New yrast and non-yrast states in $^{136}$I and medium-spin structure of $^{136}$I and $^{136}$Xe : Roles of the proton d$_{5/2}$ and the neutron h$_{9/2}$ orbitals beyond $^{132}$Sn
Résumé
In this article we report on the observation of new yrast and non-yrast states in
136
I
, populated in the prompt-
γ
spectroscopy EXILL campaign at the ILL using both
235
U
(n,f) and
241
Pu
(n,f) reactions. We propose an extension of the level scheme and interpretation of the new spectroscopic results in comparison to state-of-the-art shell-model calculations. We discuss the role of the proton
d
5
/
2
orbital in the structure of this nucleus with
Z
=
53
and the energy split between the
π
d
5
/
2
and
π
g
7
/
2
orbitals. We also provide a complete overview of all experimental information about this nucleus and include new data from
252
Cf
,
248
Cm
fission and
β
decay of
136
Te
to
136
I
. We give a new interpretation of
136
I
and its decay to
136
Xe
in terms of the influence of the neutron
h
9
/
2
orbital and the Gamow-Teller strength for
N
=
83
.