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125 Cards in this Set
- Front
- Back
What causes an atom to be unstable or radioactive?
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having neutron to proton ratio that is either too low or too high
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Isotopes have the same?
and different? |
same atomic number
different mass different number of neutrons |
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Isotones have the same?
and different? |
same number of neutrons
different atomic number different mass |
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Isobars have the same?
and different? |
Same mass
Different atomic number Different number of neutrons |
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Isomers have the same?
and different? |
SAME atomic number, mass, and number of neutrons
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What is a beta particle?
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an electron that comes out of the nucleus
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Does atomic mass include electrons?
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YES
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How does a Beta particle's mass compare with the mass of a proton or neutron?
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it is about 1,800 times smaller
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What is transmutation?
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Changing from one element to another
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What is a decay chain?
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when 1 radioactive element changes into another radioactive element and so on
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What is disintegration?
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when a nuclide emits a charged particle
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The basic unit for radioactivity is measured in?
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Disintegration per unit time
DPS (this is the SI unit) |
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The Curie is a unit for what?
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radioactivity
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What is the abbreviation for Curie?
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Ci
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1 Ci= ? DPS
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3.7 X 10^10 DPS
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1 Bq = ? DPS
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1 Bq = 1 DPS
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1 Ci = ? Bq
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1 Ci= 3.7 X 10^10 Bq
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The Curie, Becquerel, and Disintegrations per second are all units of ?
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radioactivity
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Cps stands for? and is a unit of?
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Counts Per Second, and is NOT a measurement of radioactivity, it IS just a measurement
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What is the equation for decay constant?
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The symbol for decay constant is lambda
the equation is: lambda= 0.693/half life ** make sure half life is in seconds? |
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What is a half life?
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the time it takes for 50% of the ACTIVITY to decay
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What type of curve is the activity curve for half life?
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Exponential, therefore in theory you never get to 0 activity. However, the half life only works if you have enough atoms to still be predictable
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What is the formula for activity?
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A = lambda X n
A=activity lambda=decay constant (0.693/halflife) n=number of atoms **make sure half life is in seconds? |
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As the decay constant gets SMALLER what happens to the amount of time for the half life?
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it gets BIGGER, half life and decay constant are INVERSELY PROPORTIONAL
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When lambda (decay constant) decreases, you need alot of ______ to make up for it
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you need alot of ATOMS to make up for it
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What is the decay formula?
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A = A(not) X e^-lambda(t)
t= time elapsed **the units for half life and time elapsed must MATCH! |
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When radioactivity is happening in the body it is called?
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biological
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Biological half life:
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the body gets rid of the radioactivity in a biological half life (also an exponential formula)
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Together the PHYSICAL decay and the BIOLOGICAL excretion are called?
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the EFFECTIVE HALF LIFE
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What is the symbol for effective half life?
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Teff
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what is the formula for effective half life?
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Teff = (T physical X T biological)/(T physical + T biological)
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When calculating the effective half life (Teff) you answer is going to be...?
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a little smaller than the smaller of the two half lives used in your equation
(answer will never be larger than the Tp or the Tb) |
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secular equilibrium:
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the half life of the parent is much greater than the half life of the daughter
T 1/2 of the parent >> T 1/2 daughter |
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In secular equilibrium you see what relationship between the half life of the daughter and that of the parent?
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the activity of the daughter
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Transient equilibrium:
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the activity of the parent is greater than that of the daughter (they are closer in half lives than in secular equilibrium)
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What is the relationship in TRANSIENT equilibrium between parent and daughter activity?
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activity of the daughter is building up and appears to decay with the half life of the parent
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alpha particles consist of what?
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2 protons and 2 neutrons (mass is about 4 amu) alpha particles have NO ELECTRONS
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what is the biggest type of particle?
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Alpha particle
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alpha particles occur when the neutron to proton ratio is too ______
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LOW
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all alpha emitters have an atomic number greater than _____?
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82, with one exception
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For an alpha particle, total energy released (Q) is?
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for an alpha:
Q=Mass p -mass d -mass alpha -(2)mass electron |
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what is the mass of an electron?
