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125 Cards in this Set

  • Front
  • Back
What causes an atom to be unstable or radioactive?
having neutron to proton ratio that is either too low or too high
Isotopes have the same?
and different?
same atomic number
different mass
different number of neutrons
Isotones have the same?
and different?
same number of neutrons
different atomic number
different mass
Isobars have the same?
and different?
Same mass
Different atomic number
Different number of neutrons
Isomers have the same?
and different?
SAME atomic number, mass, and number of neutrons
What is a beta particle?
an electron that comes out of the nucleus
Does atomic mass include electrons?
How does a Beta particle's mass compare with the mass of a proton or neutron?
it is about 1,800 times smaller
What is transmutation?
Changing from one element to another
What is a decay chain?
when 1 radioactive element changes into another radioactive element and so on
What is disintegration?
when a nuclide emits a charged particle
The basic unit for radioactivity is measured in?
Disintegration per unit time
(this is the SI unit)
The Curie is a unit for what?
What is the abbreviation for Curie?
1 Ci= ? DPS
3.7 X 10^10 DPS
1 Bq = ? DPS
1 Bq = 1 DPS
1 Ci = ? Bq
1 Ci= 3.7 X 10^10 Bq
The Curie, Becquerel, and Disintegrations per second are all units of ?
Cps stands for? and is a unit of?
Counts Per Second, and is NOT a measurement of radioactivity, it IS just a measurement
What is the equation for decay constant?
The symbol for decay constant is lambda
the equation is:
lambda= 0.693/half life
** make sure half life is in seconds?
What is a half life?
the time it takes for 50% of the ACTIVITY to decay
What type of curve is the activity curve for half life?
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
What is the formula for activity?
A = lambda X n
lambda=decay constant (0.693/halflife)
n=number of atoms
**make sure half life is in seconds?
As the decay constant gets SMALLER what happens to the amount of time for the half life?
it gets BIGGER, half life and decay constant are INVERSELY PROPORTIONAL
When lambda (decay constant) decreases, you need alot of ______ to make up for it
you need alot of ATOMS to make up for it
What is the decay formula?
A = A(not) X e^-lambda(t)
t= time elapsed
**the units for half life and time elapsed must MATCH!
When radioactivity is happening in the body it is called?
Biological half life:
the body gets rid of the radioactivity in a biological half life (also an exponential formula)
Together the PHYSICAL decay and the BIOLOGICAL excretion are called?
What is the symbol for effective half life?
what is the formula for effective half life?
Teff = (T physical X T biological)/(T physical + T biological)
When calculating the effective half life (Teff) you answer is going to be...?
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)
secular equilibrium:
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
In secular equilibrium you see what relationship between the half life of the daughter and that of the parent?
the activity of the daughter
Transient equilibrium:
the activity of the parent is greater than that of the daughter (they are closer in half lives than in secular equilibrium)
What is the relationship in TRANSIENT equilibrium between parent and daughter activity?
activity of the daughter is building up and appears to decay with the half life of the parent
alpha particles consist of what?
2 protons and 2 neutrons (mass is about 4 amu) alpha particles have NO ELECTRONS
what is the biggest type of particle?
Alpha particle
alpha particles occur when the neutron to proton ratio is too ______
all alpha emitters have an atomic number greater than _____?
82, with one exception
For an alpha particle, total energy released (Q) is?
for an alpha:
Q=Mass p -mass d -mass alpha -(2)mass electron
what is the mass of an electron?
0.00055 amu
1 amu = ? MeV?
931 Mev
What is the formula for the energy of an alpha particle?
E alpha = Q/ (1+ [mass of the alpha/mass of the daughter)]
the decay scheme of the alpha particle does what?
goes down and to the left
How does a beta particle relate to an electron?
A beta particle is the same thing as an electron, but it originates from INSIDE the nucleus
What is the charge of a beta particle?
What is the mass of a beta particle?
0.00055 amu
When does a beta particle occur?
when the neutron to proton ratio is too HIGH
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
Beta particles have a mass NUMBER of?
Q for beta particles is?
Q = M parent - M daughter **this gives you the answer in amu's so you might need to convert into Mev's
Is there recoil on beta particles?
Is there recoil on alpha particles?
No for beta
Yes for alpha
Are beta particles monoenergetic?
What is an antineutrino?
An infinitely small mass that has no charge and has no biological effects

