Effect of Sn content on the performance of Nb3Sn superconducting radio-frequency cavities

[Display omitted] •Effect of Sn content on the performance of Nb3Sn SRF cavities was investigated.•The ratio of Nb/Sn was slightly higher than 3.•Q0 of 1.3 GHz 1-cell Nb3Sn SRF cavity reached 3.0 × 1010 (@ 4.2 K) at low RF field. Research of Nb3Sn superconducting radio-frequency (SRF) cavities was carried out at the Institute of High Energy Physics Chinese Academy of Sciences (IHEP), in order to improve the intrinsic quality factor (Q0) and accelerating gradient (Eacc). Various recipes of coating were attempted at SRF cavities and samples made of Nb, which resulted in different Sn content. It was found that the Sn content, namely the ratio of Nb/Sn, had great influences on the performance of Nb3Sn SRF cavities. When the ratio of Nb/Sn was slightly higher than 3, the Nb3Sn SRF cavities showed the best performance during the vertical test. Q0 of 1.3 GHz 1-cell Nb3Sn SRF cavity (the ratio of Nb/Sn ≈ 3.16) reached 3.0 × 1010 (@ 4.2 K) and 1.0 × 1011 (@ 2.0 K) at low RF field. This study could provide insights on the effects of Sn content on the performance of Nb3Sn SRF cavities, which be referenced by the SRF community.