<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hi Tom,<div><br></div><div><br></div><div>It could well be that the Fe.laz provided with McStas has too high F2 values and hence produces too much scattering.</div><div><br></div><div>Via the attached .CIF from the ICSD database (from the publication Physical Review (1,1893-132,1963/141,1966-188,1969) (1917) 10, p661-p696), I have generated a .lau file through Crystallographica, also attached.</div><div><br></div><div>Running a quick simulation with the McStas 2.0 PSI_DMC instrument and this .lau (remember to adjust the BARNS flag accordingly) yields lower scattering than what the Fe.laz from the McStas 2.0 distribution, see attachments.</div><div><br></div><div>Could this be the cause of your reported issue?</div><div><br></div><div><br></div><div>Best,</div><div><br></div><div>Peter</div><div></div></body></html>