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Cosmic Ray Space Experiments

Martin Pohl

TL;DR

Cosmic Ray Space Experiments surveys space-based measurements of charged cosmic rays from $R \sim 10~\mathrm{GV}$ to beyond $10^3~\mathrm{GV}$, detailing spectra and composition of protons, helium, heavier nuclei, and leptons. It contrasts magnetic spectrometers (e.g., AMS-02) for rigidity and charge sign with calorimeters (CALET, DAMPE) for energy spectra up to the PeV range, and discusses data-processing workflows including unfolding and in-flight energy-scale calibration. Major findings include rigidity-dependent hardening of proton and helium spectra, similar breaks for light primaries and secondaries consistent with propagation effects, an antiproton flux compatible with secondary production, and a significant electron-positron excess requiring an additional source component; electron/positron spectra are well described by multi-component fits with a high-energy cutoff. The article outlines current and planned experiments (e.g., HERD, AMS-100, ALADInO) and emphasizes cross-messenger astrophysics and precise hadronic-interaction modeling for interpreting cosmic ray data.

Abstract

This article describes experiments in space which measure charged cosmic ray particles in the range from $10\,\mathrm{GV}$ to $10^5\,\mathrm{GV}$ of magnetic rigidity $p/(Ze)$. In this energy range, cosmic rays are expected to originate from sources in the Milky Way and be confined to our galaxy. Spectra of nuclei and their chemical composition are discussed. The spectrum of antiprotons and the search for heavier anti-nuclei are covered. All spectra and especially those of electrons and positrons are analysed for indications of unconventional particle sources, acceleration or transport mechanisms.

Cosmic Ray Space Experiments

TL;DR

Cosmic Ray Space Experiments surveys space-based measurements of charged cosmic rays from to beyond , detailing spectra and composition of protons, helium, heavier nuclei, and leptons. It contrasts magnetic spectrometers (e.g., AMS-02) for rigidity and charge sign with calorimeters (CALET, DAMPE) for energy spectra up to the PeV range, and discusses data-processing workflows including unfolding and in-flight energy-scale calibration. Major findings include rigidity-dependent hardening of proton and helium spectra, similar breaks for light primaries and secondaries consistent with propagation effects, an antiproton flux compatible with secondary production, and a significant electron-positron excess requiring an additional source component; electron/positron spectra are well described by multi-component fits with a high-energy cutoff. The article outlines current and planned experiments (e.g., HERD, AMS-100, ALADInO) and emphasizes cross-messenger astrophysics and precise hadronic-interaction modeling for interpreting cosmic ray data.

Abstract

This article describes experiments in space which measure charged cosmic ray particles in the range from to of magnetic rigidity . In this energy range, cosmic rays are expected to originate from sources in the Milky Way and be confined to our galaxy. Spectra of nuclei and their chemical composition are discussed. The spectrum of antiprotons and the search for heavier anti-nuclei are covered. All spectra and especially those of electrons and positrons are analysed for indications of unconventional particle sources, acceleration or transport mechanisms.

Paper Structure

This paper contains 15 sections, 5 equations, 20 figures, 3 tables.

Table of Contents

  1. Cosmic Ray Space Experiments
  2. Introduction
  3. A compact history of cosmic ray experiments in space
  4. Cosmic ray detectors in space
  5. The Alpha Magnetic Spectrometer AMS-02
  6. The calorimetric cosmic ray detectors CALET and DAMPE
  7. From data to physics
  8. Physics of galactic cosmic rays
  9. Protons and helium
  10. Primary and secondary nuclei
  11. Nuclear antimatter
  12. Electrons and positrons
  13. Complementarity with other experiments in the field
  14. Future developments
  15. Conclusions

Figures (20)

  • Figure 1: The AMS-02 cosmic ray detector on board the International Space Station
  • Figure 2: All-particle spectrum of cosmic rays Bindi_2023 from selected space experiments ($\blacksquare$) and ground arrays ($\bullet$). The AMS-02 proton spectrum Aguilar_2021 is scaled up to give a rough estimate of an all-particle spectrum at low energies. The dashed line connects the flux at $100\, \mathrm{GeV}$ to the flux at the ankle, $4\times 10^9\, \mathrm{GeV}$; its slope corresponds to a constant spectral index of $-2.84$.
  • Figure 3: Count rate of a single unshielded Geiger-Müller counter installed at the tip of a V2 ballistic rocket as a function of altitude above sea level VanAllen_1948.
  • Figure 4: Schematic of the PAMELA satellite spectrometer and its components Bonechi_2007. A time-of-flight (TOF) system with three layers determines the particle flight direction and triggers the data taking. A spectrometer with a permanent magnet and six layers of solid state tracking detectors measures the magnetic rigidity. A calorimeter with tail catcher and neutron detector completes the set-up.
  • Figure 5: Left: Artists impression of the AMS-02 detector (Credit: NASA). Right: The AMS-02 instrument installed on the main truss of the ISS with an astronaut working in a nearby site (Credit: NASA).
  • ...and 15 more figures