Level structure of light neutron-rich La isotopes beyond the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>82</mml:mn></mml:mrow></mml:math> shell closure

The high spin excited states of Lanthanum isotopes $^{140\text{--}143}\mathrm{La}$, above the $N=82$ closed shell, were populated in fission reactions. The prompt $\ensuremath{\gamma}$-ray transitions were measured using two complementary methods: (a) in coincidence with the isotopically identified fragments produced in the fission of the $^{238}\mathrm{U}+^{9}\mathrm{Be}$ system using the Variable Mode Spectrometer ($\mathrm{VAMOS}++$) and the Advanced Gamma Tracking Array (AGATA) spectrometer, and (b) high statistics threefold $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ and fourfold $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence data from the spontaneous fission of $^{252}\mathrm{Cf}$ using the Gammasphere. This work reports the first identification of a pair of parity doublet structures in $^{143}\mathrm{La}$ and the new high spin level structure in $^{140\text{--}142}\mathrm{La}$ from prompt $\ensuremath{\gamma}$-ray spectroscopy. The level structures are interpreted in terms of the systematics of neighboring odd-$Z$ nuclei above the $Z=50$ shell closure and large-scale shell model calculations. The present results indicate the presence of stable octupole deformation in $^{143}\mathrm{La}$. The excitation energy pattern and their comparison with neighboring isotones, moving away from the $N=82$ closed shell, point towards a transition from single-particle structures to an alternating parity rotational band structure in the La isotopic chain.

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Journal
Physical review. C
Published
2025-10-16
DOI
https://doi.org/10.1103/3jvn-hzdh
Primary Topic
Nuclear physics research studies
Type
article
Field-Weighted Citation Impact
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article

Level structure of light neutron-rich La isotopes beyond the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>82</mml:mn></mml:mrow></mml:math> shell closure

P. Bednarczyk, Cenxi Yuan, J. Ropert, S. Biswas et al.
Physical review. C
Nuclear physics research studies
article

Level structure of light neutron-rich La isotopes beyond the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>82</mml:mn></mml:mrow></mml:math> shell closure

P. Bednarczyk, Cenxi Yuan, J. Ropert, S. Biswas, H. L. Crawford, Y. X. Luo, V. Morel, A. V. Ramayya, S. Bhattacharyya, B. Jacquot, Loïc Ménager, G. de France, I. Stefan, A. Maj, C. Michelagnoli, E. H. Wang, G. Frémont, P. Fallon, Y. H. Kim, G. Mukherjee, E. Clément, Menglan Liu, R. Banik, J. Goupil, R. Palit, A. Lemasson, J. O. Rasmussen, J. Ljungvall, S. J. Zhu, S. Bhattacharya, C. Schmitt, J. H. Hamilton, R. M. Pérez-Vidal, A. Navin, M. Rejmund, H. J. Li
article en

Abstract

The high spin excited states of Lanthanum isotopes $^{140\text{--}143}\mathrm{La}$, above the $N=82$ closed shell, were populated in fission reactions. The prompt $\ensuremath{\gamma}$-ray transitions were measured using two complementary methods: (a) in coincidence with the isotopically identified fragments produced in the fission of the $^{238}\mathrm{U}+^{9}\mathrm{Be}$ system using the Variable Mode Spectrometer ($\mathrm{VAMOS}++$) and the Advanced Gamma Tracking Array (AGATA) spectrometer, and (b) high statistics threefold $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ and fourfold $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence data from the spontaneous fission of $^{252}\mathrm{Cf}$ using the Gammasphere. This work reports the first identification of a pair of parity doublet structures in $^{143}\mathrm{La}$ and the new high spin level structure in $^{140\text{--}142}\mathrm{La}$ from prompt $\ensuremath{\gamma}$-ray spectroscopy. The level structures are interpreted in terms of the systematics of neighboring odd-$Z$ nuclei above the $Z=50$ shell closure and large-scale shell model calculations. The present results indicate the presence of stable octupole deformation in $^{143}\mathrm{La}$. The excitation energy pattern and their comparison with neighboring isotones, moving away from the $N=82$ closed shell, point towards a transition from single-particle structures to an alternating parity rotational band structure in the La isotopic chain.

Physical review. CVol. 112(4)
Tata Institute of Fundamental Research (IN), Variable Energy Cyclotron Centre (IN), Lawrence Berkeley National Laboratory (US), Shandong University (CN), Universitat de València (ES), Homi Bhabha National Institute (IN), Vanderbilt University (US), Université Paris-Saclay (FR), Institute of Nuclear Physics (UZ), Institute for Basic Science (KR), Laboratoire National Henri Becquerel (FR), Grand Accélérateur National d'Ions Lourds (FR), Université de Strasbourg (FR), Tsinghua University (CN)
U.S. Department of Energy, Shandong University, Indo-French Centre for the Promotion of Advanced Research, Office of Science, Nuclear Physics, Lawrence Berkeley National Laboratory
Openalex Percentile: Top 87%
Nuclear physics research studies
DOIOpen Access PDFOpenAlex
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