The bidirectional Medium-Energy Proton Detector (MEPD) onboard the lunar surface exploration subsystem of the Chang’E-7 lander represents the first-ever implementation of dual-direction medium-energy proton measurements on the Moon. It is capable of providing spectral data of upward- and downward-directed medium-energy protons in the range of 0.03~30 MeV, offering crucial support for modeling the lunar particle radiation environment and for radiation protection in future crewed lunar missions. The unique challenges of ground calibration for the MEPD were addressed in this study. An electron accelerator was employed to achieve proton-equivalent energy calibration, while the full energy range was validated by analyzing the deposited energy of penetrating high-energy protons. In addition, the suppression capability against electron contamination was quantitatively evaluated through a combined approach of accelerator experiments and numerical simulations. The results show that the detector’s energy calibration deviation is better than 3%, its electron-rejection efficiency exceeds 94% for energies at or below 1.4 MeV, and the average geometric factors of the upward-and downward-facing detectors are 0.053 cm–2·sr–1 and 0.3041 cm–2·sr–1, respectively. These calibration results provide a reliable foundation for in-orbit data inversion. Furthermore, the established calibration and simulation framework offers valuable reference for the future calibration of lunar and deep-space charged-particle detectors.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |