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Alpha-decay measurement is an important source of information on nuclear structure of exotic isotopes, especially when coincident $\gamma$ rays are registered as well. Respective fine-structure $\alpha$ decays can be disentangled from complicated $\alpha$-decay spectrum and excited states in daughter nucleus can be established. This is particularly valuable for investigation of odd-odd isotopes, where coupling of unpaired proton and neutron leads to high density of relatively low-lying states in daughter nuclides. Since $\alpha$ decay is very sensitive to changes of spin, parity or configuration, it provides an insight into structural differences between initial and final states.
A typical example of odd-odd nucleus decaying via multiple fine-structure transitions is $^{180}$Tl. Its $\alpha$ decay was previously studied in Argonne National Laboratory [1,2], while $\beta$ decay and $\beta$-delayed fission were investigated at the ISOLDE facility [3] with the Windmill decay-spectroscopy set-up [4]. This contribution will report on a detailed $\alpha$-decay study of $^{180}$Tl [5] performed in the same experiment at ISOLDE. High statistics collected during the measurement allowed us to analyze $\alpha$-$\gamma$ and $\alpha$-$\gamma$-$\gamma$ coincidences. We identified many new excited states in daughter nucleus $^{176}$Au, determined multipolarities for some of the $\gamma$ decays de-exciting these states and established an extended decay scheme.
Reduced $\alpha$-decay widths for $^{180}$Tl transitions were evaluated and compared to values for unhindered decays in this region. It was found out that all decays of $^{180}$Tl are hindered, which leads us to conclusion that daughter states are of different character than the ground state in $^{180}$Tl. Alpha-decay properties of $^{180}$Tl will be discussed in connection to decay characteristics of neighboring odd-odd Tl isotopes.
[1] K. S. Toth et al., Phys. Rev. C 58, 1310 (1998).
[2] F. G. Kondev et al., EPJ Web Conf. 63, 01013 (2013).
[3] A. N. Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010); J. Elseviers et al., Phys. Rev. C 84, 034307 (2011); J. Elseviers et al., Phys. Rev. C 88, 044321 (2013).
[4] M. D. Seliverstov et al., Phys. Rev. C 89, 034323 (2014).
[5] B. Andel et al., submitted to Phys. Rev. C.
