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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Dear all, </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>following last email, I think there are possibly two more
problems in the Powder modules in McStas : </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>First in the definition of the coherent scattering cross
section, the expression: </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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. </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>In the definition of the absorbing and incoherent, my_inc
and my_a_v, the multiplication by the packing fraction is missing. </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> 80 my_a_v = sigma_a/Vc*2200;
/* Is not yet divided by v */</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> 81 my_inc = sigma_inc/Vc;</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Best,</span></font></p>
<p class=MsoAutoSig><font size=3 color=red face="Times New Roman"><span
style='font-size:12.0pt;color:red'>______________________________________</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Dr Laurent Chapon</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Instrument Scientist</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>ISIS</span></font> department</p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Bldg R3</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Rutherford Appleton Laboratory</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Chilton, Didcot</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>OX11 0QX</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>UK</span></font></p>
<p class=MsoAutoSig><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>+44(0)1235-446090</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
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