Oops, sorry. The x axis of the previous plot is actually not
resolution, but Q. My bad.
Richard
On Nov 27, 2007, at 11:26 AM, Richard Gillilan wrote:
Just a couple small images that may be of interest. The x scale is
resolution in Angstroms, the y scale is intensity (arbitrary
units). I
:40
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] To bathe or not to bathe.
Oops, sorry. The x axis of the previous plot is actually not resolution,
but Q. My bad.
Richard
On Nov 27, 2007, at 11:26 AM, Richard Gillilan wrote:
Just a couple small images that may be of interest. The x scale
, though it can be done if the set up is
sufficiently flexible.
Colin
-Original Message-
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of
Robert Sweet
Sent: 26 November 2007 00:28
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] To bathe or not to bathe.
Thanks, Ron,
Regarding
I just noticed this thread. I should make a few comments.
We regularly provide microbeam with and without Helium here at
MacCHESS. Yes, there are cases in which microbeam can give you good
diffraction on large crystals when a larger beam cannot. Just last
week we had a user group
Richard Gillilan wrote:
I am currently working on guidelines for when helium and microbeam
are necessary (based on both simulations and explicit measurements).
At the present time, my feeling is that crystals below 50 micron can
certainly make the extra hassle worthwhile. It really
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] To bathe or not to bathe.
I just noticed this thread. I should make a few comments.
We regularly provide microbeam with and without Helium here at MacCHESS.
Yes, there are cases in which microbeam can give you good diffraction on
large crystals when
Hi Juergen, the original calculation was done with I/SIG's from
scala. Yes, I am aware of the problems obtaining reliable and
meaningful I/SIG with CCD data. I have gone through the exercise of
trying to get agreement between scala and scalepack by optimizing
error model parameters ...
In our current helium box, there is a total of about 28 mm of beam
exposed. 10 mm from the aperture of the optic and 18 mm from sample
to beamstop. The 10 mm side working distance is very tight for hand
mounting (little room for tongs) and falls just outside the shield
stream for cryo.
]
***
- Original Message -
From: Richard Gillilan [EMAIL PROTECTED]
To: CCP4BB@JISCMAIL.AC.UK
Sent: Monday, November 26, 2007 12:02 PM
Subject: Re: [ccp4bb] To bathe or not to bathe.
In our current helium box, there is a total of about 28 mm of beam
Folks,
As expected, discussion about to bathe or not to bathe are starting to
expand into other aspects of data collection and processing. Along the
way I saw reference to how we use our small beams on GM/CA beamlines in
sector 23 of APS. Without going into discussions of advantages and
- Original Message -
From: Nave, C (Colin) [EMAIL PROTECTED]
Several have raised the issue of radiation damage. The strategy which
Bob mentions can make sense, ensuring fresh parts of the crystal are
regularly brought in to the beam. I would have thought 5-10 micron beams
were rather
Manjasetty, Babu wrote:
Hi there,
1. See attached for life-time of crystals (How long will my crystal lost?) at various beamlines in the world.
2. The citations for the beauty and quality of the datasets from bending magnet beamlines. Please read most of the papers from Dauter group.
Just a few comments on consider a crystal bathed in a uniform
beam.
I've not fully bought into the idea that it's OK to have the
beam smaller than the crystal. I learned most of my crystallography
in a lab dedicated to precise structure determinations, and somewhere
along the line, I picked up
It'd be interesting to determine the validity of the assumption that
absorption is simply a function of frame number.
... and direction. See, eg:
Acta Cryst. (1995). A51, 33-38[ doi:10.1107/S0108767394005726 ]
An empirical correction for absorption anisotropy
R. H. Blessing
Best,
Jon
Thanks, Ron,
Regarding the bathing question, these days the major source of error we
find in synchrotron-based data is crystal damage. Several groups, notably
the two ID23s (one each of pairs of matched canted undulators at ESRF and
APS) are producing small x-ray beams, on the order of 5-10
On Sunday 25 November 2007 14:43, Ronald E Stenkamp wrote:
Just a few comments on consider a crystal bathed in a uniform beam.
Anyway, I thought the reason people went to smaller beams was that
it made it possible to resolve the spots on the film or detector.
Isn't that the main reason for
This is true, but if we really took the air-scatter argument seriously we
would go back to the days of huge Helium-filled enclosures to get rid of
the air scatter. Some beamlines currently do direct He outflow from the
collimator toward the crystal, which reduces air scatter by the
indident
Sent: Friday, November 23, 2007 4:08 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] To bathe or not to bathe.
Jorge,
You said,
I remember one former good (small molecule ?) crystallography book
with words a kind of this the crystals should be completely
bathed by
the x-ray beam during
One additional point to add not raised by Bob is that crystals are
different. So you can shoot at one end of the crystal and say have a
mosaicity of 0.2 degrees but somewhere else it might be 1.4 or even
worse. In such cases e.g. rod like needles it pays off to have a smaller
than crystal beam
by extrapolating back to zero dose in those days.
Jim
-Original Message-
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of
Robert
Sweet
Sent: Friday, November 23, 2007 4:08 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] To bathe or not to bathe.
Jorge,
You said,
I
board [mailto:[EMAIL PROTECTED] On Behalf Of Robert
Sweet
Sent: Friday, November 23, 2007 4:08 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] To bathe or not to bathe.
Jorge,
You said,
I remember one former good (small molecule ?) crystallography book
with words a kind of this the crystals
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