e-Article
First observation of 28 O
Document Type
Author
Kondo, Y.; Achouri, N. L.; Falou, H. A.; Atar, L.; Aumann, T.; Baba, H.; Boretzky, K.; Caesar, C.; Calvet, D.; Chae, H.; Chiga, N.; Corsi, A.; Delaunay, F.; Delbart, A.; Deshayes, Q.; Dombrádi, Zs; Douma, C. A.; Ekström, Andreas, 1980; Elekes, Z.; Forssén, Christian, 1974; Gasparic, I.; Gheller, J. M.; Gibelin, J.; Gillibert, A.; Hagen, G.; Harakeh, M. N.; Hirayama, A.; Hoffman, C. R.; Holl, M.; Horvat, A.; Horváth; Hwang, J. W.; Isobe, T.; Jiang, Weiguang, 1989; Kahlbow, J.; Kalantar-Nayestanaki, N.; Kawase, S.; Kim, S.; Kisamori, K.; Kobayashi, T.; Körper, D.; Koyama, S.; Kuti, I.; Lapoux, V.; Lindberg, Simon, 1987; Marqués, F. M.; Masuoka, S.; Mayer, J.; Miki, K.; Murakami, T.; Najafi, M. A.; Nakamura, T.; Nakano, K.; Nakatsuka, N.; Nilsson, Thomas, 1965; Obertelli, A.; Ogata, K.; De Oliveira-Santos, F.; Orr, N. A.; Otsu, H.; Otsuka, T.; Ozaki, T.; Panin, V.; Papenbrock, T.; Paschalis, S.; Revel, A.; Rossi, D.; Saito, A. T.; Saito, T. Y.; Sasano, M.; Sato, H.; Satou, Y.; Scheit, H.; Schindler, F.; Schrock, P.; Shikata, M.; Shimizu, N.; Shimizu, Y.; Simon, H.; Sohler, D.; Sorlin, Olivier; Stuhl, L.; Sun, Z. H.; Takeuchi, S.; Tanaka, M.; Thoennessen, M.; Törnqvist, Hans, 1985; Togano, Y.; Tomai, T.; Tscheuschner, J.; Tsubota, J.; Tsunoda, N.; Uesaka, T.; Utsuno, Y.; Vernon, I.; Wang, H.; Yang, Z.; Yasuda, M.; Yoneda, K.; Yoshida, S.
Source
Strong interactions for precision nuclear physics (PrecisionNuclei) Stark nukleonkraft: atomkärnors kvantmekaniska egenskaper och neutronstjärnors tillståndsekvation Experimentella studier av exotiska, lätta nukleära system Exotiska nukleära system vid gränsen för existens - fysik i frontlinjen med perspektiv mot FAIR Svaga och sällsynta processer i atomkärnan: fundamentala symmetrier och mörk materia Nature. 620(7976):965-970
Subject
Language
English
ISSN
0028-0836
1476-4687
1476-4687
Abstract
Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10−21s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of 28O and 27O through their decay into 24O and four and three neutrons, respectively. The 28O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called ‘doubly magic’ nuclei. Both 27O and 28O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of 28O from a 29F beam is consistent with it not exhibiting a closed N = 20 shell structure.