[ Identification | Description | Input parameters | Links ]
Refractor ComponentSingle bulk material shape that can be used as a prism or lens. NEUTRON INTERACTION PROCESSES: The bulk material can reflect, refract, scatter and absorb neutrons, depending on the material cross sections and incident angles. The refracting material is specified from its molar weight, density, coherent scattering cross section. The refractive index is computed as: n = sqrt(1-(lambda*lambda*rho*bc/PI)) is the refraction index The surface can be coated when specifying a critical wavevector Qc, with e.g. Qc=m*0.0219 for a super mirror coating. The mirror coating can be suppressed by setting Qc=0. The critical wavevector is then set to Qc = 4*sqrt(PI*rho*bc); with rho= density*6.02214179*1e23*1e-24/weight; bc = sqrt(fabs(sigma_coh)*100/4/PI)*1e-5; COMPONENT GEOMETRY: The component shape can be a sphere, box, cylinder, biconcave spherical lens or any other shape defined from an external OFF/PLY file. sphere: radius cylinder: radius, yheight box: xwidth, yheight, zdepth OFF/PLY: geometry="filename.off or ply", xwidth, yheight, zdepth (bounding box) lens_sphere: geometry="lens_sphere", radius, zdepth (thickness) The lens_sphere geometry is composed of two concave half spheres of same radius, separated with a minimal thickness zdepth along the Z axis. Optionally, you can specify the 'geometry' parameter as a OFF/PLY file name. 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 or powercrust coordinates.xyz and viewed with geomview or java -jar jroff.jar (see below). All geometries are centred. The bulk material fills the shape, but can be set 'outside' when density is given a negative value. In this case, the material outside the bulk is void (vacuum). Usually, you should stack more than one of these to get a significant effect on the neutron beam, so-called 'compound refractive lens'. The focal length for N lenses with focal 'f' is f/N, where f=R/(1-n) and R = r/2 for a spherical lens with curvature radius 'r' COMMON MATERIALS: Should have high coherent, and low incoherent and absorption cross sections Be: density=1.85, weight=9.0121, sigma_coh=7.63, sigma_inc=0.0018,sigma_abs=0.0076 Pb: density=11.115,weight=207.2, sigma_coh=11.115,sigma_inc=0.003, sigma_abs=0.171 Pb206: sigma_coh=10.68, sigma_inc=0 , sigma_abs=0.03 Pb208: sigma_coh=11.34, sigma_inc=0 , sigma_abs=0.00048 Zr: density=6.52, weight=91.224, sigma_coh=6.44, sigma_inc=0.02, sigma_abs=0.185 Zr90: sigma_coh=5.1, sigma_inc=0 , sigma_abs=0.011 Zr94: sigma_coh=8.4, sigma_inc=0 , sigma_abs=0.05 Bi: density=9.78, weight=208.98, sigma_coh=9.148, sigma_inc=0.0084,sigma_abs=0.0338 Mg: density=1.738, weight=24.3, sigma_coh=3.631, sigma_inc=0.08, sigma_abs=0.063 MgF2: density=3.148, weight=62.3018,sigma_coh=11.74, sigma_inc=0.0816,sigma_abs=0.0822 diamond: density=3.52, weight=12.01, sigma_coh=5.551, sigma_inc=0.001, sigma_abs=0.0035 Quartz/silica: density=2.53, weight=60.08, sigma_coh=10.625,sigma_inc=0.0056,sigma_abs=0.1714 Si: density=2.329, weight=28.0855,sigma_coh=2.1633,sigma_inc=0.004, sigma_abs=0.171 Al: density=2.7, weight=26.98, sigma_coh=1.495, sigma_inc=0.0082,sigma_abs=0.231 Ni: density=8.908, weight=58.69, sigma_coh=13.3, sigma_inc=5.2, sigma_abs=4.49 Mn: (bc < 0) density=7.21, weight=54.94, sigma_coh=-1.75, sigma_inc=0.4, sigma_abs=13.3 perfluoropolymer(PTFE/Teflon/CF2): density=2.2, weight=50.007, sigma_coh=13.584,sigma_inc=0.0026,sigma_abs=0.0227 Organic molecules with C,O,H,F Among the most commonly available and machinable materials are MgF2, SiO2, Si, and Al.
| Name | Unit | Description | Default | |
| xwidth | m | width of box | 0 | |
| yheight | m | height of box/cylinder | 0 | |
| zdepth | m | depth of box | 0 | |
| radius | m | radius of sphere/cylinder | 0 | |
| geometry | str | OFF/PLY geometry file name, or NULL to use simple shape A spherical bi-concave lens can be obtained with geometry="lens_sphere" and given radius and zdepth | "NULL" | |
| R0 | 1 | Low-angle reflectivity | 0.99 | |
| sigma_coh | barn | coherent cross section of refracting material. Use negative value to indicate a negative coherent scattering length | 11.74 | |
| density | g/cm3 | density of the refracting material. density < 0 means the material is outside/before the shape. | 3.148 | |
| weight | g/mol | molar mass of the refracting material | 62.3018 | |
| sigma_inc | barn | incoherent cross section | 0 | |
| sigma_abs | barn | thermal absorption cross section | 0 | |
| Qc | Angs-1 | critical scattering vector, e.g. Qc=0.0219 for Ni coating. Set Qc=0 to use the bulk critical grazing angles. | 0 | |
| p_interact | 1 | MC Probability for scattering the ray; otherwise transmit. Use 0 to compute true probability, or specify it as e.g. 0.05 | 0.05 | |
| RMS | Angs | root mean square wavyness of the surface | 0 | |
| focus_scatter | deg | angle in which to scatter in bulk, with probability 'p_interact' | 10 | |
| verbose | 1 | flag to display detailed component behaviour | 0 | |
| p_scatter | 1 | flag to allow scattering in the refractor bulk | 1 | |
| p_reflect | 1 | flag to allow reflection (grazing angle) at the surface | 1 | |
| p_refract | 1 | flag to allow refraction at the refractor surface | 1 |
| AT ( | , | , | ) RELATIVE | |||
|---|---|---|---|---|---|---|
| ROTATED ( | , | , | ) RELATIVE |
Refractor.comp.
[ Identification | Description | Input parameters | Links ]
Generated on 2023-09-19 20:01:36