Calibration Implementation Details¶

This file is concerned with calibrating a specified set of tubes

The main function is getCalibration() which is at the end of this file. It populates an empty Calibration Table Workspace with the new positions of the pixel detectors after calibration. This Calibration Table Workspace can be used later to move the pixel detectors to the calibrated positions.

Users should not need to directly call any other function other than getCalibration() from this file.

tube_calib.constructIdealTubeFromRealTube(ws, tube, fitPar, funcForm)¶

Construct an ideal tube from an actual tube (assumed ideal)

Parameters:	ws – integrated workspace tube – specification of one tube (if several tubes, only first tube is used) fitPar – initial fit parameters for peak of the tube funcForm – listing the type of known positions 1=Gaussian; 2=edge
Return type:	IdealTube

tube_calib.correct_tube(AP, BP, CP, nDets)¶

Corrects position errors in a tube in the same manner as is done for MERLIN according to an algorithm used by Rob Bewley in his MATLAB code.

@param AP: Fit position of left (in pixels) @param BP: Fit position of right (in pixels) @param CP: Fit position of centre (in pixels) @param nDets: Number of pixel detectors in tube

Return Value: Array of corrected Xs (in pixels)

tube_calib.correct_tube_to_ideal_tube(tube_points: typing.List, ideal_tube_points: typing.List, n_detectors: int, test_mode: bool = False, polin_fit: int = 2, parameters_table: typing.Union[str, NoneType] = None) → numpy.ndarray¶

Corrects position errors in a tube given an array of points and their ideal positions.

Note that any element of tubePoints not between 0.0 and nDets is considered a rogue point and so is ignored.

Parameters:

tube_points – Array of Slit Points along tube to be fitted (in pixels) ideal_tube_points – The corresponding points in an ideal tube (Y-coords advised) n_detectors – Number of pixel detectors in tube test_mode – If true, detectors at the position of a slit will be moved out of the way to show the reckoned slit positions when the instrument is displayed. polin_fit – Order of the polynomial to fit for the ideal positions parameters_table – name of output TableWorkspace containing values and errors for optimized polynomial coefficients, as well as goodness-of-fit chi-square value. If None, no table is returned

Returns:

Array of corrected Xs (in same units as ideal tube points)

tube_calib.create_tube_calibration_ws_by_ws_index_list(integrated_workspace, output_workspace, workspace_index_list)¶

Creates workspace with integrated data for one tube against distance along tube The tube is specified by a list of workspace indices of its spectra

@param integrated_workspace: Workspace of integrated data @param workspace_index_list: list of workspace indices for the tube @param x_unit: unit of distance ( Pixel) @param show_plot: True = show plot of workspace created, False = just make the workspace.

Return Value: Workspace created

tube_calib.getCalibratedPixelPositions(input_workspace: typing.Union[str, _dataobjects.EventWorkspace, _dataobjects.Workspace2D], tube_positions: typing.Union[typing.List[int], numpy.ndarray], ideal_tube_positions: typing.Union[typing.List[int], numpy.ndarray], which_tube: typing.Union[typing.List[int], numpy.ndarray], peak_test_mode: bool = False, polin_fit: int = 2, parameters_table: typing.Union[str, NoneType] = None) → typing.Tuple[typing.List[int], typing.List[int]]¶

Get the calibrated detector positions for one tube.

The tube is specified by a list of workspace indices of its spectra. The calibration is assumed to be done parallel to the Y-axis.

Parameters:

input_workspace – Workspace with tubes to be calibrated - may be integrated or raw tube_positions – Array of calibration positions (in pixels) ideal_tube_positions – Where these calibration positions should be (in Y coords) which_tube – a list of workspace indices for the tube peak_test_mode – true if shoving detectors that are reckoned to be at peak away (for test purposes) polin_fit – Order of the polynomial to fit for the ideal positions parameters_table – name of output TableWorkspace containing values and errors for optimized polynomial coefficients, as well as goodness-of-fit chi-square value. If None, no table is returned

