POSITRON
This particle is just like an electron, except it carries a positive charge instead of a negative one.
What is a positron?
This particle is like a heavy cousin of the electron, but it doesn’t last long before decaying.
What is a muon?
These nearly massless, neutral particles are emitted during beta decay alongside electrons or positrons.
What are neutrinos (or antineutrinos)?
These particles were considered “strange” because they were produced readily in collisions but decayed slowly.
What are strange particles?
Discovered by Carl Anderson in 1932, this antiparticle was first spotted in a cloud chamber tracing cosmic rays.
Answer: What is the positron?
Muons are created when cosmic rays strike this layer of Earth’s environment.
What is the upper atmosphere?
In beta⁻ decay, this type of neutrino is released.
What is an antineutrino?
The property that distinguishes strange particles from ordinary ones is the presence of this quark.
What is the strange quark?
When a positron meets its electron counterpart, this energetic process occurs, producing two gamma photons.
What is annihilation?
The muon decays into an electron and two of these nearly massless particles.
Answer: What are neutrinos?
Neutrino oscillation experiments show that neutrinos can change flavor. What property does this prove they must have?
They must have non-zero mass.
Strange particles are created via the strong interaction but decay via the weak interaction. What conservation rule explains their unusual lifetime?
Strangeness is conserved in strong interactions but not in weak ones.
In medical imaging, this type of scan relies on positron-emitting isotopes to map biological activity in the body.
What is a PET scan (Positron Emission Tomography)?
In decay, a muon produces an electron, a muon neutrino, and an electron antineutrino. Which conservation law requires two neutrinos to appear?
Lepton number conservation.
A nuclear reactor is a strong source of electron antineutrinos. Which interaction allows us to detect them?
Inverse beta decay on protons in a detector.
The discovery of strange baryons and mesons led to this classification system, grouping hadrons by quantum numbers.
What is the Eightfold Way (Gell-Mann’s model)?
The existence of positrons was actually predicted before their discovery, by this physicist’s equation linking quantum mechanics and special relativity.
Who is Paul Dirac?
The measured magnetic moment of the muon slightly differs from the theoretical prediction. Which ongoing experiment investigates this anomaly?
The Muon g-2 experiment.
Explain how the detection of solar neutrinos confirmed the fusion reactions occurring in the Sun’s core.
The observed neutrino flux matches predictions from proton–proton chain fusion once oscillations are included
A neutral kaon (K⁰) and its antiparticle can transform into each other. What quantum phenomenon causes this mixing?
Weak-interaction oscillation (or K⁰–K⁰-bar mixing).