학술논문
First observation of high-$K$ isomeric states in $^{249}$Md and $^{251}$Md
Document Type
Working Paper
Author
Goigoux, T.; Theisen, Ch.; Sulignano, B.; Airiau, M.; Auranen, K.; Badran, H.; Briselet, R.; Calverley, T.; Cox, D.; Déchery, F.; Bisso, F. Defranchi; Drouart, A.; Favier, Z.; Gall, B.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzáň, A.; Herzberg, R. -D.; Jakobsson, U.; Julin, R.; Juutinen, S.; Konki, J.; Leino, M.; Lightfoot, A.; Lopez-Martens, A.; Mistry, A.; Nieminen, P.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rey-Herme, E.; Rubert, J.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.; Uusitalo, J.; Vandebrouck, M.; Ward, A.; Zielińska, M.; Jachimowicz, P.; Kowal, M.; Skalski, J.
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Subject
Language
Abstract
Decay spectroscopy of the odd-proton nuclei $^{249}$Md and $^{251}$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 $\geq 910$ keV was found in $^{249}$Md. In $^{251}$Md, an isomeric state with a half-life of $1.4(3)$ s and an excitation energy $\geq 844$ keV was found. Similarly to the neighbouring $^{255}$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.