Observation and spectroscopy of proton-unbound nucleus $^{21}$Al

Authors :: Kostyleva, D.
Xu, X. -D.
Mukha, I.
Acosta, L.
Bajzek, M.
Casarejos, E.
Ciemny, A. A.
Cortina-Gil, D.
Dominik, W.
Dueñas, J. A.
Espino, J. M.
Estradé, A.
Farinon, F.
Fomichev, A.
Geissel, H.
Gómez-Camacho, J.
Gorshkov, A.
Grigorenko, L. V.
Janas, Z.
Kamiński, G.
Kiselev, O.
Knöbel, R.
Korsheninnikov, A. A.
Krupko, S.
Kuich, M.
Kurz, N.
Litvinov, Yu. A.
Marquinez-Durán, G.
Martel, I.
Mazzocchi, C.
Nikolskii, E. Yu.
Nociforo, C.
Ordúz, A. K.
Pfützner, M.
Pietri, S.
Pomorski, M.
Prochazka, A.
Rodríguez-Tajes, C.
Rymzhanova, S.
Sánchez-Benítez, A. M.
Scheidenberger, C.
Simon, H.
Sitar, B.
Slepnev, R.
Stanoiu, M.
Strmen, P.
Sümmerer, K.
Szarka, I.
Takechi, M.
Tanaka, Y. K.
Weick, H.
Winfield, J. S.
Woods, P. J.
Zhukov, M. V.
Publication Year :: 2024
Abstract: We report on the observation of previously-unknown isotope $^{21}$Al, the first unbound aluminum isotope located beyond the proton dripline. The $^{21}$Al nucleus decays by one-proton (1p) emission, and its in-flight decays were detected by tracking trajectories of all decay products with micro-strip silicon detectors. The 1p-emission processes were studied by analyses of the measured angular correlations of decay products $^{20}$Mg+p. The 1p-decay energies of ground and low-lying excited states of $^{21}$Al, its mass excess and proton separation energy value $S_p$=$-1.1(1)$ MeV were determined.<br />Comment: 6 pages, 7 figures

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