Search for variability in the spectra cosmic ray protons
Abstract
Search for global time variability in the energy spectra of cosmic rays protons was carried out using data 6 experiments: CALET [1], DAMPE [2], NUCLEON [3], CREAM-III [37], AMS-02 [35] (3 years of observation) and AMS-02 [60] (7 years of observation). Approximation of all spectra (in the energy range of ∼ 6 GeV - 300 TeV) was produced by an empirical model describing experimental data as the sum of three power components: constant background and two variables of the power components with various cuts off on high energies. It turned out that the "soft" power component has slope index αH≈3 and the cutting energy of ∼ 200 GeV, and the "hard" power component has slope index αL≈2.4, the cutting energy of ∼ 100 TeV. To find the variability of spectra of cosmic rays all experiments were compared in pairs. Reliable changes in spectral curves of different experiments were not found. The causes of lack of reliable variability are discussed. Nevertheless, it was found that the cutoff parameter of "hard" spectral components of some experiments may differ by more than 5σ. Since the global variability of the spectra is not detected, it makes sense to see how well our model describes the combined pairs of spectra. It turned out that the parameters of the fits of the combined spectra coincide with the accuracy to errors with the parameters of the fits of individual spectra. The significance of the differences between the average values of the power indexes of slope "soft" and "hard" component of more than 28σ. Consequently, the "soft" and "hard" components of the spectra of protons of CR really exist. The "hard" cutoff parameter EL_cut of the fit of the pair of experiments "AMS_(3y)+DAMPE" is significantly different by 8.6σ from the corresponding cutoff parameter of the pairs of experiments "AMS_(3y)+NUCLEON". In the experiments "AMS_(7y)+DAMPE" and "AMS_(3y)+NUCLEON" parameter EL_cut reliably differ by 8.3σ. Consequently, the variability of the cutoff parameter of the "hard" component is real. In addition, our estimates show that the global variability of CR spectra (that is, the variability of the whole spectral curve) for nuclei of elements with large Z can be detected. The explanation of the difference in the fluxes of nuclei (C, O, Fe) of cosmic rays found in the AMS and CALET experiments is proposed.
- Publication:
-
Astroparticle Physics
- Pub Date:
- October 2022
- DOI:
- 10.1016/j.astropartphys.2022.102757
- Bibcode:
- 2022APh...14302757L
- Keywords:
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- Cosmic rays;
- Protons;
- Surfatron acceleration mechanism;
- Heliosphere;
- Local interstellar medium