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88 Cards in this Set
- Front
- Back
What are atoms?
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fundamental constituents of matter that maintain the properties of that element of matter
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How are electrons held in place?
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binding energy (from the nucleus)
nucleus has a positive charge, attracting the electrons and holding them in place |
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What are the 3 units for energy?
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joules
erg eV |
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What does the value of an atom's binding energy tell you?
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the value of an atom's binding energy is the amount of energy that it would take to completely remove the electron from the atom
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What determines an atom's chemical properties?
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its electron configuration
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What determines an atom's stability?
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its nuclear configuration
remember: stable means not radioactive unstable means radioactive |
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An atomic mass unit is a way to discuss the mass of an atom.
How do we describe an amu? |
an amu is equal to 1/12 the mass of a C-12 (carbon 12) atom
or 1.6605 x 10^-27 = 1 amu |
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Z stands for an atom's
a. mass number b. atomic number c. number of neutrons d. number of electrons |
atomic number
(which is the number of protons) |
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A stands for an atom's
a. mass number b. atomic number c. number of neutrons d. number of electrons |
mass number
(which is the number of protons + neutrons or the number of "nucleons") |
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True or False:
Isotope means radioactive. |
False.
An isotope of an element is one that has the same number of protons but a different number of neutrons. |
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What principle does electrostatic force refer to?
What works against the electrostatic force an atom's nucleus? |
like charges repel
strong nuclear force works against & exceeds the electrostatic force by ~100x |
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What does mass defect mean?
What does it represent? |
the mass of the parts is greater than the mass of the whole
it represents the mass equivalent of the amount of energy that must be applied to separate the nucleus into its individual components |
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What is the speed of light in a vacuum?
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3x10^8 m/sec
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1 amu = how many MeV?
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1 amu = 931 MeV
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What is the formula for nuclear binding energy?
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nuclear binding energy = (mass defect in amu) x (931 MeV)
gives you nuclear binding energy in MeV |
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An ISOTOPE of an atom has what in comparison to the atom's atomic number, mass number, and number of neutrons?
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same atomic number
different mass number different number of neutrons |
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An ISOTONE of an atom has what in comparison to the atom's atomic number, mass number, and number of electrons?
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different atomic number
different mass number same number of neutrons |
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An ISOBAR of an atom has what in comparison to the atom's atomic number, mass number, and number of neutrons?
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different atomic number
same mass number different number of neutrons |
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An ISOMER of an atom has what in comparison to the atom's atomic number, mass number, and number of electrons?
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same atomic number
same mass number same number of neutrons **same element but it is just at a different "state" of excitability <--not sure if we have to know this |
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What is transmutation?
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1 element changes into another
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What is disintegration?
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when a nuclide emits a charged particle
example: a neutron loses its negative charge to emit a beta particle; this leaves the neutron with a positive charge |
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What are the 3 units for disintegration?
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dps (disintegration per sec)
Curie (Ci) Becquerel (Bq) <--SI unit |
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1 Curie (Ci) equals how many dps (disintegrations/sec)
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1 Ci = 3.7x10^10 dps
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1 Becquerel (Bq) equals how many dps (disintegrations/sec)
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1 Bq = 1 dps
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1 Curie (Ci) equals how many Becquerels (Bq)
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1 Ci = 3.7x10^10 Bq
(same as dps because 1 dps = 1 Bq) |
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What does half life (T 1/2) measure?
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the amount of time it takes for 50% of the atom's activity to decay
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When does the activity of an atom decay to equal zero?
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NEVER.
decay is exponential - gets closer and closer to zero but never gets there (always taking 1/2 of 1/2 of 1/2) |
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What is the formula for activity?
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Activity (A) = decay constant x number of atoms (N)
*units for activity will be atoms per unit time but this means atoms disintegrated per unit time |
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What is the decay formula?
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remaining activity = original activity x e^ - decay constant*elapsed time
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The decay constant of an atom is equal to what?
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.693/half life (T 1/2) of the atom
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If you know the number of half lives that have gone by for a particular atom...
what is the easy way to calculate the remaining activity for the atom? |
remaining activity = original activity / (2^ # of T1/2 passed)
(remaining activity equals the original activity divided by 2 to the # of half lives that have gone by) |
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What is the difference between physical decay and biological decay?
How does this relate to the effective half life (T-effective or T-eff)? |
Physical decay is the decay of a radiopharmaceutical as it sits in a vial/bottle/etc. (outside the body); denoted by T-p
Biological decay is the decay of a radiopharmaceutical as it is decaying in the body; denoted by T-b relation to effective half life: T-eff = [(T-p) x (T-b)] / [(T-p) + (T-b)] (effective half life equals the product of T-p and T-b divided by the sum of T-p and T-b) |
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A state of equilibrium means that....
