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Unformatted text preview: Today’s class: • Finish Radioactive decay • S canning T unneling M icroscope (STM) • Quantum harmonic oscillator Potential energy curve for the α particle Nucleus (Z protons, & bunch of neutrons) New nucleus (Z-2 protons, bunch of neutrons) + Alpha particle (2 protons, 2 neutrons) Look at this systemE as the distance between the alpha particle and the nucleus changes. K¡ Strong attractive force (Nuclear forces) and the nucleus changes. V=0 for r b ∞ As we bring the α particle closer to the core, what happens to potential energy? r Coulomb repulsion: r e e Z k r q kq r V ) 2 )( )( 2 ( ) ( 2 1 − = = Nucleus: (Z-2) protons V(r) V(r) ~30 MeV ¡nergy Large r: coulomb force dominates Small r: Nuclear force dominates r e e Z k r q kq r V ) 2 )( )( 2 ( ) ( 2 1 − = = Review: Radioactive decay ¡dge of the nucleus (~8x10-15 m), Nuclear (‘Strong’) force starts acting strong attraction between nucleons. Potential energy drops dramatically. r 1 to 10 MeV Wave function picture: ~1-10MeV of K¡ outside ¡xponential decay in the barrier V(r) ¡nergy outside ~100MeV of K¡ inside the nucleus Wave function of the particle inside the potential well: Large K¡ b small Wavelength Wave function of the free particle: Small K¡ b Large wavelength Observations show Alpha-particles from the same...
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