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0.00055 amu
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1 amu = ? MeV?
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931 Mev
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What is the formula for the energy of an alpha particle?
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E alpha = Q/ (1+ [mass of the alpha/mass of the daughter)]
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the decay scheme of the alpha particle does what?
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goes down and to the left
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How does a beta particle relate to an electron?
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A beta particle is the same thing as an electron, but it originates from INSIDE the nucleus
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What is the charge of a beta particle?
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-1
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What is the mass of a beta particle?
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0.00055 amu
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When does a beta particle occur?
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when the neutron to proton ratio is too HIGH
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Does atomic mass include the mass of the electrons?
Does the mass NUMBER include the mass of electrons? |
Atomic mass includes electrons
Mass NUMBER does NOT include electrons |
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Beta particles have a mass NUMBER of?
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ZERO
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Q for beta particles is?
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Q = M parent - M daughter **this gives you the answer in amu's so you might need to convert into Mev's
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Is there recoil on beta particles?
Is there recoil on alpha particles? |
No for beta
Yes for alpha |
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Are beta particles monoenergetic?
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NO
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What is an antineutrino?
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An infinitely small mass that has no charge and has no biological effects
the symbol is v (same as for f |
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What is the formula for average energy?
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E with a line over it = 1/3 E max
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Decay scheme for beta particles looks like?
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down and to the right
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What is a positron?
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positrons are positively charged beta particles (B+). They are antimatter, it only exists for a very short time in nature. They come from the nucleus, they have the same mass as a beta particle
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When is a positron emitted?
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When neutron to proton ratio is too LOW
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What is a positron?
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an electron with a positive charge
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What do positrons interact with?
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positrons start to interact with matter and lose it's energy, they collide with negatively charged electrons and explode
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When a positron collides with an electron what happens?
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all the mass gets converted to energy, this is called annihilation. When a positron and an electron collide this produces two 511 Kev photons at 180 degrees apart
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Which type of imaging device uses the positron and electron collision for imaging?
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the PET scan
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When does electron capture occur?
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when the neutron to proton ratio is too LOW
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Electron capture is also called?
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K capture
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How is an x ray produced?
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When an electron gets pulled from the K shell into the nucleus (electron capture) the hole is filled by an electron in the L shell, this gives off the x ray
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What are characteristic X rays?
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They are characteristic or specific to the element from which they are emitted
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alpha and beta particles give what type of radiation?
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particulate
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x rays give off what type of radiation?
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electromagnetic
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Electromagnetic radiation does what?
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has oscillating electromagnetic waves, and does NOT require a medium
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As we increase frequency what happens to the wavelength?
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the wavelength decreases, they are INVERSELY PROPORTIONAL
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Characteristic X rays are?
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monoenergetic, they have a distinct energy
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What is a photon?
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a packet or bundle of electromagnetic radiation energy, photons are "particulate like"
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Formula for the dual nature of light?
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E (in Joules) = hv
h = plancks constant v=frequency |
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Alpha particles are _____?
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Monoenergetic
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Speed of light (c) is?
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2.998 X 10^8 m/s
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Decay constant (lambda) =?
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0.693/ T1/2
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To find what fraction of the original activity remains when you have the number of half lives do?
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1/ 2^# of half lives
1 divided by 2^# of half lives |
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When do characteristic X rays happen?
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when electrons move from outer shells to inner shells, they are MONOENERGETIC
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Bremsstrahlung means?
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breaking radiation (as in slowing it down) They are NOT MONOENERGETIC, they have a continuous energy distribution from the max energy of a beta particle on down
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Gamma rays are emitted from?
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excited nuclei, they have NOTHING to do with electrons
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Bremsstrahlung comes from?
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electrons through a medium or in matter, Bremsstrahlung is a type of X ray
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Bremsstrahlung happens when?
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When a negatively charged beta particle approaches the positively charged nucleus it has radial acceleration some of the energy will be converted to heat, and some will come off as an x ray--Bremsstrahlung X ray
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The fraction of the Energy (from incident particles) converted into X rays is ________ proportional to the atomic number of the medium through which it passes
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DIRECTLY
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NEVER use lead to shield _______?
