Re: [ccp4bb]: Re:Problems with low mosaicity

[Andy Thompson <thompson@embl-grenoble.fr>]

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I would just like to clarify a few things -

Firstly on beamline ID29 at the ESRF the quality of data collected is (in
general) good.

Secondly, in specific cases (as on any beamline or rotating anode)
infrequent failures of equipment
(a synchrotron beamline is a very complicated instrument) do occur and users
can suffer occasionally
when it is their beamtime that unearths the problem (for example in the case
of Harry Greenblatt
where a shutter failed and the only available replacement also proved to be
faulty). These problems
are shortlived (a few hours to a few days, depending on the availability of
spare parts) and infrequent
(several times per year). Reliability is continually improved in problem
areas (for example the new
shutter system developed in-house and mentioned by Harry).

Thirdly, specific problems are investigated by beamline staff when they are
reported. For example the
recent problem data reported on the bulletin board by the French group was
investigated
by beamline staff and no specific beamline problem discovered. But it
impossible to investigate problems
(for example the one mentioned below) which are not reported. Nor is it
possible to do anything in retrospect
where data is not processed on site and hence any problems not signalled
immediately.

Finally, if people do have problems with data quality, then the beamline
local contact is your first point of contact,
is best placed to know the beamline equipment and history, and will treat
your concernes seriously and professionally.
If there is really a problem talking to the local contact, then at the ESRF
you can contact the beamline scientist, beamline
operation team or even the User Organisation. Public discussion of problems
of unknown origin
(poor data can also be a result of crystal quality!) seems to me to be
wholly inappropriate.


Andy Thompson
Beamline responsible, ID29

"J. J. Müller" wrote:

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>
> Hallo,
> really an interesting point. Astonishing is, that the most people
> measured at ID29 in Grenoble in the last period.
> We measured also two datasets of different proteins with Rsym=11% in the
> inner shell and 15% in the outer what we have not seen before. The
> mosaicity is quite normal. So, one should ask the beamline people what
> is going on there?
> Juergen