[ Identification | Description | Input parameters | Links ]

# The `IncoherentPhonon_process` Component

A component to simulate inelastic scattering in the incoherent approximation Takes into account one, two, and three phonon scattering explicitly, and multi-phonon scattering (with n>4) via the saddle point method

## Identification

- Site:
- Author: Victor Laliena
- Origin: University of Zaragoza
- Date: 06.11.2018

## Description

    Part of the Union components, a set of components that work together and thus
    expects 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

    Algorithm:
    Described elsewhere, see e.g. https://doi.org/10.3233/JNR-190117

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default |
T | K | Temperature | 394 |
density | g/cm3 | Material density | 6.0 |
M | amu | ion mass | 50.94 |
sigmaCoh | barns | Coherent scattering cross section | 0.0184 |
sigmaInc | barns | Incoherent scattering cross section | 5.08 |
DOSfn | string | Path to the file that contains the DoS | NULL |
nphe_exact | 1 | Number of terms in the phonon expansion taken exact. Has to be between 1 and 3. | 1 |
nphe_approx | 1 | Number of terms in the phonon expansion taken approximate. | 0 |
approx | 1 | Approximation type: 0 gaussian, 1 saddle point | 0 |
mph_resum | 0/1 | Resumate the remaining terms of the phonon expansion via a saddle point: 0 No, 1 Yes | 0 |
nxs | 1 | Number of energy points at which the total cross sections are precomputed | 1000 |
kabsmin | A^-1 | Lower cut-off for the neutron wave-vector k | 0.1 |
kabsmax | A^-1 | Higher cut-off for the neutron wave-vector k | 25 |
interact_fraction | 1 | How large a part of the scattering events should use this process 0-1 (sum of all processes in material = 1) | -1 |
init |  |  | "init" |

AT ( | , | , |  | ) RELATIVE |  |
ROTATED ( | , | , |  | ) RELATIVE |

## Links

- Source code for `IncoherentPhonon_process.comp`.
- See https://doi.org/10.3233/JNR-190117

[ Identification | Description | Input parameters | Links ]