Table of Contents
Name | Direction | Type | Default | Description |
---|---|---|---|---|
RunNumbers | Input | string | Sample run numbers | |
Vanadium | Input | string | Preprocessed white-beam vanadium file. Allowed extensions: [‘.nxs’] | |
EmptyCanRunNumbers | Input | string | Empty can run numbers | |
EnergyBins | Input | dbl list | 1.5 | Energy transfer binning scheme (in meV) |
MomentumTransferBins | Input | dbl list | Momentum transfer binning scheme (in inverse Angstroms) | |
NormalizeSlices | Input | boolean | False | Do we normalize each slice? |
CleanWorkspaces | Input | boolean | True | Do we clean intermediate steps? |
OutputWorkspace | Output | MatrixWorkspace | S_Q_E_sliced | Output workspace |
Reduction algorithm for powder or isotropic data taken at the SNS/ARCS beamline.
Its purpose is to yield a structure factor from which a dynamic pair
distribution function
can be obtained via the
Dynamic PDF interface.
The ARCS instrument has two gaps at particular angles due to arrangement
of the banks
The gaps lead to empty bins in the histogram which in turn generate
significant errors in the final
for certain values of
.
To prevent this we carry out a linear interpolation in
at the blind-strip
angles.
If user desires to plot the OutputWorkspace with Mantid’s slice viewer, user
should choose the “# Events Normalization” view. The last step in the reduction
is performed by executing
ConvertMDHistoToMatrixWorkspace,
which requires NumEventsNormalization. Our input workspace has as many spectra
as instrument detectors. Each detector has a 2D binning in
and
.
Each detector is at a particular
angle, thus
and
are related by:
That means that only bins satisfying the above condition have counts.
Thus for detector
we have number of counts
if the
pair satisfy
the above condition. This represents a trajectory in
space.
When we execute
ConvertMDHistoToMatrixWorkspace
with binning
and E binning
,
we go detector by detectory and we look at the fragment of the
trajectory enclosed in the cell of Q-E phase space
denoted by the corners
,
,
and
.
Thus we have for detector
to look at the
pairs
within this cell for detector
, with associated
counts and associated scattering cross-section:
The scattering cross-section in the aforementioned cell of dimensions
x
is the average of all
the scattering cross sections:
where is the
boxcar function
Categories: Algorithm Index | Inelastic\Reduction
Python: DPDFreduction.py (last modified: 2019-03-05)