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McStas: Single_crystal_process

[ Identification | Description | Input parameters | Links ]

The Single_crystal_process Component

Identification

  • Site:
  • Author: Mads Bertelsen
  • Origin:
  • Date: 20.08.15

Description

This Union_process is based on the Single_crystal.comp component originally
written by Kristian Nielsen

Part of the Union components, a set of components that work together and thus
sperates geometry and physics within McStas.
The use of this component requires other components to be used.

1) One specifies a number of processes using process components like this one
2) These are gathered into material definitions using Union_make_material
3) Geometries are placed using Union_box / Union_cylinder, assigned a material
4) A Union_master component placed after all of the above

Only in step 4 will any simulation happen, and per default all geometries
defined before the master, but after the previous will be simulated here.

There is a dedicated manual available for the Union_components

Algorithm:
Described elsewhere

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
mosaic_ABarc_minutes, arc_minutes,1, 1, 1, 1, 1, 1In Plane mosaic rotation and plane vectors (anisotropic), mosaic_A, mosaic_B, A_h,A_k,A_l, B_h,B_k,B_l. Puts the crystal in the in-plane mosaic state. Vectors A and B define plane in which the crystal roation is defined, and mosaic_A, mosaic_B, denotes the resp. mosaicities (gaussian RMS) with respect to the the two reflections chosen by A and B (Miller indices).Mosaic_AB_Undefined
reflectionsstringFile name containing structure factors of reflections. Use empty ("") or NULL for incoherent scattering only0
delta_d_d1Lattice spacing variance, gaussian RMS1e-4
mosaicarc minutesCrystal mosaic (isotropic), gaussian RMS. Puts the crystal in the isotropic mosaic model state, thus disregarding other mosaicity parameters.-1
mosaic_aarc minutesHorizontal (rotation around lattice vector a) mosaic (anisotropic), gaussian RMS. Put the crystal in the anisotropic crystal vector state. I.e. model mosaicity through rotation around the crystal lattice vectors. Has precedence over in-plane mosaic model.-1
mosaic_barc minutesVertical (rotation around lattice vector b) mosaic (anisotropic), gaussian RMS.-1
mosaic_carc minutesOut-of-plane (Rotation around lattice vector c) mosaic (anisotropic), gaussian RMS-1
recip_cell1Choice of direct/reciprocal (0/1) unit cell definition0
barns1Flag to indicate if |F|^2 from 'reflections' is in barns or fm^2. barns=1 for laz and isotropic constant elastic scattering (reflections=NULL), barns=0 for lau type files0
axAA or AA^-1Coordinates of first (direct/recip) unit cell vector0
aya on y axis0
aza on z axis0
bxAA or AA^-1Coordinates of second (direct/recip) unit cell vector0
byb on y axis0
bzb on z axis0
cxAA or AA^-1Coordinates of third (direct/recip) unit cell vector0
cyc on y axis0
czc on z axis0
aadegUnit cell angles alpha, beta and gamma. Then uses norms of vectors a,b and c as lattice parameters0
bbdegBeta angle0
ccdegGamma angle0
order1Limit multiple scattering up to given order (0: all, 1: first, 2: second, ...)0
RXmRadius of horizontal along X lattice curvature. flat for 00
RYmRadius of vertical along Y lattice curvature. flat for 00
RZ0
powder1Flag to indicate powder mode, for simulation of Debye-Scherrer cones via random crystallite orientation. A powder texture can be approximated with 00
PG1Flag to indicate "Pyrolytic Graphite" mode, only meaningful with choice of Graphite.lau, models PG crystal. A powder texture can be approximated with 00
interact_fraction1How large a part of the scattering events should use this process 0-1 (sum of all processes in material = 1)-1
packing_factor1How dense is the material compared to optimal 0-11
AT ( , , ) RELATIVE
ROTATED ( , , ) RELATIVE

Links


[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43


Last Modified: Wednesday, 03-Jan-2024 19:59:11 CET
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