Neutron Scattering: Why Hydrogen is Negative

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    Neutron Scattering
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Discussion Overview

The discussion centers on the phenomenon of neutron scattering, specifically addressing why hydrogen exhibits negative scattering lengths while deuterium and most other atoms show positive scattering lengths. The conversation explores theoretical aspects and interpretations of scattering behaviors.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant asks why neutron scattering from hydrogen is negative compared to positive scattering from deuterium and other atoms.
  • Another participant seeks clarification on what is meant by "positive or negative" in this context.
  • A third participant expresses confusion regarding the term "negative scattering," suggesting a potential language issue.
  • A fourth participant clarifies that "negative scattering" refers to negative scattering length and cites a source indicating that the spin-spin interaction is stronger than the S-wave interaction for np scattering, which may lead to a phase shift.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the terminology and implications of negative scattering, indicating that the discussion remains unresolved with multiple interpretations present.

Contextual Notes

There are limitations in the clarity of terms used, particularly regarding "negative scattering" and its implications, as well as the dependence on specific theoretical frameworks referenced.

nittopuran
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A very simple question, but needs to know proper explanation. Why the neutron scattering from hydrogen is negative while deuterium and almost all other atom has positive scattering?
 
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What quantity are you saying is positive or negative?
 
I don't even know what "negative scattering" could possibly mean. I think you may have a language issue.
 
He means negative scattering length. According to http://mightylib.mit.edu/Course%20Materials/22.101/Fall%202004/Notes/Part3.pdf the spin-spin part of the interaction is stronger than the S-wave interaction for np scattering. Presumably this leads to the phase shift, though the reference only describes the calculation of the cross section.
 
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