Nuclear Physics Final Exam Terms – Flashcards
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Nuclear Chemistry
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Defined as the application of procedures and techniques common to chemistry to study the structure of the nucleus and to define the nature of the fundamental particles.
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Radiochemistry
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The chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes.
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Nuclear Physics
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Field of physics that studies the constituents of nuclei and interactions of atomic nuclei.
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Emission Spectrum
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Generates specific or characteristic wavelengths of light when electricity passes through a gas.
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Absorption Spectrum
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Where a light is shown through a gas and the same wavelengths are absorbed by the gas.
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Energy- Level Diagrams
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Useful pictorial representation of the stationary-state energies.
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Ionization Energy
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The minimum energy needed to remove a ground-state electron from an atom.
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Pauli Exclusion Principle
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No two electrons in an atom can have the same set of values for the four quantum numbers.
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Atomic Mass
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Weighted average of all the stable isotopes of the element.
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Nucleon
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A nuclear particle without reference to whether t is a proton or a neutron.
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Nuclide
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An atomic species characterized by specific values of the atomic number and mass number.
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Atomic Number
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Z; number of protons in the nucleus of the atom.
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Mass Number
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A; the sum of the number of nucleons in the nucleus.
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Nuclidic Mass (Isotopic)
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M; refers to the mass of an atom of a given nuclide relative to the mass of a 12C atom, which is set equal to exactly 12 daltons or amu.
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Radioactivity
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Refers to the particles which are emitted from the nuclei as a result of nuclear instability.
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5 Groups of Nuclidic Classification
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1. Stable Nuclides 2. Primary Natural Radionuclides 3. Secondary Natural Radionuclides 4. Induced Natural Radionuclides 5. Artificial Radionuclides
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Stable Nuclides
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no radioactive decay has been observed to date.
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Primary Natural Radionuclides
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Found now in nature which are radioactive and have persisted on Earth from the origin of the solar system.
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Secondary Natural Radionuclides
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Found in nature that have been produced by the decay of the primary natural radionuclides, but have half-lives too short for them to have survived from the origin of the solar system.
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Induced Natural Radionuclides
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Found in nature that are constantly being produced by the action of cosmic rays on earth's atmosphere.
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Artificial Radionuclides
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Man-made and do not occur to any significant extent in nature.
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Isotopes
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Nuclides that have the same Z, but different A. They have the same number of protons but differing number of neutrons.
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Isobars
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Nuclides having the same mass number (A) but different number of protons (Z)
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Isotones
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Nuclides that have the same number of neutrons (N) but a different number of protons (Z)
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Nuclear Isomers
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nuclides having the same Z and A but different states of nuclear excitation.
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Elements
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Substances that cannot be decomposed into simpler substances by chemical means
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Electromagnetic (EM) Radiation
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Process in which energy is transferred by means of electromagnetic waves.
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Natural Decay Chains (3)
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Thorium Decay Series Uranium Decay Series Actinium Decay Series
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Thorium Decay Series
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Parent 232-Th Daughter 208-Pb
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Uranium Decay Series
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Parent 238- U Daughter 206-Pb
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Actinium Decay Series
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Parent 235-U Daughter 207-PB
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Electric Quadrupole Movement
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Ellipsodal deviations from the spherical shape, this is the quantity they are described by
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Total Angular Momentum
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of a nucleus is attributed to both the intrinsic spin of the nucleons and to their orbital motion within the nucleus
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Magnetic Moment
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Any moving electrically charged object gives rise to..
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Parity
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a quantum number that is related to symmetry properties of a mathematical property called the wave function and is not a physical quantity.
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Nuclear Magic Numbers
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2, 8, 20, 28, 50, 82, 126
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Four Basic Forces in Nature
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Gravitational Electromagnetic Strong Weak
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Radioactive Decay
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Spontaneous emission of particles or electromagnetic radiation from an atom due to a transition within its nucleus.
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Electron Volt
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Defined as the amount of energy required to move one electron across a 1 volt potential.
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Recoil Energy
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imparted to the daughter nucleus is a consequence of the need to conserve momentum in the system
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Positron Annihilation
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Fate of a positron after emission from the nucleus is conversion to pure energy in a process
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Inner Bremmstrahlung
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Continuous spectrum of very low-intensity electromagnetic energy that is emitted in all Beta-decay processes.
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Auger Electrons
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Relatively low-energy atomic orbital electrons that may be emitted with or as an alternative to x-ray emission.
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Spontaneous Fission
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naturally occurring decay process in which a nucleus breaks into two fragments, with emission of 2-3 neutrons.
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Neutron-Induced Fission
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Requires the capture of a neutron to initiate the fission process.
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Fission Products
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Term used to describe the nuclides formed in a fission process.
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Neutron-Rich Nuclides
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High N/Z ratio & more likely to undergo negatron decay
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Proton-Rich Nuclides
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Low N/Z ratio & more likely to undergo positron decay
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Mass Excess
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Difference between the nuclidic mass and the mass number and represented by delta.
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Q-Value (Q)
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amount of energy released or absorbed in a reaction for a single decay
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Binding Energy (BE)
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energy released in the process of forming a nucleus from its components.
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Activity
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Rate of decay; represents the number of parent nuclides that decay per unit time
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dps
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Decays per second
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Half-life
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time needed for half of a statistically large number of radioactive atoms in a sample to decay.
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Average (Mean) Lifetime
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Average time needed for an atom to decay.
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Scattering Reactions
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An incoming particle or projectile is deflected, or scattered, away from the target nucleus.
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Inelastic Scatter
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Incoming particle loses energy to the target nucleus, causing excitation of the nuclear energy levels.
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Nuclear Reactions
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interactions between an incoming particle, photon, neutrino, or multi-nucleon nucleus and a target nucleus.
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Threshold Energy
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Minimum amount of energy needed to bring about appreciable reaction
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Cross Section
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Probability that a given nuclear reaction will occur.
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Thin Targets
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Defined as those in which the incident particles experience no significant change in intensity.
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Thick Targets
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Particle beam is significantly attenuated, the flux of particles coming out of the target is less than the incident flux.
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Ionization
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Removal of an atomic electron from an absorber atom to form an ion pair consisting of a negative electron and a more massive positive ion.
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Primary Ionization
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initiated directly by the incident radiation.
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Secondary Ionization
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produced subsequently by the ions created in the primary ionization event.
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Kinetic Energy Transfers
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interactions that impart kinetic energy to ion pairs above the amount required to form the pair.
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Molecular excitation and Atomic Electron Excitation
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Modes of interaction that may occur even when the energy transferred is less than the absorber ionization energy.
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Radiative Processes
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Those in which electromagnetic energy is released by decelerating high-velocity particles.
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Mean Range
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Absorber thickness that will stop one-half of the incident alpha particles.
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Stopping Power or Specific Ionization
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Rate of energy loss
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Bragg Curve
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A plot describing the specific ionization of alpha particles
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Photoelectric Effect
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a gamma-ray interacts with an atom in a process that results in the ejection of an electron from the atom and the complete disappearance of the gamma-ray.
