Space Group Info (c) 1994-96 Ralf W. Grosse-Kunstleve Permission to use and distribute this software and its documentation for noncommercial use and without fee is hereby granted, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in the supporting documentation. It is not allowed to sell this software in any way. This software is not in the public domain. |
Parameter Unit |
Description | Command option |
sample file | The sample file describes the geometry and properties of the sample. | -S |
Theta, dTheta, Phi, dPhi [deg] |
These parameters describe the solid angle covered by the detector. The
direction (q,f) points to the middle of the covered
area, which extends from [q-Dq, q+Dq] and [f-Df, f+Df]. q is defined as the angle between +x-axis (main flight direction of the neutrons) and the Vector R to be described. f is the angle between the +y-axis and the projection of R to the yz-plane. x,y and z form a right-handed system. !!!Note: If you specify any parameter of Dq, q, Df, f, you must specify all of them.!!! The default is a coverage of 4π |
-D, -d, -P,-p |
repetitions | 'repetitions' specifies the number of data sets (trajectories) generated for each scattered trajectory. A larger number of repetitions enriches the population on the detector and gives therefore better statistics in the spectrum. | -A |
treat all neutrons |
yes: treats neutrons not hitting the sample. no: removes neutrons not hitting the sample from the trajectory. |
-a |
transmission only |
'transmission only' specifies the simulation mode: yes: only wavelength dependent neutron transmission is handled. Neutrons hitting the sample will be attenuated by I/I0 = exp(-μ(λ)*transmission_length). The neutron flight direction is not changed. no: transmission, absorption and coherent and incoherent scattering are simulated. |
-T |
incoherent scattering | yes: neutrons are additionally scattered incoherently. no: incoherent scattering is omitted. !!!Note: This option is not considered if 'transmission only' = yes. |
-I |
nxs_sample.par |
10.0 0.0 0.0 # sample position relative in [cm] to the coordinate system defined by the preceding module cub # sample geometry (cyl, bal or cub) 2.0 1.0 2.3 # thickness or radius, width and height of the sample in [cm] 1.0 0.0 0.0 # orientation of the cylinder (does not need not be normalised) Fe.nxs # nxs parameter file to describe the unit cell composition |
The sample geometry file is assigned by the command line parameter -S. This option is mandatory. The VITESS GUI provides input fields to edit the described parameters.
Al.nxs |
# define the unit cell parameters: # space_group - the space group number or Hermann or Hall symbol [string] # lattice_a, ...b, ...c - the lattice spacings a,b,c [angstrom] # lattice_alpha, ...beta, ...gamma - the lattice angles alpha,beta,gamma [degree] # debye_temp - the Debye temperature [K] space_group = -F 4 2 3 # space group number is also allowed (= 225) lattice_a = 4.049 lattice_b = 4.049 lattice_c = 4.049 lattice_alpha = 90 lattice_beta = 90 lattice_gamma = 90 debye_temp = 429.0 # add atoms to the unit cell: # notation is "atom_number = name b_coh sigma_inc sigma_abs_2200 molar_mass x y z" # name - labels the current atom/isotope [string] # b_coh - the coherent scattering length [fm] # sigma_inc - the incoherent scattering cross section [barns] # sigma_abs_2200 - the absorption cross sect. at 2200 m/s [barns] # molar_mass - the Molar mass [g/mol] # debye_temp - the Debye temperature [K] # x y z - the Wyckoff postion of the atom inside the unit cell [atoms] add_atom = Al 3.449 0.008 0.23 26.98 0.0 0.0 0.0 |