Question

Mesons are found in

• A. Alpha rays
• B. Laser beam
• C. X-rays
• D. Cosmic rays

Hint:

Recall that mesons are massive particles created in high energy collisions, not photons like laser or X-ray light.

Answer 1

The Correct Option is D

Step 1: Mesons are subatomic particles made of one quark and one antiquark, with a mass between that of an electron and a proton. Examples are pions and kaons.

Step 2: Cosmic rays are extremely high energy particles, mostly protons, arriving from outer space. When they strike the upper atmosphere, they smash into air nuclei and create showers of secondary particles, and pions, a type of meson, are produced in these collisions.

Step 3: This is actually how mesons were first discovered experimentally, scientists studied cosmic ray tracks using photographic emulsions carried to high altitude and found particles with masses between the electron and proton, which turned out to be mesons.

Step 4: Alpha rays are simply helium nuclei emitted during radioactive decay, they are not mesons. A laser beam is a stream of photons of a single wavelength, produced by stimulated emission, again not mesons. X-rays are also photons, just at a shorter wavelength than visible light, not particles like mesons at all.

Step 5: So cosmic rays are the correct answer, since they are the natural source where mesons actually occur.