I hope you are all well. I am trying to restrict the energy scored using a couple of EVENTBIN cards to score only the energy deposited due to the interactions of the primary particles (which would be protons) with the atomic electrons. I need to use the COMSCW.f subroutine for this matter because I would like to multiply my results by some factor (for example the GETLET function). Is there any way to impose this restriction?
Looking at the MGDRAW.f subroutine, I planned to use the information in “Emfsco” but I am not sure if that information is available in the COMSCW.f subroutine by default or how it can be included. I wrote a very rudimentary pseudo COMSCW.f subroutine which would outline what I need. Please find it attached.
Thank you very much for your reply! I think I posed my question wrongly. My focus was intended to be on how to restrict the interactions, not the particles (although I will certainly need to do that as well so thank you for the LTRACK instructions!). I would like to store the energy deposited due to only electronic interactions.
This means that you are interested in ionization losses, which in condensed history codes like FLUKA are not described by distinct interactions with single electrons (this would imply in practical cases an infinite tracking time), rather by continuous energy deposition along the primary charged particle track. Therefore, what @dprelipc suggested was exactly meant to filter energy deposition events of this kind, associated to the primary proton transport (they are also accessible in the top part of the mgdraw.f user routine, opposite to point-like energy deposition events accessible in the ENTRY ENDRAW of mgdraw.f).
Nevertheless, one has to keep in mind that secondary electrons are explicitly generated above the delta ray threshold and deposit energy on their own, in the course of their independent transport.
Thank you very much for your reply and for the clarification! Does the continuous energy deposition consider both electronic and hadronic energy depositions (for the case of heavier ions for examples)? And if so, is there anyway to somehow separate them to consider only the electronic part?
Not sure I understand what you mean with the hadronic part. In real life, all energy deposition shall be eventually attributed to electrons. In the simulation picture, a hadron (proton or heavy ion) undergoing continuous ionization deposits energy that is attributed to itself. It’s also subject to discrete events, such as delta ray generation or nuclear reactions, which produce secondary particles that are then tracked independently and deposit energy on their own. If you refer to non-ionizing energy losses (NIEL), these are included in the continuous energy deposition along the step, but can be scored separately by means of the dedicated NIEL-DEP generalized particle.
Thank you once again for your reply. To see if I understood correctly, the NIEL is included in the continuous energy deposition and can be scored separately, could the continuous energy deposition attributed to ionization caused by the primaries be scored by itself then?
I guess you could score ENERGY and NIEL-DEP separately for the same binning and then subtract one from the other, but I do not think that would work for my case.
I think that my better asked question would be, is it possible to score only the continuous energy deposition/loss of primaries due to ionization with a single scoring card possibly using a fluscw.f or comscw.f subroutine?
Dear Daniel, practically speaking, electronic stopping power (ionization) coincides with the total stopping power (ionization + NIEL) in most cases, since the nuclear stopping power (NIEL) becomes comparable to the electronic one only at very low energies (for high Z ions, whose NIEL fraction is larger, this happens anyway only below 1 MeV/n). Thereby, while separate NIEL scoring may be of interest (e.g., in relation to Displacements Per Atom assessment, which can be directly obtained by means of DPA-SCO), a separate ionization scoring is not really justified (practically coinciding with the total).
I see, thank you for your reply. We are interested in the low energy regime, and I wanted to see the differences we would obtain by considering ionization losses alone.
Thank you for your reply and your help! Just to double check, then, in order to score the energy deposited due to ionization alone, my COMSCW factor should read:
COMSCW = (ONEONE-TKNIEL)
One further question, although maybe it should be posted in a different topic, is it possible to add the energy transferred to delta rays at the comscw.f level without using the DELTARAY card? For example. I would be looking for something like “tkniel” but for this case, so that:
COMSCW = (ONEONE-TKNIEL+"TKDELTARAY")
I am aware that you can set DELTARAY(WHAT(1))<0 in order to do this, but, I would like to avoid this if possible in order to score different cases of delta ray production threshold in the same simulation.
The trackr.inc documentation of TKNIEL is misleading: it appears it is not the fraction but the actual energy deposition going into NIEL. Shall be amended. Considering this, and following along the lines of the replies above, since COMSCW is the multiplicative factor to be applied to the energy deposition (given in parameter RULL as you can see in the subroutine header), you’d have to attempt something a la
COMSCW=ONEONE-TKNIEL/RULL
in order to subtract any contribution from nuclear stopping (typically small unless at very low energies) and consider just ionization losses.
In order to obtain non-zero values of TKNIEL, you’ll need to add somewhere in your input a USRBIN to score NIEL-DEP, DPA-SCO, RES-NIEL, or DPA-NRES.
Note that proton collisions transferring an energy to target electrons larger than the delta-ray production threshold are sampled (and the resulting electron is tracked) explicitly. The explicitly tracked electron is no longer linked to the primary proton, so you cannot intercept it in the same call to COMSCW.
You can, however, request a very high delta ray production threshold (see the EMFCUT card): the delta rays are then not emitted and the energy that they would otherwise carry away is instead apportioned along the proton step. Under these circumstances, the approach to intercept
all proton ionization losses via COMSCW should be effective (though the spatial energy deposition spectrum will necessary be compressed since now no e- are sampled to potentially deposit energy elsewhere → up to you to decide if this matters or not with respect to the size of your geometry/scoring). Instead, when the delta-ray production threshold is low, what you get in the RULL above are the restricted (i.e. sub-threshold) ionization losses.
Thank you very much for your reply! One very last question,
Can this USRBIN card have any characteristics, i.e. any type of geometry binning, any number of bins, any location of such bins, etc…? I assume that at least the NIEL USRBIN card should cover the same volume as the other USRBIN cards I am considering for the COMSCW routine.
I believe the sufficient bit is to have a USRBIN requesting any of the aforementioned quantities to trigger the separate evaluation of NIEL-related quantities (the grid shouldn’t matter).