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1.07 Interactions of Radiation with Matter

Terms in this set (40)

Results from the interaction of a high energy beta penetrates the electron cloud surrounding the nucleus of the atom and experiences the strong electrostatic attractive force of the positively charged nucleus which results in changing the particles velocity and emits an x-ray. Enhanced with high Z materials and high energy electrons. (braking, white or general radiation) (1.07.01)
Bremsstrahlung
Any process which results in removing a bound electron from an electrically neutral atom or molecule by adding enough energy to the electron to overcome its binding energy. This leaves the atom with a net positive charge and creates an ion pair comprising of the negative electron and positive atom. (1.07.01)
Ionization
Any process that adds enough energy to an electron or nucleon of an atom so that it occupies a higher energy state (smaller binding energy). No ions are produced and the atom remains electrically neutral. (1.07.01)
Excitation
The average distance traveled by a radiation in an absorbing material is (1.07.02)
Range
Average penetration depth into the absorber before it loses all its kinetic energy and stops (1.07.02)
Range
The number of ion pairs formed by the particle per unit path length, and is often used when the energy loss is continuous and constant, such as with betas (electrons) or alphas. (1.07.02)
Specific Ionization
The average amount of energy needed to produce an ion pair in a given medium is (1.07.02)
W-Value
The average energy locally deposited in an absorber resulting from a charged particle per unit distance of travel (keV/cm). (1.07.02)
Linear Energy Transfer
For a given absorber, the average energy lost by a charged particle per unit distance traveled is (1.07.02)
Stopping Power
What are the units for W-Value? (1.07.02)
eV/ion pair
What are the units for Specific Ionization? (1.07.02)
ion pair/cm
What are the units for Linear Energy Transfer? (1.07.02)
keV/cm
What are the units for Range? (1.07.02)
cm
What are the units for Stopping Power? (1.07.02)
keV/cm
Two major mechanisms of energy transfer for alpha particulate radiation are excitation and (1.07.03)
Ionization
Three major mechanisms of energy transfer for beta particulate radiation are excitation, ionization and (1.07.04)
Bremsstrahlung
Bremsstrahlung occurs when (1.07.04)
A high-energy beta penetrates the electron cloud surrounding the nucleus of the atom and experiences the strong electrostatic attractive force of the positively charged nucleus, which results in changing the particle's velocity/kinetic energy and a bremsstrahlung x ray being emitted.
Photon interaction with matter causing ionization includes (1.07.05)
Compton scattering and photoelectric effect
All-or-none energy loss. The photon imparts all of its energy to an orbital electron. Significant energy < 1 MeV. (1.07.05)
Photoelectric effect
Partial energy loss for the incoming photon. The photon interacts with an atom's orbital electron and only part of the energy is transferred to the electron. Significant energy (200keV to 5MeV) (1.07.05)
Compton Scattering
Occurs when all the photons energy is converted to mass. Only occurs in the presence of a strong electric field. Gamma disappears into the nucleus and a positron/electron pair is created. (1.07.05)
Pair Production
The minimum photon energy required for Pair Production is (1.07.05)
1.022 MeV
Photon energies of less than 1 MeV and photon energies between 200 keV to 5 MeV most usually interact with matter via ___ and ___ respectively (1.07.05)
Photoelectric effect, Compton scattering
With regard to neutron energy classifications, which type of neutron has the highest kinetic energy (1.07.06)
Relativistic
With regard to neutron energy classifications, which type of neutron has the lowest kinetic energy (1.07.06)
Thermal
Neutrons < 2 MeV are considered to be ___ neutrons (1.07.06)
slow
Neutrons > 2 MeV are considered to be ___ neutrons (1.07.06)
fast
What is the kinetic energy value for Fast Neutrons? (1.07.06)
10 keV to 20 MeV
What is the kinetic energy value for Thermal Neutrons? (1.07.06)
~0.025 eV (<0.5 eV)
What is the kinetic energy value for Intermediate Neutrons? (1.07.06)
0.5 eV to 10 keV
What is the kinetic energy value for Relativistic Neutrons? (1.07.06)
>20 MeV
Neutron activation, Charged particle emission, and fission are all a possible result of (1.07.07)
Neutron capture of slow neutrons
The process of converting a stable nucleus to its radioactive counterpart by neutron bombardment is called (1.07.07)
Neutron activation (radiative capture)
Occurs when a neutron strikes a nucleus of about the same mass as that of the neutron and transfers much of its energy to the nucleus which recoils with energy lost by the neutron. No gamma radiation is given off but the recoil nucleus can be knocked away from its electrons and cause ionization and excitation. (1.07.08)
Elastic scattering
Occurs when a neutron strikes a large nucleus and penetrates for a short period of time, transfers energy to a nucleon inside, and then exits with a small decrease in energy. The nucleus is left in an excited state emitting gamma radiation that can cause ionization and excitation. (1.07.08)
Inelastic scattering
Multiple scattering by a neutron is the slowing-down or moderation mechanism for fast neutrons to reach thermal energies. This process is sometimes called (1.07.08)
Thermalization
What are typical shielding characteristics of alpha radiation? (1.07.09)
Thin amounts of most materials (paper, unbroken layer dead skin cells, few cm of air)
What are typical shielding characteristics of beta radiation? (1.07.09)
Low-Z and low-density materials (rubber, plastic, aluminum, glass, wood)
What are typical shielding characteristics of gamma radiation? (1.07.09)
High-Z and high density materials (lead, steel, depleted uranium, tungsten)
What are typical shielding characteristics of neutron radiation? (1.07.09)
Hydrogenous material for moderation (oil, polyethylene plastic, water) and capture material for absorption (boron, cadmium).
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