Nuclear & Particle Physics — 60 Terms Defined

Isotones Nuclear & Particle Physics Dimensionless Species Nuclides of different chemical elements that share the exact same number of neutrons N = A - Z while possessing different proton numbers Z. N = A - Z = Constant

Isotopes Nuclear & Particle Physics Dimensionless Species Variants of a particular chemical element that possess identical atomic numbers Z (same number of protons) but different mass numbers A (different number of neutrons). Nuclide Symbol: ᴬ_Z X (Same Z, Different A)

Large Hadron Collider (LHC) Nuclear & Particle Physics TeV (Tera-electronvolts) The world's largest and highest-energy particle accelerator, located in a 27-kilometer underground circular tunnel at CERN near Geneva. Center-of-Mass Energy √s = 13.6 TeV

Leptons Nuclear & Particle Physics Elementary Particle Class A family of elementary spin-1/2 fermions that do not experience the strong nuclear interaction. Spin = ½, Baryon Number B = 0, Lepton Number L = 1

Liquid Drop Model Nuclear & Particle Physics MeV (Binding Energy Calculation) A classical nuclear model treating the atomic nucleus as an incompressible liquid droplet of dense nuclear fluid bound by short-range nuclear forces. E_b = a_v A - a_s A^(2/3) - a_c Z²/A^(1/3) - a_a (A-2Z)²/A + δ

Mass Defect Nuclear & Particle Physics u (Atomic Mass Units) or MeV/c² The difference between the total mass of an atom's individual free nucleons and the actual smaller mass of the bound atomic nucleus. Δm = Z m_p + (A - Z) m_n - M_nucleus

Mean Life Nuclear & Particle Physics Seconds or Years The average expected lifetime of a radioactive nucleus before undergoing radioactive decay. τ = 1 / λ = t_½ / ln(2) ≈ 1.443 t_½

Mesons Nuclear & Particle Physics Composite Boson Class Hadronic subatomic particles composed of one valence quark and one valence antiquark bound by gluons. Quark Content: q q̄, Spin = 0, 1, Baryon Number = 0

Muon Nuclear & Particle Physics MeV/c² (Mass Energy) A second-generation elementary charged lepton with a mass approximately 207 times greater than an electron. m_μ ≈ 105.66 MeV/c², τ_μ ≈ 2.2 μs, Spin = ½

Neutrino Nuclear & Particle Physics eV/c² (Mass Limit) An extremely light, electrically neutral spin-1/2 elementary lepton that interacts almost exclusively via the weak nuclear force. m_ν < 0.1 eV/c², Spin = ½, Charge = 0

Neutrino Oscillations Nuclear & Particle Physics Probability (0 to 1) A quantum mechanical phenomenon in which a neutrino created with a specific lepton flavor changes flavor as it propagates through space. P(ν_α → ν_β) = sin²(2θ) sin²(1.27 Δm² L / E)

Nuclear Binding Energy Nuclear & Particle Physics MeV (Mega-electronvolts) The minimum energy required to completely disassemble an atomic nucleus into its constituent protons and neutrons. E_b = Δm c² = [Z m_p + (A - Z) m_n - M_nucleus] c²

Nuclear Fission Nuclear & Particle Physics MeV (Mega-electronvolts) A nuclear reaction in which a heavy nucleus splits into two or more smaller daughter nuclei accompanied by the release of neutrons and substantial energy. ¹₀n + ²³⁵₉₂U → ²³⁶₉₂U* → ¹⁴¹₅₆Ba + ⁹²₃₆Kr + 3 ¹₀n + Q (~200 MeV)

Nuclear Fusion Nuclear & Particle Physics MeV (Mega-electronvolts) A nuclear reaction in which two light atomic nuclei collide and combine to form a single heavier nucleus, releasing vast amounts of energy. ²₁H + ³₁H → ⁴₂He + ¹₀n + 17.6 MeV

Nuclear Reactor Nuclear & Particle Physics MWth or MWe (Power Capacity) An engineered facility in which a controlled self-sustaining nuclear chain reaction is maintained to generate thermal energy for electrical power generation. Multiplication Factor k = Neutrons in generation (i+1) / Neutrons in generation i

Nuclear Shell Model Nuclear & Particle Physics Quantized Energy Shells A quantum nuclear model describing nuclear energy levels in terms of individual nucleons moving inside a central potential well with strong spin-orbit coupling. Magic Numbers: 2, 8, 20, 28, 50, 82, 126

Nuclear Stability Nuclear & Particle Physics Dimensionless N/Z Ratio A measure of a nuclide's resistance to spontaneous radioactive decay, determined by the balance between nuclear strong attraction and proton Coulomb repulsion. N/Z ≈ 1 (for light nuclei), N/Z ≈ 1.5 (for heavy nuclei)

Parity Violation Nuclear & Particle Physics Symmetry Violation The discovery that the weak nuclear force distinguishes between left-handed and right-handed spatial orientations, violating spatial mirror symmetry (P-parity). P |Ψ(x, y, z)⟩ = - |Ψ(-x, -y, -z)⟩ (Violated in weak decays)

Q-Value Nuclear & Particle Physics MeV (Mega-electronvolts) The net amount of energy released or absorbed during a nuclear reaction or radioactive decay process. Q = (m_reactants - m_products) c²

Quantum Chromodynamics (QCD) Nuclear & Particle Physics Non-Abelian Gauge Theory The relativistic quantum field theory describing the strong nuclear interaction between color-charged quarks and gluons. L_QCD = q̄ (i γ^μ D_μ - m) q - ¼ G^a_μν G^a,μν

Quark Flavor Nuclear & Particle Physics Quantum Numbers (S, C, B, T) The quantum property that distinguishes the six fundamental types of quarks in the Standard Model. 6 Flavors: u, d, c, s, t, b

Quarks Nuclear & Particle Physics Fractional Elementary Charge e Fundamental spin-1/2 elementary particles that experience all four fundamental interactions and combine via the strong force to form hadrons. q = +⅔ e (u, c, t), q = -⅓ e (d, s, b)

Radioactive Decay Nuclear & Particle Physics Bq (Bequerels = decays/s) or Ci (Curies) The spontaneous process by which an unstable atomic nucleus loses energy by emitting ionizing radiation (particles or electromagnetic rays). N(t) = N₀ e^(-λ t), A(t) = λ N(t)

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)