I am looking at the survival biasing coding in the physics.cpp source, function void sample_neutron_reaction(Particle& p).
Russian roulette is applied at the end of the function. If the particle is killed, then p.alive() is /false/.
My question is this: should this event be scored in one of the internal tallies, such as TallyEvent::KILLED ? Or is it sufficient that the reduced particle weight from implicit capture is accounted for in the absorption() function, where p.keff_tally_absorption() is incremented.