In-beam γ -ray and electron spectroscopy of $^{249,251}$Md

R. Briselet (1) , Ch. Theisen (1) , B. Sulignano (1) , M. Airiau (1) , K. Auranen , D.M. Cox , F. Déchery (1, 2) , A. Drouart (1) , Z. Favier (1) , B. Gall (2) , T. Goigoux (1) , T. Grahn , P.T. Greenlees , K. Hauschild (3) , A. Herzan , R.-D. Herzberg , U. Jakobsson , R. Julin , S. Juutinen , J. Konki , M. Leino , A. Lopez-Martens (3) , A. Mistry , P. Nieminen , J. Pakarinen , P. Papadakis , P. Peura , P. Rahkila , E. Rey-Herme , J. Rubert (2) , P. Ruotsalainen , M. Sandzelius , J. Sarén , C. Scholey , J. Sorri , S. Stolze , J. Uusitalo , M. Vandebrouck (1) , A. Ward , M. Zielínska (1) , B. Bally (1) , M. Bender (4) , W. Ryssens

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 IPHC - Institut Pluridisciplinaire Hubert Curien
3 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
4 IP2I Lyon - Institut de Physique des 2 Infinis de Lyon

The odd-Z Md251 nucleus was studied using combined γ-ray and conversion-electron in-beam spectroscopy. Besides the previously observed rotational band based on the [521]1/2− configuration, another rotational structure has been identified using γ-γ coincidences. The use of electron spectroscopy allowed the rotational bands to be observed over a larger rotational frequency range. Using the transition intensities that depend on the gyromagnetic factor, a [514]7/2− single-particle configuration has been inferred for this band, i.e., the ground-state band. A physical background that dominates the electron spectrum with an intensity of ≃60% was well reproduced by simulating a set of unresolved excited bands. Moreover, a detailed analysis of the intensity profile as a function of the angular momentum provided a method for deriving the orbital gyromagnetic factor, namely gK=0.69−0.16+0.19 for the ground-state band. The odd-Z Md249 was studied using γ-ray in-beam spectroscopy. Evidence for octupole correlations resulting from the mixing of the Δl=Δj=3 [521]3/2− and [633]7/2+ Nilsson orbitals were found in both Md249,251. A surprising similarity of the Md251 ground-state band transition energies with those of the excited band of Lr255 has been discussed in terms of identical bands. Skyrme-Hartree-Fock-Bogoliubov calculations were performed to investigate the origin of the similarities between these bands.

Mots clés: Nuclear Structure

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

R. Briselet, Ch. Theisen, B. Sulignano, M. Airiau, K. Auranen, et al.. In-beam γ -ray and electron spectroscopy of $^{249,251}$Md. Phys.Rev.C, 2020, 102 (1), pp.014307. ⟨10.1103/PhysRevC.102.014307⟩. ⟨hal-02483892⟩