Comparison with NIST

In this section we compare the remage simulation output with theoretical predictions from the NIST database.

Electron interactions

We calculate stopping power and integrated path length of the simulated electrons and compare them with data from the ESTAR database (a short description of the reported quantities is available here).

The simulation physics is modified by the commands:

/process/inactivate msc
/RMG/Processes/DefaultProductionCut 1 km
/RMG/Processes/SensitiveProductionCut 1 km

  • Multiple Coulomb scattering is disabled, since it prevents us to measure the true integrated particle path length in the simulation (unless a very short step size limit is set).

  • the high production cuts ensure that no secondaries are created. This is required to correctly measure the bremsstrahlung component of the CSDA loss.

An effect of the step length is visible. The larger the step length, the larger the difference to the expected integrated path length.

The statistical uncertainties are dominated by energy-loss fluctuations. They are kept enabled here to show the effect of the user-chosen step length values. Especially the stopping power at low step sizes are the most affected.

Note

The simulated stopping powers are derived from the energy deposition in the first step and its length. This leads to the stopping powers only matching with the ESTAR-provided values until a material-specific energy.

Below that, the energy is fully deposited in one single small step, from which we cannot estimate the stopping power at the incident energy any more. For these low energies, we plot the incident energy over the full expected ranged from ESTAR data as the expectation value.

Electron interactions in natural germanium

Monoenergetic electrons are simulated in a natural germanium sphere of 15 cm radius.

Electron integrated path lengths versus initial electron energy. Electron integrated path lengths versus initial electron energy.
Distribution of electron integrated path lengths. Distribution of electron integrated path lengths.
Stopping power. Stopping power.

Simulation of electrons in natural germanium with default settings (i.e. no tuning of production cuts or step length).

Electron interactions in liquid argon

Monoenergetic electrons are simulated in a liquid argon sphere of 15 cm radius.

Electron integrated path lengths versus initial electron energy. Electron integrated path lengths versus initial electron energy.
Distribution of electron integrated path lengths. Distribution of electron integrated path lengths.
Stopping power. Stopping power.

Simulation of electrons in natural germanium with default settings (i.e. no tuning of production cuts or step length).

Electron interactions in copper

Monoenergetic electrons are simulated in a copper sphere of 15 cm radius.

Electron integrated path lengths versus initial electron energy. Electron integrated path lengths versus initial electron energy.
Distribution of electron integrated path lengths. Distribution of electron integrated path lengths.
Stopping power. Stopping power.

Simulation of electrons in natural germanium with default settings (i.e. no tuning of production cuts or step length).

Note

Simulation and analysis scripts are available in tests/nist.