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Chirality is one of the most intriguing phenomena observed in atomic nuclei. It has been extensively reported in doubly odd nuclei within the mass region around A ≈ 130 [1]. A vital test for confirming the presence of chirality in nuclei involves examining the behavior of their in-band transition probabilities [2]. Given this context, precise lifetime measurements of excited states are essential. This is evident in the case of Lanthanum isotopes [3,4], where the nearly energy degenerates bands are observed but their respective transition probabilites do not follow the predicted behavior. Chiral vibration has been observed in $^{130}$La [5] but not in $^{132}$La [2], although both nuclei exhibit nearly degenerate energy bands. To explore the presence of chirality on the more neutron-deficient side of lanthanum isotopes, we have conducted an experiment to populate high-spin states and measure the lifetimes of excited states in $^{126}$La, with the aim of investigating its chiral character. The experiment has employed the $^{112}$Sn($^{16}$O, pn)$^{126}$La reaction at a beam energy of 68 MeV. The ROSPHERE array, consisting of twenty-two Compton-suppressed HPGe detectors arranged in multiple angular rings, has been used for γ-ray detection. We have successfully populated the main band and its partner bands and have observed Doppler-shifted γ-ray line shapes. The extraction of lifetimes from these line shapes is currently under investigation.
[1] K. Starosta, T. Koike, C. J. Chiara, et al., Phys. Rev. Lett. 86, 971 (2001).
[2] E. Grodner, J. Srebrny, A. A. Pasternak, et al., Phys. Rev. Lett. 97, 172501 (2006).
[3] K.Y. Ma, J.B. Lu, D. Yang, H.D. Wang, et al., Phys. Rev. C 85, 054306 (2012).
[4] K.Y. Ma, J.B. Lu, S.P. Ruan, D. Yang, et al., Phys.Rev. C 88, 057302 (2013).
[5] M. Ionescu-Bujor, S. Aydin, N.Marginean, et al., Phys. Rev. C98, 054305 (2018).