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McStas: Tunneling_sample Component

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

The Tunneling_sample Component

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

Identification

  • Author: Kim Lefmann
  • Origin: Risoe
  • Date: 10.05.07
  • Version:(Unknown)

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.
Name Unit Description Default
thickness m Thickness of cylindrical sample in (x,z) plane 0
radius m Outer radius of sample in (x,z) plane 0.01
focus_r m Radius of disk containing target. Use 0 for full space 0
p_interact 1 MC Probability for scattering the ray; otherwise transmit 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 0.05
zdepth m depth of sample 0
sigma_abs barns Absorbtion cross section pr. unit cell 5.08
sigma_inc barns Total incoherent scattering cross section pr. unit cell 4.935
Vc 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
ftun  
fQE  
VarsV  

Links


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

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Mon Jun 26 12:27:17 2017


Last Modified: Monday, 26-Jun-2017 14:27:17 CEST
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