Unlocking the Muon Puzzle with IACTs

IACTs (Imaging Atmospheric Cherenkov Telescopes) are typically used for gamma-ray astronomy. Muons are produced in hadronic showers and IACTs can detect these muons, which are normally considered background noise. The information from these muons can be used to study cosmic ray showers. One way to study cosmic rays is by observing the muon lateral distribution, which is the muon density as a function of the distance from the shower core. Another way is by determining the muon slant height, which is the distance from the muon production point along the shower axis to the telescope. Studying muon lateral distribution and slant height may help us to better understand hadronic interaction models.

Challenges: One challenge is that IACTs have a low effective area for muons. Also, IACTs typically only detect one muon per shower event. To reconstruct a muon lateral distribution, you need to know the effective area of the telescope array, which is difficult to determine. Current methods for determining the muon production height underestimate the true height.

These challenges may be overcome with the use of future IACT arrays, such as the Cherenkov Telescope Array (CTA). CTA will have a much larger effective area for muons, with more telescopes in a denser configuration. CTA will also have a higher data rate, which will allow for more precise measurements. Improvements to current muon identification algorithms, including machine learning and citizen science approaches, could also help to improve muon detection.

Publication: A.M.W. Mitchell et al., "Potential for measuring the longitudinal and lateral profile of muons in TeV air showers with IACTs", Astroparticle Physics 111, 2019, Pages 23-34, arXiv:1903.12040

Acknowledements: Podcast prepared with Google/NotebookLM. Illustration credits: IN2P3/HESS