The propagation process of cosmic rays in the Galaxy (GCR) is a critical topic of research towards an understanding of GCR origins and interpretations of recently discovered `anomalous' spectral features like the hardening spectra of many elements starting at a few hundred GeV/n and an increasing positron fraction from about 10 GeV to 300 GeV. Constraints on models of propagation require measurements of secondary species of various kinds, e.g., stable nuclei like boron, or unstable isotopes like Be10, which probe different model parameters. Therefore, a full picture of the propagation process can only be achieved with inputs from more than one experiment.
The Cosmic Ray Energetics And Mass instrument on the International Space Station (ISS-CREAM) is dedicated to measurements of fluxes of GCR elements from protons to Fe nuclei from 1 TeV up to the cosmic-ray `knee'. Data is available from an on-orbit operation that extended for 539 days, where boron fluxes (or boron-to-carbon ratios) could be extracted. The High Energy Light Isotope eXperiment (HELIX) is a magnetic spectrometer that is devoted to measurements of light (up to Ne) isotopes. It is under development and making steady progress towards a summer 2024 high-altitude balloon campaign in Kiruna, Sweden.
I will first present analysis results with the ISS-CREAM instrument with a focus on the measurement of boron-to-carbon ratios. Challenges with the energy calibration of its calorimeter persist throughout the analysis efforts and attempts at a resolution will be discussed. Then I will outline the development, testing, calibration, and performance optimization of the time-of-flight (TOF) system on HELIX. It will also be demonstrated that the TOF system is capable of resolving timing at the level of 50 ps for particles with Z > 3, which is crucial to the success of the HELIX mission.