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Where are the neutrons coming from?

?. ?. ?. ?. ?. Where are the neutrons coming from?. Spallation Physics 101. Linear Accelerator. Cockroft-Walton Injector. WNR Facility. Proton Storage Ring. Central Control Room. ER1/2. Lujan Center. 1L Target. 1L-Target. Proton beam. Bulk Shield. Window. Moderators. W-targets.

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Where are the neutrons coming from?

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  1. ? ? ? ? ? Where are the neutrons coming from? Spallation Physics 101

  2. Linear Accelerator Cockroft-Walton Injector WNR Facility Proton Storage Ring

  3. Central Control Room ER1/2 Lujan Center 1L Target

  4. 1L-Target Proton beam Bulk Shield Window Moderators W-targets Reflector

  5. Proton beam Window Moderators W-targets Reflector

  6. Lower Tier Moderators LQD SPEAR Asterix FP8/LAPTRON Pharos FDS NPDF SMARTS SCD FP5 HIPD HIPPO

  7. Upper Tier Moderators NPD-g IN500 DANSCE PCS

  8. p+ Spallation Process

  9. Intra-Nuclear Cascade

  10. Statistical Thermodynamics Nuclear Evaporation Model Fermi gas of free particles in a collective potential

  11. cold neutrons epi-thermal neutrons thermal neutrons Moderator functions Moderation and Slowing Down Thermalization and Diffusion

  12. Moderation/Slowing Down (incoherent inelastic scattering) #01 Neutron wavelength shorter than lattice parameters Moderator Atoms Epi-thermal neutron

  13. Moderation/Slowing Down (incoherent inelastic scattering) #02

  14. Neutron wavelength of the same order as the lattice constants Coherent elastic scattering (Bragg-reflection) • Scattering on vibrational modes of polyatomic molecules Discrete oscillators Thermalization and Diffusion • Absorption

  15. Maxwell Distribution: Thermal Spectrum

  16. Diffusion equation: Simplified form: Storage Time #01

  17. HIPPO instrument 1L Target Thermal neutrons Sample Location

  18. Do you know where the neutrons are coming from? If not, please fill free to ask questions!

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