Hi Chandra, If I remember correctly, the SSRL beam lines 12-2 and 14-1 allow kappa offset plus you can swing out the detector. You might have to come up with a special collection strategy, that you collect in resolution bins to avoid overlaps.
Jürgen P.S. my previous messages got blocked, let’s see if this one passes. > On Aug 20, 2019, at 5:18 AM, colin.n...@diamond.ac.uk > <colin.n...@diamond.ac.uk> wrote: > > I agree with Ed that focusing on the detector might be better than on the > crystal. An alternative is to reduce the beam divergence which might be > easier on some beamlines. > > The idea is to ensure the instrument parameters (e.g. beam size, beam > divergence, detector distance) and data collection parameters (e.g. rotation > increments) do not degrade the diffraction pattern. This should ensure all > spots which are intrinsically separated are properly resolved. I don't really > see the need for a multi circle goniometer if this is done. If the spots are > naturally smeared due to crystal imperfections then they overlap anyway. In > this case, as Ed says, one has to ensure the profiles are adequately sampled > so that any deconvolution procedure has a chance of succeeding. > > Colin > > > -----Original Message----- > From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> On Behalf Of Edward A. Berry > Sent: 19 August 2019 17:08 > To: ccp4bb <ccp4bb@jiscmail.ac.uk> > Subject: Re: [ccp4bb] [EXTERNAL] Re: [ccp4bb] Better Beamline suggestion! > > I would respectfully suggest that higher pixel resolution does not generally > help much in these situations. If an average spot is 10 or more pixels wide > then the profile is defined pretty well. But if the spots overlap, they still > overlap with higher pixel density. It may make profile fitting more accurate, > allowing more accurate "deconvolution" of the compound spot into its > components, but it will not improve the overlap. Smaller or better-focused > (on the detector, not the crystal?) beam, and longer camera length can help. > It is analogous to chromatography- If two peaks coming off the column > overlap, collecting smaller fractions will not help to resolve them. It may > allow a better-informed decision on the cut-off points when you pool the > fractions, but it won't separate the overlap. > On the other hand a multi-circle goniometer is very useful. I remember in > one of our last trips at SSRL (2007-8?) we used a (Huber 4-circle?) and it > was very easy to have the long axis in the plane of the image throughout the > rotation. In the absence of such you can resort to carefully bending the > loop or bending the pin (Jim Holton made a nifty device for bending the pin) > while keeping the xtal bathed in the cold stream. > > > On 08/19/2019 11:12 AM, graeme.win...@diamond.ac.uk wrote: >> Chandra >> >> What you are looking for here is a beamline with a detector with many pixels >> (so you can resolve the long axis) and a multi-axis goniometer - probably a >> SmarGon / kappa and an Eiger 16M would make a good combination for this. >> Searching on >> >> https://urldefense.proofpoint.com/v2/url?u=http-3A__biosync.sbkb.org_&d=DwIFAg&c=ogn2iPkgF7TkVSicOVBfKg&r=cFgyH4s-peZ6Pfyh0zB379rxK2XG5oHu7VblrALfYPA&m=VcmIp54F7yM1JdiEMdBdR0y7xinGb-nsn2-3LI_BHto&s=5VFyqMBHljO-AEcXr3-pqjF8xFyEejXetVFOxOXLp_Y&e= >> >> Should allow you to make up a short list >> >> Best wishes Graeme >> >> On 19 Aug 2019, at 16:08, Chandramohan Kattamuri >> <00001c5b7cb6c764-dmarc-requ...@jiscmail.ac.uk<mailto:00001c5b7cb6c764-dmarc-requ...@jiscmail.ac.uk>> >> wrote: >> >> >> Dear All >> We recently collected a data set at APS, Chicago with unit cell dimensions >> of 68.4; 68.4 and 991.6 A. Our diffraction data extends to 3A with the APS >> set up, however, the long axis has been problematic, resulting in streaking >> of the diffraction data and requires a very specific orientation of the >> crystal for usable diffraction. Can anyone recommend beamlines that can give >> us higher resolution, or a source with a better goniometer allowing for more >> angle manipulation after looping? >> Thank a lot >> Chandra K >> >> >> >> >> ________________________________ >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.jiscmail.ac.uk_cgi-2Dbin_webadmin-3FSUBED1-3DCCP4BB-26A-3D1&d=DwIFAg&c=ogn2iPkgF7TkVSicOVBfKg&r=cFgyH4s-peZ6Pfyh0zB379rxK2XG5oHu7VblrALfYPA&m=VcmIp54F7yM1JdiEMdBdR0y7xinGb-nsn2-3LI_BHto&s=NIk481IQQfkQVGsehEs9ptANwtNDLPRMWSSzJRcFHUY&e= >> >> > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 > > -- > This e-mail and any attachments may contain confidential, copyright and or > privileged material, and are for the use of the intended addressee only. 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