Searching for $^{76}$Ge neutrinoless double beta decay with the CDEX-1B experiment

B. T. Zhang, L. T. Yang, Q. Yue, K. J. Kang, Y. J. Li, H. P. An, Greeshma C., J. P. Chang, Y. H. Chen, J. P. Cheng, W. H. Dai, Z. Deng, C. H. Fang, X. P. Geng, H. Gong, Q. J. Guo, X. Y. Guo, L. He, S. M. He, J. W. Hu, H. X. Huang, T. C. Huang, H. T. Jia, X. Jiang, S. Karmakar, H. B. Li, J. M. Li, J. Li, Q. Y. Li, R. M. J. Li, X. Q. Li, Y. L. Li, Y. F. Liang, B. Liao, F. K. Lin, S. T. Lin, J. X. Liu, S. K. Liu, Y. D. Liu, Y. Liu, Y. Y. Liu, Z. Z. Liu, H. Ma, Y. C. Mao, Q. Y. Nie, J. H. Ning, H. Pan, N. C. Qi, J. Ren, X. C. Ruan, Z. She, M. K. Singh, T. X. Sun, C. J. Tang, W. Y. Tang, Y. Tian, G. F. Wang, L. Wang, Q. Wang, Y. F. Wang, Y. X. Wang, H. T. Wong, S. Y. Wu, Y. C. Wu, H. Y. Xing, R. Xu, Y. Xu, T. Xue, Y. L. Yan, N. Yi, C. X. Yu, H. J. Yu, J. F. Yue, M. Zeng, Z. Zeng, F. S. Zhang, L. Zhang, Z. H. Zhang, Z. Y. Zhang, K. K. Zhao, M. G. Zhao, J. F. Zhou, Z. Y. Zhou, J. J. Zhu
Nuclear Experiment, Nuclear Experiment (nucl-ex), High Energy Physics - Experiment (hep-ex), Instrumentation and Detectors (physics.ins-det)
2023-04-30 16:00:00
We operated a p-type point contact high purity germanium (PPCGe) detector (CDEX-1B, 1.008 kg) in the China Jinping Underground Laboratory (CJPL) for 500.3 days to search for neutrinoless double beta ($0\nu\beta\beta$) decay of $^{76}$Ge. A total of 504.3 kg $\cdot$ day effective exposure data was accumulated. The anti-coincidence and the multi/single-site event (MSE/SSE) discrimination methods were used to suppress the background in the energy region of interest (ROI, $1989-2089$ keV for this work) with a factor of 23. A background level of 0.33 counts/(keV $\cdot$ kg $\cdot$ yr) was achieved. The lower limit on the half life of $^{76}$Ge $0\nu\beta\beta$ decay was constrained as $T_{1/2}^{0\nu}\ > \ {2.2}\times 10^{23}\ \rm yr\ (90\% \ C.L.)$, corresponding to the upper limits on the effective Majorana neutrino mass: $\langle m_{\beta\beta}\rangle < 2.3-5.2\ \mathrm{eV}$.
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