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Particulate stuff, because that creates X rays, because it has a high atomic number
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low density=_____ atomic number
High density=_______ atomic number |
low density, low atomic number
high density, high atomic number |
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An alternative to characteristic X rays are?
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the creation of Auger electrons, this happens when the energy is transferred to another orbital electron that results in that electron being kicked out (an Auger electron)
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Excitation energy normally comes out as a gamma ray, but what is the alternative?
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can instead be transferred to an orbital electron causing the orbital to be emitted called a CONVERSION ELECTRON
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Conversion electrons come from?
Auger electrons come from? |
Gamma
Characteristic X rays |
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How does an ion get created?
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incident radiation interacts with an orbital electron and imparts sufficient energy to expel it from the atom, this creates an ion (makes a positive ion because it lost an electron)
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The electron kicked out when a positive ion is made is considered a what?
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negative ion
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Ion pairs are what?
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the positive ion (positive atom) with the negative ion (the kicked out electron)
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ionization potential
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the amount of energy required to remove the least tightly bound electron
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excitation
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raising the electrons to a higher electron energy but not enough to make them leave
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specific ionization
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the number of ion pairs formed per unit distance traveled by the incident radiation
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linear energy transfer (LET)
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the AVERAGE energy deposited per unit path length (distance) traveled by the incident radiation
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alpha particles are _____ LET
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they are HIGH LET, they lose their energy very fast
alpha particles are the biggest particles with 2 charges |
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Beta particles have a _____ LET
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LOW let, they are small and lose their energy slowly, they have 1 charge
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How do alpha particles penetrate?
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alpha particles are the LEAST penetrating type of radiation, because they have a HIGH LET, their range in air is only several cm, in tissue they go 1X10^ - 4 cm
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how do beta particles penetrate?
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they have a max range in a material which is dependent on the energy of the beta particle
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Which kind of radiation is easily shielded?
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charged particles (alpha and beta) are easily shielded, we use a LOW density or LOW atomic number shields for charged particles
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gamma rays come from where?
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the nucleus
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X rays come from where?
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the movement of electrons
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Pair Production is?
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the direct conversion of electromagnetic radiation to mass
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an incident photon causes?
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as it approaches the nucleus its energy is converted to mass in the form of an electron and a positron
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The threshold for pair production is greater than ______?
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1.02 Mev
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If pair production occurs, then what happens?
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all the incident radiation is converted to 2 masses, and electron and a positron
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Compton Scattering
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has a photon interacting with an OUTER shell electron and you get a scattered photon and a kicked out electron
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Compton scattering--
Input: Output: |
Input:moderate energy photon acting on an outer shell electron
Output: emitted electron and lower energy scattered photon |
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Compton scattering has what energy?
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medium energy
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Photoelectric absorption:
Input: Output: |
Input: low energy photon acting on an INNER shell electron
Output: electron emitted, NO scattered photon |
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You use a ____ atomic number absorber to increase the likelihood of photoelectric absorption
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a HIGH atomic number absorber (like lead)
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Roentgen (R)
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exposure unit. exposure must be measured in AIR and we only measure GAMMA and X RAYS (only electromagnetic radiation) (NOT charged particles)
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rad (radiation absorbed dose)
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it is a measure of the energy deposited per unit MASS
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1 rad = _____ erg/gram
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1 rad=100erg/gram
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rad (radiation absorbed dose) are measured from?
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ANY type of radiation in ANYTHING
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1 gray=_____rad's?
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1 gray=100 rads
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why don't we use rads very much?
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it doesn't take into account the effects of different types of radiation (like alpha particles and beta particles have very different effects)
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rem means?
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Roentgen equivalent man
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what is an rem?
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a unit of EQUIVALENT DOSE
rems=rads X quality factor |
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quality factor for alpha particles is?
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20
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the quality factor is 1 for which types of radiation?
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X ray, Gamma rays, and beta particles
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1 Sievert=____rem
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1 Sv=100 rem
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1 gray=?
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1 gray = 1J/kg = 100 rads
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the quality factor is?
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a radiation weighting factor
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