A missing part of the Total Energy Deposited

Getting Started
1

Hi,

In the attached document, I have collected the energy data of a run of 10 e- with an energy of 10 MeV on a material plate.
I noticed that the total energy deposited by the particle is is not always equal to the energy variation between the two points of a step.

What is the reason for this ?

Kinds,
Younes

eboundary.txt (3.1 KB)

The conditions on this data are:
{
Track Parent ID == 0
AND
PreStepPoint == PlateVolume
AND
( PostStepPoint == fGeomBoundary OR PostStepPoint == PlateVolume )}

2

If you have a SteppingAction, take a look at G4Step::GetNumberOfSecondariesInCurrentStep(). If secondaries are created (like ionizaton electrons, decays, whatever), their energy is not included in GetTotalEnergyDeposit().

3

I made a call on the secondary numbers of the primaries from my SteppingAction class, and clearly the missing energies were transferred to the descendants. Thank you.

However, I expected to have 13 events, since the total number of secondaries for the primaries was 13, while I get 22 events as a results for PID==1. (please see attached)

Are these 9 particles considered secondaries? Where do they get their energies from?

Kinds,
Younes

Attached the results for PID==1,2… all with the creator process name and the number of secondaries.

eboundary_.txt (7.2 KB)

4

You’re looking at individual steps, not separate tracks.

5

One more question:
Why does the electron created by ionization in line 30 have the same Parent ID and Track ID as the gamma created by Bremsstrahlung in line 32 ? (please see eboundary_.txt above)

Kinds,
Younes

6

Are these tracks from one single event, or have you jumbled up multiple events together? If you use /run/beamOn with a number greater than 1, I would encourage you to include the event number in your printout.

7

Things are becoming clearer to me now, thanks to you!

However, I don’t understand the transition that event 7 did as one example.

It entered the simulation with 10 MeV, It lost 2.6072265 MeV, of which 0.0340097 MeV yielded to its descendant (by Bremsstrahlung).

Where has the remaining 2.5732169 MeV of energy gone? Is it lost by excitation of the medium?

Regards,
Younes

(please see EID7, lines 44-46 : eboundary__.txt (7.4 KB) )

8

I found the answer to my last question in this comment.

I quote it here for the benefit of future readers: energy deposition at a step is the sum of ionisation energy loss, which includes energy transfer for atoms below production threshold of secondary particles: delta-electrons, bremsstrahlung gamma, low energy nuclear recoil after elastic scattering.

Cheers,
Younes

9

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