HELIX's RICH detector. This thesis will first give a scientific background on the basics of cosmic ray physics. It will then present an analysis demonstrating how HELIX's scientific goals motivate the development of the RICH detector and how its proper design and calibration affect the final results. Next, this thesis will discuss the properties of silicon photomultipliers (SiPMs), which are used to create the RICH detector's focal plane, as well as the work done to characterize and calibrate those selected for use in HELIX. This thesis will also discuss the development, debugging, and integration of the front end electronics used in the RICH's focal plane. Finally, it will outline the construction, installation into the payload, and in-place calibration of the full RICH detector.