Geometry

The default geometry is a single planar slab geometry with 26 layers (the boundaries are equivalent to the default SHIELDOSE [R16] thicknesses, but the geometry as a whole isn’t). The material for the default geometry is Aluminium.

PreInit> /geometry/layer/list
/geometry/layer/list

-------------------------------------------------------------
---> The geometry setup has 26 layers:
  Layer No.   1            Aluminium:     50 um
  Layer No.   2            Aluminium:     50 um
  Layer No.   3            Aluminium:    100 um
  Layer No.   4            Aluminium:    100 um
  Layer No.   5            Aluminium:    100 um
  Layer No.   6            Aluminium:    100 um
  Layer No.   7            Aluminium:    100 um
  Layer No.   8            Aluminium:    100 um
  Layer No.   9            Aluminium:    100 um
  Layer No.  10            Aluminium:    200 um
  Layer No.  11            Aluminium:    500 um
  Layer No.  12            Aluminium:    500 um
  Layer No.  13            Aluminium:    500 um
  Layer No.  14            Aluminium:    500 um
  Layer No.  15            Aluminium:      1 mm
  Layer No.  16            Aluminium:      1 mm
  Layer No.  17            Aluminium:      1 mm
  Layer No.  18            Aluminium:      1 mm
  Layer No.  19            Aluminium:      1 mm
  Layer No.  20            Aluminium:      1 mm
  Layer No.  21            Aluminium:      1 mm
  Layer No.  22            Aluminium:      2 mm
  Layer No.  23            Aluminium:      2 mm
  Layer No.  24            Aluminium:      2 mm
  Layer No.  25            Aluminium:      2 mm
  Layer No.  26            Aluminium:      2 mm

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PreInit>

When a user-defined geometry is required, the first thing to do is to remove the default geometry

PreInit> /geometry/layer/delete 0
/geometry/layer/delete 0
PreInit> /geometry/layer/list
/geometry/layer/list

-------------------------------------------------------------
---> The geometry setup has 0 layers:

-------------------------------------------------------------
PreInit>

Then the user has to specify whether planar slab or spherical shell geometry is used, e.g.

PreInit>
PreInit> /geometry/layer/shape sphere
/geometry/layer/shape sphere
PreInit>

The default geometry shape is planar slab. It is mandatory to issue the command /geometry/update after any changes to the geometry setup to apply the changes.

Note

layer thicknesses less than an equivalent of 10 microns of Silicon or Aluminium are not recommended for nonMC analyses.

Planar/Slab geometry

The command to add a new layer is /geometry/layer/add. It takes 5 parameters in the same line:

• position - integer denoting after which layer the new layer will be inserted

• material - name of the material for the layer

• colour index - number of the colour used to visualise the layer (see Geometry colours)

• thickness - layer thickness in terms of units

• unit - unit of the thickness.

Use 0 as the layer number to insert the first layer.

In the example below, using a spherical geometry, an Aluminium and a Silicon layer are created first, then a layer of Air is inserted between the Aluminium and Silicon layers, i.e., after layer 1.

PreInit> /geometry/layer/shape sphere
PreInit> /geometry/layer/delete 0
PreInit> /geometry/layer/add 0 Aluminium 2 1 cm
PreInit> /geometry/layer/add 1 Silicon   4 1 mm
PreInit> /geometry/layer/list

-------------------------------------------------------------
---> The geometry setup has 2 layers:
  Layer No.   1            Aluminium:      1 cm
  Layer No.   2              Silicon:      1 mm

-------------------------------------------------------------
PreInit> /geometry/layer/add 1 Air 5 1 mm
PreInit> /geometry/layer/list

-------------------------------------------------------------
---> The geometry setup has 3 layers:
  Layer No.   1            Aluminium:      1 cm
  Layer No.   2                  Air:      1 mm
  Layer No.   3              Silicon:      1 mm

-------------------------------------------------------------
PreInit>

Spherical shell geometry

The shells in a spherical geometry configuration are defined the same way as the layers in planar geometry. A couple of points should be noted however:

1. The first layer is the outer-most shell.

2. The last shell, i.e., the inner most one, is a solid sphere.

So the same commands in the example above will initially create a solid silicon sphere with a radius of 1 mm surrounded by an Aluminium shell 1 cm thick, then with the addition of the Air layer, the geometry will have a 1 mm air “gap” between the Silicon and Aluminium layers.

This figure shows the above geometry, consisting of a 1 cm outer layer of Aluminium (grey), a 1 mm inner layer of Air (blue), and a 1 mm radius inner sphere of silicon (red).

Geometry colours

There are 12 predefined colours in MULASSIS (indexed 1 to 12). The user can add more colours; see Command List for commands of /geometry/colour.

PreInit> /geometry/colour/list
/geometry/colour/list
 There are  12 colour defined

     Colour Index   1      white
     Colour Index   2       grey
     Colour Index   3  dark_grey
     Colour Index   4        red
     Colour Index   5       blue
     Colour Index   6       cyan
     Colour Index   7    magenta
     Colour Index   8     yellow
     Colour Index   9  dark_blue
     Colour Index  10      green
     Colour Index  11 dark_green
     Colour Index  12   dark_red

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Mulassis/ml-v02-00/r342