lec27(2x2)

lec27(2x2) - E = mc 2 E p m p c 2 = 938 MeV m p = 938 MeV c...

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12/6/11 1 Structure of the Nucleus 2 4 He A=mass number Z=atomic number element Nucleus = neutrons + protons Z = atomic number = number of protons N =number of neutrons A =atomic mass number (nucleon number) A= Z + N 12/6/11 2 Isotopes 2 4 He 2 3 He 2 6 He 12/6/11 3 Mass of Nucleons about 1800 times that of the electron 12/6/11 4 Size of the Nucleus 3 7 Li 1 femtometer = 10 -15 m 50,000 times smaller than an atom Approximately spherical r = r o A 1 3 A = r r o ! " # $ % 3 A is proportional to the volume of the sphere. As A increases, the radius of the nuclear sphere increases.
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12/6/11 5 Size of the Nucleus A = r r o ! " # $ % 3 A is proportional to the volume of the sphere. As A increases, the radius of the nuclear sphere increases. 12/6/11 6 Electric Potential Energy of the Nucleus PE = k q 1 q 2 r For Helium, PE ~ 1 MeV ionization energy of Hydrogen atom is 13.6 eV. ... 1 MeV is 100,000 times larger! 12/6/11 7 Mass & Energy Scales in Nuclear Physics
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Unformatted text preview: E = mc 2 E p m p c 2 = 938 MeV m p = 938 MeV c 2 1 u = 1.66 x 10 ! 27 kg = 931.5 MeV c 2 atomic mass unit which is 1/12 of the mass of a carbon atom C12 6 mass of a proton 12/6/11 8 Radioactive Decay 12/6/11 9 Half Life N = N o e ! " t N o 2 = N p e ! T 1/2 ln2 = T 1/2 T 1/2 = ln2 # 0.693 ! 1/2 = decay constant Large ! short T 1/2 12/6/11 10 Activity Large ! short T1/2 12/6/11 11 Fission & Fusion 12/6/11 12 Fission 12/6/11 13 Fission 1. Different reaction products, for U238 up to 90 different fission reactions 2. produces more neutrons that uses can lead to chain reaction 3. binding energy of U238 is smaller than binding energy of fission products. Energy is released as gamma rays & kinetic energy. Produces a large amount of energy 12/6/11 14 Fusion Two nuclei join to form a new particle...
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lec27(2x2) - E = mc 2 E p m p c 2 = 938 MeV m p = 938 MeV c...

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