Results for “Half-Life”
6 terms
Half-Life
Nuclear & Particle Physics
Seconds, Hours, or Years
The time required for half the radioactive nuclei in a given sample to undergo spontaneous radioactive decay.
t_½ = ln(2) / λ ≈ 0.693 / λ, N(t) = N₀ (½)^(t / t_½)
Radiocarbon Dating
Nuclear & Particle Physics
Years Before Present (BP)
A radiometric dating method that measures the residual decay activity of Carbon-14 in organic materials to determine their age up to ~50,000 years.
t = -(t_½ / ln 2) ln(A(t) / A₀), t_½ = 5730 years
Beta Decay
Nuclear & Particle Physics
MeV (Continuous Spectrum)
A radioactive decay process mediated by the weak nuclear force in which a nucleus emits a beta particle (electron or positron) and a neutrino.
β⁻: n → p + e⁻ + ν̄_e; β⁺: p → n + e⁺ + ν_e
Decay Constant
Nuclear & Particle Physics
s⁻¹ or years⁻¹
The probability per unit time that an individual radioactive nucleus will undergo spontaneous nuclear decay.
λ = -(1 / N) (dN / dt) = ln(2) / t_½
Radioactive Tracer
Nuclear & Particle Physics
MBq or mCi (Administered Activity)
A chemical compound containing a radioisotope used to trace chemical or biological pathways through living organisms or industrial systems.
A(t) = A₀ e^(-λ t) (Short half-life diagnostic radiopharmaceutical)
Radon Gas Migration
Geophysics & Environmental Physics
Bq/m³ or pCi/L (Activity Concentration)
The environmental migration of radioactive Radon-222 gas from decaying uranium in rocks and soil into indoor building spaces.
Decay Chain: ²³⁸U → ²²⁶Ra → ²²²Rn (Half-life = 3.82 days)