High Cross-Section Values in Indium Reactions

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Dear FLUKA experts
I am reaching out to seek your guidance regarding an issue I am experiencing while using FLUKA to calculate cross-sections for indium reactions.

We are currently simulating a simple geometry setup consisting of a blackhole, void, and a target with the beam positioned at x = -0.1cm, along with the inclusion of Coalescence and Photonuclear models. Our objective is to calculate the cross-sections for proton-, deuteron-, and alpha-induced reactions on indium isotopes.

However, we have observed some discrepancies in our results:

1.Natural Indium Reaction: For the natural proton-induced reaction:

natIn(p,x)110Sn

The cross-sections are consistently higher than experimental data over the entire energy range. Could you please advise on how we can accurately calculate the cross-sections for natural indium and potentially correct these discrepancies?
Capture (5)(1)
natIn(p,x)110Sn(1).inp (5.1 KB)

  1. Proton-Induced Reactions: For reactions such as:

    111Cd(p,2n)110mIn
    112Cd(p,n)109In
    111Cd(p,3n)109In

The calculated cross-sections are significantly higher, particularly around the peak regions. Additionally, the excitation functions are shifted towards higher energy values compared to reported data.

  1. Deuteron-Induced Reaction: For the reaction:

    110Cd(d,2n)110mIn

The entire excitation function curve appears to be shifted towards the right (i.e., higher energies) relative to expected results.
Capture (3)(1)
110Cd(d,2n)110mIn(1).inp (4.7 KB)

  1. Alpha-Induced Reactions: For reactions such as:

    107Ag(a,n)110mIn
    107Ag(a,2n)109In

    The cross-sections show reasonable agreement with experimental data but only either below or above the peak value, not consistently throughout the entire range.

We have cross-verified our simulation parameters and model configurations but still observe these inconsistencies, especially when compared to the reported EXFOR data.

Could you kindly provide insights on how we might adjust our simulation settings or models to achieve better alignment with experimental cross-sections, especially in the cases where the peaks are shifted or where the calculated values are too high or the tail region where other theoretical nuclear model codes are in agreement with the data but not with FLUKA.

Thank you in advance for your time and support.

Best regards,

3

Dear Sajid,

There is nothing manifestly wrong with your simulation settings.

For the proton-induced partial cross sections, we indeed acknowledge a discrepancy by a factor of at most ~2.

For the deuteron-induced partial cross section, we acknowledge a smaller yet still observable discrepancy. This is arguably true even among the experimental curves themselves: the red curve (with which FLUKA is nearly compatible) appears to peak at somewhat higher deuteron energies than the blue curve.

Note that FLUKA’s models are conceived to provide a globally coherent picture across reaction channels on a broad energy range, without ad-hoc parameter tunings to enhance local agreements. This naturally comes at the expense of the occasional local discrepancy in particular channels / at particular energies. Indeed, FLUKA is not meant as a framework where one can plug in cross sections at will (this could locally cure one excitation curve or another, but might compromise other general performances).

Still, we take good note of the discrepancies you report for future versions of the code.

Cesc