What is the definition of Lorentz factor?

[Lojzek]

Can anyone explain how Lorentz factor is defined (the one from theory of diffraction,
not special relativity)? I read that intensity of diffracted beam is proportional to
Lorentz factor, but I could not find its definition.
On what parameters does the Lorentz factor depend? How does the Lorentz factor change inside a polycrystal sample? Does it belong to the whole sample, one grain or part of a grain?

 

[asheg]

Please take a look at:

http://www.google.com/url?sa=t&sour...sg=AFQjCNGp6IboH3dVw3xpFexLjpu0wNQ_4g&cad=rja

 

[read]

Can anyone explain how Lorentz factor is defined (the one from theory of diffraction,
not special relativity)? I read that intensity of diffracted beam is proportional to
Lorentz factor, but I could not find its definition.
On what parameters does the Lorentz factor depend? How does the Lorentz factor change inside a polycrystal sample? Does it belong to the whole sample, one grain or part of a grain?

Lorentz factor originates from an integration of 3D delta-function (Bragg peak) in certain coordinate system to get the integrated intensity. If we consider constant-lambda experiment then the Lorenz factor will be \lambda^3/\sin(2\theta) for a Bragg peak from a single crystal. Note, the integrated intensity is not just counts/sec, but has the dimension counts*degrees/sec. For the powder case the answer depends on the detector that is used. Additional integration along the Debay cones within some limits given by the detector perpendicular to the scattering plane modifies the Lorentz to be \lambda^3/\sin(2\theta)/\sin(\theta).