<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi new user,<div class=""><br class=""></div><div class="">I won’t comment on your request for the ‘.instr’ files. I don't, however, understand how you plan to get Q-resolution from a vanadium sample?</div><div class=""><br class=""></div><div class="">Vanadium scatters isotropically. The scattering cross-section is pretty much purely incoherent and elastic. It’s a good choice to get the energy resolution of a spectrometer, but not the Q-resolution for a diffractometer.</div><div class=""><br class=""></div><div class="">Normally, I’d recommend using the Bragg peaks from a powdered crystalline sample to get the Q-resolution. The sample component should give resolution-limited peaks. Once you’ve simulated the scattering, you can then plot the widths of the peaks as a function of Q to get the resolution. You can even fit the widths with an appropriate analytical function to get the resolution for all Q.</div><div class=""><br class=""></div><div class="">If you’re planning an instrument for liquids, you don’t need brilliant Q-resolution. You should probably simulate for only one peak at a time, or with only a few peaks, to avoid problems with peaks merging at high Q. I think a component like ‘Powder1’ will suffice, although it will take a longer time to simulate because you will need to run it for a number of peaks over the usable range of Q on your instrument. Alternatively, you can choose something like ‘PowderN’ with, say beryllium as a sample, but edit the input file to only have ~10 peaks over the usable range of Q for your instrument.</div><div class=""><br class=""></div><div class="">I’m guessing that your instrument will be a TOF diffractometer. The resolution should probably be pretty flat. You can get more information on TOF resolution functions at:</div><div class=""><a href="http://wwwisis2.isis.rl.ac.uk/Disordered/Manuals/ATLAS manual and SSG.pdf" class=""><span class="Apple-tab-span" style="white-space:pre"> </span></a><a href="http://wwwisis2.isis.rl.ac.uk/Disordered/Manuals/ATLAS manual and SSG.pdf" class="">http://wwwisis2.isis.rl.ac.uk/Disordered/Manuals/ATLAS%20manual%20and%20SSG.pdf</a></div><div class=""><br class=""></div><div class=""><div class="">I’m also not sure what a "Q detector" is. Personally, I would use a straight-forward monitor that measured the position and energy (possibly as a time-of-flight) of the neutron and then calculate Q myself from there. I see that there is one component (TOF2Q_cylPSD_monitor) that will also convert to Q, but I’ve never used it so I can’t vouch for it.</div><div class=""><br class=""></div></div><div class="">Sorry I can’t be more help.</div><div class=""><br class=""></div><div class="">Cheers,</div><div class=""><br class=""></div><div class="">Andrew</div><div class=""><br class=""></div><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 12 Dec 2017, at 01:14, 韩泽华 <<a href="mailto:hanzh@ihep.ac.cn" class="">hanzh@ihep.ac.cn</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">Dear all
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I'm a new hand on McStas.I hope for some help from you.
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Recently I've been trying to make a series of simulations of a Total Scattering Diffractometer, which is almost like NIMROD. Now I'm facing two problems.
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First, I want to make a simulation with a D2O sample and then detect Q. I've got "D2O-coh.sqw" and "D2O-inc.sqw", but I couldn't get a correct result. Could you offer me some "*.instr" files or codes containing a D2O sample or H2O sample together with a Q detector?
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Second, I want to get a result of the Q-resolution of the Diffratometer with a Vanadium sample. Can I use a Detector Component to get the Q-resolution directly, even though at a certain angle? If it can be, please offer me some "*.instr" files or codes as well. If it can't be, then what should I do to get enough data to calculate the Q-resolution afterwards?
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Finally I'd like to remind that all my simulations are based on a Total Scattering Diffractometer.
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I'd appreciate all your help and suggestions.
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PS: I may have sent it yesterday, but with no reply, I think I need to send it once again. May you forgive my disturbance.
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A new user
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