Cosmic rays are energetic particles originating from outside of the solar system. Victor Hess first discovered cosmic rays in 1912 with a series of balloon flights. While we have learned a lot about the properties of these particles over a hundred years of study, their origin still remains a mystery. We know that most cosmic rays are charged nuclei comprised of a wide range of elements from hydrogen to uranium. Cosmic rays include the most energetic particles we have observed in the Universe, with energies far higher than the particles generated by human-made accelerators. By improving the measurements of cosmic rays, LEMMA aims to search for the origin of these particles, to study the dynamics of high-energy particles in our Galaxy and beyond, and to test fundamental physics.
High-energy particles interact with the nucleons in the atmosphere, and generate secondary particles. These particles, in turn, undergo continuous interactions until they lose most of their energy. To avoid the complications introduced by these interactions in the atmosphere, detectors must be sent either into space or the stratosphere to measure cosmic rays directly. Zero-pressure balloons can lift payloads weighing up to about a ton to an altitude of 40 km, where only 1% of the atmosphere is left above. Balloon experiments typically have a cycle of about five years from design, development, construction, flight, and up through data analysis. With typical collaborations ranging in size from 10-30, working on balloon experiments provides unique opportunities to gain hands-on experience in every aspect of the experiment, working closely with experts. This also provides a good learning stage to understand how to design, build, and test instruments for the near-space environment.
My research in cosmic rays
My research interest is to find the origin of Galactic cosmic rays. I have participated in various cosmic ray balloon experiments to pursue this goal, including CREAM (Cosmic Ray Energetics And Mass), CREST (Cosmic Ray Electron Synchrotron Telescope), and most recently HELIX (High Energy Light Isotope eXperiment). HELIX is designed to measure the fluxes of cosmic ray isotopes, which will provide unique data to study the propagation of cosmic rays in our Galaxy. As cosmic rays bend inside magnetic fields, understanding how cosmic rays travel inside our Galaxy is very important for interpreting the cosmic ray fluxes measured at Earth to search for the origin of these particles. I am currently the project scientist for HELIX. HELIX is aiming to have a series of balloon flights with the first flight scheduled in 2022. I am also interested in developing particle detectors for future balloon experiments.
HELIX experiment: aiming to have a flight in 2022
CREAM experiment: Antarctica flight in 2004 (CREAM-1), 2005 (CREAM-2), 2007 (CREAM-3)
CREST experiment: Antarctica flight in 2011