Radiative processes included when using the PAIRBREM card

Physics, Transport and Magnetic Fields
3

Dear Sergio,

Thanks for your question.

Concerning Bremsstrahlung by muon and charged-hadron projectiles (p), in FLUKA you’ll get a photon energy spectrum following

\frac{\text{d}\sigma}{\text{d}\nu} \sim \frac{1}{\nu}\left[ 1 - \nu + \frac{3}{4} \nu^2\right],\qquad \nu = \frac{E_\gamma}{E_p},

where E_\gamma and E_p are the energies of the emitted photon and the kinetic energy of the projectile, respectively.

That should essentially correspond to Nuclear Bremsstrahlung in the list above, with a complementary screening/polarization term applied to it. Needless to say, if a delta ray (secondary electron) is produced in another interaction, it too will emit Bremsstrahlung (depending on EMFCUT settings) as per the postscript below.

It’s worth pointing out that muons and charged-hadron projectiles (p) of less than

E_\text{min}=m_pc^2\sqrt{\frac{2000}{Z_t}}\ \text{ GeV},

in a material with atomic number Z_t will not emit Bremsstrahlung in FLUKA in view of its low likelihood compared to e.g. ionization or even nuclear reaction processes. For protons in H, Al, and U, E_\textrm{min} is about 41.9 GeV, 11.16 GeV, and 4.4 GeV, respectively.

Cheers,

Cesc

PS: for electron (and positrons) FLUKA will give you electron-nucleus and electron-electron Bremsstrahlung.