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McStas: Tunneling_sample

[ Identification | Description | Input parameters | Links ]

The Tunneling_sample Component

A Double-cylinder shaped all-incoherent scatterer with elastic, quasielastic (Lorentzian), and tunneling (sharp) components.

Identification

  • Site:
  • Author: Kim Lefmann
  • Origin: Risoe
  • Date: 10.05.07

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, zdepth.
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(thickness=0.001,radius=0.01,yheight=0.02,focus_r=0.035,
target_index=1)

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
thicknessmThickness of cylindrical sample in (x,z) plane0
radiusmOuter radius of sample in (x,z) plane0.01
focus_rmRadius of disk containing target. Use 0 for full space0
p_interactMC Probability for scattering the ray; otherwise transmit [1]1
f_QEFraction of quasielastic scattering [1]0
f_tunFraction of tunneling scattering (f_QE+f_tun < 1) [1]0
gammaLorentzian width of quasielastic broadening (HWHM) [meV]0
E_tunTunneling energy [meV]0
target_xX-position of target to focus at [m]0
target_yY-position of target to focus at [m]0
target_zZ-position of target to focus at [m]0.235
focus_xwhoriz. dimension of a rectangular area [m]0
focus_yhvert. dimension of a rectangular area [m]0
focus_awhoriz. angular dimension of a rectangular area [deg]0
focus_ahvert. angular dimension of a rectangular area [deg]0
xwidthhoriz. dimension of sample, as a width [m]0
yheightmvert. dimension of sample, as a height0.05
zdepthdepth of sample [m]0
sigma_absAbsorbtion cross section pr. unit cell [barns]5.08
sigma_incTotal incoherent scattering cross section pr. unit cell [barns]4.935
VcUnit cell volume [AA^3]13.827
target_index1relative index of component to focus at, e.g. next is +10
AT ( , , ) RELATIVE
ROTATED ( , , ) RELATIVE

Links


[ Identification | Description | Input parameters | Links ]

Generated on 2023-09-19 20:01:36


Last Modified: Wednesday, 03-Jan-2024 19:59:10 CET
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