Regarding daftness, it seems that the detector is wider than tall, which should improve the ratio of Lorentz-problematic reflections to good, fast-moving ones. So I assume it was a choice between that and excluding some spots in the gap--an appropriate calculation could be done to see whether this is appropriate.
I was curious about the polarization issue you mentioned: how does horizontal orientation speak to polarization? I don't understand the connection. All the best, Jacob Keller -----Original Message----- From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Gerard Bricogne Sent: Saturday, July 15, 2017 5:31 PM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Pilatus Issues Dear John, Having just seen Andreas's message regarding the best source of support to address your enquiry, I have a further remark to make about your instrument. As this is a lab instrument, the Omega axis would be vertical, and indeed the beam stop shadow (vertical on the top module) and the diffuse shadow of the sample holder (vertical on the bottom module) would confirm this. This being the case, it is quite simply *daft* to have the gap between the two modules being horizontal. That is done on purpose on synchrotron beamlines because of the polarisation of the beam (which is why Omega is horizontal on such beamlines), but in a lab system the gap should be in the vertical direction. As currently placed in your system, this gap is cutting into perfectly good data, whereas if it were vertical instead, it would only cut out data that are getting perilouly close to the cusp anyway. You should ask the manufacturer of your diffractometer to rotate your detector by 90 degrees! Someone in the OEM world forgot about the Lorentz factor ;-) . With best wishes, Gerard. -- On Fri, Jul 14, 2017 at 05:14:03PM +0100, John Hardin wrote: > Hi, > > We have recently noticed an issue with our Pilatus (biased pixels/vertical > lines). > I was curious as to whether anyone else has seen this or might know what > could have caused it? > > Best, > John >
