The High Energy Light Isotope Experiment (HELIX): A Balloon-borne Superconducting Magnetic Spectrometer*

Propagation of cosmic rays and properties of the Galaxy can be studied through measurements of secondary cosmic ray isotopes. Radioactive isotopes such as Be-10 probe the confinement lifetime. I will present the High Energy Light Isotope eXperiment (HELIX), which aims to measure the Be-10/Be-9 ratio at energies higher than any previous detector. HELIX is a balloon-borne magnet spectrometer utilizing a superconducting magnet of magnitude ~1 T together with a silica aerogel ring imaging Cherenkov counter (RICH) to identify the masses of relativistic particles. HELIX is scheduled to fly in Antarctica in 2020, and makes use of NASA's long duration ballooning capability. I will review the capability of the first HELIX flight to help constrain cosmic ray confinement in the Galaxy.