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Author(s)
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Parr, E (West Scotland U. ; SUPA, UK) ; Smith, J F (West Scotland U. ; SUPA, UK) ; Greenlees, P T (Jyvaskyla U.) ; Auranen, K (Jyvaskyla U.) ; Chapman, R (West Scotland U. ; SUPA, UK) ; Cullen, D M (Manchester U.) ; Grahn, T (Jyvaskyla U.) ; Grocutt, L (West Scotland U. ; SUPA, UK) ; Herzáň, A (Jyvaskyla U. ; Bratislava, Inst. Phys.) ; Herzberg, R D (Liverpool U.) ; Hodge, D (Manchester U.) ; Jakobsson, U (Jyvaskyla U. ; Royal Inst. Tech., Stockholm) ; Julin, R (Jyvaskyla U.) ; Juutinen, S (Jyvaskyla U.) ; Konki, J (Jyvaskyla U. ; CERN) ; McPeake, C (Liverpool U.) ; Mengoni, D (INFN, Padua ; Padua U.) ; Mistry, A K (Liverpool U.) ; Mulholland, K F (West Scotland U. ; SUPA, UK) ; O'Neill, G G (Liverpool U.) ; Pakarinen, J (Jyvaskyla U.) ; Papadakis, P (Jyvaskyla U. ; Daresbury) ; Partanen, J (Jyvaskyla U.) ; Peura, P (Jyvaskyla U.) ; Rahkila, P (Jyvaskyla U.) ; Ruotsalainen, P (Jyvaskyla U.) ; Sandzelius, M (Jyvaskyla U.) ; Sarén, J (Jyvaskyla U.) ; Scheck, M (West Scotland U. ; SUPA, UK) ; Scholey, C (Jyvaskyla U.) ; Siciliano, M (Jyvaskyla U. ; INFN, Padua ; Padua U. ; IRFU, Saclay) ; Smolen, M (West Scotland U. ; SUPA, UK) ; Sorri, J (Jyvaskyla U. ; STUK, Helsinki) ; Stolze, S (Jyvaskyla U. ; Argonne, PHY) ; Taylor, M J (Manchester U. ; U. Manchester (main)) ; Uusitalo, J (Jyvaskyla U.) |
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Abstract
| Fine structure in the α decay of $^{221}_{90}$Th, populating excited states in $^{217}_{88}$Ra, was studied using αγ-coincidence spectroscopy. Two α-decay branches from $^{221}$Th have been newly observed, with $E_{\alpha} \mathrm{(keV)} [b_{\alpha}(\%)]=7951(8)[0.14(3)]$ and $8247(3)[1.51(12)]$, together with three previously known branches. Also, two new states in $^{217}$Ra were identified at $E = 177$ and 227 keV. The ground-state configurations of the odd-$A$, $N = 131$ transitional isotones above $^{208}$Pb are interpreted from their α-decay fine structure systematics and considered in terms of predictions using spherical shell and reflection-asymmetric models. |