Rad Physics Summer Final

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Author:
jaxkaty
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305682
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Rad Physics Summer Final
Updated:
2015-07-25 21:00:06
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radiation physics
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IU
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Rad Physics Summer Final
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  1. Three types of radioactivity observed for radium


    1)α (alpha)
    particles 
    2)β (beta)
    particles
    3)γ(gamma)
    rays
  2. Number of disintegrations is______ to
    number of atoms
    proportional
  3. Decay equations
    A=A0e(-.693/T1/2)t
  4. Radioactivity was discovered by ____in ____.
    • Henri Becquerel
    • 1896
  5. Activity is defined as:
    material  A
    the rate of decay of a radioactive
  6. 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)
  7. Specific
    activity ≡
    activity per unit mass
  8. Units of radioactivity
    • Historical:
    • Curie (Ci)

    • SI:
    • Becquerel (Bq)
  9. One Curie = _______dps
    3.7 × 1010  dps

    • –approx.
    • activity of 1 g Radium, now 3.61x1010 dps)
  10. Becquerel
    (Bq) =__disintegration/second
    1
  11. 1 Ci = __ GBq
    37
  12. 1mCi = ___Ci = ____dps
    • 10-3
    •  3.7 *107
  13. 1μCi____Ci = ____dps
    • 10-6
    • 3.7 *104
  14. 1MBq =__Bq = __dps
    1 MBq =10=106  dps  


    1GBq = 109Bq =109dps
  15. Mean life or average life (Tave)
    is ____________.
    time it would take source decaying with constant (initial) activity to decay completely
  16. The mean life equation:
    1.44*T1/2
  17. Cumulative activity =
    A0*mean life(1.44*T1/2)
  18. Total # of disintegrations =
    Activity*1.44*T1/2
  19. Total dose=
    mean life * initial dose

    (1.44 * T1/2 * initial dose)

    like for LDR implants
  20. Applications that use mean life:
    • total dose (mean life * initial dose)
    • total disintegrations (mean life * activity)
    • cumulative activity (mean life * original activity)
  21. Radioactive isotopes of lighter elements
    achieve stability by keeping ____constant through ____or______.
    • mass number
    • beta decay
    • K capture (K-shell electron which is captured)
  22. how does magnetic field affect gamma rays?
    it doesn't, because it has no charge
  23. Are alpha particles or beta particles bent more by a magnetic field?
    beta
  24. which unit is smaller, a Bq or a Ci?
    Bq is much smaller than a Ci
  25. 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
  26. 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
  27. There are two types of radioactive equilibrium-
    what are they and which involves a generator("cow")?
    • Transient("cow") -used in nuke med
    • Secular
  28. 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)
  29. This is an example of "milking the cow" or transient equilibrium
  30. be able to recognize
  31. All matter is composed of ____,
    distinguished by physical and chemical properties of its _____.
    • elements
    • atoms
  32. Radius of atom: 
    radius of nuclues
    • 10-10 m
    • 10-14 m
  33. Primary Beam:
    Particles which have not experienced collision
  34. Secondary Beam:
  35. Particles which have experienced collisions
  36. The secondary beam is also known as the:
    scattered beam
  37. The nucleus is composed of:
    • protons(+)
    • and
    • neutrons(no charge)
  38. A=
    mass number (number of protons +neutrons)
  39. Isotopes:
    same # protons

    different # neutrons
  40. Isotones: =
    • same # neutrons
    • different # protons
  41. Isobars:
    same # nucleons

    different# protons
  42. Isomers:
    • same # protons
    • same #neutrons
    • nucleus different energy state
  43. Nuclei gain stability when:
    neutrons and protons are evenly paired

    But as the Z increases, more neutrons are needed (n/p greater than 1)
  44. Nuclei gain stability for
    Z< 20 when the n/p is:
    ~ 1.0
  45. Nuclei gain stability for
    Z> 20 when the n/p is:
    >1.0


    (Z GREATER than 20
     n/p GREATER than 1)
  46. 1 amu =
    1/12 mass of 12C
  47. Unit charge =
    • 1.6 x 10-19 C
    •  any single electron or proton carries this charge
  48. Atomic weight (AW)= mass of atom in amu
    mass of atom in amu
  49. Gram atomic mass =
    the mass, in grams, of one mole of atoms in a monatomic chemical element

    Mass in grams = atomic weight = 1 mole
  50. 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),
  51. Avogadro’s number =
    6.022 x 1023 atoms
  52. # atoms/g =
    • NA/AW
    • Avogadro's Number/Atomic weight

  53. # electrons/g =
    (NA x Z)/AW
  54. 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)
  55. Mass and energy equivalence:
    E = mc2
  56. 1eV=___J
    1.6*10-19
  57. 1 MeV=____eV
    1 MeV = 1 x 106 eV
  58. The number of electrons which can occupy a shell = 2n2
    2n2

    • *Remember n= the shell #
    • K=1
    • L=2 etc.
  59. Binding energy (increases/decreases) as distance to nucleus decreases .
    • Binding energy (increases/decreases) as distance to nucleus decreases
    • (potential energy decreases)
  60. Characteristic radiation – energy=
    difference in electron orbital energy
  61. If sufficient energy is transferred to an orbital electron, it is:
    ejected from the atom
  62. What are the four forces in nature?
    • 1)Gravitational
    • 2)Electromagnetic
    • 3)Weak nuclear
    • 4)Strong nuclear
  63. Which force is responsible for decay?
    weak nuclear
  64. Strong nuclear force - creates:
    • “potential well” for particles within
    • also keeps particles in nucleus
  65. Which force creates “potential barrier” for approaching charged particles?
    Electrostatic (Coulomb) force
  66. Protons, neutrons, electrons, and other subatomic particles can travel at high speeds (approaching speed of light) and:
    transfer energy.
  67. EM radiation is produced by oscillating:
    EM fields
  68. EM radiation is energy propagated at the speed of:
    light (c)
  69. Electromagnetic Radiation Wave Model
    c=?
    • c=vλ  
    • v-frequency in cycles per second
    • λ=wave length(distance between two peaks)
  70. Photon E=
    E=hv= hc/λ  

    • h=plank's constant (6.62 * 10 -34  )
    • E is in eV
    • λ  is in m
  71. Energy of photons equation(shortcut)
    1.24*10 -6  / λ 

    • E is in eV
    • λ  is in m
  72. Ionization takes place beyond a specified _______.
    energy
  73. *remember
    e=mc2
    e=hv
  74. Types of radioactive decay:
    )α – particle decay
    2)β  particle decay   
         a)β+ positron emission   
         b)β- negatron emission
    3)Electron capture–alternative to positron emission
    4)Internal conversion–isomeric transitionα –
  75. alternative to positron emission?
    Electron capture

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