Assessing AESOP-Lite Time of Flight Performance via Alpha Particle Detection*

The Anti-Electron Sub-Orbital Payload Low Energy (AESOP-Lite) experiment involves a series of balloon flights, with the most recent flight conducted in early January 2024 from McMurdo Station in Antarctica. AESOP-Lite features a cosmic ray detector and is designed as the successor to the Low Energy Electron Experiment (LEE). Unlike LEE, AESOP-Lite includes a magnetic spectrometer to distinguish positrons from electrons, complemented by a Cherenkov detector and scintillators for enhanced particle identification. AESOP-Lite's first flight was in May 2018 from Kiruna, Sweden to Ellesmere Island, Canada. The experiment's main objective is to measure the spectrum of low-energy electrons and positrons (20 MeV to 300 MeV). The addition of time-of-flight instrumentation for the McMurdo flight was intended to improve the rejection of background from upward traveling particles. In this presentation, we demonstrate the evaluation of the time-of-flight system's performance using the detection of cosmic-ray alpha particles and the electron/positron measured time distribution. Our results indicate additional improvements to the AESOP-Lite time-of-flight software will be needed for better resolution of large atomic nuclei in the next flight.