[Ifeffit] Re: Ifeffit Digest, Vol 22, Issue 1
Bruce Ravel
ravel at phys.washington.edu
Thu Dec 2 13:51:19 CST 2004
Hi,
There are three aspects to this morning's thread that I'll comment on.
(1) I won't disagree that XAS data should be presented to the
beamline user in the form of signal as a function of energy.
That should be considered a standard format for data
presentation. That said, it is, apparently, less clear to me
than to some others what Athena should and shouldn't do. Athena
already has utilities for e.g. converting from keV to eV (a
fairly trivial chore) and converting dispersive data measured as
a function of pixel position into data as a function of energy (a
fairly tricky chore). It's not clear to me that encoder to
energy conversion is so very different from those.
It'll be easy enough to ignore, if it really bugs you ;-)
(2) I am uncomfortable with the phrase "the Athena test". I cannot
comfortably be a part of any discussion of file standardization
that has such an obvious conflict of interest built in from the
get-go.
(3) Supporting data harvested from SPEC files has long been on my
list of things to do. A good, object-oriented interface to spec
files built with perl would take a week or two of solid work to
build and test properly. I am aware of many beamlines (a few at
the ESRF for example, as well as any crystallography beamline
that wants to pop off a quick absorption scan) that use SPEC, so
that would be a useful thing to have -- not just for Athena but
for anything in perl that wants to play with SPEC files. (A
quick google search turns up nothing of the sort, sadly.)
The issue of incompletely documented columns is, as Matt pointed
out, a real one with SPEC files. However, it's not a problem
unique to SPEC files. DND-CAT, for instance, produces files that
have that problem in spades. (Well... the ones that Dave Barton
keeps sending to me do...!) Dealing with non-obvious files is
the reason that Athena's column-selection dialog replots the data
every time you click one of the column buttons. This allows you
to poke at an unclear file until you find some columns that make
sense.
B
--
Bruce Ravel ----------------------------------- ravel at phys.washington.edu
Code 6134, Building 3, Room 405
Naval Research Laboratory phone: (1) 202 767 2268
Washington DC 20375, USA fax: (1) 202 767 4642
NRL Synchrotron Radiation Consortium (NRL-SRC)
Beamlines X11a, X11b, X23b
National Synchrotron Light Source
Brookhaven National Laboratory, Upton, NY 11973
My homepage: http://feff.phys.washington.edu/~ravel
EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/
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