A helper class for calculating neutron's gravitional drop. More...

#include <GravitySANSHelper.h>

Public Member Functions
double	calcComponents (const double wavAngstroms, double &xFrac, double &yFrac) const
	Calculate the sins and cosins of angles as required to calculate Q is 2 dimensions. More...

double	calcSinTheta (const double wavAngstroms) const
	Caclulates the sin of the that the neutron left the sample at, before the effect of gravity. More...

double	gravitationalDrop (const double wav) const

	GravitySANSHelper ()

	GravitySANSHelper (const API::SpectrumInfo &spectrumInfo, const size_t index, const double extraLength=0.0)
	sets up the object with workspace data and calculates cached values ready to calculate gravitional effects across a spectrum More...

Private Member Functions
double	calcSinTheta () const
	getDetLoc must have been called before this is used to calculate the sin of the angle More...

const Kernel::V3D &	getDetLoc (const double wav) const
	Finds the location of the detector the neutron would have entered if it followed a straight line path from the sample. More...

double	gravitationalDrop (const double L2, const double waveLength, const double extraLength) const
	Calculates the distance a neutron coming from the sample will have deviated from a straight tragetory before hitting a detector. More...

Private Attributes
Kernel::V3D	m_beamLine
	the displacement from the source to the sample More...

double	m_beamLineNorm
	twice the distance from the source to the sample More...

double	m_cachedDrop
	the drop that was last caclulated, this allows m_cachedDetLoc to be recalculated each time without its original value being stored More...

Kernel::V3D	m_cachedLineOfSight
	the location that the neutron would have been detected at if it continued in a straight line, without gravity More...

double	m_dropPerAngstrom2
	the drop is proportional to the wavelength squared, storing this drop increases calculation speed a lot More...

Kernel::V3D	m_samplePos
	coordinates of the sample More...

Detailed Description

A helper class for calculating neutron's gravitional drop.

Only works for SANS because Mantid has no convention on which was is up or down. For this to work y must increase with distance from the earth

Author: Steve Williams, ISIS Rutherford Appleton Laboratory

Date: 26/01/2009

Definition at line 22 of file GravitySANSHelper.h.

Constructor & Destructor Documentation

◆ GravitySANSHelper() [1/2]

Mantid::Algorithms::GravitySANSHelper::GravitySANSHelper ( )

inline

Definition at line 24 of file GravitySANSHelper.h.

◆ GravitySANSHelper() [2/2]

Mantid::Algorithms::GravitySANSHelper::GravitySANSHelper	(	const API::SpectrumInfo &	spectrumInfo,
		const size_t	index,
		const double	extraLength = `0.0`
	)

sets up the object with workspace data and calculates cached values ready to calculate gravitional effects across a spectrum

Parameters

spectrumInfo	:: SpectrumInfo of workspace
index	:: Workspace index of spectrum to do the calculation for
extraLength	:: extra length for gravity correction

Definition at line 22 of file GravitySANSHelper.cpp.

References gravitationalDrop(), index, Mantid::API::SpectrumInfo::l2(), m_cachedLineOfSight, m_dropPerAngstrom2, m_samplePos, and Mantid::API::SpectrumInfo::position().

Member Function Documentation

◆ calcComponents()

double Mantid::Algorithms::GravitySANSHelper::calcComponents	(	const double	wavAngstroms,
		double &	xFrac,
		double &	yFrac
	)		const

Calculate the sins and cosins of angles as required to calculate Q is 2 dimensions.

Parameters

[in]	wavAngstroms	wavelength of the neutron in Angstrom
[out]	xFrac	the component in the x direction
[out]	yFrac	component in the y direction

Returns: sin of the angle theta to the detector

Definition at line 49 of file GravitySANSHelper.cpp.

References calcSinTheta(), getDetLoc(), Mantid::Kernel::V3D::X(), and Mantid::Kernel::V3D::Y().

Referenced by Mantid::Algorithms::Qxy::exec().

◆ calcSinTheta() [1/2]

double Mantid::Algorithms::GravitySANSHelper::calcSinTheta ( ) const

private

getDetLoc must have been called before this is used to calculate the sin of the angle

Returns: the sin of theta

Definition at line 77 of file GravitySANSHelper.cpp.

References m_beamLine, m_beamLineNorm, m_cachedLineOfSight, Mantid::Kernel::V3D::norm(), and Mantid::Kernel::V3D::scalar_prod().

Referenced by calcComponents(), and calcSinTheta().

◆ calcSinTheta() [2/2]

double Mantid::Algorithms::GravitySANSHelper::calcSinTheta ( const double wavAngstroms ) const

Caclulates the sin of the that the neutron left the sample at, before the effect of gravity.

