<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div></div><div><br></div><div><div><div>On 28 Oct 2013, at 09:09 , 陈彦舟 <<a href="mailto:wokaoyan1981@126.com">wokaoyan1981@126.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="line-height: 1.7; font-size: 14px; font-family: arial;"><div style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">Hello all,<o:p></o:p></font></span></div><div style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">The thickness of plate-shaped sample </font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: Calibri; mso-hansi-font-family: Calibri">α</span><span lang="EN-US"><font face="Calibri">-Fe on Residual Stress Neutron Diffractometer has been optimized by McStas. <span style="mso-spacerun: yes"> </span>According to the result, best thickness corresponding to the maximal intensity is around 9mm. see picture 1 and models pdc1 and pdc2 in enclosure.<o:p></o:p></font></span></div><div style="text-align: center; margin: 0cm 0cm 0pt;"><span lang="EN-US"><v:shapetype id="_x0000_t75" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><o:p></o:p></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri"><picture1.png></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">However, the theoritical optimized thickness calculated from the following formula is around 46mm which is 5 times as large as the simulated one.<o:p></o:p></font></span></div><div style="text-align: center; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">T<sub>opt</sub>=1/</font></span><span style="FONT-FAMILY: 宋体">Σ</span><font face="Calibri"><sub><span lang="EN-US">a</span></sub><span lang="EN-US">=1/N</span></font><span style="FONT-FAMILY: 宋体">σ</span><font face="Calibri"><sub><span lang="EN-US">a</span></sub><span lang="EN-US">=V/n</span></font><span style="FONT-FAMILY: 宋体">σ</span><sub><span lang="EN-US"><font face="Calibri">a<o:p></o:p></font></span></sub></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri"><span style="mso-spacerun: yes"> </span>T<sub>opt</sub>:<sub> </sub>Optimized thickness<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri"><span style="mso-spacerun: yes"> </span><span style="mso-spacerun: yes"> </span></font></span><span style="FONT-FAMILY: 宋体">Σ</span><font face="Calibri"><sub><span lang="EN-US">a</span></sub><span lang="EN-US">:macroscopic absorption cross section<o:p></o:p></span></font></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri"><span style="mso-spacerun: yes"> </span>N:Atomic number density<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><span style="mso-spacerun: yes"><font face="Calibri"> </font></span></span><span style="FONT-FAMILY: 宋体">σ</span><font face="Calibri"><sub><span lang="EN-US">a</span></sub><span lang="EN-US">: micro absorption cross section<o:p></o:p></span></font></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri"><span style="mso-spacerun: yes"> </span>n:number of atoms per unit cell<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri"><span style="mso-spacerun: yes"> </span>V: Volume of each unit cell<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">As for </font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: Calibri; mso-hansi-font-family: Calibri">α</span><font face="Calibri"><span lang="EN-US">-Fe, V=23.55</span><span style="mso-bidi-font-family: Calibri" lang="EN-US">Å</span><sup><span lang="EN-US">3</span></sup><span lang="EN-US">, n=2, </span></font><span style="FONT-FAMILY: 宋体">σ</span><font face="Calibri"><sub><span lang="EN-US">a</span></sub><span lang="EN-US">=2.56 barn<o:p></o:p></span></font></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">Then T<sub>opt</sub>=46mm<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">Will anybody please explain the difference between two results?<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><o:p><font face="Calibri"> </font></o:p></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">Best wishes,<o:p></o:p></font></span></div><div style="text-align: left; margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Calibri">Tom<o:p></o:p></font></span></div></div><br><br><span title="neteasefooter"><span id="netease_mail_footer"></span></span><span><picture1.png></span><span><pdc2.instr></span><span><pdc1.instr></span>_______________________________________________<br>mcstas-users mailing list<br><a href="mailto:mcstas-users@mcstas.org">mcstas-users@mcstas.org</a><br>http://mailman.mcstas.org/cgi-bin/mailman/listinfo/mcstas-users<br></blockquote></div><br></div></body></html>