Coherent Backscattering from Multiple Scattering Systems - KOPS ...

Evaluation of the wide angle data
function d = diffuson (theta,l,R)
z0 = 2/3 * l * (1 + R) / (1 - R) ;
mu = cos(theta) ;
d = ( mu .* (z0/l + mu./(mu+1)) ) ./ (z0/l + 1/2) ;
end
function c = cooperon (theta,k,l,R,D,tau)
z0 = 2/3 * l * (1 + R) / (1 - R) ;
mu = cos(theta) ;
q = k * sin(theta) ;
L_a = sqrt (D * tau) ;
q_a = sqrt (q.^2 + 1/(D*tau)) ;
c = ( l * (l + L_a)^2 * ( (1 - exp(-2*q_a*z0)) ./ ...
(q_a*l) + 2*mu ./ (mu+1) ) ) ...
./ ( L_a^2 * ( l + (1 - exp(-2*z0/L_a)) * L_a ) * ...
( l*q_a + (mu+1) ./ (2*mu) ).^2 ) ;
c_add = (8 * pi * a(k,l,R)) / (3 * k^2 * l * (l + 2 * z0)) * mu ./ (mu + 1) ;
c = c - c_add ;
end
function a = a (k,l,R)
theta = 0.00001*pi : 0.00001*pi : pi/2 ;
z0 = 2/3 * l * (1 + R) / (1 - R) ;
mu = cos(theta) ;
q = k * abs(sin(theta)) ;
E_A = trapz ( theta, ...
3/(8*pi) * 1./(q*l + (mu+1)./(2*mu)).^2 ...
.* ( (1 - exp(-2*q*z0))./(q*l) + (2*mu)./(mu+1) ) ...
.* sin(theta) ) ;
E_BC = trapz ( theta, ...
1/(k*l)^2 * mu./(mu+1) ...
.* sin(theta) ) ;
a = E_A / E_BC ;
end
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