I wouldnt expect radiation damage to cause twinning!
1) maybe you have different indexing for the 2 passes? Have you used
pointless to check if this could happen (depends on SG and cell dimensions)
Ask for "match reference set in input and give it sca1 as input 1, then
check sca2
2) use pointless to examine quality of symmetry matches before merging -
maybe you have the wtrong SG?
Eleanor
On Wed, 4 Jan 2012 08:54:38 -0600, Jacob Keller
<[log in to unmask]> wrote:
> Need more info: how many degrees per frame? Also, on integration, do
> various stats change over the 'sets?
>
> JPK
>
> On Wed, Jan 4, 2012 at 7:42 AM, Zhiyi Wei <[log in to unmask]>
wrote:
>> Dear all,
>>
>> I recently collected a dataset (~2000 frames) from a single crystal.
>> If merge first 600 frames (sca1) or last 600 frames (sca2), Rmerge
>> values from scalepack seem to be ok (~10%) though rejection ratios are
>> high (~5%). But if I merge all frames together, Rmerge value goes up
>> to ~20% and rejection is extremely high (~20%). Then, I checked sca1
>> and sca2 by xtriage in phenix. Surprisingly, the logfiles told me that
>> sca1 is no twining while sca2 is very likely to be twinned. I never
>> met this case before. So, I am wondering if it is possible from a
>> non-twinned structure to a twinned structure just due to radiation
>> damage. If the answer is yes, does it mean that I should not collect a
>> large number of frames to amplify anomalous signals by using this
>> crystal?
>>
>> Thanks a lot!
>>
>> Best,
>> Zhiyi
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