Observation of a Strongly Isospin-Mixed Doublet in Si 26 via β -Delayed Two-Proton Decay of P 26

• Published in: Physical review letters 2022-12, Vol.129 (24), Article 242502
• Main Authors: Liu, J. J., Xu, X. X., Sun, L. J., Yuan, C. X., Kaneko, K., Sun, Y., Liang, P. F., Wu, H. Y., Shi, G. Z., Lin, C. J., Lee, J., Wang, S. M., Qi, C., Li, J. G., Li, H. H., Xayavong, Latsamy, Li, Z. H., Li, P. J., Yang, Y. Y., Jian, H., Gao, Y. F., Fan, R., Zha, S. X., Dai, F. C., Zhu, H. F., Li, J. H., Chang, Z. F., Qin, S. L., Zhang, Z. Z., Cai, B. S., Chen, R. F., Wang, J. S., Wang, D. X., Wang, K., Duan, F. F., Lam, Y. H., Ma, P., Gao, Z. H., Hu, Q., Bai, Z., Ma, J. B., Wang, J. G., Wu, C. G., Luo, D. W., Jiang, Y., Liu, Y., Hou, D. S., Li, R., Ma, N. R., Ma, W. H., Yu, G. M., Patel, D., Jin, S. Y., Wang, Y. F., Yu, Y. C., Hu, L. Y., Wang, X., Zang, H. L., Wang, K. L., Ding, B., Zhao, Q. Q., Yang, L., Wen, P. W., Yang, F., Jia, H. M., Zhang, G. L., Pan, M., Wang, X. Y., Sun, H. H., Xu, H. S., Zhou, X. H., Zhang, Y. H., Hu, Z. G., Wang, M., Liu, M. L., Ong, H. J., Yang, W. Q.
• Format: Article
• Language: English
• ISSN: 0031-9007; 1079-7114; 1079-7114
• DOI: 10.1103/PhysRevLett.129.242502

beta decay of proton-rich nuclei plays an important role in exploring isospin mixing. The beta decay of P-26 at the proton drip line is studied using double-sided silicon strip detectors operating in conjunction with high-purity germanium detectors. The T = 2 isobaric analog state (IAS) at 13 055 keV and two new high-lying states at 13 380 and 11 912 keV in Si-26 are unambiguously identified through beta-delayed two-proton emission (beta 2p). Angular correlations of two protons emitted from Si-26 excited states populated by P-26 beta decay are measured, which suggests that the two protons are emitted mainly sequentially. We report the first observation of a strongly isospin-mixed doublet that deexcites mainly via two-proton decay. The isospin mixing matrix element between the Si-26 IAS and the nearby 13 380-keV state is determined to be 130(21) keV, and this result represents the strongest mixing, highest excitation energy, and largest level spacing of a doublet ever observed in beta-decay experiments.