[ Identification | Description | Input parameters | Links ]

The Incoherent Component

Incoherent sample (such as Vanadium) sample, with quasielastic component OR or global energy transfer.



A Double-cylinder shaped incoherent scatterer (like Vanadium)
with both elastic and quasielastic (Lorentzian) components.
No multiple scattering (but approximation available). Absorption included.
Sample focusing:
The area to scatter to is a disk of radius 'focus_r' situated at the target.
This target area may also be rectangular if specified focus_xw and focus_yh
or focus_aw and focus_ah, respectively in meters and degrees.
The target itself is either situated according to given coordinates (x,y,z),
or defined with the relative target_index of the component to focus
to (next is +1).
This target position will be set to its AT position. When targeting to
centered components, such as spheres or cylinders, define an Arm component
where to focus to.
Sample shape:
Sample shape may be a cylinder, a sphere, a box or any other shape
box/plate:       xwidth x yheight x zdepth (thickness=0)
hollow box/plate:xwidth x yheight x zdepth and thickness>0
cylinder:        radius x yheight (thickness=0)
hollow cylinder: radius x yheight and thickness>0
sphere:          radius (yheight=0 thickness=0)
hollow sphere:   radius and thickness>0 (yheight=0)
any shape:       geometry=OFF file

The complex geometry option handles any closed non-convex polyhedra.
It computes the intersection points of the neutron ray with the object
transparently, so that it can be used like a regular sample object.
It supports the PLY, OFF and NOFF file format but not COFF (colored faces).
Such files may be generated from XYZ data using:
qhull < coordinates.xyz Qx Qv Tv o > geomview.off
powercrust coordinates.xyz
and viewed with geomview or java -jar jroff.jar (see below).
The default size of the object depends of the OFF file data, but its
bounding box may be resized using xwidth,yheight and zdepth.

Example: Incoherent(radius=0.05,focus_r=0.035, pack=1, target_index=1)
Incoherent(geometry="socket.off",focus_r=0.035, pack=1, target_index=1)

Input parameters

Parameters in boldface are required; the others are optional.
geometrystrName of an Object File Format (OFF) or PLY file for complex geometry. The OFF/PLY file may be generated from XYZ coordinates using qhull/powercrust0
radiusmOuter radius of sample in (x,z) plane0
xwidthmHoriz. dimension of sample (bounding box if off file), as a width0
yheightmVert. dimension of sample (bounding box if off file), as a height. A sphere shape is used when 0 and radius is set0
zdepthmDepth of sample (bounding box if off file)0
thicknessmThickness of hollow sample0
target_ymposition of target to focus at0
focus_rmRadius of disk containing target. Use 0 for full space0
focus_xwmhoriz. dimension of a rectangular area0
focus_yhmvert. dimension of a rectangular area0
focus_awdeghoriz. angular dimension of a rectangular area0
focus_ahdegvert. angular dimension of a rectangular area0
target_index1Relative index of component to focus at, e.g. next is +10
pack1Packing factor1
p_interact1MC Probability for scattering the ray; otherwise transmit1
f_QE1Fraction of quasielastic scattering (rest is elastic)0
gamma1Lorentzian width of quasielastic broadening (HWHM)0
EtransmeVGlobal energy-transfer, for use in inelastic settings0
deltaEmeVWidth in energy around Etrans, for use in inelastic settings0
sigma_absbarnsAbsorption cross section pr. unit cell at 2200 m/s5.08
sigma_incbarnsIncoherent scattering cross section pr. unit cell5.08
VcAA^3Unit cell volume13.827
concentric1Indicate that this component has a hollow geometry and may contain other components. It should then be duplicated after the inside part (only for box, cylinder, sphere)0
order1Limit multiple scattering up to given order 0 means all (default), 1 means single, 2 means double, ...0


[ Identification | Description | Input parameters | Links ]

Generated on 2023-09-19 20:01:36