Measurement of cosmic-ray carbon and oxygen energy spectra with CALET

The CALorimetric Electron Telescope (CALET) is a space mission installed on the International Space Station (ISS) in August 2015. In addition to high precision measurements of the electron spectrum up to TeV scale, CALET will also investigate the mechanism of cosmic-ray (CR) acceleration and propagation in the Galaxy, by performing direct measurements of the energy spectra and elemental composition of CR nuclei from H to Fe, and the abundance of trans-iron elements up to about Z = 40. The instrument consists of two layers of segmented plastic scintillators to identify the particle charge, a thin (3 radiation lengths) tungsten-scintillating fiber calorimeter providing accurate particle tracking, and a thick (27 radiation lengths) calorimeter made of lead-tungstate crystal logs. In this paper, we discuss the analysis procedure developed to reconstruct and select carbon and oxygen nuclei in cosmic rays and present the preliminary measurement of their energy spectra based on the analysis of the data collected from October 2015 to February 2018.