First of all I would like to thanks @Rohit Yadav for introducing this important topic and problem.
It is amazing that FLUKA can give results like this with peak energies and Intensities accuracy with this low order.
1- l have a question, is it possible and how to generate the results in Gaussian form, not in a summing form as now , this is needed to show the compare with the experimental measuring spectrum shown in the following figure.
2- ِAnother Inquiry regarding, the background of the resulting calculation its models and sequences… Where one can find detailed explanation to read and take it as a reference through publishing activities.
The spreading of the peaks is intrinsic in the experimental detection of the particles of interest, which come with its own resolution. To replicate such spectrum, your model should be as close as possible to the actual experimental set up.
The USRBDX card can adjusted to give particle spectra and for photon too. This result of FLUKA are based on some models and mathematics and data base too. I would like to read about this and get familiar about the sequence of this in detail. Are there detailed writings on this?
Radioactive decays are simulated in a delayed fashion at the end of the prompt history (if the user requests it through RADDECAY). Products from the radioactive decay chain are calculated in line with the decay database, which is built from RIPL (IAEA - see decay records) complemented by ENSDF for the electron capture rate.
If you are interested in knowing more about those two data sources, you can very simply download RIPL from their website: It is an ASCII file with a reasonably easy to read format. ENSDF is trickier to download, spread in 300+ ASCII files and following a quite convoluted format. We advise you to use the NNDC web interface allowing you to browse the ENSDF database for any requested nuclide/decay.
Emitted particles are then transported and subject to respective interactions, as summarized in the didactic material of our courses.
Many many thanks for this detail answer. It is amazing By FLUKA one can get a radioactive decay spectrum without either B.g and/or sum peak noise (flat spectrum). This facility can be considered as unique an advanced feature which can help in a wide simulation applications.