Do we use astronomical gamma-ray detectors on Earth's surface?
A) No. The atmosphere blocks all gamma rays from space. Thus, we cannot use gamma-ray detectors on Earth's surface.
B) Yes. Gamma rays have a narrow "window" through Earth's atmosphere. So we can detect enough of them to form images.
C) Yes, but these detectors are actually pointed downward to detect rays coming through Earth. Only cosmic gamma rays have enough energy to penetrate Earth, which acts as a filter for gamma rays generated by terrestrial sources.
D) Yes, but these detectors actually detect Cherenkov radiation produced by particles struck by gamma rays high in the atmosphere. Thus, the gamma-ray detection is very indirect.

Question

Quizplus · Accepted Answer

Gamma-ray detectors on Earth's surface are designed to detect Cherenkov radiation, which is produced by particles that are struck by gamma rays in the atmosphere. This method of detection is very indirect, but it allows us to study the high-energy gamma rays that are produced by cosmic sources. The Earth's atmosphere acts as a filter for gamma rays generated by terrestrial sources, so most of the gamma rays that these detectors detect are from distant sources in the universe.

Do We Use Astronomical Gamma-Ray Detectors on Earth's Surface