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Part Two: Particles and Atoms.
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NEU
Abbreviated
Study Guide
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- The nucleus carries a positive charge.
- Protons and Neutrons are collectively known as "Nucleons".
- The diameter of the nucleus is relatively small compared to the diameter of the atom.
- Electrons carry a negative charge.
- Electrons, protons, and neutrons ARE NOT all about the same size.
(Protons and neutrons are, but electrons are much
smaller.)
- The nucleus contains 99.9% of the mass of the atom and about 10E-10 of the volume.
- The number of orbital electrons is equal to the number of protons in electrically neutral atoms.
- A Proton is an elementary particle that is identical with the nucleus of a Hydrogen atom and carries a positive charge.
- C0-60: The element is Cobalt, with 60 nucleons, 27 protons, 33 neutrons.
- An atom of a Carbon-12 has six protons, and six neutrons. If a Carbon-12 atom and an alpha particle were fused together,
an Oxygen-16 isotope would result.
- 95Am-241 has 95 protons and 146 neutrons.
- 38Sr-90 decays by emission to Y-90. You would add 1 to the number of protons, so the scientific nomenclature of the daughter is 39Y-90
- The highest to lowest relative penetration of 1 MeV Alpha, Beta, and Gamma rays is: Gamma, Beta, Alpha.
- Charged particles interact with matter by Excitation and Ionization.
- Ionizing radiation interacts with the orbital electrons of an atom and creates two particles of opposite charge, these particles are called ion pairs.
- The primary mechanisms whereby charged particles lose energy in transversing materials are ionization and excitation affecting the electronic structure of the material atoms.
- Alpha Particles (a) are Helium Nuclei emitted from the nucleus of an unstable atom.
- The interaction between alpha particles and atoms is most through columbic. (electrostatic)
- A 7 Mev Alpha particle travels in air 2 inches.
- The range of beta particles in air depends on the energy of the particle.
- The range of 1Mev beta particle in air is about 10 ft. (12ft actual per Mev)
- A beta particle can be either a positively or negatively charged electron.
- The electron has a negative electrostatic charge, and is equal in charge intensity to the
proton. It's mass is 1/1838 that of a proton.
- A beta particle is an electron (1/1838 mass of a proton) emitted from the nucleus of a radioactive isotope.
- Bremsstrahlung radiation is originated by a high energy beta particle as it decelerates near a heavy nucleus.
- The secondary radiation produced when beta particles are stopped by shielding is
Bremsstrahlung.
- The difference between X-rays and gamma photons of the same energy is their origins.
- Nuclear radiation refers to the emanation of the energetic particles and/or the electromagnetic wave from the nucleus of the atom.
- Atomic radiation refers to electromagnetic waves emitted from the electron shell.
- A single quanta of electromagnetic energy is called a photon.
- Gamma photons originate in the nucleus of the atom.
- After undergoing Compton Scattering, a gamma photon is deflected off at an angle with reduced energy.
- Pair Production is when a high energy photon enters the vicinity of an atoms nucleus, the photon energy is converted into an electron-positron pair. (1.022MeV.)
- Pair production is when a high energy photon (more than 1.022 Mev) enters the vicinity of an atom's nucleus, the photon energy is converted into an electron-positron pair.
- X-rays come from electromagnetic ionizing radiation emitted by an orbital electron as it moves from the L shell to the K
shell (changing energy levels).
- X-ray radiation refers to electromagnetic waves associated with electronic energy transition.
(electron cloud)
- During photoelectric effect, a gamma photon gives up all of its energy to orbital electrons.
- The photon (gamma) interaction where a portion of the photons kinetic energy is transferred to an atom's orbital electron is called Compton scattering.
- The minimum energy photon in theory for a pair production is 1.022 Mev, however, this type of interaction in not observed for photons having energies less than about 2.5 Mev.
- Neutrons can cause ionization indirectly by knocking charged particles out of the nucleus.
(Protons out of H-1)
- A Neutron has no charge.
- Fast Neutrons are the most severe external radiation hazard.
- H-1 (Hydrogen) has the most effect on the thermalization of fast neutrons as far as biological chemicals.
- In soft tissue, fast neutrons lose 80% to 90% of their energy by interacting
with hydrogen.
- The chief difference between fast and slow neutrons is their (kinetic) energy.
- - Elastic scattering slows down neutrons because it causes a neutron to lose
kinetic energy without exciting the target nucleus.
- After an inelastic scattering process, the excited nucleus will emit a gamma photon.
- A neutron is absorbed and a gamma is released, is the best description of the method of inelastic
scattering pertaining to neutrons.
- Beta decay process: During radioactive decay, a nucleus emits an electrically charged particle equal in mass to an electron.
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