Measurement of Heavy Nulei beyond Iron in Cosmic Rays with the DAMPE Experiment

Abstract

Dark Matter Particle Explorer (DAMPE) is a calorimetric-type, satellite-borne detector. One important scientific object of DAMPE is to measure the flux of cosmic ray nuclei, which is fundamental for understanding the cosmic ray origin and propagation mechanism. Heavy nuclei beyond Iron in Cosmic Rays play an important role for studying the outstanding issues in the grand cycle of matter in the Galaxy. Thanks to the good charge resolution of the DAMPE PSD detector (∼0.06e for protons, ∼0.3e for iron), the primary charges in a wide range from proton (Z=1) to Zirconium (Z=40) can be identified. In seven years of data-taking from 2016 to 2022, DAMPE has collected data with more than 3 × 10 6 nuclei with Z≥26. In order to reduce the contamination of Iron in the flux of heavier nuclei in cosmic rays, new charge identification methods have been studied, and the relativistic rise effect has been corrected. Here, such tools and the methods of charge identification aiming to the spectrum measurement will be introduced.

From SuperTIGER to TIGERISS

“…It is difficult to simultaneously measure the high flux of 1 H and 2 He that comprise ∼99% of the GCRs with an instrument having the dynamic range and exposure needed to resolve the UHGCRs. Instruments like the CAlorimetric Electron Telescope (CALET) [10] and the Dark Matter Particle Explorer (DAMPE) [11] are capable of measuring abundances from 1 H into the UHGCRs, but since they are not optimized for UHGCR measurements, they do not have the best resolution for them. Instruments designed to measure the GCRs above 2 He can better optimize resolution and/or dynamic range for UHGCR measurements, including SuperTIGER (16 ≤ Z ≤ 56) [3], TIGERISS (5 ≤ Z ≤ 82), and the Advanced Composition Explorer Cosmic Ray Isotope Spectrometer (ACE-CRIS) (6 ≤ Z ≤ 38) [12,13], which has also made the only UHGCR isotope measurements through 38 Sr. Measurements of the UHGCR abundances through 83 Bi have been made by the the third High-Energy Astronomy Observatory (HEAO-3) Heavy Nuclei Experiment (HNE) [14] and by the Ariel 6 [15] satellite missions that could not resolve individual elements and measured charge groups.…”