\(\renewcommand\AA{\unicode{x212B}}\)

FindDetectorsPar v1

Summary

The algorithm returns the angular parameters and second flight path for a workspace detectors (data, usually availble in par or phx file)

Properties

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	The name of the workspace that will be used as input for the algorithm
ReturnLinearRanges	Input	boolean	False	if set to true, the algorithm would return linear detector’s ranges (dx,dy) rather then angular ranges (dAzimuthal,dPolar)
ParFile	Input	string	not_used.par	An optional file that contains of the list of angular parameters for the detectors and detectors groups; If specified, will use data from file instead of the data, calculated from the instument description. Allowed extensions: [‘.par’, ‘.phx’]
OutputParTable	Input	string		If not empty, a name of a table workspace which will contain the calculated par or phx values for the detectors

Description

Identifies geometrical parameters of detectors and groups of detectors after the workspaces were grouped using ASCII or XML map file. Located in DataHandling\Instrument\Detectors group and intended to be used as Child Algorithm of SaveNXSPE algorithm, though can be deployed independently. Dynamic casting from iAlgorithm and accessors functions return calculated parameters to SaveNXSPE when FindDetectorsPar used as the Child Algorithm of SaveNXSPE procedure;

Internal Child Algorithm identifies the group topology, namely if a group of detectors is arranged into a rectangular shape or in a ring. The algorithm calculates the geometrical centre of the detectors group and 6 points, located within +-1/4 width of the first detector of the group. If the centre or any of these points belong to the group of the detectors itself, the group assumed to have a rectangular topology, and if not – the cylindrical one (ring).

Single detector defined to have the rectangular shape.

After identifying the topology, the parameters are calculated using formulas for angles in Cartesian or Cylindrical coordinate systems accordingly

par and phx files

These files are ascii files which are used to describe the combined detectors geometry defined by map files. There are no reasons for you to use it unless this Mantid algorithm is working unsatisfactory for you. In this case you can quickly modify and use par file until this algorithm is modified. It is your responsibility then to assure the correspondence between mapped detectors and parameters in the par file.

The par files are simple ASCII files with the following columns:

1st column      sample-detector distance (m)
2nd  "          scattering angle (deg)
3rd  "          azimuthal angle (deg)   (west bank = 0 deg, north bank = -90 deg etc.)   (Note the reversed sign convention cf .phx files)
4th  "          width  (m)
5th  "          height (m)

When processed by this algorithm, 4th and 5th column are transformed into angular values.

Phx files are Mslice phx files, which do not contain secondary flight path. This path is calculated by the algorithm from the data in the instrument description and the angular values are calculated as in nxspe file. There are no reason to use phx files to build nxspe files at the moment unless you already have one and need to repeat your previous results with Mantid.

Usage

Caution

This algorithm is meant to be run as a child algorithm to one of the previously mentioned algorithms. However, it can be used alone.

Note

To run these usage examples please first download the usage data, and add these to your path. In Mantid this is done using Manage User Directories.

Example - Pars with (dPolar, dAzimuthal)

ws = Load("MAR11001.raw")
# Output workspace is None if OutputParTable is not used)
pars = FindDetectorsPar(ws, OutputParTable="pars")
# pars is a TableWorkspace
print("Workspace type = {}".format(pars.id()))
# Show width column headers
print("Width headers = ( {} , {} )".format(pars.getColumnNames()[3], pars.getColumnNames()[4]))

Output:

Workspace type = TableWorkspace
Width headers = ( polar_width , azimuthal_width )

Example - Pars with (dX (width), dY (height))

ws = Load("MAR11001.raw")
# Output workspace is None if OutputParTable is not used)
pars = FindDetectorsPar(ws, ReturnLinearRanges=True, OutputParTable="pars")
# pars is a TableWorkspace
print("Workspace type = {}".format(pars.id()))
# Show width column headers
print("Width headers = ( {} , {} )".format(pars.getColumnNames()[3], pars.getColumnNames()[4]))

Output:

Workspace type = TableWorkspace
Width headers = ( det_width , det_height )

Categories: AlgorithmIndex | DataHandling\Instrument

Source

C++ header: FindDetectorsPar.h

C++ source: FindDetectorsPar.cpp