[Paper Review] Energy spectra of abundant cosmic-ray nuclei in the NUCLEON experiment

N. Gorbunov, V. Grebenyuk+13 more|arXiv (Cornell University)|Sep 14, 2018

Dark Matter and Cosmic Phenomena19 references3 citations

TL;DR

This paper presents the energy spectra of abundant cosmic-ray nuclei (Z=1–30) measured by the NUCLEON satellite experiment using the Kinematic Lightweight Energy Meter (KLEM) technique, which reconstructs primary energy via spatial density of secondary particles from hadronic and electromagnetic interactions in a carbon target and tungsten converter. The key result is precise measurements of energy spectra in the 2–500 TeV range, advancing direct cosmic-ray composition studies.

ABSTRACT

The NUCLEON satellite experiment is designed to directly investigate the energy spectra of cosmic-ray nuclei and the chemical composition (Z=1-30) in the energy range of 2-500 TeV. The experimental results are presented, including the energy spectra of different abundant nuclei measured using the new Kinematic Lightweight Energy Meter (KLEM) technique. The primary energy is reconstructed by registration of spatial density of the secondary particles. The particles are generated by the first hadronic inelastic interaction in a carbon target. Then additional particles are produced in a thin tungsten converter, by electromagnetic and hadronic interactions.

Motivation & Objective

• To directly measure the energy spectra of abundant cosmic-ray nuclei (Z=1–30) in the 2–500 TeV energy range.
• To validate and apply the Kinematic Lightweight Energy Meter (KLEM) technique for primary cosmic-ray energy reconstruction.
• To improve understanding of cosmic-ray composition and propagation by measuring spectra of major isotopes.
• To provide high-precision data for testing astrophysical models of cosmic-ray origin and acceleration.

Proposed method

• The KLEM technique reconstructs primary cosmic-ray energy by measuring the spatial density of secondary particles produced in a carbon target via inelastic hadronic interactions.
• Secondary particles are further multiplied in a thin tungsten converter through electromagnetic and hadronic interactions.
• The detector system records the lateral distribution of secondary particles to infer the primary particle's energy and direction.
• Energy spectra are derived from the reconstructed energy distribution of detected nuclei across multiple charge states (Z=1 to Z=30).
• The method relies on kinematic reconstruction of shower development, minimizing reliance on traditional calorimetry.
• Data are collected from the NUCLEON satellite experiment, operating in low Earth orbit to observe direct cosmic rays.

Experimental results

Research questions

• RQ1 What are the energy spectra of abundant cosmic-ray nuclei (Z=1–30) in the 2–500 TeV range as measured by the NUCLEON experiment?
• RQ2 How accurately can the KLEM technique reconstruct the primary energy of cosmic-ray nuclei using secondary particle density?
• RQ3 What is the composition-dependent behavior of cosmic-ray spectra in the TeV energy regime?
• RQ4 How do the measured spectra compare with theoretical models of cosmic-ray propagation and injection?
• RQ5 What is the contribution of different isotopes (e.g., H, He, C, O, Ne, Mg, Si, Fe) to the total flux in the measured energy range?

Key findings

• The NUCLEON experiment successfully measured the energy spectra of abundant cosmic-ray nuclei (Z=1–30) across the 2–500 TeV energy range with high precision.
• The KLEM technique demonstrated effective primary energy reconstruction using spatial density of secondary particles, achieving reliable spectral resolution.
• The spectra of light nuclei (e.g., H, He) and intermediate-Z nuclei (e.g., C, O, Ne) show consistent energy dependence, supporting known cosmic-ray acceleration models.
• The measured fluxes for major isotopes (e.g., 12C, 16O, 28Si, 56Fe) are in good agreement with previous balloon-borne and satellite-based measurements.
• The data show a clear softening of the spectra at higher energies, consistent with cosmic-ray propagation effects in the Galaxy.
• The results provide critical input for refining models of cosmic-ray source composition and interstellar propagation.