Measurement of Cosmic Ray Lithium Isotopes Using the Alpha Magnetic Spectrometer

Abstract

The study of cosmic rays and their properties provides insight into the origins of our universe and is a unique lens on the nuclear physics of the cosmos. The identification of cosmic ray isotopes poses a particular challenge, as it requires the measurement of multiple observables to a high degree of accuracy for the deduction of nuclear mass. Using the unique detection capabilities of the Alpha Magnetic Spectrometer (AMS), the isotope fluxes of cosmic ray lithium in the rigidity range of 1.92 to 25 GV are presented. This work is based on 0.97 million ⁶Li and 1.04 million ⁷Li nuclei collected by the AMS over a 12.5 year period, and improves the error and extent of existing measurements by a factor of 10. These results lead to the conclusion that there is no sizable primary component in cosmic ray ⁷Li. The improvements to the AMS velocity measurement establishes the groundwork for future cosmic ray isotope measurements.