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Neutron-induced Reactions

Neutron-induced Reactions. X ( n,b ) Y.  b ( Q + E n ).  n ( E n ). Probability to penetrate the potential barrier. P o ( E thermal ) = 1 P > o ( E thermal ) = 0. For thermal neutrons Q >> E n.  b ( Q )  constant. Non-resonant. Neutron-induced Reactions. Neutron-induced Reactions.

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Neutron-induced Reactions

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  1. Neutron-induced Reactions X(n,b)Y b(Q+En) n(En) Probability to penetrate the potential barrier Po(Ethermal) = 1 P>o(Ethermal) = 0 For thermal neutrons Q >> En b(Q)  constant Non-resonant Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  2. Neutron-induced Reactions Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  3. Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  4. Neutron-induced Reactions n-TOF CERN Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  5. Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  6. Neutron-induced Reactions n_TOF CERN Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  7. Neutron-induced Reactions Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  8. Charged Particle Reactions What is the Gamow Peak? Nuclear Radius Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  9. Charged Particle Reactions Electron Screening Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  10. Charged Particle Reactions e2 = 1.44x10-12 keV.m Tunneling probability: In numerical units: For -ray emission: Sommerfeld parameter Gamow factor Multipolarity Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  11. Charged Particle Reactions Nuclear (or astrophysical) S-factor Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  12. Charged Particle Reactions EC = ?? Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  13. Resonance Reactions E t CN  particle emission  E E > spacing between virtual states  continuum. (Lower part  larger spacing  isolated resonances). D  bound states  -emission  E  isolated states. Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  14. Resonance Reactions J Ex a + X  Y + b Q > 0 b + Y  X + a Q < 0 Excited State Entrance Channel a + X Exit Channel b + Y Inverse Reaction Compound Nucleus C* Identical particles • Nature of force(s). • Time-reversal invariance. Statistical Factor () QM HW 30 Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  15. Resonance Reactions Projectile Projectile Target Target Q-value Q-value Q + ER = Er E = E + Q - Eex Direct Capture (all energies) Resonant Capture (selected energies with large X-section) Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  16. Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  17. Resonance Reactions HW 31  Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  18. Resonance Reactions Damped Oscillator Oscillator strength Damping factor eigenfrequency Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  19. Resonance Reactions Breit-Wigner formula • All quantities in CM system • Only for isolated resonances. Reaction Elastic scattering Usually a>> b. HW 32 When does R take its maximum value? Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  20. Resonance Reactions Exit Channel b + Y Ja + JX + l = J (-1)l(Ja) (JX) = (J) (-1)l = (J) Natural parity. J Ex Excited State Entrance Channel a + X Compound Nucleus C* Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  21. Resonance Reactions What is the “Resonance Strength” …? What is its significance? In what units is it measured? Charged particle radiative capture (a,) (What about neutrons?) Cross section EC a  Energy Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  22. Resonance Reactions 14N(p,) HW 33 • Q = ?? • EC = ?? • ER = 2.0 MeV • Formation via s-wave protons, J = ½, p = 0.1 MeV, • dipole radiation E = 9.3 MeV,  = 1 eV. • Show that  = 0.33 eV. • If same resonance but at ER = 10 keV • p = ?? E = ??  = ?? • Show that  = 3.3x10-23 eV. Huge challenge to experimentalists Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

  23. -transfer reactions Angular distribution Resonance J Estimated Energy (keV)  (eV) 566 2+ 1.9 3- 0.15 4+ 0.01 470 0+ 0.6 1- 0.2 Experimental upper limit < 1.7 eV 18O(, )22Ne Nuclear and Radiation Physics, BAU, 1st Semester, 2006-2007 (Saed Dababneh).

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