Overview of the HERD space mission

Abstract

The High Energy cosmic Radiation Detector (HERD) is a prominent space-borne instrument to be installed on-board the Chinese Space Station (CSS) around 2027, resulting from a collaboration among Chinese and European institutions. Primary scientific goals of HERD include: precise measurements of the cosmic ray (CR) energy spectra and mass composition at energies up to few PeV, electron/positron spectra up to tens of TeV, CR anisotropy, gamma ray astronomy and transient studies, along with indirect searches for Dark Matter candidates. The detector is configured to accept incident particles from both its top and four lateral sides. Owing to its pioneering design, more than one order of magnitude increase in geometric acceptance is foreseen, with respect to previous and ongoing experiments. HERD is conceived around a deep (∼ 55 X 0, 3 λI ) 3D cubic calorimeter (CALO), forming an octagonal prism. Fiber Trackers (FiTs) are instrumented on all active sides, with a Plastic Scintillator Detector (PSD) covering the calorimeter and tracker. Ultimately, a Silicon Charge Detector (SCD) envelops the above-stated sub-detectors, while a Transition Radiation Detector (TRD) is instrumented on one of its lateral faces, for energy calibration in the TeV scale. This work illustrates HERD’s latest advancements and scientific objectives along with an overview of upcoming activities.

Measurement of the p+He energy spectrum with the DAMPE space mission

“…The fit indicates the presence of a spectral softening at 28.8 +6.2 −4.4 TeV with a significance of 6.6𝜎 and confirms the previous DAMPE results in both proton and helium spectra [17,18]. § a similar approach was adopted in previous studies such as [17,18,40,41] PoS(ICRC2023)138 p+He spectrum with DAMPE Francesca Alemanno Moreover, the result from this work is consistent with indirect measurements, although further observations from future space-borne experiments (e.g., HERD [42,43]) and a spectral extension at higher energies are required to provide further insights. Notably, the p+He spectrum provides a new indication of a potential second hardening around 150 TeV, supported by preliminary findings from the HAWC collaboration [44], and giving hints to the existence of PeVatrons [45].…”

Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission

“…The comparison with indirect measurements shows an overall consistency, although this picture will be clarified with further observations made by future space-borne experiments (e.g. HERD [48,49]) along with a spectral extension at higher energies. The p+He spectrum shows a novel hint regarding a possible direct detection of a second hardening around 150 TeV, also suggested by preliminary results from the HAWC collaboration [50] and foreseen in [51].…”

The Plastic Scintillator Detector of the HERD space mission

“…The High Energy cosmic-Radiation Detection (HERD) [2,3] facility is designed to address the aforementioned requirements, as one of the prominent instruments to be installed on-board the China Space Station (CSS), with a projected duration of more than 10 years. HERD will be capable of directly studying features in the spectra CR nuclei with optimal precision, up to enegies of a few PeV, while also providing insights on various topics concerning: gamma ray astronomy (energies larger than 100 MeV); the electron+positron spectrum and its fine structure up to tens of TeV, while searching for possible signatures of dark matter (DM) annihilation or decay products, owing to its wide Field-of-View (FoV).…”