[neutron-mc] Other problems with Powder modules

Chapon, LC (Laurent) L.C.Chapon at rl.ac.uk
Thu Mar 31 19:24:28 CEST 2005

Dear all, 

following last email, I think there are possibly two more problems in
the Powder modules in McStas : 


First in the definition of the coherent scattering cross section, the


my_s_v2 = PI*PI*PI*pack*DW/(Vc*Vc*V2K*V2K)*(j_1*F2_1/q_1) is not quite
right. I think a factor 4 is missing, it should be 4PI^3. 


In the definition of the absorbing and incoherent, my_inc and my_a_v,
the multiplication by the packing fraction is missing. 


 80 my_a_v = sigma_a/Vc*2200;           /* Is not yet divided by v */

 81 my_inc = sigma_inc/Vc;




Dr Laurent Chapon

Instrument Scientist

ISIS department

Bldg R3

Rutherford Appleton Laboratory

Chilton, Didcot

OX11 0QX




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