# α -decay study of 182,184Tl

C. Van Beveren, Andrei Andreyev, A. E. Barzakh, Thomas Cocolios, R. P. de Groote, D. V. Fedorov, V N Fedosseev, R. Ferrer, L. Ghys, Mark Huyse, U Koster, J. Lane, V. Liberati, K. M. Lynch, B. A. Marsh, P. L. Molkanov, T. J. Procter, E. Rapisarda, K. Sandhu, Maxim SeliverstovPiet Van Duppen, M. Venhart, M. Veselsky

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## Abstract

α -decay spectroscopy of ##IMG## [http://ej.iop.org/images/0954-3899/43/2/025102/jpgaa0a95ieqn3.gif] {${}^{\mathrm{182,184}}$} Tl has been performed at the CERN isotope separator on-line (ISOLDE) facility. New fine-structure α decays have been observed for both isotopes. α -decay branching ratios of 0.089(19)%, 0.047(6)% and 1.22(30)% have been deduced for the (10 − ), (7 + ) and (2 − ) states respectively in 184 Tl and a lower limit of 0.49% for the α -decay branching ratio of 182 Tl. A new half-life of 9.5(2) s for the (2 − ) state in 184 Tl and 1.9(1) s for the low-spin state in 182 Tl has been deduced. Using α – γ coincidence analysis, multiple γ rays were observed de-exciting levels in ##IMG## [http://ej.iop.org/images/0954-3899/43/2/025102/jpgaa0a95ieqn4.gif] {${}^{\mathrm{178,180}}$} Au fed by ##IMG## [http://ej.iop.org/images/0954-3899/43/2/025102/jpgaa0a95ieqn5.gif] {${}^{\mathrm{182,184}}$} Tl α decays. The γ transitions connecting these low-lying states in ##IMG## [http://ej.iop.org/images/0954-3899/43/2/025102/jpgaa0a95ieqn6.gif] {${}^{\mathrm{178,180}}$} Au are essential to sort the data and possibly identify bands from in-beam studies in these isotopes. Owing to the complex fine-structure α decays and limited knowledge about the structure of the daughter nuclei, only partial level schemes could be constructed for both gold isotopes in the present work. Reduced α -decay widths have been calculated and are compared with values obtained in neighboring odd-A and even-A thallium isotopes. Except for the allowed α decay of the 184 Tl (10 − ) state, the other fine-structure α decays observed in this study are hindered. This points to strong structural changes between parent thallium and daughter gold isotopes.
Original language English 25102 1-23 23 Journal of physics g-Nuclear and particle physics 43 2 https://doi.org/10.1088/0954-3899/43/2/025102 Published - 8 Jan 2016