the symbol is v (same as for f
What is the formula for average energy?
E with a line over it = 1/3 E max
Decay scheme for beta particles looks like?
down and to the right
What is a positron?
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
When is a positron emitted?
When neutron to proton ratio is too LOW
What is a positron?
an electron with a positive charge
What do positrons interact with?
positrons start to interact with matter and lose it's energy, they collide with negatively charged electrons and explode
When a positron collides with an electron what happens?
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
Which type of imaging device uses the positron and electron collision for imaging?
the PET scan
When does electron capture occur?
when the neutron to proton ratio is too LOW
Electron capture is also called?
K capture
How is an x ray produced?
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
What are characteristic X rays?
They are characteristic or specific to the element from which they are emitted
alpha and beta particles give what type of radiation?
x rays give off what type of radiation?
Electromagnetic radiation does what?
has oscillating electromagnetic waves, and does NOT require a medium
As we increase frequency what happens to the wavelength?
the wavelength decreases, they are INVERSELY PROPORTIONAL
Characteristic X rays are?
monoenergetic, they have a distinct energy
What is a photon?
a packet or bundle of electromagnetic radiation energy, photons are "particulate like"
Formula for the dual nature of light?
E (in Joules) = hv
h = plancks constant
Alpha particles are _____?
Speed of light (c) is?
2.998 X 10^8 m/s
Decay constant (lambda) =?
0.693/ T1/2
To find what fraction of the original activity remains when you have the number of half lives do?
1/ 2^# of half lives

1 divided by 2^# of half lives
When do characteristic X rays happen?
when electrons move from outer shells to inner shells, they are MONOENERGETIC
Bremsstrahlung means?
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
Gamma rays are emitted from?
excited nuclei, they have NOTHING to do with electrons
Bremsstrahlung comes from?
electrons through a medium or in matter, Bremsstrahlung is a type of X ray
Bremsstrahlung happens when?
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
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
NEVER use lead to shield _______?
Particulate stuff, because that creates X rays, because it has a high atomic number
low density=_____ atomic number
High density=_______ atomic number
low density, low atomic number
high density, high atomic number
An alternative to characteristic X rays are?
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)
Excitation energy normally comes out as a gamma ray, but what is the alternative?
can instead be transferred to an orbital electron causing the orbital to be emitted called a CONVERSION ELECTRON
Conversion electrons come from?
Auger electrons come from?
Characteristic X rays
How does an ion get created?
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)
The electron kicked out when a positive ion is made is considered a what?
negative ion
Ion pairs are what?
the positive ion (positive atom) with the negative ion (the kicked out electron)
ionization potential
the amount of energy required to remove the least tightly bound electron
raising the electrons to a higher electron energy but not enough to make them leave
specific ionization
the number of ion pairs formed per unit distance traveled by the incident radiation
linear energy transfer (LET)
the AVERAGE energy deposited per unit path length (distance) traveled by the incident radiation
alpha particles are _____ LET
they are HIGH LET, they lose their energy very fast
alpha particles are the biggest particles with 2 charges
Beta particles have a _____ LET
LOW let, they are small and lose their energy slowly, they have 1 charge
How do alpha particles penetrate?
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
how do beta particles penetrate?
they have a max range in a material which is dependent on the energy of the beta particle
Which kind of radiation is easily shielded?
charged particles (alpha and beta) are easily shielded, we use a LOW density or LOW atomic number shields for charged particles
gamma rays come from where?
the nucleus
X rays come from where?
the movement of electrons
Pair Production is?
the direct conversion of electromagnetic radiation to mass
an incident photon causes?
as it approaches the nucleus its energy is converted to mass in the form of an electron and a positron
The threshold for pair production is greater than ______?
1.02 Mev
If pair production occurs, then what happens?
all the incident radiation is converted to 2 masses, and electron and a positron
Compton Scattering
has a photon interacting with an OUTER shell electron and you get a scattered photon and a kicked out electron
Compton scattering--
Input:moderate energy photon acting on an outer shell electron
Output: emitted electron and lower energy scattered photon
Compton scattering has what energy?
medium energy
Photoelectric absorption:
Input: low energy photon acting on an INNER shell electron
Output: electron emitted, NO scattered photon
You use a ____ atomic number absorber to increase the likelihood of photoelectric absorption
a HIGH atomic number absorber (like lead)
Roentgen (R)
exposure unit. exposure must be measured in AIR and we only measure GAMMA and X RAYS (only electromagnetic radiation) (NOT charged particles)
rad (radiation absorbed dose)
it is a measure of the energy deposited per unit MASS
1 rad = _____ erg/gram
1 rad=100erg/gram
rad (radiation absorbed dose) are measured from?
ANY type of radiation in ANYTHING
1 gray=_____rad's?
1 gray=100 rads
why don't we use rads very much?
it doesn't take into account the effects of different types of radiation (like alpha particles and beta particles have very different effects)
rem means?
Roentgen equivalent man
what is an rem?
rems=rads X quality factor
quality factor for alpha particles is?
the quality factor is 1 for which types of radiation?
X ray, Gamma rays, and beta particles
1 Sievert=____rem
1 Sv=100 rem
1 gray=?
1 gray = 1J/kg = 100 rads
the quality factor is?
a radiation weighting factor