CORRFACT

Summary

allows to alter material density for dE/dx and nuclear processes on a region-by-region basis ​​

(see also ASSIGNMAt, COMPOUND, LOW–MAT, MATERIAL, MAT–PROP)

WHAT(1) > 0.0:

density scaling factor for charged particle ionisation​ processes (dE/dx​, delta ray​ production, Mand Bhabha scattering​)​

= 0.0:

ignored

-2.0…0.0:

|WHAT(1)| assumed relative to WHAT(2), the final density correction factor will be |WHAT(1)| X WHAT(2)

≤ -2.0:

reset to default

Default

: 1.0

WHAT(2) > 0.0:

density scaling factor for all other processes

= 0.0:

ignored

< 0.0:

reset to default

Default

: 1.0

WHAT(3) :

not used

WHAT(4) :
lower index bound (or corresponding name) of regions where the scaling factors shall apply
(“From region ``WHAT(4)``…”)
Default

: 2.0

WHAT(5) :
upper index bound (or corresponding name) of regions where the scaling factors shall apply
(“…to region ``WHAT(5)``…”)
Default

= WHAT(4)

WHAT(6) =
step length in assigning region numbers
(“…in steps of ``WHAT(6)`` ”)
Default

= 1.0

SDUM

: not used

Default

(option CORRFACT not requested): no density scaling factors are applied


Note

  1. Option CORRFACT is mainly used in connection with voxel geometries​ derived from a CT scan​, where particle transport is done often in an equivalent material (e.g. water)​, but accounting for the density variations provided by scan at the voxel level. While this approach is reliable for what concerns ionisation, other reactions, which do not scale with density, must be simulated for the actual material composition.

  2. Only density scaling factors in the range [2/3 , 3/2] are allowed.

Example, in a number-based input:

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...
* Multiply density by a 0.85 factor for what concerns atomic processes
* in regions 7, 8, 9, 10, 11, 12
CORRFACT        0.85       0.0       0.0       7.0       12.

The same example, in a name-based input, supposing that the geometry is made of 12 regions:

CORRFACT        0.85       0.0       0.0  The7thRg  @LASTREG
* Note the use of the name @LASTREG to indicate the maximum number of regions
* in the problem