I am new to Fluka and Flair, before i only worked with c++ packages like Geant4, Pythia8. I want to compare Geant4 and Fluka for one experiment. In Geant4 i can access all secondaries data on each step. This way i can get spectrums of particles when they leave target(i simply call function to give me particle energy on the last step before it deletes). Using flair i understood how to use USRBIN. But how can i simulate perfect detector that returns value of energy, or transverse momentum of certain particle, for example muons.
In order to get the energy spectrum of any kind of particle you can use USRTRACK card what defines a detector for a track-length fluence estimator. Please, check the details about how to define the card in the manual. The information can be extracted from the produced “usrtrk_*_tab.lis” file and plotted directly in FLAIR via “USR-1D” option.
Notice that the result is given in terms of “differential distribution of fluence” (cm-2 GeV-1 per incident primary) or “track-length” (cm GeV-1 per incident primary) in case the volume of the region is not specified. Therefore, do not forget to normalize by the number of primary.
Let us know if this is what you were looking for.
Thanks for your answer! Sometimes i get lost because i am not very good at english. FLUKA: USRTRACK at this manual they say that to get fluence energy spectrum i should make some procedure. Do i understand correctly that fluence energy spectrum is number of particles passing through detecting area with certain energy?
In this case, the fluence energy spectrum refers to the particles travelling over the detector volume. Please, note that what USRTRACK provides is particle fluence in units of cm-2 GeV-1 per incident primary unit weight IF the volume of the region is given. The detector should be a region already defined in your geometry. The “procedure” mentioned in the manual (Note 1) is related to the integral value, which is already given in the sum.lis file, so you do not need to post-process the information.
In order to get the number of particles travelling through a given surface with certain energy is better to use the USRBDX card instead. You have to select the two neighboring regions that define the surface of interest and include the energy and solid angle limits. Since this card scores double differential particle distribution, the result is given per primary and per range of each variable involved (energy and solid angle).