[ Identification | Description | Input parameters | Output parameters | Links ]

`Sample_nxs`

Component-
**Author:**Mirko Boin -
**Origin:**Helmholtz-Zentrum Berlin fuer Materialien und Energie (Germany) -
**Date:**Oct 2014 -
**Version:**(Unknown)

Features: - coherent and incoherent scattering, absorption and transmission - multiple scattering - wavelength-dependent neutron cross section calculation - unit cell definition (via input file) - focussing option for scattered neutrons (via d_phi) - strain gradient simulation for axial symmetric samples (...to be extended) Geometry is a powder filled cylinder or a box defined by radius or xwidth, yheight, zthick respectively. The component handles coherent and incoherent scattering (also multiple scattering), absorption and transmission. Hence, it is suitable for diffraction (scattering) and imaging (transmission) instruments at the same time. In order to improve the neutron statistics at the detector these individual features can be enabled/disabled using TransOnly, IncohScat, MultiScat. For example, if scattering shall not be monitored (e.g. imaging), then TransOnly can be set to 1 to let the component calculate the neutron transmission through the sample only. Likewise, incoherent scattering can be switched on and off. The decision of whether a neuron shall be scattered, absorbed or transmitted is based on the wavelength-dependent neutron cross sections (nxs), i.e. the neutron velocity is used here. These cross sections represent the individual scattering and absorption probabilities for each individual neutron. However, the calculation of neutron cross sections depends on the material defined for this sample component. Therefore, several input parameters such as the crystal structure and the atoms involved (isotope mass, coherent scattering length, ...). This information is provided by an input file with the following format:

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 |

Name | Unit | Description | Default |
---|---|---|---|

TransOnly | 0 | ||

IncohScat | 1 | ||

MultiScat | 1 | ||

xwidth | 0.05 | ||

yheight | 0.05 | ||

zthick | 0.05 | ||

radius | 0.0 | ||

nxsFileName | "" | ||

max_hkl | 8 | ||

d_phi | 0 | ||

strainFileName | "" |

Name | Unit | Description | Default |
---|---|---|---|

isrect |
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intersect |
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nxs_init_success |
|||

p_transmit |
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xsect_total |
|||

xsect_coherent |
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xsect_incoherent |
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xsect_absorption |
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lambda |
|||

velocity |
|||

fullpath |
|||

t1 |
|||

t2 |
|||

uc |
|||

A |
|||

mu_factor |
|||

sd |
|||

V2L |

- Source code for
`Sample_nxs.comp`

.

[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Sun Jun 16 09:10:11 2019