[Gate-users] Neutron fluence below 1 eV for proton beams

[Botnariuc, Daniela]

Dear GATE experts,

I am trying to score the fluence of secondary neutrons in a proton therapy plan and I am using the following code to do so (using the QGSP_BIC_HP physics list):

/gate/actor/addActor  EnergySpectrumActor               espect
/gate/actor/espect/attachTo                                   patient
/gate/actor/espect/addFilter particleFilter
/gate/actor/espect/particleFilter/addParticle neutron
/gate/actor/espect/energySpectrum/setEmin               0.001 eV
/gate/actor/espect/energySpectrum/setEmax               250 MeV
/gate/actor/espect/energySpectrum/setNumberOfBins      500
/gate/actor/espect/setLogBinWidth  true
/gate/actor/espect/enableNbPartSpectrum   true
/gate/actor/espect/saveAsText                               true
/gate/actor/espect/save                                 output/espectrum.root

In the output file, the minimum energy of the spectrum is however 1 eV (10-^6 MeV) and I was wondering if there is a way to score thermal neutrons of energies down to around 0.02 eV. My suspicion is that I need to adjust the physics list or threshold parameters - is anyone able to help me with this?

Thank you in advance!

Kind regards,
Daniela Botnariuc
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