ComptonPeakProfile

Description

The ComptonPeakProfile describes the Neutron Compton profile with either a Voigt or Gaussian approximation, depending on an energy cutoff value. It takes three input parameters:

  • Intensity: I

  • Position: P

  • SigmaGauss: σG

and three attributes,

  • WorkspaceIndex

  • Mass

  • VoigtEnergyCutOff

The VoigtEnergyCutOff is used to determine whether a Gaussian or Voigt function is used to fit the peak. If the final energy, as read from the input workspace, is greater than the VoigtEnergyCutOff a normalised Gaussian approximation is used,

I2πσT2exp(0.5(xP)2σT2)

where σT2 is the total variance, defined by

σT2=σG2+Γ2

where Γ is the half-width-half-maximum, estimated from the input data.

If instead, the energy is below the cutoff an approximation to a Voigt function is used with the following inputs:

LorentzAmp=I
LorentzPos=P
LorentzFWHM=2Γ
GaussianFWHM=0.5σGln(4)

Attributes (non-fitting parameters)

Name

Type

Default

Description

Mass

VoigtEnergyCutOff

WorkspaceIndex

Properties (fitting parameters)

Name

Default

Description

Intensity

1.0

Intensity parameter

Position

1.0

Peak position parameter

SigmaGauss

1.0

Width parameter

Categories: FitFunctions | General

Source

C++ header: ComptonPeakProfile.h

C++ source: ComptonPeakProfile.cpp