학술논문
Mass, spectroscopy and two-neutron decay of $^{16}$Be
Document Type
Working Paper
Author
Monteagudo, B.; Marqués, F. M.; Gibelin, J.; Orr, N. A.; Corsi, A.; Kubota, Y.; Casal, J.; Gómez-Camacho, J.; Authelet, G.; Baba, H.; Caesar, C.; Calvet, D.; Delbart, A.; Dozono, M.; Feng, J.; Flavigny, F.; Gheller, J. -M.; Giganon, A.; Gillibert, A.; Hasegawa, K.; Isobe, T.; Kanaya, Y.; Kawakami, S.; Kim, D.; Kiyokawa, Y.; Kobayashi, M.; Kobayashi, N.; Kobayashi, T.; Kondo, Y.; Korkulu, Z.; Koyama, S.; Lapoux, V.; Maeda, Y.; Motobayashi, T.; Miyazaki, T.; Nakamura, T.; Nakatsuka, N.; Nishio, Y.; Obertelli, A.; Ohkura, A.; Ota, S.; Otsu, H.; Ozaki, T.; Panin, V.; Paschalis, S.; Pollacco, E. C.; Reichert, S.; Rousse, J. -Y.; Saito, A. T.; Sakaguchi, S.; Sako, M.; Santamaria, C.; Sasano, M.; Sato, H.; Shikata, M.; Shimizu, Y.; Shindo, Y.; Stuhl, L.; Sumikama, T.; Sun, Y. L.; Tabata, M.; Togano, Y.; Tsubota, J.; Uesaka, T.; Yang, Z. H.; Yasuda, J.; Yoneda, K.; Zenihiro, J.
Source
Subject
Language
Abstract
The structure and decay of the most neutron-rich beryllium isotope, $^{16}$Be, has been investigated following proton knockout from a high-energy $^{17}$B beam. Two relatively narrow resonances were observed for the first time, with energies of $0.84(3)$ and $2.15(5)$ MeV above the two-neutron decay threshold and widths of $0.32(8)$ and $0.95(15)$ MeV respectively. These were assigned to be the ground ($J^{\pi}=0^+$) and first excited ($2^+$) state, with $E_x=1.31(6)$ MeV. The mass excess of $^{16}$Be was thus deduced to be $56.93(13)$ MeV, some $0.5$ MeV more bound than the only previous measurement. Both states were observed to decay by direct two-neutron emission. Calculations incorporating the evolution of the wavefunction during the decay as a genuine three-body process reproduced the principal characteristics of the neutron-neutron energy spectra for both levels, indicating that the ground state exhibits a strong spatially compact dineutron component, while the 2$^+$ level presents a far more diffuse neutron-neutron distribution.