List of switches

The flexibility of AM\(^3\) is implemented by switches which allow to turn on/off processes and optimizations: Interaction channels can be switched on and off individually by means of binary switches. For example, running

am3.set_process_electron_compton_cooling(1)

switches on electron and positron energy losses due to inverse Compton scattering. On the contrary, setting a process to 0 makes the solver skip the calculation of that process. This can be used for testing purposes, or to improve the code performance in cases where it is known that a given process is not relevant. The switches mainly use the naming patterns for particles and interactions introduced in the Code Overview.

The readout is symmetric to the set functions. E.g., to retrieve the setting for the electron compton cooling, use

am3.get_process_electron_compton_cooling()

Main switches for energy loss and secondary emission

Process	Switch	Value	Default
Synchrotron	am3.set_process_<particle>_syn()	0 (off) / 1 (on)	1 for electron and proton, 0 for pion and muon
Inverse Compton	am3.set_process_<particle>_compton()	0 (off) / 1 (on)	1 for electron and proton, 0 for pion and muon
Photon-photon pair production	am3.set_process_annihilation()	0 (off) / 1 (on)	1
Bethe-Heitler pair production	am3.set_process_bethe_heitler()	0 (off) / 1 (on)	1
Photopion production	am3.set_process_photopion()	0 (off)/1 (on)	1
Proton-proton interactions	am3.set_process_pp()	0 (off) / 1 (on)	1

For every master switch listed above, there is an additional _cooling switch for energy losses and a _emission switch for photon emission.

For example, by running

am3.set_process_muon_syn_cooling(1)
am3.set_process_muon_syn_cooling_cooling(1)
am3.set_process_muon_syn_cooling_emission(0)

we tell the solver to account for muon energy losses due to synchrotron, but to ignore the resulting photon emission. All _cooling and _emission switches have a default value of 1.
Note: The photo-pion induced loss term for photons deviates from the above pattern and can be switched to 0 (off)/1 (on) using am3.set_process_photopion_photon_loss

Switches for other physics processes

A range of additional processes may be included using the following:

Process	Switch	Values	Default
Phsyical escape	am3.set_process_escape()	0 (off) / 1 (on)	1
Volume expansion	am3.set_process_expansion()	0 (off) / 1 (on)	1
Adiabatic cooling of charged particles	am3.set_process_adiabatic_cooling()	0 (off) / 1 (on)	1
Pion decay	am3.set_process_pion_decay()	0 (off) / 1 (on)	1
Muon decay	am3.set_process_muon_decay()	0 (off) / 1 (on)	1
Synchrotron self-absorption	am3.set_process_ssa()	0 (off) / 1 (on)	1
Include quantum synchrotron regime	am3.set_process_quantum_syn()	0 (off) / 1 (on)	0

Notes: (1) The escape rate depends on escape timescale and escape fractions, while both expansion and adiabatic cooling rate depend on the expansion timescale. (2) Pion and muon decay are necessary to estimate neutrino emission. (3) Quantum synchrotron (relevant in case of strong magnetic fields) is only included for electrons.

For proton-proton interactions, additional switches to select the interaction description and the transition to the \(\delta\)-function description are available:

• am3.set_pp_transition_energy_to_delta_approx() sets the proton energy below which the delta approximation is used in eV. Default value is 100 GeV.

• am3.set_pp_model_charged_pions() sets the model underlying charged pions from pp interactions. Pass 0 (SIBYLL)/ 1 (QGSJET). Default value is 0.

• am3.set_pp_model_neutral_pions() sets the model underlying neutral pions from pp interactions. Pass 0 (SIBYLL)/ 1 (QGSJET)/ 2 (Geant4)/ 3 (Pythia8). Default value is 0.

• set_process_pp_emission_pi0_into_cascade() is used to specify the treatment of neutral pion decay. Pass 0 to use the Kelner+ (2006) treatment combined with the decay as photo-pion produced neutral pions, or 1 to use the treatment of Kafexhiu et al 2014. Default is 0.

Switches for performance optimization

Switch	Value	Default	Description
Inverse Compton emission
am3.set_optimize_compton_emission_emin()	Energy	\(10^{-3}\) eV	Min. energy point photon emission
am3.set_optimize_compton_target_emax()	Energy	\(10^{6}\) eV	Max. Grid energy target photon field
am3.set_optimize_compton_target_grid()	0 (off)/ 1 (on)	1	Use every second bin of target photon field
am3.set_optimize_compton_emission_grid()	0 (off)/ 1 (on)	1	Calculate every second bin of emitted photon field (interpolate inbetween)
Photon-photon pair production
am3.set_optimize_annihilation_pair_emission()	0 (off)/ 1 (on)	0	Use 7-bin approximation for emitted pairs
Bethe-Heitler pair production
am3.set_optimize_bethe_heitler_outgoing_pairs_grid()	0 (off)/ 1 (on)	1	Skip every second energy bin of emitted pairs
am3.set_optimize_bethe_heitler_incoming_protons_min()	Energy	1 TeV	Min. energy target protons
am3.set_optimize_bethe_heitler_target_photon_max()	Energy	\(\sim\) 511 keV	Max. energy target photon field
Photopion production
am3.set_optimize_photopion_target_photon_grid()	0 (off)/ 1 (on)	1	Skip every 2nd energy bin of target photons
am3.set_optimize_photopion_target_photon_max()	Energy	\(\sim\) 511 keV	Max. energy target photon field

If optimizers are switched on it is advised to test the results for accuracy.

Other switches

Process	Switch	Value	Default
Trace photon components	am3.set_process_parse_sed()	0 (off) / 1 (on)	0
Turn off all hadronic processes	am3.set_process_hadronic()	0 (off) / 1 (on)	1
Electrons and positrons separately (0) or together (1)	am3.set_process_merge_positrons_into_electrons	0 (off) / 1 (on)	0
Calculate maximal energies for template injection	am3.set_estimate_max_energies()	0 (off) / 1 (on)	0