First structure information on the exotic 149 La from the -decay of 149 Ba

A. Syntfeld; H. Mach; W. Płóciennik; W. Kurcewicz; B. Fogelberg

doi:10.1140/epja/i2003-10192-1

EPJ

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2023 Impact factor 2.6

Hadrons and Nuclei

Open Access

Eur. Phys. J. A (2004) 20: 359-363
https://doi.org/10.1140/epja/i2003-10192-1

Letter

First structure information on the exotic ¹⁴⁹ La from the $\beta^-$ -decay of ¹⁴⁹ Ba

A. Syntfeld¹^*, H. Mach², W. Płóciennik³, W. Kurcewicz¹ and B. Fogelberg²

¹ Institute of Experimental Physics, Warsaw University, Hoża 69, 00-681, Warsaw, Poland
² Department of Radiation Sciences, Uppsala University, 611 82, Nyköping, Sweden
³ Department of Nuclear Spectroscopy, Sołtan Institute for Nuclear Studies, 05-400, Świerk, Poland

^* e-mail: syntfeld@ipj.gov.pl

Abstract

The $\beta^-$ -decay of ¹⁴⁹Ba to ¹⁴⁹La has been investigated by means of $\gamma$ - and X-ray spectroscopy, and a partial level scheme of ¹⁴⁹La has been constructed for the first time. It includes thirteen $\gamma$ -rays and ten excited states. The exotic ¹⁴⁹La is the heaviest lanthanum for which spectroscopic information is now available. We have applied the shell correction approach with the axially deformed Woods-Saxon potential in order to calculate the deformation energy for the ¹⁴⁹La ground state. The deformed ground state was found at $\beta_2 \simeq$ 0.23, $\beta_3 \simeq$ 0 and $\beta_4 \simeq$ 0.12.