Parameters

wavAngstroms :: the neutrons' wave length in Angstoms

Returns: the sin of theta

Definition at line 38 of file GravitySANSHelper.cpp.

References calcSinTheta(), and getDetLoc().

Referenced by Mantid::Algorithms::Q1D2::convertWavetoQ().

◆ getDetLoc()

const V3D & Mantid::Algorithms::GravitySANSHelper::getDetLoc ( const double wav ) const

private

Finds the location of the detector the neutron would have entered if it followed a straight line path from the sample.

Parameters

wav	:: wavelength of the neutron in Angstrom

Returns: a reference to the cached location

Definition at line 63 of file GravitySANSHelper.cpp.

References gravitationalDrop(), m_cachedDrop, and m_cachedLineOfSight.

Referenced by calcComponents(), and calcSinTheta().

◆ gravitationalDrop() [1/2]

double Mantid::Algorithms::GravitySANSHelper::gravitationalDrop	(	const double	l2,
		const double	waveLength,
		const double	extraLength
	)		const

private

Calculates the distance a neutron coming from the sample will have deviated from a straight tragetory before hitting a detector.

If calling this function many times for the same detector you can call this function once, with waveLength=1, and use the fact drop is proportional to wave length squared .This function has no knowledge of which axis is vertical for a given instrument

Parameters

l2	:: distance between sample and detector the neutron entered
waveLength	:: the neutrons wave length in meters
extraLength	:: additional length

Returns: the deviation in meters

Pre-factor in gravity calculation: gm^2/2h^2

Definition at line 96 of file GravitySANSHelper.cpp.

References Mantid::PhysicalConstants::g, Mantid::PhysicalConstants::h, Mantid::Kernel::l2, and Mantid::PhysicalConstants::NeutronMass.

◆ gravitationalDrop() [2/2]

double Mantid::Algorithms::GravitySANSHelper::gravitationalDrop ( const double wav ) const

inline

Definition at line 29 of file GravitySANSHelper.h.

References m_dropPerAngstrom2.

Referenced by Mantid::Algorithms::Q1DWeighted::calculate(), getDetLoc(), and GravitySANSHelper().

Member Data Documentation

◆ m_beamLine

Kernel::V3D Mantid::Algorithms::GravitySANSHelper::m_beamLine

private

the displacement from the source to the sample

Definition at line 35 of file GravitySANSHelper.h.

Referenced by calcSinTheta().

◆ m_beamLineNorm

double Mantid::Algorithms::GravitySANSHelper::m_beamLineNorm

private

twice the distance from the source to the sample

Definition at line 37 of file GravitySANSHelper.h.

Referenced by calcSinTheta().

◆ m_cachedDrop

double Mantid::Algorithms::GravitySANSHelper::m_cachedDrop

mutableprivate

the drop that was last caclulated, this allows m_cachedDetLoc to be recalculated each time without its original value being stored

Definition at line 47 of file GravitySANSHelper.h.

Referenced by getDetLoc().

◆ m_cachedLineOfSight

Kernel::V3D Mantid::Algorithms::GravitySANSHelper::m_cachedLineOfSight

mutableprivate

the location that the neutron would have been detected at if it continued in a straight line, without gravity

Definition at line 44 of file GravitySANSHelper.h.

Referenced by calcSinTheta(), getDetLoc(), and GravitySANSHelper().

◆ m_dropPerAngstrom2

double Mantid::Algorithms::GravitySANSHelper::m_dropPerAngstrom2

private

the drop is proportional to the wavelength squared, storing this drop increases calculation speed a lot

Definition at line 41 of file GravitySANSHelper.h.

Referenced by gravitationalDrop(), and GravitySANSHelper().

◆ m_samplePos

Kernel::V3D Mantid::Algorithms::GravitySANSHelper::m_samplePos

private

coordinates of the sample

Definition at line 33 of file GravitySANSHelper.h.

Referenced by GravitySANSHelper().

The documentation for this class was generated from the following files:

Framework/Algorithms/inc/MantidAlgorithms/GravitySANSHelper.h
Framework/Algorithms/src/GravitySANSHelper.cpp

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ GravitySANSHelper() [1/2]

◆ GravitySANSHelper() [2/2]

Member Function Documentation

◆ calcComponents()

◆ calcSinTheta() [1/2]

◆ calcSinTheta() [2/2]

◆ getDetLoc()

◆ gravitationalDrop() [1/2]

◆ gravitationalDrop() [2/2]

Member Data Documentation

◆ m_beamLine

◆ m_beamLineNorm

◆ m_cachedDrop

◆ m_cachedLineOfSight

◆ m_dropPerAngstrom2

◆ m_samplePos