AbstractOver the last 60 years, there have been a number of studies aimed at understanding the
mechanisms that drive deformation. The A∼100 region has been particularly intriguing
due to a rapid change from spherical to deformed nuclear shapes at N=59, the suddenness
of these changes is not well understood. The results presented in this thesis provide new
information about the shape and structure of the Z=39, N=63 nucleus, 102Y. Previous
studies at the TRISTAN facility at Brookhaven National Laboratory and at the JOSEF
recoil separator at the Research Centre Julich have established the possible existence of ¨
a low-lying isomeric state in 102Y, but no spin or parity assignments could be made, nor
could the excitation energy be established.
In the current work, an initial experiment conducted using the double Penning trap
system at the University of Jyv¨askyl¨a, Finland, utilised the Ramsey cleaning technique to
separate ions in the ground state from ions in the isomeric state. This experiment was
able to establish an upper limit of 100 keV to the excitation energy of the isomeric state.
In a second experiment at the University of Jyv¨askyl¨a the gamma decay in 102Zr following
the beta decay of long-lived states in 102Y was measured simultaneously using a post-trap
γ-spectroscopy setup. The results support the existence of two β-decaying states in 102Y,
and new γ-ray transitions have been added to level scheme for 102Zr. A supplementary
data set obtained at the Radioactive Isotope Beam Factory, RIKEN, Japan provided an
alternative way to study the decay of the two long-lived states in 102Y. The results confirm
the two different decay chains identified previously at TRISTAN and JOSEF.
With the aid of BCS calculations, spin and parities for the ground and isomeric states
in 102Y have been assigned for the first time as 5− and 0− respectively, arising from the
coupling of a 5/2 neutron and 5/2 proton. Combining the theoretical calculations
with the experimental data it has been shown that the 5− ground state predominantly
populates negative parity states in 102Zr via allowed transitions, while the 0− isomeric
state primarily populates positive parity states in 102Zr via first-forbidden decays.
|Date of Award||Jun 2018|
|Supervisor||Alison Bruce (Supervisor)|
Spin and parity assignment for the ground and isomeric states in <sup>102</sup>Y
Nobs, C. (Author). Jun 2018
Student thesis: Doctoral Thesis