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ConvertSpiceDataToRealSpace v1¶

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Summary ¶

Load a HFIR powder diffractometer SPICE file.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	TableWorkspace	Mandatory	Input table workspace for data.
RunInfoWorkspace	Input	MatrixWorkspace	Mandatory	Input matrix workspace containing sample logs. It can be the RunInfoWorkspace output from LoadSpiceAscii. It serves as parent workspace in the algorithm.
RunStart	Input	string		User specified run start time of the experiment in case that the run start time is not specified in the input RunInfoWorkspace.
Instrument	Input	string	HB2A	Instrument to be loaded. Allowed values: [‘HB2A’]
DetectorPrefix	Input	string	anode	Prefix of the name for detectors.
RunNumberName	Input	string	Pt.	Log name for run number/measurement point.
RotationAngleLogName	Input	string	2theta	Log name for rotation angle as the 2theta value of detector 0.
MonitorCountsLogName	Input	string	monitor	Name of the sample log to record monitor counts of each run.
DurationLogName	Input	string	time	Name of the sample log to record the duration of each run.
OutputWorkspace	Output	MDEventWorkspace	Mandatory	Name to use for the output workspace.
OutputMonitorWorkspace	Output	MDEventWorkspace	Mandatory	Name to use for the output workspace.
DetectorEfficiencyTableWorkspace	Input	TableWorkspace		Name of a table workspace containing the detectors’ efficiency.

Description ¶

This algorithm is to load HFIR Spice powder diffraction data to MDWorkspaces. HB2A is the only one instrument supported by this algorithm. HB2A will be supported in future.

Inputs ¶

Required workspaces ¶

There are two input Workspaces that are required for this algoriths. Both of them stores the data from a SPICE file.

One is a TableWorkspace that stores the data, including detectors’ counts and sample environment logs’ value, measured per data points. The other is a MatrixWorkspace that stores the sample logs, and serves the parent MatrixWorkspace for all temporary MatrixWorkspaces that are created during the algorithm’s execution.

These two workspaces can be obtained by executing algorithm LoasSpiceAscii.

Optional workspaces ¶

An optional TableWorkspace is for applying detectors’ efficiency factor to the raw detectors’ counts. It is required to a 2-column TableWorkspace. Column 0 is of integer type for detector IDs, while Column 1 is of double type for detector efficiency factor (\(f\)). The corrected counts is equal to \(counts^{raw}/f\).

Outputs ¶

Two MDEventWorkspaces will be output from this algorithm.

One MDWorkspaces stores the experimental data. Each MDEvent is a data point measured on one detector. Thus if in the experiment, M detectors moves N times, then there will be total \(M \times N\) MDEvents. It also stores the sample environment logs values in its ExperimentInfo.

The other MDWorkspaces stores the monitor counts of each detector at each measurement.

Format of SPICE data file ¶

There are two parts of content in SPICE data file. One is the run information, in which line that starts with #.

In most cases, the run information is give as

# run info name = run info value

The other is the experimental data. The first item is an integer as the index of experimental data point.

How to combine measurements ¶

Powder diffractometers rotates its detectors to achieve the coverage and resolution. Hence the output of of a run should include all the measurements.

MDEventWorkspace is the best solution to combine all the measurements to a single workspace and keep all the information for future reduction.

Apply MDWorkspaces to HFIR powder diffractometer experiment ¶

Run ¶

In an HFIR powder diffractometer scan, one measurement is made at a certain rotational angle. Such one meaurement constains 44 detectors’ counts, instrument setup (such as rotation angle) and sample environment logs. As it is translated to MDWorkspace, such a measurement constitutes a {it run}.

Essential logs for building MDWorkspace ¶

There are a few sample logs that are essential to create the MDWorkspaces for the HFIR powder diffractometers. The algorithm allows the user to specify these logs

Rotation angle to determine the \(2\theta\) for detector 0. The default is ‘2theta’;
Prefix of the logs for detectors. The default is ‘anode’. In present HB2A’s SPICE file, the detectors are labelled as ‘anode1’, ‘anode2’, and etc;
Monitor counts for each measurement. The default is ‘monitor’;
Duration of each measurement. The default is ‘time’.

Sample Logs ¶

Sample logs will be written to the ExperimentInfo for each run. There are N+1 ExperimentInfo in the MDWorkspace that stores the detectors’ counts.

The first N ExperimentInfo are for the N measurements. The sample logs’s value measured of that data point will be recorded in the corresponding ExperimentInfo. Hence each of these N ExperimentInfo will contains a set of sample logs, each of which contains only one log entry.

The last one, i.e., ExperimentInfo[N], contains the combined sample logs from all the runs. Hence for an experiment with N runs.

Temporary MD File ¶

In this algorithm, the MDEvnetWorkspaces are created by loading from a temporary MD file, which is generated from a set of MatrixWorkspaces. Each MatrixWorkspace stores the data for one individual measurement.

The format of the MD files are like

DIMENSIONS
x X m 100
y Y m 100
z Z m 100
# Signal, Error, RunId, DetectorId, coord1, coord2, ... to end of coords
MDEVENTS
125 1 1 1 0.209057 0 1.98904
133 1 1 2 0.30052 0 1.97729
114 1 1 3 0.391584 0 1.96129
130 1 1 4 0.485503 0 1.94018
143 1 1 5 0.577963 0 1.91467
135 1 1 6 0.667844 0 1.8852
120 1 1 7 0.753968 0 1.85244
115 1 1 8 0.840013 0 1.81504
145 1 1 9 0.925819 0 1.77281
117 1 1 10 1.00779 0 1.72753
105 1 1 11 1.08951 0 1.67719
102 1 1 12 1.16527 0 1.62547
108 1 1 13 1.24041 0 1.56888
110 1 1 14 1.31159 0 1.50988
... ...

If there are N detectors of the instruments and M measurements in total, then there will be \(M\times N\) MDEvents listed in the MD file.

Workflow ¶

The 2 input workspaces of algorithm ConvertSpiceDataToRealSpace are the output of algorithm LoadSpiceAscii. Therefore, in order to load an HB2A or HB2B data from a SPICE file, LoadSpiceAscii should be called first.

Usage ¶

Example - load a SPICE .dat file for HB2A:

# create table workspace and parent log workspace
LoadSpiceAscii(Filename='HB2A_exp0231_scan0001.dat',
      IntegerSampleLogNames="Sum of Counts, scan, mode, experiment_number",
      FloatSampleLogNames="samplemosaic, preset_value, Full Width Half-Maximum, Center of Mass",
      DateAndTimeLog='date,MM/DD/YYYY,time,HH:MM:SS AM',
      OutputWorkspace='Exp0231DataTable',
      RunInfoWorkspace='Exp0231ParentWS')

# load for HB2A
ConvertSpiceDataToRealSpace(InputWorkspace='Exp0231DataTable',
      RunInfoWorkspace='Exp0231ParentWS',
      OutputWorkspace='Exp0231DataMD',
      OutputMonitorWorkspace='Exp0231MonitorMD')

# output
datamdws = mtd["Exp0231DataMD"]
print("Number of events = {}".format(datamdws.getNEvents()))

Output:

Number of events = 2684

Categories: AlgorithmIndex | Diffraction\ConstantWavelength | DataHandling\Text

Source ¶

C++ header: ConvertSpiceDataToRealSpace.h

C++ source: ConvertSpiceDataToRealSpace.cpp