About McStas Download Documentation 
[ Identification  Description  Input parameters  Output parameters  Links ] The
A sample for phonon scattering based on cross section expressions from Squires, Ch.3.
Possibility for adding an (unphysical) bandgap.

Name  Unit  Description  Default 

radius  m  Outer radius of sample in (x,z) plane  
yheight  m  Height of sample in y direction  
sigma_abs  barns  Absorption cross section at 2200 m/s per atom  
sigma_inc  barns  Incoherent scattering cross section per atom  
a  AA  fcc Lattice constant  
b  fm  Scattering length  
M  a.u.  Atomic mass  
c  meV/AA^(1)  Velocity of sound  
DW  1  DebyeWaller factor  
T  K  Temperature  
target_x  m  position of target to focus at . Transverse coordinate  0 
target_y  m  position of target to focus at. Vertical coordinate  0 
target_z  m  position of target to focus at. Straight ahead.  0 
target_index  1  relative index of component to focus at, e.g. next is +1  0 
focus_r  m  Radius of sphere containing target.  0 
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 
gap  unphysical  [meV] Bandgap energy  0 
Name  Unit  Description  Default 

V_rho  AA^3  Atomic density  
V_my_s  m^1  Attenuation factor due to incoherent scattering  
V_my_a_v  m^1  Attenuation factor due to absorbtion  
DV  
parms 
Phonon_simple.comp
.
[ Identification  Description  Input parameters  Output parameters  Links ]
Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Mon Jan 13 14:50:07 2020