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Level structure of light neutron-rich La isotopes beyond the N=82 shell closure

Fuente: arXiv

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Main Authors:	Navin, A., Wang, E. H., Bhattacharyya, S., Liu, Menglan, Yuan, Cenxi, Rejmund, M., Lemasson, A., Biswas, S., Kim, Y. H., Michelagnoli, C., Hamilton, J. H., Ramayya, A. V., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, Soumik, Clement, E., Crawford, H. L., de France, G., Fallon, P., Goupil, G. Fremont J., Jacquot, B., Li, H. J., Ljungvall, J., Luo, Y. X., Maj, A., Menager, L., Morel, V., Mukherjee, G., Palit, R., Perez-Vidal, R. M., Rasmussen, J. O., Ropert, J., Schmitt, C., Zhu, S. J.
Format:	Preprint
Published:	2026
Subjects:	Nuclear Experiment
Online Access:	Acceder al recurso
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_version_	1866912849941495808
author	Navin, A. Wang, E. H. Bhattacharyya, S. Liu, Menglan Yuan, Cenxi Rejmund, M. Lemasson, A. Biswas, S. Kim, Y. H. Michelagnoli, C. Hamilton, J. H. Ramayya, A. V. Stefan, I. Banik, R. Bednarczyk, P. Bhattacharya, Soumik Clement, E. Crawford, H. L. de France, G. Fallon, P. Goupil, G. Fremont J. Jacquot, B. Li, H. J. Ljungvall, J. Luo, Y. X. Maj, A. Menager, L. Morel, V. Mukherjee, G. Palit, R. Perez-Vidal, R. M. Rasmussen, J. O. Ropert, J. Schmitt, C. Zhu, S. J.
author_facet	Navin, A. Wang, E. H. Bhattacharyya, S. Liu, Menglan Yuan, Cenxi Rejmund, M. Lemasson, A. Biswas, S. Kim, Y. H. Michelagnoli, C. Hamilton, J. H. Ramayya, A. V. Stefan, I. Banik, R. Bednarczyk, P. Bhattacharya, Soumik Clement, E. Crawford, H. L. de France, G. Fallon, P. Goupil, G. Fremont J. Jacquot, B. Li, H. J. Ljungvall, J. Luo, Y. X. Maj, A. Menager, L. Morel, V. Mukherjee, G. Palit, R. Perez-Vidal, R. M. Rasmussen, J. O. Ropert, J. Schmitt, C. Zhu, S. J.
contents	The high spin excited states of Lanthanum isotopes $^{140-143}$La, above the $N=82$ closed shell, have been populated in fission reactions. The prompt $γ$-ray transitions were measured using two complementary methods; a) in coincidence with the isotopically identified fragments produced in the fission of the $^{238}$U+$^{9}$Be system using the VAMOS++ and the AGATA spectrometers and b) high statistics three-fold $γ-γ-γ$ and four-fold $γ-γ-γ-γ$ coincidence data from the spontaneous fission of $^{252}$Cf using the Gammasphere. This work reports the first identification of a pair of parity doublet structures in $^{143}$La and the new high spin level structure in $^{140-142}$La from prompt $γ$-ray spectroscopy. The level structures are interpreted in terms of the systematics of neighbouring odd-$Z$ nuclei above $Z=50$ shell closure and large-scale shell model calculations. The present results indicate the presence of stable octupole deformation, in $^{143}$La. The excitation energy pattern and their comparison with neighbouring 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.
format	Preprint
id	arxiv_https___arxiv_org_abs_2601_18673
institution	arXiv
publishDate	2026
record_format	arxiv
spellingShingle	Level structure of light neutron-rich La isotopes beyond the N=82 shell closure Navin, A. Wang, E. H. Bhattacharyya, S. Liu, Menglan Yuan, Cenxi Rejmund, M. Lemasson, A. Biswas, S. Kim, Y. H. Michelagnoli, C. Hamilton, J. H. Ramayya, A. V. Stefan, I. Banik, R. Bednarczyk, P. Bhattacharya, Soumik Clement, E. Crawford, H. L. de France, G. Fallon, P. Goupil, G. Fremont J. Jacquot, B. Li, H. J. Ljungvall, J. Luo, Y. X. Maj, A. Menager, L. Morel, V. Mukherjee, G. Palit, R. Perez-Vidal, R. M. Rasmussen, J. O. Ropert, J. Schmitt, C. Zhu, S. J. Nuclear Experiment The high spin excited states of Lanthanum isotopes $^{140-143}$La, above the $N=82$ closed shell, have been populated in fission reactions. The prompt $γ$-ray transitions were measured using two complementary methods; a) in coincidence with the isotopically identified fragments produced in the fission of the $^{238}$U+$^{9}$Be system using the VAMOS++ and the AGATA spectrometers and b) high statistics three-fold $γ-γ-γ$ and four-fold $γ-γ-γ-γ$ coincidence data from the spontaneous fission of $^{252}$Cf using the Gammasphere. This work reports the first identification of a pair of parity doublet structures in $^{143}$La and the new high spin level structure in $^{140-142}$La from prompt $γ$-ray spectroscopy. The level structures are interpreted in terms of the systematics of neighbouring odd-$Z$ nuclei above $Z=50$ shell closure and large-scale shell model calculations. The present results indicate the presence of stable octupole deformation, in $^{143}$La. The excitation energy pattern and their comparison with neighbouring 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.
title	Level structure of light neutron-rich La isotopes beyond the N=82 shell closure
topic	Nuclear Experiment
url	https://arxiv.org/abs/2601.18673