So far I finally set everything up for my simulation (at least I’m not aware of something I missed atm…) and I wonder how to verify the simulation.
The experiment is quite simple: I’m using a x-ray generator which irradiates 50x a specific dosimeter people are carrying for observation purposes. These devices provide a single so-called H_T(10) value in the end. I’m not sure about whether this is really the correct term here (actually I’ll get a Hp(10) value) but it is at least very similar to it.
Now I want to simulate this but I wonder especially about which values I have to take into account or to use to compare. E.g. I’m recording the the number of photons entering the detectors and since I know the energy each one deposits ( G4double partEdep = aStep->GetTotalEnergyDeposit(); ?) I can sum these values up and then I’d have the deposited total energy. But this is, obviously, very prone to the number of photons I’m producing in the first place.
when you reference to photons per second, the number of simulated events/number of photons implies a certain (virtual) time interval that this number corresponds to.
this can be aligned to whatever rate you have in real life.
yes, that is possible. maybe take a pencil and paper and do the math that you need.
and you don’t need to actually match the quantity 1:1, you can also calculate the scaling number for the first one, and scale the second accordingly. e.g. go for 1% if desired dose, or 0.1s instead of 1s, or…
… or throw N photons and see that your dose is 1/M of what you need, then you know it would be N x M photons that produce the full dose
Thanks for the input, I will consider this!
I would like to use the thread to go into details according to my specific application:
The geometry consists only of two x-ray particle sources, three layers of specific material and three dosimeters/detectors on it. The layers are only a few mm thick in total and the detectors are also only 0.5 mm thick. Around the particle sources is a thin layer of aluminum (The yellow large box does not matter, it has no material assigned to it):
As I see these very discrete values I wonder whether these are physically correct? That the deposited mean energy is very similar makes at least sense to me, the amount itself I don’t know and I don’t know how to estimate it (from theory or reality…) but from my,… let’s say in this context naive knowledge I’d expect a continuous spectrum of deposited energy, or?
Yep, as far as I understand it correctly, the above plot shows the average deposited energy per particle, right?
When I sum up the energies from the TTrees it is much more (strongly dependent on how many photons I generate, as expected).
But the deposited energy per particle should be continuous, though, or?
if the plot was made with the code from your other thread that i linked to
, then no. it then shows the total energy of the incident particles, and with the first step into the SD, the track is killed. The plot shows the spectrum of your source (which also explains why the subplots are all so similar: it is just a histogram of your source energy distribution).
The mean values are quite identical as when I use a detector with a thickness of 0.5 mm.
The total energy of the particles GetTotalEnergy() (respectively if I understand correctly, the remaining energy?) looks as: