The level of reduction is represented in the various possible locations in the data tree where information is stored.
E.g. for a monochromatic beam it is sufficient to supply the wavelength information
(value, resolution and unit) only once. The right place is the
experiment/measurement section. But for a energy-dispersive
set-up the wavelength might be given for each measurement point in
and extra column.
Below several examples of hierarchical structures are given for various measurement schemes and levels of reduction. Shown are only the entries relevant for this discussion.
monochromatic, angle-dispersive scheme
The wavelength and its resolution are given only once because
they are constant. But the angle points to the column where
the individual values are given. These allow for footprint correction.
experiment:
measurement:
scheme: angle-dispersive
wavelength: {value: 4.0, resolution: {type: constant, sigma: 0.1}, unit: angstrom}
angle: {column: 5}
reduction:
input files:
- file: data1
- file: data2
columns:
- {column: 1, variable: Qz, unit: 1/angstrom}
- {column: 2, variable: R}
- {column: 3, variable: sR}
- {column: 4, variable: sQz, unit: 1/angstrom}
- {column: 5, variable: angle, unit: deg}
energy-dispersive scheme, one angle
The wavelength column allows for absorption correction.
experiment:
measurement:
scheme: energy-dispersive
wavelength: {column: 5}
angle: {value: 1.2, resolution: {type: const, sigma: 0.02}, unit: deg}
reduction:
input files:
- file: data1
- file: data2
columns:
- {column: 1, variable: Qz, unit: 1/angstrom}
- {column: 2, variable: R}
- {column: 3, variable: sR}
- {column: 4, variable: sQz, unit: 1/angstrom}
- {column: 5, variable: wavelength, unit: angstrom}
energy-dispersive scheme, various angular settings
The wavelength information applies for all input files, thus it is
in the experiment/measurement section.
The angle here describes the individual raw data files.
Both entries are information for the user, since the level of
reduction assumed here (merging of the data form both raw files) does not allow
for later absorption or footprint corrections.
experiment:
measurement:
scheme: energy-dispersive
wavelength: {min: 3.0, max: 12.0, resolution: {type: const, sigma: 0.1}, unit: angstrom}
reduction:
input files:
- file: data1
angle: {value: 1.2, spread: 0.02, unit: deg}
- file: data2
angle: {value: 2.4, spread: 0.02, unit: deg}
columns:
- {column: 1, variable: Qz, unit: 1/angstrom}
- {column: 2, variable: R}
- {column: 3, variable: sR}
- {column: 4, variable: sQz, unit: 1/angstrom}
angle- and energy-dispersive, various angular settings, compact
Data are re-binned and histogrammed to a (given) Qz grid.
Resolution information is partially lost.
The universal wavelength and the raw file specific
angle are descriptive. They can hardly be used
for data analysis.
experiment:
measurement:
scheme: angle- and energy-dispersive
wavelength: {min: 3.0, max: 12.0, spread: 0.1, unit: angstrom}
reduction:
input files:
- file: data1
angle: (min: 0.6, max: 2.0, unit: deg}
- file: data2
angle: (min: 2.4, Max: 3.8, unit: deg}
columns:
- {column: 1, variable: Qz, unit: 1/angstrom}
- {column: 2, variable: R}
- {column: 3, variable: sR)}
- {column: 4, variable: sQz, unit: 1/angstrom}
angle- and energy-dispersive, various angular settings, detailed
Data might be re-binned, but are not histogrammed. I.e. there might be
several entries with (about) the same Qz, but with different wavelength and
angle and thus sQz.
The analysis software might use either sQz or the (wavelength, angle)
tuple, where the resolution information for both is given in the universal
part. Besides this, the universal wavelength and the raw file specific
angle are descriptive and not meant for data analysis.
experiment:
measurement:
scheme: angle- and energy-dispersive
wavelength:
min: 3.0
max: 12.0
resolution: {type: prop, sigma: 0.02}
unit: angstrom
column: 5
angle:
resolution: {type: const, sigma: 0.01}
unit: deg
column: 6
reduction:
input files:
- file: data1
angle: (min: 0.6, max: 2.0, unit: deg}
- file: data2
angle: (min: 2.4, max: 3.8, unit: deg}
columns:
- {column: 1, variable: Qz, unit: 1/angstrom}
- {column: 2, variable: R}
- {column: 3, variable: sR}
- {column: 4, variable: sQz, unit: 1/angstrom}
- {column: 5, variable: wavelength, unit: angstrom}
- {column: 6, variable: angle, unit: deg}
tasks
- What are the consequences for the reduction software?
- What is the consequence for the analysis software when the information might be found in various places in the file?