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 Author: jaxkaty ID: 305682 Filename: Rad Physics Summer Final Updated: 2015-07-25 21:00:06 Tags: radiation physics Folders: IU Description: Rad Physics Summer Final Show Answers:

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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
• 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
• 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),
6.022 x 1023 atoms
52. # atoms/g =
• NA/AW

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)
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)
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