Cosmic-ray isotope measurements with HELIX (high energy light isotope experiment)

Cosmic rays, high energy particles originating from outside of the solar system, are believed to be dominated by particles from our Galaxy at least up to the energy of 10^15 eV. Recent precise measurements of leptons and light nuclei below 1 TeV/nucleon by the satellite experiments PAMELA and AMS-02 are challenging the classical paradigm of Galactic cosmic-ray astrophysics. It is essential to understand the propagation of these particles to study the origins of discrepancies with the classical models. Detailed measurements of isotopes with known decay times can provide unique data to constrain the propagation models by providing the acceleration and the propagation timescales of cosmic rays.

HELIX (High Energy Light Isotope eXperiment) is designed to measure the clock isotope 10^Be up to 10 GeV/n. HELIX consists of a 1 Tesla superconducting magnet with a high-resolution tracking system and a ring-imaging Cherenkov detector to make precise measurements to energies more than an order of magnitude higher than currently available. To cover a wide energy range from 0.1 GeV/n to 10 GeV/n, the HELIX collaboration chose to have at least two flights with different detector designs. The first stage of HELIX is scheduled to have a long duration balloon flight out of McMurdo Station during NASA’s 2020/21 Antarctic balloon campaign. I will present the design, current status of instrumental development, and the future plans for HELIX.