\section{Comparison of neutron data libraries}
This section investigates the differences emerging when changing the neutron data libraries. All other parameters of the depletion model  are kept identical, including the high-energy neuron data above 20 MeV (taken from TENDL), the proton data and the proton spallation model. The libraries used are those introduced in Sect. \ref{nuclear_data}.
The outcomes are shown in term of deviation with respect to the concentrations obtained with the reference library, that is, JEFF-3.1.2. The relative deviations are reported in Fig. \ref{lib_sens}.
\begin{figure}[h]
\centering
\includegraphics[width=0.95\textwidth]{images/plots/LBE/lib_sens.png}
\caption{EoI concentrations of relevant nuclides obtained with different neutron NDL. The outcomes are compared to the reference library: JEFF-3.1.2}\label{lib_sens}
\end{figure}

Excellent agreement is shown for $^{208}$Po and $^{209}$Po. This behaviour was expected since most of the production in the spallation target assembly comes from proton reactions.

$^{16}$N is produced by $(n,\alpha)$ reaction in $^{19}$F. The corresponding cross section has a higher threshold and it is slightly lower in the range 10-20 MeV in JENDL-4.0u.
This partially explains the 5\% underestimation.

$^3$H is produced both from neutron and proton induced reactions in lead and bismuth. Compared to JEFF-3.1.2, all other nuclear data libraries result in a lower prediction by maximum 6\%.\\

The mercury isotopes show a common trend.  The production of $^{194}$Hg, $^{195}$Hg and $^{197}$Hg is overestimated by JEFF-3.3 and ENDF/B-VIII.0 and underestimated by JENDL-4.0u, with respect to JEFF-3.1.2.
% Part of their production scheme is bond to $^{196}$Hg, which can explain a certain amount of the deviation even if the cross sections in the range from 1~keV to 20~MeV are same in all considered nuclear data libraries.
% The difference could lie on the different evaluations at high energy.
Part of their production comes from $^{196}$Hg and a different buildup of this nuclide can be the reason of the discrepancies.  
The deviation of $^{203}$Hg is the largest among the mercury isotopes.
Completely different estimations are produced when using JEFF-3.3 and JENDL-4.0u, respectively overestimating and underestimating by 55\% the concentration of the nuclide.
The underestimation by JENDL-4.0u is common to all Hg nuclides and it is emphasized in this case.
The overestimation by JEFF-3.3 can be partially explained looking at the different evaluation of $^{202}$Hg $(n,\gamma)$ cross section with respect to the previous version, presented in Fig. \ref{xsHg202}.
\begin{figure}[h!]
\centering
\includegraphics[width=0.85\textwidth]{images/plots/LBE/xsHg202.png}
\caption{$^{202}$Hg $(n, \gamma)$ cross section data: absolute values for JEFF-3.1.2 and JEFF-3.3.}\label{xsHg202}
\end{figure}
A resonance region appears below 0.1 MeV and a high energy tail between 5 and 20 MeV is added. The underestimation observed in JENDL-4.0u is not related of the capture cross section of  $^{202}$Hg, that shows the same evaluation in JEFF-3.1.2 and JENDL-4.0u. The discrepancy between the concentrations obtained with the two library partly comes from a different estimation of the concentration of $^{202}$Hg, whose reason was not investigated. The deviation in the concentration of $^{203}$Hg is not fully understood and therefore a deeper analysis must be performed. 
% Larger differences could interest the higher energy region.\\

The different estimation of $^{210}$Po is due to two different evaluations.
JEFF-3.1.2 is in agreement with ENDF/B-VIII.0 while JEFF-3.3 shows the same deviation of JENDL, providing an underestimation of about 44\%. 
%The difference must lie in the evaluation of $^{209}$Bi $n,\gamma$ cross section. Tab. \ref{rr_bi210_lib} shows the integrated cross sections obtained with the different nuclear data libraries to appreciate the behaviour discussed.
The problem lies in the evaluated cross sections of $^{209}$Bi and it is fully discussed in \cite{Fiorito2018Po}.
% \begin{table}[h]
%     \centering
%     \caption{Variation of $^{209}$Bi $(n,\gamma)$ reaction rate as function of the nuclear data library. Ratio respect to reference library (JEFF-3.1.2) is shown in the second line.}
% \begin{tabular}{lrrrr}

% \toprule
% &   JEFF-3.1.2 & JEFF-3.3 & ENDF/B-VIII.0 & JENDL-4.0u\\
% \midrule
% \textbf{Reaction rate  $s^{-1}$} &   4.13e-12 & 2.30e-12 & 4.01e-12 & 2.30e-12\\
% \textbf{Ratio} &   1 & 0.56 & 0.97 & 0.56\\
% \bottomrule
% \end{tabular}


%     \label{rr_bi210_lib}
% \end{table}\\