Space Radiation Volume Tally

Problem Description

This problem illustrates how to calculate the total energy deposited on a piece of target silicon shielded in aluminum. All elements are constructed from Constructive Solid Geometry, with the shield made by subtracting one sphere from another to create a shell around the silicon target. A spherical surface particle source is used for this simulation.

It also shows how to use tabulated energy spectrum of differential fluence given in spectrum.txt file.

This is a good example to demonstrate setting up basic shielding problems in RSim.

Opening the Simulation

The shielded target example is accessed from within RSim by the following actions:

• Select the New → From Example… menu item in the File menu.
• In the resulting Examples window expand the RSim for Basic Radiation option.
• Expand the Basic Examples option.
• Select Space Radiation Volume Tally and press the Choose button.
• In the resulting dialog, create a New Folder if desired, and press the Save button to create a copy of this example.

All of the properties and values that create the simulation are now available in the Setup Window as shown in Fig. 53. You can expand the tree elements and navigate through the various properties, making any changes you desire. The right pane shows a 3D view of the geometry, if any, as well as the grid, if actively shown.

Fig. 53 Setup Window for the shielded target example.

Simulation Properties

This example demonstrates two physics features, and how CSG can be incorporated into RSim Simulations.

Under the Basic Settings tab the number of events to be simulated can be selected, as well as the verbosity of the output

The particle source selected is a spherical surface and simulates 1 electron per event. The energy is based on a 2 column text file supplied with the example. The 2 column text file consists

This example has tallies to record the dose deposited on the shield and target, as well as the number of tracks that get cut from the simulation in the shield in the target.

Running the Simulation

After performing the above actions, continue as follows:

• Proceed to the Run Window by pressing the Run button in the left column of buttons.
• To run the file, click on the Run button in the upper left corner of the Logs and Output Files pane. You will see the output of the run in the right pane. The run has completed when you see the output, “Engine completed successfully.” This is shown in Fig. 54.

Fig. 54 The Run Window at the end of execution.

Visualizing the Results

After the run has completed the results of all tallies can be visualized.

• Expand Scalar Data
• Select TracksTerminatedInShield
• Select TracksTerminatedInTarget

Further Experiments

The dose on the target can be greatly changed by altering the thickness of the shield, along with increasing the number of terminated tracks recorded in the shield. You can also add Number of Tracks tallies to see the difference in how many tracks get cut from the simulation vs. pass through the shield.