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the energy radiated is balanced by the energy absorbed
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Explain secular equilibrium.
(when does it occur & the general idea) |
occurs when the half life of the parent is MUCH MUCH greater than the half life of the daughter
the activity of the daughter will build up to the activity of the parent and appears to decay with the half life of the parent |
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Explain transient equilibrium.
(when does it occur & the general idea) |
occurs when the half life of the parent is greater than the half life of the daughter (as opposed to MUCH MUCH greater as seen with secular equilibrium)
the activity of the daughter will build up to the activity of the parent and appears to decay with the half life of the parent (yes - this part is the same as secular) |
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Alpha particles
-mass number? -atomic number? -charge? -mass? |
mass number = 4
atomic number = 2 charge = 2+ mass = ~4 amu |
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Alpha particle emission occurs when the neutron/proton ratio is
a. too low b. too high c. equal |
the neutron/proton ratio is too LOW
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All alpha emitters have an atomic number that is ...
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greater than 82
(there is 1 exception but we do not have to know it) |
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For an alpha particle, what is the formula for total energy released (Q)
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Q = M-parent - M-daughter - M-alpha - 2M-electron
M = mass ***this formula gives you total energy released in amu - he usually wants the answer in MeV so you will multiply by 931 MeV) |
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What is the formula for the total energy of an alpha particle (Q-alpha)?
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Q-alpha = Q / [1 + (M-alpha/M-daughter)]
total energy of alpha particle equals total energy released divided by 1 plus the mass of the alpha particle divided by the mass of the daughter |
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What does "monoenergetic" mean?
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a particular nuclide will always have the same amount of energy
**alpha particles & characteristic x-rays are monoenergetic |
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Beta particles (B-)
- charge? - "mass number"? - "atomic number"? |
charge: -1
mass number: 0 atomic number: -1 |
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Beta particle emission occurs when the neutron/proton ratio is...
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when the neutron/proton ratio is too HIGH
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For a beta particle, what is the formula for total energy released (Q)?
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Q = M-parent - M-daughter
M means mass **because subtracting the M-beta will cancel out with adding the M-electron since they are equal |
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Why is it that beta particles (B-) are not monoenergetic?
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because when emitted, an anti-neutrino (v) is also emitted
the energy will be divided between the beta particle and the anti-neutrino |
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What is the formula for the average energy of a beta particle (B-)
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average energy = 1/3 maximum energy
**maximum energy = Q (total energy) |
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A beta particle (B-) is the same thing as an electron except for what one factor?
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its point of origin is in the nucleus
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A positron is the same thing as an electron except for what 2 factors?
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its point of origin is in the nucleus
it has a positive charge (+1) |
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Positrons
- charge? - "mass number" ? - "atomic number" ? |
charge: 1+
mass number: 0 atomic number: 1 |
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Emission of positrons (B+) occurs when the neutron/proton ratio is...
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when the neutron/proton ratio is too LOW
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All positron emitters have an atomic number that is...
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less than 82
**since both alpha and positron emission occurs when the neutron/proton ratio is too low, the difference of when each occurs is based on the atomic number |
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For positron particles, what is the formula for total energy released (Q)
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Q=M-parent - M-daughter - 2M-electron
M means mass |
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What occurs soon after positrons are emitted?
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annihilation
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Explain the process of annihilation for a positron particle.
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A positron attracts an electron.
They collide & explode. 100% of the mass is converted into energy so that you end up with two 511 keV photons that are 180 degrees apart from each other |
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What is electron capture?
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rather than emitting a particle, an orbital electron is captured
this will occur because the mass of the parent is not enough to "cover" the mass of the daughter (Q = M-parent - M-daughter would not lead to any energy left to be released) |
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Electron capture occurs when the neutron/proton ratio is....
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when the neutron/proton ratio is too LOW
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True or False: No radiation is emitted when electron capture occurs.
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False.
Electromagnetic radiation will occur when electron capture occurs. ("characteristic x-rays") |
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Explain how electron capture causes characteristic x-rays.
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An electron gets sucked into the nucleus, leaving a "hole" in the electron shell.
An electron from an outer shell will "drop" to fill the hole. This gives off an amount of energy that is equal to the difference of the energies between the shells in the form of a characteristic x-ray. |
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Electromagnetic radiation exists in bundles of energy that are referred to as _____.
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photons
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What is the formula associated with the dual nature of light?
