Muon Detection and Direction Reconstruction with the Upgraded 1-ton Water Cherenkov Prototype Detector at CJPL-I

@misc{wang2026muon,
  title = {{Muon Detection and Direction Reconstruction with the Upgraded 1-ton Water Cherenkov Prototype Detector at CJPL-I}},
  author = {Yapeng Wang and Yuzi Yang and Shaomin Chen and Wei Dou and Haoyang Fu and Guanghua Gong and Lei Guo and Ziyi Guo and XiangPan Ji and Jianmin Li and Jinjing Li and Bo Liang and Ye Liang and Ling Liu and Qian Liu and Zhiyi Liu and Wentai Luo and Ming Qi and Wenhui Shao and Haozhe Sun and Jian Tang and Yuyi Wang and Zhe Wang and Changxu Wei and Jun Weng and Yiyang Wu and Benda Xu and Chuang Xu and Tong Xu and Tao Xue and Haoyan Yang and Aiqiang Zhang and Bin Zhang and Xinshun Zhang and Yang Zhang and Zhicai Zhang and Lin Zhao and Yangheng Zheng},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.35135},
  eprint = {2609.35135},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.35135},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Muon Detection and Direction Reconstruction with the Upgraded 1-ton Water Cherenkov Prototype Detector at CJPL-I
AU  - Yapeng Wang
AU  - Yuzi Yang
AU  - Shaomin Chen
AU  - Wei Dou
AU  - Haoyang Fu
AU  - Guanghua Gong
AU  - Lei Guo
AU  - Ziyi Guo
AU  - XiangPan Ji
AU  - Jianmin Li
AU  - Jinjing Li
AU  - Bo Liang
AU  - Ye Liang
AU  - Ling Liu
AU  - Qian Liu
AU  - Zhiyi Liu
AU  - Wentai Luo
AU  - Ming Qi
AU  - Wenhui Shao
AU  - Haozhe Sun
AU  - Jian Tang
AU  - Yuyi Wang
AU  - Zhe Wang
AU  - Changxu Wei
AU  - Jun Weng
AU  - Yiyang Wu
AU  - Benda Xu
AU  - Chuang Xu
AU  - Tong Xu
AU  - Tao Xue
AU  - Haoyan Yang
AU  - Aiqiang Zhang
AU  - Bin Zhang
AU  - Xinshun Zhang
AU  - Yang Zhang
AU  - Zhicai Zhang
AU  - Lin Zhao
AU  - Yangheng Zheng
PY  - 2026
DA  - 2026/09/28
PB  - arXiv
DO  - 10.48550/arxiv.2609.35135
UR  - https://arxiv.org/abs/2609.35135
AB  - The 1-ton prototype detector for Jinping neutrino experiment (JNE-1ton) has completed its hardware upgrade and has been successfully operated in both water and liquid-scintillator modes at CJPL-I, which is situated under a 2400-m rock overburden. During the upgrade, the detector's mechanical support structure and PMT layout were redesigned. The original Hamamatsu PMTs were replaced with 8-inch MCP-PMTs from North Night Vision, increasing the PMT count from 30 to 60. The detector was then operated in water mode for 85 days (Water-I) and 79 days (Water-II). From the accumulated water-mode data, we derive a muon detection efficiency (Water-II) that is approximately 59% higher than that of the pre-upgrade liquid scintillator detector. The measured muon flux is ϕ_I+II = (3.55 ± 0.43_stat± 0.28_syst) × 10^−10 cm^−2s^−1, which is consistent with the previous measurement. Owing to the characteristic angular dependence of Cherenkov radiation and the increased PMT coverage, the uncertainty in muon direction reconstruction is approximately 6^∘, which corresponds to a reduction to 30% of its previous value. Notably, one rare up-going muon event was clearly identified. It is excluded from the cosmic-ray muon flux sample and opens a new window for neutrino-induced event studies in the deepest underground laboratory in China. This work marks the first time that CJPL has employed a cost-effective water detector for muon flux measurement.
ER  -