Rad Physics Summer Final

 Three types of radioactivity observed for radium 1)α (alpha)particles  2)β (beta)particles3)γ(gamma)rays Number of disintegrations is______ to number of atoms proportional Decay equations A=A0e(-.693/T1/2)t Radioactivity was discovered by ____in ____. Henri Becquerel1896 Activity is defined as: material  A the rate of decay of a radioactive ΔN/Δt= -λN (the change in the number of atoms divided by the change in time =the negative decay constant times the number of atoms) Specific activity ≡ activity per unit mass Units of radioactivity Historical: Curie (Ci) SI:Becquerel (Bq) One Curie = _______dps 3.7 × 1010  dps –approx.activity of 1 g Radium, now 3.61x1010 dps) Becquerel (Bq) =__disintegration/second 1 1 Ci = __ GBq 37 1mCi = ___Ci = ____dps 10-3 3.7 *107 1μCi____Ci = ____dps 10-63.7 *104 1MBq =__Bq = __dps 1 MBq =106 =106  dps   1GBq = 109Bq =109dps Mean life or average life (Tave) is ____________. time it would take source decaying with constant (initial) activity to decay completely The mean life equation: 1.44*T1/2 Cumulative activity = A0*mean life(1.44*T1/2) Total # of disintegrations = Activity*1.44*T1/2 Total dose= mean life * initial dose (1.44 * T1/2 * initial dose) like for LDR implants Applications that use mean life: total dose (mean life * initial dose)total disintegrations (mean life * activity)cumulative activity (mean life * original activity) Radioactive isotopes of lighter elements achieve stability by keeping ____constant through ____or______. mass numberbeta decayK capture (K-shell electron which is captured) how does magnetic field affect gamma rays? it doesn't, because it has no charge Are alpha particles or beta particles bent more by a magnetic field? beta which unit is smaller, a Bq or a Ci? Bq is much smaller than a Ci All nuclei with Z>___ are unstable and lose mass by ___ decay. Naturally occurring isotopes occur in the (name 3) series. 82 (heavy nuclei)alpha(they also emit gamma and beta)Uranium, Thorium, Actinium Radioactive equilibrium occurs when the half life of the“daughter” product is: occurs when the half life of the“daughter” product is less than the half life of the parent There are two types of radioactive equilibrium- what are they and which involves a generator("cow")? Transient("cow") -used in nuke medSecular In _____equilibrium, the daughter's half life is much less than the 1/2 life of the parent secular an example would be 226Ra (T1/2=1622 y) and daughter 222Ra (T1/2=3.8 d) This is an example of "milking the cow" or transient equilibrium be able to recognize All matter is composed of ____, distinguished by physical and chemical properties of its _____. elementsatoms Radius of atom:  radius of nuclues 10-10 m10-14 m Primary Beam: Particles which have not experienced collision Secondary Beam: Particles which have experienced collisions The secondary beam is also known as the: scattered beam The nucleus is composed of: protons(+) and neutrons(no charge) A= mass number (number of protons +neutrons) Isotopes: same # protonsdifferent # neutrons Isotones: = same # neutronsdifferent # protons Isobars: same # nucleons different# protons Isomers: same # protons same #neutrons nucleus different energy state Nuclei gain stability when: neutrons and protons are evenly paired But as the Z increases, more neutrons are needed (n/p greater than 1) Nuclei gain stability for Z< 20 when the n/p is: ~ 1.0 Nuclei gain stability forZ> 20 when the n/p is: >1.0(Z GREATER than 20 n/p GREATER than 1) 1 amu = 1/12 mass of 12C Unit charge = 1.6 x 10-19 C any single electron or proton carries this charge Atomic weight (AW)= mass of atom in amu mass of atom in amu Gram atomic mass = the mass, in grams, of one mole of atoms in a monatomic chemical element Mass in grams = atomic weight = 1 mole define mole The mole is a unit of measurement for amount of substance. It is defined as the amount of any chemical substance that contains as many elementary entities, e.g., atoms, molecules, ions, or electrons, as there are atoms in 12 grams of pure carbon-12 (12C), Avogadro’s number = 6.022 x 1023 atoms # atoms/g = NA/AWAvogadro's Number/Atomic weight # electrons/g = (NA x Z)/AW What is the mass defect? Total Mass of the atom < sum of its   constituent parts The mass defect (difference) is the binding energy of the nucleus(nuclear force) Mass and energy equivalence: E = mc2 1eV=___J 1.6*10-19 1 MeV=____eV 1 MeV = 1 x 106 eV The number of electrons which can occupy a shell = 2n2 2n2 *Remember n= the shell #K=1L=2 etc. Binding energy (increases/decreases) as distance to nucleus decreases . Binding energy (increases/decreases) as distance to nucleus decreases (potential energy decreases) Characteristic radiation – energy= difference in electron orbital energy If sufficient energy is transferred to an orbital electron, it is: ejected from the atom What are the four forces in nature? 1)Gravitational2)Electromagnetic3)Weak nuclear4)Strong nuclear Which force is responsible for decay? weak nuclear Strong nuclear force - creates: “potential well” for particles withinalso keeps particles in nucleus Which force creates “potential barrier” for approaching charged particles? Electrostatic (Coulomb) force Protons, neutrons, electrons, and other subatomic particles can travel at high speeds (approaching speed of light) and: transfer energy. EM radiation is produced by oscillating: EM fields EM radiation is energy propagated at the speed of: light (c) Electromagnetic Radiation Wave Model c=? c=vλ   v-frequency in cycles per secondλ=wave length(distance between two peaks) Photon E= E=hv= hc/λ   h=plank's constant (6.62 * 10 -34  )E is in eVλ  is in m Energy of photons equation(shortcut) 1.24*10 -6  / λ  E is in eVλ  is in m Ionization takes place beyond a specified _______. energy *remembere=mc2e=hv Types of radioactive decay: )α – particle decay2)β  particle decay         a)β+ positron emission        b)β- negatron emission3)Electron capture–alternative to positron emission4)Internal conversion–isomeric transitionα – alternative to positron emission? Electron capture Authorjaxkaty ID305682 Card SetRad Physics Summer Final DescriptionRad Physics Summer Final Updated2015-07-26T01:00:06Z Show Answers