# A Study of Stray Neutron Field Measurements for the Neutron Scattering Instruments at CSNS
## 4 Conclusions  
The stray neutron field inside the neutron scattering instruments at CSNS is characterized by wide energy distribution, spanning from the thermal range to hundreds of MeV. The neutron spectra vary with the locations, and the fluence rate could change by several orders of magnitude as well. In this paper, a stray neutron measurement technique using an ERBSS and a commercial NADED was proposed. To verify the reliability of the method, stray neutron spectra, integral fluence rates, and H*(10) values were measured at the entrance (location A) and exit (location B) of the labyrinth of the BL06 beam line at \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Quality**} & \multirow{2}{*}{**Energy Range**} & \multicolumn{2}{c}{**Decation A (no PE)**} & \multicolumn{2}{c}{**Simulation**} & \multicolumn{2}{c}{**Experiment**} & \multicolumn{2}{c}{**Simulation**} \\ \cline{3-8}  & & \multicolumn{2}{c}{**Location A (no PE)**} & & \multicolumn{2}{c}{**Location B (no PE)**} \\ \hline \multirow{8}{*}{
\begin{tabular}{c} Integral \\ fluence/proportion (\%) \\ \end{tabular} } & \(<\)1 eV & \(3.8\times 10^{-12}/6.31\) & \(5.6\times 10^{-12}/57.2\) & \(4.2\times 10^{-14}/80.5\) & \(4.0\times 10^{-14}/85.1\) \\  & 1 eV-1 keV & \(1.0\times 10^{-12}/17.1\) & \(2.5\times 10^{-12}/25.8\) & \(7.1\times 10^{-15}/13.6\) & \(5.2\times 10^{-15}/11.0\) \\  & 1 keV-1 MeV & \(1.0\times 10^{-12}/17.1\) & \(1.6\times 10^{-12}/16.6\) & \(3.0\times 10^{-15}/5.8\) & \(2.0\times 10^{-15}/4.2\) \\  & \(>\)1 MeV & \(1.4\times 10^{-15}/2.4\) & \(5.6\times 10^{-14}/0.6\) & \(5.3\times 10^{-17}/0.1\) & \(2.3\times 10^{-17}/0.05\) \\  & Total & \(6.1\times 10^{-12}\) & \(9.8\times 10^{-12}\) & \(5.2\times 10^{-14}\) & \(4.7\times 10^{-14}\) \\ \cline{2-8}  & \multicolumn{2}{c}{**Location B + PE (1 cm)**} & \multicolumn{2}{c}{**Location B + PE (2 cm)**} \\ \cline{2-8}  & \(<\)1 eV & \(1.9\times 10^{-13}/84.7\) & \(1.8\times 10^{-13}/90.7\) & \(2.1\times 10^{-13}/82.8\) & \(2.1\times 10^{-13}/90.1\) \\  & 1 eV-1 keV & \(2.6\times 10^{-14}/11.9\) & \(1.6\times 10^{-14}/8.1\) & \(2.8\times 10^{-14}/11.1\) & \(1.6\times 10^{-14}/6.9\) \\  & 1 keV-1 MeV & \(1.1\times 10^{-14}/5.0\) & \(4.8\times 10^{-15}/2.4\) & \(1.2\times 10^{-14}/4.7\) & \(5.2\times 10^{-15}/2.3\) \\  & \(>\)1 MeV & \(1.8\times 10^{-16}/0.1\) & \(5.5\times 10^{-17}/0.03\) & \(2.0\times 10^{-16}/0.1\) & \(7.2\times 10^{-17}/0.03\) \\  & Total & \(2.2\times 10^{-13}\) & \(2.0\times 10^{-13}\) & \(2.5\times 10^{-13}\) & \(2.3\times 10^{-13}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Integral neutron fluence rate (n/cm\({}^{2}\)/proton) and their percentages in different energy ranges. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Quality**} & \multirow{2}{*}{**Energy Range**} & \multicolumn{2}{c}{**Location A (no PE)**} & \multicolumn{2}{c}{**Location B (no PE)**} & \multicolumn{2}{c}{**Location B + PE (1 cm)**} & \multicolumn{2}{c}{**Location B + PE (2 cm)**} \\ \cline{3-8}  & & **Sim.** & **Exp.** & **Sim.** & **Exp.** & **Sim.** & **Exp.** & **Sim.** & **Exp.** \\ \hline \multirow{8}{*}{\
\begin{tabular}{c} H\({}^{\star}\)(10) \\ 1 keV-1 MeV \\ 1 keV-1 MeV \\ \end{tabular} } & \(<\)1 eV & 70.7 & 52.4 & 0.50 & 0.57 & 2.3 & 2.5 & 2.6 & 2.8 \\  & 1 keV-1 MeV & 41.2 & 15.1 & 0.08 & 0.10 & 0.2 & 0.4 & 0.2 & 0.4 \\  & 1 keV-1 MeV & 84.2 & 96.0 & 0.08 & 0.15 & 0.2 & 0.5 & 0.2 & 0.6 \\  & \(>\)1 MeV & 23.5 & 68.3 & 0.01 & 0.02 & 0.02 & 0.08 & 0.03 & 0.1 \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Total \\ \end{tabular} } & MCNPX & 219.6 & & & & & & & 3.05 \\  & ERBSS & & \(231.8\pm 34.8\) & & \(0.85\pm 0.13\) & & \(3.53\pm 0.53\) & & \(3.89\pm 0.58\) \\  & NADED & & \(279.0\pm 55.8\) & & \(1.10\pm 0.22\) & & \(3.56\pm 0.72\) & & \(4.20\pm 0.84\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: H*(10) values for different energy ranges obtained from simulated and experimental spectra from ERBSS, and total ambient dose equivalent rate (\(\mu\)Sv/h @ 80 kW) from simulations and measurements. CSNS.