First observation of 20B and 21B
Abstract
The most neutron-rich boron isotopes 20B and 21B have been observed for the first time following proton removal from 22N and 22C at energies around 230 MeV/nucleon. Both nuclei were found to exist as resonances which were detected through their decay into 19B and one or two neutrons. Two-proton removal from 22N populated a prominent resonance-like structure in 20B at around 2.5 MeV above the one-neutron decay threshold, which is interpreted as arising from the closely spaced 1-,2- ground-state doublet predicted by the shell model. In the case of proton removal from 22C, the 19B plus one- and two-neutron channels were consistent with the population of a resonance in 21B 2.47+-0.19 MeV above the two-neutron decay threshold, which is found to exhibit direct two-neutron decay. The ground-state mass excesses determined for 20,21B are found to be in agreement with mass surface extrapolations derived within the latest atomic-mass evaluations.
Keywords
Cite
@article{arxiv.1901.00455,
title = {First observation of 20B and 21B},
author = {S. Leblond and F. M. Marqués and J. Gibelin and N. A. Orr and Y. Kondo and T. Nakamura and J. Bonnard and N. Michel and N. L. Achouri and T. Aumann and H. Baba and F. Delaunay and Q. Deshayes and P. Doornenbal and N. Fukuda and J. W. Hwang and N. Inabe and T. Isobe and D. Kameda and D. Kanno and S. Kim and N. Kobayashi and T. Kobayashi and T. Kubo and J. Lee and R. Minakata and T. Motobayashi and D. Murai and T. Murakami and K. Muto and T. Nakashima and N. Nakatsuka and A. Navin and S. Nishi and S. Ogoshi and H. Otsu and H. Sato and Y. Satou and Y. Shimizu and H. Suzuki and K. Takahashi and H. Takeda and S. Takeuchi and R. Tanaka and Y. Togano and A. G. Tuff and M. Vandebrouck and K. Yoneda},
journal= {arXiv preprint arXiv:1901.00455},
year = {2019}
}
Comments
Accepted for publication in Physical Review Letters. Supplemental Material at http://link.aps.org/supplemental/10.1103/PhysRevLett.121.262502