Convert angle to signed Q#

Summary#

Convert an angle relative to its direct-beam or diffraction centre into signed Q.

Metadata#

Import path: modacor.modules.technique_modules.scattering.angle_to_q.AngleToQ
Source: src/modacor/modules/technique_modules/scattering/angle_to_q.py
Module ID: AngleToQ
Module version: 20261003.1
Keywords: scattering angle, two theta, Bragg angle, Q, momentum transfer, geometry

Required data keys#

angle

Modifies#

Q: signal, uncertainties, units, axes

Required arguments#

with_processing_keys
photon_source
photon_units_source

Default configuration#

{
  "angle_convention": "scattering_angle",
  "angle_key": "angle",
  "angle_zero": null,
  "angle_zero_units": null,
  "center_key": "beam_center",
  "output_key": "Q",
  "output_units": "1/nm",
  "photon_source": null,
  "photon_uncertainties_sources": {},
  "photon_units_source": null,
  "with_processing_keys": null
}

Argument specification#

Argument	Type	Required	Default	Dependency role	Description
`angle_convention`	str	No	scattering_angle	-	Angle convention: scattering_angle/two_theta uses sin(angle/2); bragg_angle/theta uses sin(angle).
`angle_key`	str	No	angle	-	Angular-coordinate BaseData key.
`angle_zero`	float or int or NoneType	No	-	-	Optional configured angle zero, overriding center_key.
`angle_zero_units`	str or NoneType	No	-	-	Units for angle_zero; defaults to the input angle units.
`center_key`	str or NoneType	No	beam_center	-	Angle-zero BaseData key used when angle_zero is None; None means zero angle.
`output_key`	str	No	Q	-	Output BaseData key.
`output_units`	str	No	1/nm	-	Momentum-transfer output units.
`photon_source`	str or NoneType	Yes	-	-	IoSources key for scalar or angle-shaped photon energy or wavelength metadata.
`photon_uncertainties_sources`	dict	No	{}	-	Uncertainty sources for photon energy or wavelength metadata.
`photon_units_source`	str or NoneType	Yes	-	-	IoSources key for photon energy or wavelength units.
`with_processing_keys`	str or list or NoneType	Yes	-	-	DataBundle key or keys whose angular coordinates are converted.

Notes#

Uses Q = 4pi/lambdasin(angle/2) for scattering_angle/two_theta and Q = 4pi/lambdasin(angle) for bragg_angle/theta. Photon metadata is loaded from IoSources; energy or wavelength representation is inferred from its units and converted with uncertainty-aware BaseData arithmetic. The angle sign is retained.