High Energy Light Isotope eXperiment

HELIX is a balloon-borne experiment designed to measure the chemical and isotopic abundances of light cosmic ray nuclei. Measurements by HELIX, especially of ¹⁰Be from 0.2 GeV/n to beyond 3 GeV/n, will provide an essential set of data for the study of propagation processes of the cosmic rays. HELIX consists of a 1 Tesla superconducting magnet with a high-resolution drift-chamber tracker, time of flight detector, and a ring-imaging Cherenkov detector. The instrument is planned to have a long-duration balloon flight during an upcoming northern or southern hemisphere balloon campaign.

Measurements of this kind at lower energies have in the past provided profound insights into the nature and origin of cosmic rays, revealing, for instance, information about acceleration and confinement timescales, and exposing some conspicuous discrepancies between solar and cosmic-ray abundances.