Chen, S. Chen, M. Feng, L.W. Hao, J.K. Lin, L. Liu, K.X. Quan, S.W. Wang, F. Zhu, F. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-TUPO049 English 442-444 TUPO049 cavity vacuum accelerating-gradient niobium superconducting-cavity Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-TUPO049 http://jacow.org/linac2018/papers/tupo049.pdf Nitrogen doping studies were carried out at Peking University. A series of 1.3 GHz single cell cavities fabricated with OTIC large grain niobium material were annealed and doped in the furnace of Peking University, and electropolished by a simple EP device. Light doping recipe and heavy doping recipe are both adopted for comparison. The results and analysis are presented in this paper.