[ Identification | Description | Input parameters | Links ]

# The `FZP_simple` Component

Fresnel zone-plate as a thin object approximation.

## Identification

- Site:
- Author: A Komar Ravn, and Erik B Knudsen
- Origin: NBI/DTU
- Date: Aug, 2015

## Description

    A simple phenomenological thin-object approximation of a Fresnel Zone Plate.
    This component was adapted for neutrons from the original component
    written for helium scattering.
    The focal length of the Zone Plate is determined by the formula:
    \[f = 2*r*dr/(lambda)\]
    If a diffraction order other than 1 is wanted the focal distance is scaled accordingly.

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default |
rad | m | Radius of the zone-plate. |  |
dr | m | Width of the outermost ring-slit. |  |
bs0rad | m | Radius of the central blocking zone. | 0 |
order | m | Use this diffaction order. | 1 |
eta |  | Efficiency of the FZP. For neutrons and (order==1) typically {5...30}%. Overrides the sigma_x cross sections. | 0.1 |
sigma_abs | barn | 2200 m/s absorption cross section. | 0 |
sigma_inc | barn | Incoherent scattering cross section. | 0 |
sigma_coh | barn | Coherent scattering cross section. | 0 |
rho |  |  | 1 |
thickness | m | Thickness of the FZP. Note that the FZP still is modelled as a thin object. The thickness is used in conjunction with the sigma_x cross sections. | 0 |
gamma |  | Duty cycle of the Zone plate - used merely for absorption estimation. | 0.5 |

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

## Links

- Source code for `FZP_simple.comp`.

[ Identification | Description | Input parameters | Links ]