Muon Analysis¶

Instrument¶

1	Instrument	Selection of instrument that the experiments were run on. It is an advantage if an Instrument Definition File ( IDF) is available for the instrument selection.
2	Time Zero	Time zero value (). Any bins before that time will be discarded. If From datafile is checked, the value stored in the loaded Muon data file is used.
3	First Good Data	Time of the first good data (). If Time Axis is set appropriately on the Settings tab then it is used as a start value for the X-axis. If From datafile is checked, the value stored in the loaded Muon data file is used.
4	Dead Time Correction	The type of Dead Time Correction to apply to the loaded file. Available choices: None. Don’t apply the correction. From Data File. Use Dead Time table stored in the loaded Muon data file. From Disk. Specify a custom Nexus file that has a Dead Time table. If this is selected, a Dead Time File text box will be shown so you can specify the file or browse to its location.
5	Dead Time File	If Dead Time Correction is set to From Disk, you can choose a Nexus file which contains a table with Dead Times, and will be applied to the loaded data file.

Data Files¶

Detector Grouping¶

Plot Data¶

Run Information etc.¶

Controls and description¶

Group table¶

Pair table¶

Default: multiple fitting disabled¶

By default, multiple dataset fitting is not enabled and the interface will look just as it did pre-Mantid 3.8.

In this case, the only thing that this tab will contain is a specialised version of the Fit Property Browser. When the tab is open, this fit property browser is used by default within MantidPlot.

Note that, in this mode, simultaneous fits are not possible. The intention is that this mode could be useful for users who are accustomed to the existing UI, or if a bug is found in the new UI.

TF asymmetry enabled¶

The TF asymmetry mode can be enabled by checking the “TF Asymmetry” checkbox in the Settings table of the data analysis tab. Loading transverse field asymmetry data into muon analysis will automatically enable TF asymmetry mode. When this is activated, the data analysis tab has two main differences to the pre 3.8 version. Firstly there is an additional row in the Data table (normalization). The second difference is the addition of the “TF Asymmetry Fit” button in the fitting tab. Selecting this fitting option will recalculate the normalization based on the user fitting function.

Multiple fitting enabled¶

The multiple fitting functionality can be enabled by checking the “Enable multiple fitting” checkbox on the Settings tab. When this is activated, the tab is divided into multiple sections vertically.

Fit Function¶

The uppermost of the three vertical sections is the Fit Function section, which is a FunctionBrowser just like in the General/Multi dataset fitting interface (and numerous other places in Mantid). Functions can be added by right-clicking. If more space is needed, this section can be expanded by dragging its lower edge downwards.

The function browser has three columns - property, value and global. The values shown are those of the currently selected/plotted dataset. The global column contains a checkbox for each function parameter which, when checked, sets this parameter to be shared between all fits.

Parameters can be fixed, tied and constrained by right-clicking. In addition, just as in the general multi dataset fitting interface, when highlighting a non-global function parameter, a small button will appear next to its value. This button will open the “Edit local parameter values” dialog, which offers greater control of function parameters for each dataset.

Data¶

The next section of the tab is the data selector, which controls the dataset(s) that will be fitted. By default, this will be a single dataset, the same as the data loaded on the Home tab. The dataset(s) can be changed here and, if more than one is selected, they will all be fitted simultaneously.

The “Display Parameters For” boxes consist of a backwards button, a drop-down selection and a forward button. The drop-down list shows all datasets currently selected, and the left and right buttons cycle through them. The currently selected dataset has its parameters shown in the Fit Function (upper) widget, and will be plotted.

For a multi-dataset fit, the “Label” box is enabled. This allows the user to input a label for the simultaneous fit.

Data Table¶

The data table allows the user to modify the selected data for the fitting. This includes the start and end times, which can also be updated by dragging the blue dashed lines in the plot. The “Groups/Pairs to fit” box provides a drop-down menu with three options (all groups, all pairs and custom). Selecting custom will produce a pop-up box with tick boxes for each of the available groups and pairs. If a user wants to update the custom selection the Groups/Pairs button can be pressed from the ReselectData section at the bottom ofthe tab (this is only enabled if a custom selection is set). Underneath displays the “Selected Groups”.

The next row is the “Periods to fit” option, which is only displayed for multiple period data. This will automatically be populated with each of the periods (e.g. 1,2,3) and a custom option. Selecting custom will produce a pop-up with checkboxes for all of the periods. Selecting custom will also enable the “Periods” button in the ReselectData section and pressing this button will allow the user to alter their custom selection.

Additional Options¶

Near the bottom of the tab contains selected fit options that can be adjusted, just as elsewhere in Mantid. The only option specific to the Muon Analysis interface is Fit To Raw Data. When this option is set to True, the fitting process is done using the raw (unbinned) data, even if the DataBinning is set.

Reselect data¶

At the bottom of the tab is the “Reselect Data” section. This includes three buttons “Groups/Pairs”, “Periods” and “Combine Periods”. The “Groups/Pairs” and “Periods” buttons are only when the relevant options in the data table are set to custom. Pressing the button will produce a pop-up that will allow the user to modify their selection.

The “Combine Periods” button is only enabled if multiple periods are available. Pressing the button will generate a pop-up with two boxes. The top one is for adding periods (as a comma seperated list or with “+”) and the bottom box is for subtraction (as a comma sepearted list). Everything in the top and bottom boxes are summed seperatley and the results are then used in the subtraction.

Sequential fitting¶

In MantidPlot 3.1 a specialized sequential fitting dialog for MuonAnalysis was introduced. It allows users to fit various data sets to the chosen fit model, applying all of the interface settings.

The dialog can be opened from the Fit menu in Fit → Sequential Fit.

After the options have been set and the Start button has been pressed, the dialog goes through every data file and does the following:

1. Loads the file
2. Applies all of the settings as set on the interface, e.g. dead time correction, grouping, binning.
3. Runs the Fit algorithm using the fit model specified in the Fit Property Browser on this tab.
4. Puts the fit-result workspaces inside the MuonSeqFit_%LABEL% group.

After that’s done, you can retrieve the results in two ways:

• Go to the ResultsTable tab and export fitted parameters as a table.
• Use the workspaces in the MuonSeqFit_%LABEL% group to plot the fitted curves.

Values¶

The table contains a list of log values present in all of the workspaces in the Fitting results table. The ones selected will be included in the results table.

In the case of start and end times (run_start and run_end), the option is given to write these either as text or number. The text option gives an ISO- formatted string (eg. 2016-07-06T10:10:34) and the numeric option gives the time as a number of seconds. Zero seconds is taken as the start time of the first run in the selected set.

Fitting Results¶

This table contains a list of fitted workspaces. You can choose whether you want to see individual fits only, or a specific sequential (see SequentialFitting ) or simultaneous (see DataAnalysis) fit label.

Fitted parameters of the selected workspaces will be added to the results table.

Workspaces might be coloured differently. Workspaces of different colours have different fitting models and therefore couldn’t be included in the same Results table. (If looking at simultaneous fits, different colours could also indicate that the fits had different numbers of datasets).

As well as selecting workspaces, the fourth radio button - “Multiple” - can be used to create a table of multiple simultaneous fits, one row per label. In such a table, each global parameter gets one column and local parameters get one column per dataset.

Table¶

This allows you to specify the name of the resulting table and create it using the log values and workspaces you’ve selected.

Data Plot Style¶

These options control the style of the plot. They will be applied to all new plots. The currently connected plot (if any) is updated as well.

1	Connect Points	Option for how the points will be represented on the plot: Scatter. Data points only. Line + symbol. Data points connected by a line. Line. A line without data points.
2	Time axis	Type of the start value of the X-axis: Start at First Good Data. Uses the First Good Data value from the Home tab. Start at Time Zero. Uses 0. Worth noting that workspaces will be cropped according to the Time Zero value on the Home (HomeInstrument) tab, which means that X-value of 0 will essentially be equal to the Time Zero value. Custom Value. Uses the specified value.
3	Start	First value of the X-axis ().
4	Finish	Last value of the X-axis (). If empty, the last available value is used.
5	Minimum	Minimum value on the Y-axis. If empty, is determined automatically.
6	Maximum	Maximum value on the Y-axis. If empty, is determined automatically.
7	Autoscale	If checked, the values of Minimum and Maximum are determined automatically based on the max/min values of the data.
8	Show error bars	If checked, the curves will have error bars attached to them.

Data Binning¶

1	Bin size	Display the size of the bin in the currently loaded data. This is usually 0.016 for Muon instruments.
2	Binning type	What type of binning is applied to the loaded data: None. No binning is applied - raw data. Fixed. Binning with fixed steps. Variable. Binning with varying steps.
3	Binning parameters	For fixed binning: number of bins in a single step. For example, if data is collected in bins of size 0.016 and we specify 5 here, then the data will be re-binned using a bin size of 0.08. For variable binning: see the Params property of Rebin. Note Rebin is executed with FullBinsOnly=True.

General¶