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

# The `Tunneling_sample` Component

Modified from: Vanadium sample.

## Identification

- Author: Kim Lefmann
- Origin: Risoe
- Date: 10.05.07
- Version: 1.3

## Description

    A Double-cylinder shaped all-incoherent scatterer
    with both elastic, quasielastic (Lorentzian), and tunneling (sharp)
    components. No multiple scattering. Absorbtion included.
    The shape of the sample may be a box with dimensions xwidth, yheight, zthick.
    The area to scatter to is a disk of radius 'focus_r' situated at the target.
    This target area may also be rectangular if specified focus_xw and focus_yh
    or focus_aw and focus_ah, respectively in meters and degrees.
    The target itself is either situated according to given coordinates (x,y,z),
    or defined with the relative target_index of the component to focus
    to (next is +1).
    This target position will be set to its AT position. When targeting to
    centered components, such as spheres or cylinders, define an Arm component
    where to focus to.

    The outgoing polarization is calculated as for nuclear spin incoherence:
      P' = 1/3*P-2/3P = -1/3P
    As above multiple scattering is ignored .

    Example: Tunneling_sample(radius_i=0.001,radius_o=0.01,h=0.02,focus_r=0.035,
              target_index=1)

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
--- | --- | --- | ---
radius_i | m | Inner radius of sample in (x,z) plane | 0
radius_o | m | Outer radius of sample in (x,z) plane | 0.01
h | m | Height of sample y direction | 0.05
focus_r | m | Radius of disk containing target. Use 0 for full space | 0
frac | 1 | MC Probability for scattering the ray; otherwise penetrate | 1
f_QE | 1 | Fraction of quasielastic scattering | 0
f_tun | 1 | Fraction of tunneling scattering (f_QE+f_tun < 1) | 0
gamma | meV | Lorentzian width of quasielastic broadening (HWHM) | 0
E_tun | meV | Tunneling energy | 0
target_x | - |  | 0
target_y | m | position of target to focus at | 0
target_z | - |  | 0.235
focus_xw | m | horiz. dimension of a rectangular area | 0
focus_yh | m | vert. dimension of a rectangular area | 0
focus_aw | deg | horiz. angular dimension of a rectangular area | 0
focus_ah | deg | vert. angular dimension of a rectangular area | 0
xwidth | m | horiz. dimension of sample, as a width | 0
yheight | m | vert. dimension of sample, as a height | 0
zthick | m | thickness of sample | 0
sig_a | barns | Absorbtion cross section pr. unit cell | 5.08
sig_i | barns | Total incoherent scattering cross section pr. unit cell | 4.935
V0 | AA^3 | Unit cell volume | 13.827
target_index | 1 | relative index of component to focus at, e.g. next is +1 | 0

## Output parameters

Name | Unit | Description | Default
--- | --- | --- | ---
StructVarsV |  |  |
VarsV |  |  |

## Links

- Source code for `Tunneling_sample.comp`.
- Test results (not up-to-date).

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