Doctoral thesis
Open access

Measurement of Cosmic-Ray Sulfur, Argon and Calcium Fluxes with the Alpha Magnetic Spectrometer on the International Space Station

ContributorsRobyn, Erwanorcid
Number of pages191
Imprimatur date2023-08-30
Defense date2023-08-28

Cosmic rays consist of high-energy elementary particles and ionised nuclei travelling through space. Since their discovery, the scientific investigation of cosmic rays has posed numerous questions regarding how they are produced, accelerated, and propagated. Many of these inquiries remain unanswered to this day. Sulfur (S) in cosmic rays is projected to be predominantly of primary origin, indicating its creation by astrophysical sources like supernovae. Among the primary elements lighter than iron (Fe), it is the heaviest. On the other hand, both argon (Ar) and calcium (Ca) are expected to be a combination of primary and secondary, resulting from primary spallation within the interstellar medium. Precisely measuring the presence of these three nuclei in cosmic rays provides a means to explore the underlying mechanisms governing their production, acceleration, and propagation.

This thesis starts with an introduction to the fundamental concepts of cosmic-ray physics. Subsequently, it delves into the details of the Alpha Magnetic Spectrometer (AMS-02) and its sub-detectors. The achievement of this research lies in the first-ever measurements of the flux of sulfur, argon, and calcium nuclei in cosmic rays as a function of magnetic rigidity, defined as the ratio of momentum to charge. The measurement of sulfur flux covers a magnetic rigidity range spanning from 2.15 GV to 3 TV. Similarly, the fluxes of argon and calcium are measured within a magnetic rigidity range from 2.4 GV to 1.2 TV. These remarkable measurements are based on an extensive dataset collected during the initial ten years of operation of AMS-02, precisely from May 19, 2011, to May 3, 2021, aboard the International Space Station (ISS). The dataset comprises an impressive total of 362 thousand identified events as sulfur nuclei, 134 thousand events as argon nuclei, and 195 thousand events as calcium nuclei. The unprecedented precision of the measurements allows the extraction, compared to silicon and fluorine, of the primary and secondary components of these three nuclei in cosmic rays in a model-independent way.

  • AMS
  • Alpha Magnetic Spectrometer
  • Cosmic Rays
Citation (ISO format)
ROBYN, Erwan. Measurement of Cosmic-Ray Sulfur, Argon and Calcium Fluxes with the Alpha Magnetic Spectrometer on the International Space Station. 2023. doi: 10.13097/archive-ouverte/unige:171532
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Creation09/19/2023 11:40:01 AM
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