Thermal Modelling, Metrology, and Hodoscope Development for the High Energy Light Isotope eXperiment

Abstract

HELIX is a balloon-borne payload designed to measure isotopic abundances of light cosmic ray nuclei using its 1 T magnetic spectrometer to obtain high resolution 10Be to 9Be isotope ratio measurements. Following thermal vacuum, magnet, and integration testing, its first flight took place in the Boreal summer of 2024. This thesis covers three projects contributing to the HELIX collaboration. The HELIX thermal model was created to simulate the temperature and pressure conditions’ effects on component temperatures. Thermal Desktop was used to model individual components with geometric, optical, and material accuracy. Case studies for various launch locations, dates, and conditions were evaluated and used to determine external foam configurations as well as heater purchases for sensitive instruments. The Metrology project developed a procedure for measuring and analyzing HELIX spatial coordinate data for verifying detector positions during the various stages of its balloon campaign. The method developed was successful in attaining the desired accuracy to within 1 mm when the incident measurement angle remained below 60°. This project demonstrated that the process of collecting point measurements for the entirety of the HELIX payload with a Total Station was too time-consuming for this experiment, and led to the method of a more sophisticated device for measuring HELIX, the CREAFORM MaxSHOT 3D. An anticipated second HELIX balloon flight will aim to increase statistics and test detector upgrades for the instrument. The hodoscope, a particle detector made to measure position along one axis, is one such device for which a proposed new design is being prototyped. The upgraded design developed in this thesis aims to feature one SiPM for every scintillating fiber to refine its resolution without the mechanical weaving of the first model. Individual Hamamatsu SiPMs were studied as a prototyping measure, with IV-curves generated, breakdown voltages characterized at various temperatures, and photo-electron spectra measured. Prototyping measurements and designs are presented.