Y Shimizu, K P Rykaczewski, N Fukuda, N T Brewer, I. Dillmann, R K Grzywacz, S Nishimura, B C Rasco, J L Tain, H Suzuki, H Takeda, D S Ahn, T. Sumikama, N Inabe, K Yoshida, H Ueno, S. Michimasa, A. Algora, J M Allmond, Jorge Agramunt, H. Baba, S. Bae, C G Bruno, R Caballero-Folch, F. Calviño, P J Coleman-Smith, G Cortes, T. Davinson, C Domingo-Pardo, A Estrade, S. Go, C J Griffin, Jung Min Ha, O Hall, L J Harkness-Brennan, J Heideman, T Isobe, D. Kahl, M. Karny, L H Khiem, T T King, G G Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J Liang, J. J. Liu, G. Lorusso, Miguel Madurga, K Matsui, K. Miernik, F Montes, A I Morales, P. Morrall, N Nepal, R D Page, V H Phong, M. Piersa-Siłkowska, M. Prydderch, V F E Pucknell, M M Rajabali, B Rubio, Y. Saito, H. Sakuraï, J Simpson, Mandip Singh, D W Stracener, A Tarife no-Saldivia, S L Thomas, A. Tolosa-Delgado, M. Wolińska-Cichocka, P J Woods, X X Xu, R. Yokoyama
Abstract A search for new neutron-rich isotopes beyond $Z=28$ and $N=50$ was performed using a 345 MeV/nucleon $^{238}$U beam at RI Beam Factory in RIKEN Nishina Center. The BigRIPS separator and state-of-the-art radiation detectors were used to efficiently separate and identify the produced nuclei. For the first time, we have observed and determined the production cross sections for eight neutron-rich isotopes $^{72}$Cr, $^{74,75}$Mn, $^{77}$Fe, $^{79,80}$Co, $^{85}$Cu, and $^{90}$Ga. This study broadens our understanding of nuclear existence and paves the way for investigating the properties of neutron-rich medium-mass nuclei.