Returns:

list of pixel detector IDs, and list of their calibrated positions

tube_calib.getCalibration(input_workspace: typing.Union[str, _dataobjects.Workspace2D], tubeSet: tube_spec.TubeSpec, calibTable: _dataobjects.TableWorkspace, fitPar: tube_calib_fit_params.TubeCalibFitParams, iTube: ideal_tube.IdealTube, peaksTable: _dataobjects.TableWorkspace, overridePeaks: typing.Dict[int, typing.List[typing.Any]] = {}, excludeShortTubes: float = 0.0, plotTube: typing.List[int] = [], range_list: typing.Union[typing.List[int], NoneType] = None, polinFit: int = 2, peaksTestMode: bool = False, parameters_table_group: typing.Union[str, NoneType] = None) → None¶

Get the results the calibration and put them in the calibration table provided.

Parameters:

input_workspace – Integrated Workspace with tubes to be calibrated tubeSet – Specification of Set of tubes to be calibrated ( TubeSpec object) calibTable – Empty calibration table into which the calibration results are placed. It is composed by ‘Detector ID’ and a V3D column ‘Detector Position’. It will be filled with the IDs and calibrated positions of the detectors. fitPar – A TubeCalibFitParams object for fitting the peaks iTube – The IdealTube which contains the positions in metres of the shadows of the slits, bars or edges used for calibration. peaksTable – Peaks table into which the peaks positions will be put overridePeaks – dictionary with tube indexes keys and an array of peaks in pixels to override those that would be fitted for one tube excludeShortTubes – Exlude tubes shorter than specified length from calibration plotTube – List of tube indexes that will be ploted range_list – list of the tube indexes that will be calibrated. Default None, means all the tubes in tubeSet polinFit – Order of the polynomial to fit against the known positions. Acceptable: 2, 3 peaksTestMode – true if shoving detectors that are reckoned to be at peak away (for test purposes) parameters_table_group – name of the WorkspaceGroup containing individual TableWorkspace tables. Each table holds values and errors for the optimized coefficients of the polynomial that fits the peak positions (in pixel coordinates) to the known slit positions (along the Y-coordinate). The last entry in the table holds the goodness-of-fit, chi-square value. The name of each individual TableWorkspace is the string parameters_table_group plus the suffix _I, where I is the tube index as given by list range_list. If None, no group workspace is generated.

This is the main method called from calibrate() to perform the calibration.

tube_calib.getCalibrationFromPeakFile(ws, calibTable, iTube, PeakFile)¶

Get the results the calibration and put them in the calibration table provided.

@param ws: Integrated Workspace with tubes to be calibrated @param calibTable: Calibration table into which the calibration results are placed @param iTube: The ideal tube @param PeakFile: File of peaks for calibration

tube_calib.getPoints(integrated_ws, func_forms, fit_params, which_tube, show_plot=False)¶

Get the centres of N slits or edges for calibration

It does look for the peak position in pixels by fitting the peaks and edges. It is the method responsible for estimating the peak position in each tube.

Note

This N slit method is suited for WISH or the five sharp peaks of MERLIN .

Parameters:	integrated_ws – Workspace of integrated data func_forms – array of function form 1=slit/bar, 2=edge fit_params – a TubeCalibFitParams object contain the fit parameters which_tube – a list of workspace indices for one tube (define a single tube) show_plot – show plot for this tube
Return type:	array of the slit/edge positions (-1.0 indicates failed to find position)

tube_calib.get_ideal_tube_from_n_slits(integrated_workspace, slits)¶

Given N slits for calibration on an ideal tube convert to Y values to form a ideal tube for correctTubeToIdealTube()

@param integrated_workspace: Workspace of integrated data @param slits: positions of slits for ideal tube (in pixels)

Return Value: Ideal tube in Y-coords for use by correctTubeToIdealTube()

tube_calib.read_peak_file(file_name)¶

Load the file calibration

It returns a list of tuples, where the first value is the detector identification and the second value is its calibration values.

Example of usage:

for (det_code, cal_values) in readPeakFile(‘pathname/TubeDemo’):

print(det_code) print(cal_values)