## 5 Conclusions  
Markus chamber and Bragg peak chamber were employed to determine DAP and calibrate beam monitor in terms of number of protons per MU. Both methods illustrate consistent results. A preliminary uncertainty analysis is presented for DAP measurement. Correction factors should be carefully calculated when using the direct determination of DAP. Single-spot method with the Bragg peak chamber can be employed as an alternative for DAP determination.  
Conceptualization, L.Z. and X.W.; methodology, L.Z. and X.W.; software, L.Z.; validation, X.X. and X.W.; formal analysis, L.Z.; investigation, L.Z.; resources, M.Z.; data curation, M.Z.; writing--original draft preparation, L.Z.; writing--review and editing, L.Z. and X.W.; visualization, L.Z.; supervision, X.X.; project administration, X.W.; funding acquisition, X.W. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Energy (MeV)**} & \multicolumn{3}{c}{**Number of Protons per MU**} & \multicolumn{3}{c}{**Standard Deviation**} & \multirow{2}{*}{**Percent Difference**} \\ \cline{2-2} \cline{5-6}  & **MC** & **BPC** & **Mean Value** & **MC** & **BPC** & \\ \hline
235 & \(1.10\times 10^{9}\) & \(1.10\times 10^{9}\) & \(1.10\times 10^{9}\) & \(2.59\times 10^{6}\) & \(4.24\times 10^{5}\) & \(-0.73\%\) \\
212.6 & \(1.03\times 10^{9}\) & \(1.02\times 10^{9}\) & \(1.02\times 10^{9}\) & \(3.96\times 10^{6}\) & \(3.77\times 10^{6}\) & \(-0.98\%\) \\
185.8 & \(9.35\times 10^{8}\) & \(9.29\times 10^{8}\) & \(9.32\times 10^{8}\) & \(2.30\times 10^{6}\) & \(2.52\times 10^{6}\) & \(-0.65\%\) \\
179.9 & \(9.10\times 10^{8}\) & \(9.06\times 10^{8}\) & \(9.08\times 10^{8}\) & \(3.90\times 10^{6}\) & \(1.35\times 10^{6}\) & \(-0.44\%\) \\
174.2 & \(8.91\times 10^{8}\) & \(8.82\times 10^{8}\) & \(8.87\times 10^{8}\) & \(6.09\times 10^{6}\) & \(7.85\times 10^{5}\) & \(-1.02\%\) \\
166.6 & \(8.61\times 10^{8}\) & \(8.57\times 10^{8}\) & \(8.59\times 10^{8}\) & \(3.22\times 10^{6}\) & \(4.38\times 10^{5}\) & \(-0.47\%\) \\
148.7 & \(7.89\times 10^{8}\) & \(7.85\times 10^{8}\) & \(7.87\times 10^{8}\) & \(3.78\times 10^{6}\) & \(4.00\times 10^{5}\) & \(-0.51\%\) \\
140.1 & \(7.58\times 10^{8}\) & \(7.52\times 10^{8}\) & \(7.55\times 10^{8}\) & \(3.20\times 10^{6}\) & \(1.08\times 10^{6}\) & \(-0.80\%\) \\
86.8 & \(5.20\times 10^{8}\) & \(5.16\times 10^{8}\) & \(5.18\times 10^{8}\) & \(5.93\times 10^{6}\) & \(3.48\times 10^{5}\) & \(-0.78\%\) \\
83.8 & \(5.12\times 10^{8}\) & \(4.99\times 10^{8}\) & \(5.05\times 10^{8}\) & \(1.15\times 10^{7}\) & \(1.73\times 10^{5}\) & \(-2.61\%\) \\
70.6 & \(4.28\times 10^{8}\) & \(4.29\times 10^{8}\) & \(4.28\times 10^{8}\) & \(3.12\times 10^{6}\) & \(7.21\times 10^{5}\) & \(0.23\%\) \\ \hline \end{tabular}
\end{table}
Table 2: Number of protons per MU and the standard deviation derived from Markus chamber and Bragg peak chamber measurements.  
**Funding:** This research was funded the National Key Research and Development Program (No.2016 YFC0105406) and National Natural Science Foundation of China (No.61571262, No.11575095, No.61171115).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors appreciate [PERSON] of Shanghai Advanced Proton facility for the experiments and [PERSON] for the grammar correction.  
**Conflicts of Interest:** The authors declare no conflict of interest.