Towards saturation of the electron-capture delayed fission probability: the new isotopes ²⁴⁰Es and ²³⁶Bk

Konki, J.; Khuyagbaatar, J.; Uusitalo, J.; Greenlees, P.T.; Auranen, K.; Badran, H.; Block, M.; Briselet, R.; Cox, D.M.; Dasgupta, Mahananda; Di Nitto, A.; Düllmann, Ch.E.; Grahn, T.; Hauschild, K.; Herzán, A.; Herzberg, R.-D.; Heßberger, F.P.; Hinde, David; Julin, R.; Juutinen, S.; Jäger, E.; Kindler, B.; Krier, J.; Leino, M.; Lommel, B.; Lopez-Martens, A.; Luong, D.H.; Mallaburn, M.; Nishio, K.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rezynkina, K.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.; Sulignano, B.; Theisen, Ch.; Ward, A.; Yakushev, A.; Yakusheva, V.

Towards saturation of the electron-capture delayed fission probability: the new isotopes ²⁴⁰Es and ²³⁶Bk

Date

2016-11-24

Authors

Konki, J.

Khuyagbaatar, J.

Uusitalo, J.

Greenlees, P.T.

Auranen, K.

Badran, H.

Block, M.

Briselet, R.

Cox, D.M.

Dasgupta, Mahananda

Publisher

Elsevier

Abstract

The new neutron-deficient nuclei ²⁴⁰Es and ²³⁶Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from ²⁴⁰Es produced in the fusion–evaporation reaction ²⁰⁹Bi(³⁴S,3n) ²⁴⁰Es. Half-lives of 6(2)s and 22ˍ₆⁺¹³s were obtained for ²⁴⁰Es and ²³⁶Bk, respectively. Two groups of α particles with energies Eα=8.19(3)MeV and 8.09(3)MeV were unambiguously assigned to ²⁴⁰Es. Electron-capture delayed fission branches with probabilities of 0.16(6) and 0.04(2) were measured for ²⁴⁰Es and ²³⁶Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilities in more neutron-deficient isotopes.