The source properties

The source properties define the distance of the source from the detector and how the alpha emitters should be deposited into the source. Using the source window you can define whether the emitters are in particles, homogeneous source or combination of both.

To specify the distance of the source from the detector use the following control:

The 'source-detector distance' field

Specifies the distance of the source from the detector. The distance is measured from the top surface of the source (or the highest point in case of convex / concave sources).

To select the type of  deposition of the alpha emitters use the following controls:

The 'homogeneous source type' button

Selects the source type to be a homogeneous. This means that the alpha particle emitters are distributed into a homogeneous matrix of non-active material. See specifying a homogeneous source.
The 'radioactive particles source type' button

Selects the source type to be radioactive particles. This means that the alpha particle emitters are contained in particles of non-active material. See specifying radioactive particles source.
The 'radioactive particles in homogeneous source matrix type' button

Selects the source type to be radioactive particles embedded in a homogeneous matrix. This means that the alpha particle emitters are contained in particles of non-active material, and in addition the particles are contained in a homogeneous matrix of non-active material. See specifying radioactive particles in a homogeneous source matrix.


Specifying a homogeneous source

In this type of source the alpha particle emitters are contained in a homogeneous source matrix of non-active material.When a homogeneous source type is selected it can be defined by the following properties:

The source diameter

The source is assumed to be cylindrical, and this is the diameter of the cylinder.
Central thickness

The thickness of the source at its center. This can be used together with the side thickness to specify a source that has convex of concave upper surface (the surface facing the detector)
Side thickness

The thickness of the source at its side. This can be used together with the central thickness to specify a source that has convex of concave upper surface (the surface facing the detector)
Thickness fluctuation

The maximum thickness fluctuations in the source. The source can have thickness fluctuations that are uniformly distributed between 0 and this value.
Density

The density of the source material. 

The source material can be defined using the following controls:

'Source element composition' table

This table displays the elemental composition of the source. By clicking on the white portion of table you will be able to edit the material. See editing materials with the material editor.


Specifying radioactive particles source

In this type of source the alpha particle emitters are encapsulated in particles of non-active material. When a radioactive particles source type is selected, the properties of the particles depend on the desired characteristics of the particles to simulate.

The characteristics of the particles are:

Particle occurrence. Use the following controls  to specify the occurrence and location of the particles:

'Single particle' button

Selects only single particle at specified location to contain the emitter. The location can be edited with the two fields for x and y - coordinates of the particle. The origin of the coordinatesystem coincides with the center of the detector window.
Important: This option disables the lognormal size distribution.
'Many particles' button

Selects many particles to be randomly generated to contain the emitters. The diameter of the area where the particles will be generated can be specified in the field below.

Particle type. Use the following controls to specify the type of particles to simulate.

'Spherical particle type' button

Selects spherical shape to be used for the particle(s) simulated. 
'Ellipsoidal particle type' button

Selects ellipsoidal shape to be used for the particle(s) simulated.
Important: This option disables the use of a lognormal size distribution. All particles are considered to have the same size instead.
'Spherical surface layer type' button

Selects a layer of radioactive material on the surface of spherical particles to be used in the simulation.

Particle size. Use the following controls to specify the size of the particles to simulate.
Important: This option is not available when simulating single particle

'All particles have the same size' button

Selects all particles to have the same size. The size of the particles can be defined in particle properties.
'Lognormally distributed particle size' button

Selects the particles size to be lognormally distributed. The parameters of the distribution can be specified in particle properties.
Important: This option is not available if single particle or ellipsoidal particle type are selected

The properties of the particles vary according to the desired characteristics explained above. It is important to realize that not all properties are available with all combinations of characteristics, for instance specifying a lognormal size distribution obviously excludes the particle size property but presents the parameters of the distribution for editing instead.

The properties of the particles are:

Particle diameter

The diameter of the particle(s) to simulate.
Only available with spherical particle type.
Particle X diameter

The diameter of the particle(s) along the X - axis.
Only available with ellipsoidal particle type.
Particle Y diameter

The diameter of the particle(s) along the Y - axis.
Only available with ellipsoidal particle type.
Particle Z diameter

The diameter of the particle(s) along the Z - axis. This is the axis that points towards the detector.
Only available with ellipsoidal particle type.
Mean diameter

The mean diameter of the particle(s).
Only available with lognormal size distribution
Geometric standard deviation

The geometric standard deviation of the particle(s) diameter.
Only available with lognormal size distribution
Diameter ceiling

The maximum diameter of the particle(s).
Only available with lognormal size distribution
Particle density

Density of the particle material.        

The particle material can be defined using the following controls:

'Particle element composition' table

This table displays the elemental composition of the particles. It is noteworthy that although elements such as uranium and plutonium can be specified, the particle material is still considered to be non-active. By clicking on the white portion of table you will be able to edit the material. See editing materials with the material editor.


Specifying radioactive particles in a homogeneous matrix source

In this type of source, the alpha particle emitters are contained in particles of non-active material, and the particles are contained in a source matrix of non-active material. When this type of source is selected, you must define both the particles and the source matrix.

 For the particles the procedure is very much similiar to specifying radioactive particles source. But with some exceptions however:

-Single particle simulation is not supported in this scheme.

-Since the particles are now embedded in the source matrix, it is possible to define the way the particles have penetrated the matrix. The rest of the source matrix properties are same as in the homogeneous source case, see source matrix properties.

'Uniform depth distribution' button

Specifies that uniform distribution should be used in distributing the particles into the source matrix.
'Exponential depth distribution' button

Specifies that exponential distribution should be used in distributing the particles into the source matrix. The parameters of the exponential depth distribution can then be edited in the particle properties.

- Particle properties for specifying the exponential depth distribution are included. The rest of the particle properties are same as in the radioactive particles source case, see radioactive particle properties.

Percentage to distribute exponentially

The percentage of the generated particles to be distributed exponentially. The rest are on the surface of the source matrix.
Mean penetration depth

The mean depth the exponentially distributed particles will penetrate the source matrix. 
- The exponential depth distribution can not be used with ellipsoidal particle type!

The source matrix housing the particles is defined much in the same way as in specifying a homogeneous source. Some exceptions do exist however:

-Only central thickness is used if exponential depth distribution is selected! The source matrix is considered cylindrical.

See also:
The source page
Radionuclides in the source