Double Bragg Peaks

I am trying to simulate 80MeV in the Hadrontherapy application. For lower energies I only get one Bragg peak, as I should. At 70MeV I start to see a shallower Bragg peak.

Has anyone seen a problem like this before? Are there solutions to this problem?

Here is my 80MeV in orange compared to experimental data in blue.

thank you

I also encountered the similar problem before. If you are still using the existing beamline, some element of the beamline causes this. So, I circumvented this issue with commenting out the beamline and just put the source you want before the phantom. I hope it helps.

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Yes, thank you. When I don’t have any collimators in the way I have only one peak.


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I’ve seen this in a real water phantom. The reference chamber had slipped and was taking energy out of some of the beam causing a double B-P. So, some of the beam is hitting your collimators and losing energy.