Fitters

Two-dimensional datasets can be opened in available Fitters. These GUI applications contain standard data processing technics and constitute additional utility allowing for more detailed inspection and quantitative analysis of investigated data.

Two, MDC and EDC Fitters are implemented within piva, including methods useful when dealing with momentum and energy distribution curves, respectively.

MDC Fitter

MDC Fitter allows to investigate momentum distribution curves (MDCs) across available energy range. User interactively can perform subtraction of polynomial background and fit (asymmetric) Lorentzian line shape within selected fitting range.

Its layout is shown and described below.

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a

Utilities panel, see description below.

b

Main data panel showing investigated 2D dataset. Contains sliders allowing to slice through data.

c

MDC panel extracted at the energy selected with a slider in main data panel.

MDC Fitter’s Utilities Panel

Utilities panel contains all image processing and analysis features.

Image tab

Combines widgets and functionalities of volume and image tabs of the DataViewers.

Fitting tab

Contains all widgets useful for interactive fitting of MDCs.

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Lorentzian’s parameters

  • \(\mu\) - expected value,

  • \(\Gamma\) - full width at half maximum,

  • \(\alpha, \beta\) - asymmetry factors of fitted line shape,

  • \(a\) - normalization factor.

Box at the bottom displays fit results.

fit range

Set fitting range, displayed as a grey shadow on MDC panel.

bgr range

Set background range, indicated with two vertical dashed lines on MDC panel. The region between the lines (which supposed to contain entire peak) will be excluded during background fitting.

bgr poly

Select order of the background polynomial.

results

  • append fit results (expected value) on the Main data panel and store results in Fitters memory.

  • edit collected results; opens txt file with saved parameters.

  • load saved or update edited parameters.

  • save fitted parameters to txt file.

EDC Fitter

EDC Fitter allows to investigate energy distribution curves (EDCs) and perform gap analysis.

Its layout is shown and described below.

Image not found.

a

Utilities panel, see description below.

b

Main data panel showing investigated 2D dataset. Contains sliders allowing to slice through data.

c

EDC panel extracted at the momentum selected with a slider in main data panel.

EDC Fitter’s Utilities Panel

I addition to basic functionalities of volume and image tabs of the DataViewers, EDC Fitter allows to narrow energy range and symmetrize EDCs around the Fermi level.

Development

At the moment only basic methods are implemented within piva Fitters, leaving a large playground for improvement. Users are highly encouraged to contribute and extend their capabilities or implement entirely new plugins. This can be done directly through github or alternatively by contacting the development team: