Neutron Scattering: Why Hydrogen is Negative

[nittopuran]

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?

 

[bcrowell]

What quantity are you saying is positive or negative?

 

[Vanadium 50]

I don't even know what "negative scattering" could possibly mean. I think you may have a language issue.

 

[fzero]

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.