Position of Photon Creation Simulations

Tantalum, Aluminum Beamstop, and Air

Volumes: 1 = Target, 2 = Beamstop, 3 = Tracker, 4 = Chamber, 5 = Else

Volumes: 1 = eBrem, 2 = eIoni, 3 = msc, -1 = Else

Simulation Parameters

Target Matter: Tantalum

Target Length: 0.0508cm

Beamstop Matter: Aluminum

Beamstop Thickness: 1.27cm

Chamber Matter: Air

Tracker Matter: Air

World Matter: Vacuum

Target physically starts at -84.4cm and ends at -84.3492cm

Beamstop starts at -84.3492cm and ends at -83.0792cm

The tracker starts at -83.0792cm and ends at -3.0792cm

Conclusion

The beamstop is not thick enough to prevent electrons from traveling through the Tantalum to brem off of the air in the tracker.

Tantalum, No Beamstop, and Air

Volumes: 1 = Target, 2 = Beamstop, 3 = Tracker, 4 = Chamber, 5 = Else

Volumes: 1 = eBrem, 2 = eIoni, 3 = msc, -1 = Else

Simulation Parameters

Target Matter: Tantalum

Target Length: 0.0508cm

Beamstop Matter: Vacuum

Beamstop Thickness: 1.27cm

Chamber Matter: Air

Tracker Matter: Air

World Matter: Vacuum

Target physically starts at -84.4cm and ends at -84.3492cm

Beamstop starts at -84.3492cm and ends at -83.0792cm

The tracker starts at -83.0792cm and ends at -3.0792cm

Conclusion

Majority of photons are being created in the Tantalum target with some electrons traveling through the Tantalum to brem in the tracker.

Tantalum, No Beamstop, and Vacuum in every volume but target

This image is showing that the majority of the photons are created on the front and rear faces of the target, with very little happening in between.

Volumes: 1 = Target, 2 = Beamstop, 3 = Tracker, 4 = Chamber, 5 = Else

Volumes: 1 = eBrem, 2 = eIoni, 3 = msc, -1 = Else

Simulation Parameters

Target Matter: Tantalum

Target Length: 0.0508cm

Beamstop Matter: Vacuum

Beamstop Thickness: 1.27cm

Chamber Matter: Vacuum

Tracker Matter: Vacuum

World Matter: Vacuum

Target physically starts at -83.0508cm and ends at -83.0cm

Beamstop starts at -83cm and ends at -81.73cm

The tracker starts at -81.73cm and ends at -1.73cm

Conclusion

All of the photons are being created inside the tantalum, electrons are definitely making it though the tantalum.

In this simulation, I commented out the beamstop instead of setting the matter to vacuum, which explains why the position is shifted by roughly 1cm from the 2 simulations above this one.

Tantalum with thickness just over 1 radiation length

This image is showing that the majority of the photons are created on the front and rear faces of the target, with very little happening in between.

Volumes: 1 = Target, 2 = Beamstop, 3 = Tracker, 4 = Chamber, 5 = Else

Volumes: 1 = eBrem, 2 = eIoni, 3 = msc, -1 = Else

Simulation Parameters

Target Matter: Tantalum

Target Length: 0.500 cm

Beamstop Matter: Vacuum

Beamstop Thickness: 1.27cm

Chamber Matter: Vacuum

Tracker Matter: Vacuum

World Matter: Vacuum

Target physically starts at -83.5cm and ends at -83.0cm

Beamstop starts at -83.0cm and ends at -81.73cm

The tracker starts at -81.73cm and ends at -1.73cm

Conclusion

All of the photons are being created inside the tantalum.

Tantalum with thickness just over 2 radiation lengths

This image is showing that the majority of the photons are created on the front and rear faces of the target, with very little happening in between.

Volumes: 1 = Target, 2 = Beamstop, 3 = Tracker, 4 = Chamber, 5 = Else

Volumes: 1 = eBrem, 2 = eIoni, 3 = msc, -1 = Else

Simulation Parameters

Target Matter: Tantalum

Target Length: 1.000 cm

Beamstop Matter: Vacuum

Beamstop Thickness: 1.27cm

Chamber Matter: Vacuum

Tracker Matter: Vacuum

World Matter: Vacuum

Target physically starts at -83.5cm and ends at -83.0cm

Beamstop starts at -83.0cm and ends at -81.73cm

The tracker starts at -81.73cm and ends at -1.73cm

Conclusion

All of the photons are being created inside the tantalum.

Tantalum with thickness of 2.5cm

Error creating thumbnail: File missing

This image is showing that the majority of the photons are created on the front and rear faces of the target, with very little happening in between.

File:2 5cm Tant Brem Position.png

This image is showing that the majority of the photons are created on the front and rear faces of the target, with very little happening in between.

Error creating thumbnail: File missing

This image is showing that the majority of the photons are created on the front and rear faces of the target, with very little happening in between.

Simulation Parameters

See images for differing physics between the simulations.

Target Matter: Tantalum

Target Length: 2.5 cm

Beamstop Matter: Vacuum

Beamstop Thickness: 1.27cm

Chamber Matter: Vacuum

Tracker Matter: Vacuum

World Matter: Vacuum

Target physically starts at -85.5cm and ends at -83.0cm

Beamstop starts at -83.0cm and ends at -81.73cm

The tracker starts at -81.73cm and ends at -1.73cm

Conclusion

In the Brem & Ionization simulation the majority of the photon creation happens at the end face of the Tantalum. There is a spike at the first face of the target and also a bit of grass in between, this leads me to believe that the particle tracking in the simulation isn't working correctly, or is counting every interaction of every photon, which would explain why there is a huge spike of counts at the end face of the target.

In the Ionization simulation, there were no photons created.

TriMev Simulations