I didn't really comprehend WTF dual nature of light is so...this card kinda sucks but we do have to know the formula... |
e = hv
e = energy in Joules h = planck's constant (value will be given on exam) v = frequency (use the value of the speed of light in a vacuum 3x10^8 m/sec) *this gives you the answer in Joules but he may want it in MeV - the conversion for this will be provided |
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What are the 2 types of electromagnetic radiation?
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1 - x-rays
sub-types: characteristic x-rays Bremsstrahlung x-rays 2 - gamma rays |
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Explain how we get Bremsstrahlung x-rays.
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A beta (B-) particle approaches an atom.
The positive charge in the atom's nucleus attracts the beta particle, causing it to radially accelerate. The beta particle will lose energy and part of that energy will be converted into Bremsstrahlung x-ray. |
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What is true of the fraction of energy converted into Bremsstrahlung x-rays?
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the fraction of energy converted into Bremsstrahlung x-rays is DIRECTLY PROPORTIONAL to the atomic number of the medium through which they pass
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Explain how an Auger electron can be emitted.
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Electron capture occurs
Electron moves from outer shell in to fill this hole Energy from this is transferred to an orbital electron, causing it to be emitted (referred to as an Auger electron) **compared to when the energy goes directly out in the form of a characteristic xray |
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Explain how a conversion electron can be emitted.
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An atom has a nucleus in an excited state.
Excitation energy is transferred to an orbital electron, causing it to be emitted (called a conversion electron) **compared to when the energy goes directly out in the form of a gamma ray |
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What is ionization?
What does it create? |
when incident radiation interacts with an orbital electron and imparts enough energy to expel it from the atom
creates an ion pair (electron expelled is a negative ion, atom remaining is a positive ion) |
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What does the ionization potential of an atom refer to?
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the amount of energy required to remove the least tightly bound electron from the atom
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What is excitation?
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incident radiation interacts with an orbital electron and imparts energy that raises the electron to a higher energy level, but does not impart enough energy to expel it from the atom
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What does specific ionization refer to?
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the number of ion pairs formed per unit distance traveled by the incident radiation
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What does linear energy transfer (LET) refer to?
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the average energy deposited per unit distance traveled by the incident radiation
high energy deposition corresponds to high LET (losing a lot of energy due to a lot of ionization) |
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Alpha particles are ___ LET while beta particles are ___ LET
(high vs low) |
alpha - high
*because it has big mass and a double charge beta - low *because it is small with a single charge |
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The least penetrating type of particulate radiation are _____ particles.
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alpha
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What is an alpha particle's range in tissue?
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about 1 x 10^-4 cm
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What are the 3 types of interactions between electromagnetic radiation and matter?
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pair production
compton scattering photoelectric absorption |
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What is pair production?
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direct conversion of electromagnetic radiation to mass
an incident photon with energy greater than 1.02 MeV passes through a nucleus and its energy is converted to mass to yield an electron and a beta particle |
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What is compton scattering?
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an incident photon with moderate energy interacts with an electron in an outer shell of an atom
the electron is emitted and the photon is scattered so... input: photon with moderate energy output: an emitted electron from a shell and a scattered photon |
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What is photoelectric absorption?
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a low energy incident photon interacts with an inner shell electron
the electron is emitted ALL energy from the incident photon is transferred to the electron so there is NO scattered photon in the output |
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What increases the likelihood of the occurance of photoelectric absorption?
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an absorber with a high atomic number
(this is why lead is a good shield) |
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What is the unit for measuring
-exposure? -dose? -equivalent dose? |
exposure: R (Roentgen)
dose: rad (radiation absorbed dose) equivalent dose: rem (Roentgen equivalent man) |
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What are the 2 restrictions of measuring exposure?
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can ONLY be measured in AIR
is ONLY measured for electromagnetic radiation |
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The SI unit for the Roentgen (R) is...
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1 coulomb/kg of air
*doesn't have a name |
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What does exposure (the Roentgen) measure?
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the charge generated in the air
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What does dose (the rad) measure?
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energy deposited per unit mass
QUANTITY ONLY |
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1 Rad = what?
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1 Rad = 100 ergs/g
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What is the SI unit for the rad
What is the conversion between them Also another conversion to memorize |
the Gray (Gy)
1 Gy = 100 rads also know: 1 Gy = 1 Joule/kg |
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How do we find rems?
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measure dose (rads)
multiply by the quality factor |
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What is the quality factor used when finding rems for an alpha particle? for beta? for gamma? for x-ray?
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alpha: 20
beta, gamma, x-ray: 1 |
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What is the SI unit for equivalent dose (rems)
conversion factor? |
Sievert (Sv)
1 Sv = 100 Rem |