Relative Composition and Energy Spectra of Light Nuclei in Cosmic Rays: Results From Ams-01

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 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 −1. The isotopic ratio 7 Li/ 6 Li 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.

The AMS-02 Silicon Tracker Status

“…The different CR species such as electrons, protons, helium nuclei (from bottom to top) as well as the less abundant Z > 2 nuclei are apparent from the figure. The figure also shows the low rigidity behavior and the Z dependence of the energy depositions, according the ∼ Z 2 /β BetheBloch dependence and consistently with previous performance studies [6,3]. Intensive studies are currently ongoing for modeling the detector response to the different charges and performing the…”

“…A first version of the experiment, AMS-01, operated successfully in a 10-day shuttle mission (STS-91) in June 1998 [1]. The AMS-01 mission provided results on CR protons, helium, electrons, positrons, antiprotons, antihelium search, light nuclei and light isotopes [1,2,3,4]. The second generation detector AMS-02 was launched with the STS-134 flight on May 16 th 2011 and installed in the ISS on May 19 th 2011.…”

GeV-TeV cosmic-ray spectral anomaly as due to reacceleration by weak shocks in the Galaxy

“…Model parameters used: η = 1.02, D 0 = 9 × 10 28 cm 2 s −1 , ρ 0 = 3 GV, a = 0.33, q C = 2.24, q O = 2.26, s = 4.5, p c = 1 PeV/c, f C = 0.024%, f O = 0.025%,ν = 25 SNe Myr −1 kpc −2 and φ = 450 MV. Data: HEAO (Engelmann et al 1990), CRN (Swordy et al 1990), CREAM (Ahn et al 2008), AMS-01 (Aguilar et al 2010), ATIC (Panov et al 2008;Orth et al 1978;Simon et al 1980;Webber et al 1985), and TRACER (Obermeier et al 2011). energy spectra shown in Fig. 2 are also observed in the ratio.…”

“…Figure 4 shows the result on the boron-to-carbon ratio (solid line) along with the measurement data. The data are from High Energy Astronomy Observatory Program (HEAO: Engelmann et al 1990), Cosmic Ray Nuclei Experiment (CRN; Swordy et al 1990), CREAM (Ahn et al 2008), Alpha Magnetic Spectrometer (AMS-01; Aguilar et al 2010), ATIC (Panov et al 2008;Orth et al 1978;Simon et al 1980;Webber et al 1985), and TRACER (Obermeier et al 2011). For comparison, we have also shown the best-fit result for the case of pure diffusion (dashed line), i.e., without reacceleration (η = 0), taken from Thoudam & Hörandel (2013).…”

Assessment of spectral and angular characteristics of sub-GLE events using the global neutron monitor network

“…While the characteristics of the low energy part of GCR and SEPs can be assessed using satellite-borne measurements (e.g. Aguilar et al, 2010;Adriani et al, 2016), the higher energy part, specifically GLE particles are studied by NMs (e.g. Dorman, 2004, and references therein).…”