- Chapter 11 Nuclear Physics 11-1 Isotope Protons 9 11 23 36 52 66 74 86 Neutrons 9 14 28 48 68 82 101 136 11-2 The momentum of an electron

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249 Chapter 11 ! Nuclear Physics 11-1. Isotope Protons Neutrons 99 11 14 23 28 36 48 52 68 66 82 74 101 86 136 11-2. The momentum of an electron confined within the nucleus is: The momentum must be at least as large as ) p, so and the electron’s kinetic energy is . This is twenty times the observed maximum beta decay energy, precluding the existence of electrons in the nucleus. 11-3. A proton-electron model of 6 Li would consist of 6 protons and 3 electrons. Protons and electrons are spin-1/2 (Fermi-Dirac) particles. The minimum spin for these particles in the lowest available energy states is , so 6 Li (S=0) cannot have such a structure. 11-4. A proton-electron model of 14 N would have 14 protons and 7 electrons. All are Fermi-Dirac spin-1/2 particles. In the ground state the proton magnetic moments would add to a small fraction of the proton magnetic moment of 2.8 : N , but the unpaired electron would give the system a magnetic moment of the order of that of an electron, about 1 : B . Because : B is approximately 2000 times larger than : N , the 14 N magnetic moment would be about 1000 times the observed value, arguing against the existence of electrons in the nucleus.
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Chapter 11 ! Nuclear Physics 250 11-5. The two proton spins would be antiparallel in the ground state with . So the deuteron spin would be due to the electron and equal to 1/2 S . Similarly, the proton magnetic moments would add to zero and the deuteron’s magnetic moment would be 1 : B . From Table 11-1, the observed deuteron spin is 1 S (rather than 1/2 S found above) and the magnetic moment is 0.857 : N , about 2000 times smaller than the value predicted by the proton-electron model. 11-6. Isotopes Isotones (a) 18 F 17 F 19 F 16 N 17 O (b) 208 Pb 206 Pb 210 Pb 207 Tl 209 Bi (c) 120 Sn 119 Sn 118 Sn 121 Sb 122 Te 11-7. Nuclide Isobars Isotopes (a) (b) (c) 11-8. where R 0 = 1.2 fm = 1.2 × 10 ! 15 m
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Chapter 11 ! Nuclear Physics 251 11-9. (a) (b) (c) 11-10. (a) (b) (c) (d) 11-11. (a)
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Chapter 11 ! Nuclear Physics 252 (Problem 11-11 continued) (b) (c) 11-12. (This is Equation 11-13 on the Web page www.whfreeman.com/modphysics4e.) The values of the a i in MeV/c 2 are given in Table 11-3 (also on the Web page). For 23 Na: This result differs from the measured value of 31.972071u by only 0.009%. 11-13. (a) : (b) : (c) :
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Chapter 11 ! Nuclear Physics 253 11-14. (Equation 11-2) where Z = 20 for Ca and ) U = 5.49 MeV from a table of isotopes (e.g., Table of Isotopes 8th ed., Firestone, et al., Wiley 1998). 11-15. (a) (Equation 11-19) at (b) 11-16. (a) (b) (c) 11-17. (Equation 11-19) (a) At At
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Chapter 11 ! Nuclear Physics 254 (Problem 11-17 continued) (b) 11-18. (a) or nearly the same. (b)
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Chapter 11 ! Nuclear Physics 255 11-19. (a) when when Notice that this time interval equals three half-lives. (b) (c) Thus, 11-20. (a) and (b) t 1/2 . 3.6 min counts ' s 1/2R 0 t, min (c) Estimating from the graph, the next count (at 8 min) will be approximately 230 counts/s.
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This homework help was uploaded on 04/03/2008 for the course PHYSICS 7C taught by Professor Lin during the Spring '08 term at University of California, Berkeley.

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- Chapter 11 Nuclear Physics 11-1 Isotope Protons 9 11 23 36 52 66 74 86 Neutrons 9 14 28 48 68 82 101 136 11-2 The momentum of an electron

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