Atomic and Nuclear Stucture

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Atomic and Nuclear Stucture

• Atom - smallest unit of a chemical element
• Size on the order of 10-8 cm (1 Angstrom)
• Contains Z electrons (Qe -1e, me 0.511
  MeV/c2, s ½ h)
• e 1.602x10-19 Coulomb
• and
• Nucleus
• Size on the order of 10-13 cm (1 femtometer 1
  Fermi )
• Contains more than 99.9 of the mass of the atom
• Made of Z protons and N neutrons
• Proton (Qp 1e, mp 938.28 MeV/c2 , s ½ h)
• Neutron (Qn 0, mn 939.57 MeV/c2 , s ½ h)
• A Atomic mass Z N
• Held together by strong nuclear force
• ZXN where X chemical symbol

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Special Relativity

• E mc2
• gm0c2
• T m0c2
• where m0 rest mass and g (1- v2/c2)-1/2
• E2 p2c2 m0c2

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Quantum mechanics is needed to understand
nuclear systemsWave functions Schrodingers
equationBarrier penetration Coulomb
barrierAngular momentum coupling angular
momenta add vectoriallySelection rules in
decays and reactions Fermi, Gamow Teller b
decays Weisskopf estimates for g decays
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Nuclear binding energy curve
Fission
Fusion
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Semi-empirical mass formula
Mass parabolas
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Exponential decay law

• dN/dt -lN
• N(t) N0 e-lt
• t1/2 ln2/l

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The Chart of the Nuclides A 2-D Periodic Table
Nuclei have shells similar to the electron shells
in an atom. The electron shells determine
the atomic and chemical properties the nuclear
shells determine the nuclear properties.
Proton
Nuclear excitations single-particle (Shell
Model) rotational vibrational
Neutron
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Shell Model
Krane
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Nuclear Reactions
Direct reactions ? e.g. 40Ca(d,p)41Ca Compound
nucleus reactions ? e.g. 208Pb(48Ca, 3n)253No
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Nuclei at the Extreme of Mass
Man-made Radioactivity the heaviest elements
Natural Radioactivity
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Nuclear Reactions in Stars
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Applications of Nuclear Science
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Further Level of Structure
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Sources of nuclear data

• Isotopes Project at LBNL
• http//ie.lbl.gov
• National Nuclear Data Center at BNL
• www.nndc.bnl.gov
• National Institute of Science and Technology
• http//physics.nist.gov

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Good References

• K. S. Krane, Introductory Nuclear Physics
• B. L. Cohen, Concepts of Nuclear Physics
• E. Segre, Nuclei and Particles

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Topics Covered in This Course

• Radioactive Decay - Ch. 3
• Nuclear Structure Ch. 7, 8
• Alpha Decay Ch. 9
• Beta Decay Ch. 10
• Gamma Decay Ch. 11
• Fission Ch. 12
• Low-Energy Reactions Ch. 13
• Nuclear astrophysics

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Homework 1 Due Monday January 28

• Read Chapters 1 and 2
• Chapter 2
• Problems 2, 4, 5, 7, 9