9. Nuclear Physics Flashcards
band of stability
decay occurs to reach stablitybetween neutrons and protons (Z)
types of decay
beta minus (neutrons > protons)
beta plus/positron or electron capture (protons > neutrons)
alpha decay
beta minus decay
neutrons > protons; turn neutron into positron through beta particle emission
isobaric transition (mass does not change)
emission of beta particle changes charge of neutron from neutral to positive; and balance out energy loss
how to shield a beta emitter
plastic shielding
lead will generate bremmstahlung due to high Z
beta positive decay
protons > neutrons
positively charged proton converted into neutral neutron by addition of neutrino
511 keV positron emission
positron/electron collide and products with 511 keV photons are emitted 180 degrees apart from one another
electron capture
protons > neutrons
change proton into neutron by adding an electron
isobaric procedure; mass does not change
atomic number decreases since proton lost
often coupled to isomeric transition (emission of gamma photons)
isomeric transition
energy emission after isobaric transition
gamma emission usually
-multiple peaks for different tracers
gallium 4, indium 2
isobaric transition
beta emission, positiron emission, electron capture
how many peaks does gallium have
4
how many peaks does indium have
2
metastable
intermediate stae after transition from isobaric before isomeric transition
allows time to utilize nuclide before gamma emission for medical sue
alpha decay
heavy unstable atom with lots of tissue damage
positron emission
beta positive
production of tracers
cyclotron, nuclear reactor, radionuclide generator
cyclotron
produces elements via transmutation; carrier free (no parents to clean up/decay)
vacuum chamber in circular path accelerates particle to bombardment chamber to produce radioisotopes
nuclear reactor
spontaneous fissuino of uranium 235 into lighter fragments which will emit fission neutrons to produce unstable uranium 236
disadvantage: low yield and other undesired radioisotopes
cyclotron produced radioisotopes
molybdenum 99, fluorine 18, gallium 67m thallium 201
reactor produced radioisotopes
molybdenum 98 (can then go into cyclotron)
iodine 131
xenon 133
thallium 201
radionuclide generator
molybdenum is made in a Tc generator
molybendum vs tc halflife
Mo 67 hrs
Tc 6 hrs
Mo decays and is washed off with ____ to generate ___
saline to generate Tc stuck to Na
break through
Mo in a sample of Tc that washed off the generator
radionuclide purity test
evaluate for breakthrough Mo by evaluating photopeaks in sample
Mo assayed first: high energy Mo (740 keV) will NOT be attenuated by lead shield
NRC standar for radionuclide purity
NRC allows no more than 0.15 micro Ci of Mo per 1 milli Ci of Tc at the time of administration
if ratio <0.038 at time of elution, material will be suitable for injection/administration for at least 12 hrs