Modern Physics – Mesons are predominantly found in which natural/high-energy source?

Introduction / Context:
Mesons are hadronic particles (such as pions and kaons) composed of a quark–antiquark pair. Historically, mesons were discovered in secondary particle showers produced when high-energy cosmic rays strike the Earth’s atmosphere. Recognizing where mesons are commonly observed links particle physics to astrophysical phenomena.

Given Data / Assumptions:

• The question asks for a natural or high-energy source where mesons are found.
• Options include electromagnetic radiation (laser, X-rays, gamma rays) and cosmic rays (high-energy charged particles).
• Mesons are massive particles, not photons.

Concept / Approach:
Cosmic rays are primarily protons and heavier nuclei traveling at relativistic speeds. When they collide with atmospheric nuclei, they produce showers containing pions (pi-mesons) and kaons, which then decay into muons and neutrinos. Electromagnetic radiation (laser/X/gamma) consists of photons and does not by itself constitute mesons.

Step-by-Step Solution:
Identify meson nature: hadrons, not light.Select the source that generates particle cascades: cosmic rays in the atmosphere.Eliminate purely photonic options.

Verification / Alternative check:
Particle detectors at mountain altitudes and collider experiments both record meson production from high-energy collisions—consistent with cosmic-ray air showers.

Why Other Options Are Wrong:

• Laser beam: coherent light (photons), not hadrons.
• X-rays: high-energy photons; do not “contain” mesons.
• Gamma rays: also photons; not mesons.

Common Pitfalls:
Assuming any “high-energy radiation” contains all particle types. Only collisions producing hadronic showers yield mesons.

Final Answer:
Cosmic rays