Eur. Phys. J. A (2021) 57: 321
https://doi.org/10.1140/epja/s10050-021-00631-4

Regular Article - Experimental Physics

First observation of high-K isomeric states in Md and Md

¹ Irfu, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
² Department of Physics, University of Jyvaskyla, P.O. Box 35, 40014, Jyvaskyla, Finland
³ Department of Physics, Oliver Lodge Laboratory, University of Liverpool, L69 7ZE, Liverpool, UK
⁴ Institut Pluridisciplinaire Hubert Curien, 67037, Strasbourg, France
⁵ IJCLab, IN2P3-CNRS, Orsay Campus, 91405, Orsay, France
⁶ Institute of Physics, Slovak Academy of Sciences, 84511, Bratislava, Slovakia
⁷ Institute of Physics, University of Zielona Góra, Z. Szafrana 4a, 65-516, Zielona Gora, Poland
⁸ National Centre for Nuclear Research, Pasteura 7, 02-093, Warsaw, Poland
⁹ Radiation and Nuclear Safety Authority-STUK, Laippatie 4, 00880, Helsinki, Finland
¹⁰ University of Lund, Box 118, 221 00, Lund, Sweden
¹¹ Laboratory of Radiochemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, 00014, Helsinki, Finland
¹² CERN, 1211, Geneva 23, Switzerland
¹³ GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
¹⁴ Fortum, Power Division, P.O. Box 100, 00048, Fortum, Finland
¹⁵ STFC Daresbury Laboratory, Daresbury, WA4 4AD, Warrington, UK
¹⁶ International Atomic Energy Agency, Vienna, Austria
¹⁷ Physics Division, Argonne National Laboratory, 9700 South Cass Avenue, 60439, Lemont, IL, USA

^b christophe.theisen@cea.fr

Received: 2 July 2021
Accepted: 14 November 2021
Published online: 1 December 2021

Abstract

Decay spectroscopy of the odd-proton nuclei Md and Md has been performed. High-K isomeric states were identified for the first time in these two nuclei through the measurement of their electromagnetic decay. An isomeric state with a half-life of 2.8(5) ms and an excitation energy keV was found in Md. In Md, an isomeric state with a half-life of 1.4(3) s and an excitation energy keV was found. Similarly to the neighbouring Lr, these two isomeric states are interpreted as 3 quasi-particle high-K states and compared to new theoretical calculations. Excited nuclear configurations were calculated within two scenarios: via blocking nuclear states located in proximity to the Fermi surface or/and using the quasiparticle Bardeen–Cooper–Schrieffer method. Relevant states were selected on the basis of the microscopic-macroscopic model with a deformed Woods–Saxon potential. The most probable candidates for the configurations of K-isomeric states in Md nuclei are proposed.