The Second LHAASO Collaboration Conference in 2026 & The Academic Symposium for the 10th Anniversary of the LHAASO collaboration

The absence of cosmic ray flux data with known energy and composition in the high-energy range makes it impossible to perform a direct absolute calibration of the energy scale for ground-based cosmic ray experiments. This leads to a discrepancy between the measured cosmic ray energy and its true energy, which affects not only the fine structure of the cosmic ray spectrum but also the absolute flux of the energy spectrum. The Moon shadow formed by cosmic rays blocked by the Moon will experience a westward shift due to the magnetic field between the Earth and the Moon. The magnitude of this shift is inversely proportional to the energy of the cosmic rays and directly proportional to their charge. Consequently, the Moon shadow shift can be utilized to calibrate the absolute energy scale of ground-based cosmic ray experiments. However, at 100 TeV, the westward shift of protons and helium nuclei, which make up the majority of cosmic rays, is too small compared to the pointing accuracy of the detectors, making the measurement of the shift at energies above 100 TeV with large systematic uncertainty. This work proposes a method for calibrating the absolute energy of cosmic rays at 100 TeV using the Moon shadow formed by irons and estimates the capability of LHAASO to measure the iron Moon shadow.