The *Particle Sources* element contains all particle sources of the simulation.
All particle sources contain the same options, but are differentiated based on the specification type. Multiple particle sources may be used in a single simulation.

pointA point source can specify the x,y and z coordinates of the point. All particles will emit from this point. The point is visualized by a sphere. The radius of this sphere is controlled by therepresentationRadiusproperty, it has no effect on the simulation.

surfaceTo create a surface source first create a Sphere, Box, or Cylinder CSG object. It must then be assigned the MaterialSourceto designate that it is being used as a particle source. At this time any Cylinder or Box source must be axis-aligned. All particles will emit from the surface.

volumeTo create a volume source first create a Sphere, Box, or Cylinder CSG object. It must then be assigned the MaterialSourceto designate that it is being used as a particle source. At this time any Cylinder or Box source must be axis-aligned.

planeA plane source will emit particles from the 2D plane specified. The available types of planes are.

xy planeThis is a rectangular plane on the xy axis.

offsetThe z coordinate of the plane.xMinThe lower x coordinate of the plane.xMaxThe upper x coordinate of the plane.yMinThe lower y coordinate of the plane.yMaxThe upper y coordinate of the plane.xz planeThis is a rectangular plane on the xz axis.

offsetThe y coordinate of the plane.xMinThe lower x coordinate of the plane.xMaxThe upper x coordinate of the plane.zMinThe lower z coordinate of the plane.zMaxThe upper z coordinate of the plane.yz planeThis is a rectangular plane on the yz axis.

offsetThe x coordinate of the plane.yMinThe lower y coordinate of the plane.yMaxThe upper y coordinate of the plane.zMinThe lower z coordinate of the plane.zMaxThe upper z coordinate of the plane.xy ellipsisAn ellipsis (or circle) on the xy plane

rXThe x-radius of the ellipsis.rYThe y-radius of the ellipsis.xThe center of the ellipsis on the x axis.yThe center of the ellipsis on the y axis.zThe center of the ellipsis on the z axis.xz ellipsisAn ellipsis (or circle) on the xz plane

rXThe x-radius of the ellipsis.rZThe z-radius of the ellipsis.xThe center of the ellipsis on the x axis.yThe center of the ellipsis on the y axis.zThe center of the ellipsis on the z axis.yz ellipsisAn ellipsis (or circle) on the yz plane

rYThe y-radius of the ellipsis.rZThe z-radius of the ellipsis.xThe center of the ellipsis on the x axis.yThe center of the ellipsis on the y axis.zThe center of the ellipsis on the z axis.

number of particles per eventThis is the number of particles to emit for each event.

particle typeThe type of particle to emit. The available particles are:

electronprotonneutronpositronalphagammaion

atomic numberAtomic number of the ion.nucleon numberNumber of nucleons in the ion.chargeCharge of the ion.nuclear excitationExcitation of the ion.

Angular DistThe type of angular distribution of the particle source.

OmnidirectionalWith an omnidirectional angular distribution the fluence for each direction is proportional to thecosineof the angle between the source direction and local noraml of the surface.

min thetaThe minimum angle, 0 degrees corresponds to the -Z axis.max thetaThe maximum angle, 180 degrees corresponds to the +Z axis.If Computed Normalization is selected, and the source is not a point, the angular distribution factor is calculated as \(\frac{1}{4}*(\sin^{2}(max theta) - \sin^{2}(min theta)\)

If the source is a point, the angular distribution factor is \(\frac{1}{2}*(\cos(min theta) - \cos(max theta)\)

IsotropicIf emitting from a rectangular slab or plane, the final distribution of particles will not in fact be isotropic as the angle of emission will impact the resulting fluence.

min thetaThe minimum angle, 0 degrees corresponds to the -Z axis.max thetaThe maximum angle, 180 degrees corresponds to the +Z axis.If Computed Normalization is selected, the angular distribution factor is 1.0

Beam1DA beam1D source will feature a uniform dispersion angle around the beam. The beam angular distribution is only available with planar sources.

dispersion angleThe dispersion angle of the beam.beam directionEither positive or negative, this will send the particles on the corresponding axial direction.If a Beam1D angular distribution is used, Computed Normalization cannot be used.

Energy SpectrumThe energy spectrum of the particle source. Options are

MonoEnergetic

monoEnergy of the source.unitsUnits of the energy source specified.fluenceUsed in normalization calculations ifComputed Normalizationis selected.If using computed normalization, the energy normalization factor will take the form \(\frac{gradient}{2}max^{2}+intercept*max-\frac{gradient}{2}min^{2}+intercept*min\)

LinearThe linear distribution takes the form y = gradient * energy + intercept

minMinimum energy.maxMaximum energy.unitsUnits of the energy source.interceptIntercept of the linear curve.gradientThe source strength multiplier.If using computed normalization, the energy normalization factor will take the form \(\frac{gradient}{2}max^{2}+intercept*max-\frac{gradient}{2}min^{2}+intercept*min\)

Power LawThe power law distribution takes the form y = gradient * energy ^ alpha

minMinimum energy.maxMaximum energy.unitsUnits of the energy source.alphaThe exponential of the energy distribution.gradientThe source strength multiplier.If using computed normalization, the energy normalization factor will take the form \(\frac{gradient}{(alpha + 1)} * max^{alpha + 1} - \frac{gradient}{(alpha + 1)} * min^{alpha + 1}\)

ExponentialThe exponential distribution takes the form \(y = coefficient * e ^(\frac{energy}{eZero})\)

minMinimum energy.maxMaximum energy.unitsUnits of the energy source.coefficientThe source strength multiplier.eZeroBase value of the exponential.If using computed normalization, the energy normalization factor will take the form \(-coefficient*eZero*e^{\frac{-Emax}{eZero}} + coefficient*eZero*e^{\frac{-Emin}{eZero}}\)

2 Column FileThe 2 column file needs to be arranged in order of Energy|Differential Fluence increasing from row to row.The integral flux is given in units of particles/cm^2/second^2, while the differential flux is given as particles/cm^2/second^2/MeV

file nameName of the file.max integral fluxUsed in normalization calculations ifComputed Normalizationis selected.min integral fluxUsed in normalization calculations ifComputed Normalizationis selected.interpolation typeInterpolation between points of the file.

linearpower-lawcubic splineexponentialIf using computed normalization, the energy normalization factor is the difference between the max and min integral flux. These values need to be specified directly, as various models will give slightly different values.

GaussianThis gives a guassian energy distribution, and does not allow for a computed normalization to be used.

energy centerCenter of the gaussian distribution.sigmaThe standard deviation of the gaussian distribution.unitsThe units of the energy center.

- With either the Computed or Manual normalization factors, the normalization is itself calculated in the same way. This is normalization to a current going through the primary surface, multiplying the final results by surfaceArea/Nparticles * (energyNormalizationFactor * angularNormalizationFactor)
Where surfaceArea is the surface area of the source, and Nparticles is the number of particles emitted by the source.

**No Normalization**If selected the source will not be normalized.**Computed Normalization**If computed normalization is used, the normalization factors are calculated as described in the energy spectrum and angular dist.**Manual Normalization**With manual normalization the angular and energy normalization factors are specified directly.