Relative Composition and Energy Spectra of Light Nuclei in Cosmic Rays. Results from AMS-01

TL;DR

This paper presents measurements of light nuclei ratios in cosmic rays using AMS-01 data, providing insights into cosmic ray propagation and highlighting a discrepancy in Be production predictions.

Contribution

It reports new measurements of light nuclei ratios and isotopic ratios in cosmic rays, enhancing constraints on propagation models.

Findings

Measured Li/C, Be/C, B/C ratios in 0.35-45 GeV/nucleon range

Determined 7Li/6Li isotopic ratio in 2.5-6.3 GV range

Identified a 10-15% overproduction of Be in models

Abstract

Measurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined using the B/C ratio, the study of extended sets of ratios can provide stronger constraints on the propagation models. In this paper the relative abundances of the light nuclei lithium, beryllium, boron and carbon are presented. The secondary to primary ratios Li/C, Be/C and B/C have been measured in the kinetic energy range 0.35-45 GeV/nucleon. The isotopic ratio 7Li/6Li is also determined in the magnetic rigidity interval 2.5-6.3 GV. The secondary to secondary ratios Li/Be, Li/B and Be/B are also reported. These measurements are based on the data collected by the Alpha Magnetic Spectrometer AMS-01 during the STS-91 space shuttle flight in 1998 June. Our experimental results are in substantial agreement with other measurements, where they exist. We describe our light-nuclei data with a diffusive-reacceleration model. A 10-15% overproduction of Be is found in the model predictions and can be attributed to uncertainties in the production cross-section data.