Inverse odd-even staggering in nuclear charge radii and possible octupole collectivity in At revealed by in-source laser spectroscopy

Barzakh, A. E.*; Cubiss, J. G.*; Andreyev, A. N.; Seliverstov, M. D.*; Andel, B.*; Antalic, S.*; Ascher, P.*; Atanasov, D.*; Beck, D.*; Biero, J.*; Blaum, K.*; Borgmann, Ch.*; Breitenfeldt, M.*; Capponi, L.*; Cocolios, T. E.*; Day Goodacre, T.*; Derkx, X.*; De Witte, H.*; Elseviers, J.*; Fedorov, D. V.*; Fedosseev, V. N.*; Fritzsche, S.*; Gaffney, L. P.*; George, S.*; Ghys, L.*; Heberger, F. P.*; Huyse, M.*; Imai, Nobuaki*; Kalaninova, Z.*; Kisler, D.*; Kster, U.*; Kowalska, M.*; Kreim, K.*; Lane, J. F. W.*; Liberati, V.*; Lunney, D.*; Lynch, K. M.*; Manea, V.*; Marsh, B. A.*; Mitsuoka, Shinichi; Molkanov, P. L.*; Nagame, Yuichiro* ; Neidherr, D.*; Nishio, Katsuhisa   ; Ota, Shuya; Pauwels, D.*; Popescu, L.*; Radulov, D.*; Rapisarda, E.*; Revill, J. P.*; Rosenbusch, M.*; Rossel, R. E.*; Rothe, S.*; Sandhu, K.*; Schweikhard, L.*; Seles, S.*; Truesdale, V. L.*; Van Beveren, C.*; Van den Bergh, P.*; Van Duppen, P.*; Wakabayashi, Yasuo*; Wendt, K. D. A.*; Wienholtz, F.*; Whitmore, B. W.*; Wilson, G. L.*; Wolf, R. N.*; Zuber, K.*

Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in At have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope At has been found to be larger than the average.