First experimental constraint of the spectroscopic amplitudes for the α-cluster in the 11B ground state oleh Y.P. Shen, B. Guo, T.L. Ma, D.Y. Pang, D.D. Ni, Z.Z. Ren, Y.J. Li, Z.D. An, J. Su, J.C. Liu, Q.W. Fan, Z.Y. Han, X.Y. Li, Z.H. Li, G. Lian, Y. Su, Y.B. Wang, S.Q. Yan, S. Zeng, W.P. Liu