Abstract
A chiral system is identified by the presence of a pair of near-degenerate ΔI=1 rotational
bands [1]. To date, a number of nuclei located in, A≈80, 100, 130 and 190 mass regions
were proposed as exhibiting chiral pairs. The chiral systems in the Tl isotopes in the 190
mass region, specifically those built on the πh9/2 ⊗ vi−n
13/2 configurations (where n=1,2,3),
have been studied in recent years, and a competition between a chiral pair and another
band built on the same configuration has been observed in 193,194Tl. 195Tl was studied
before but no such competition was reported. The most recent study on 195Tl reported
two chiral systems [2]. That work was followed by theoretical calculations using the
particle-rotor model which suggested that only one of the pairs was chiral while the other
one was planar [3]. To understand the nature of the bands in 195Tl, the high-spin states in
this nucleus were investigated at iThemba LABS using the 181Ta(18O, 4n)195Tl reaction.
The γ rays emitted during this experiment were detected with the AFRican Omnipurpose
Detector for Innovative Techniques and Experiments (AFRODITE) γ-ray spectrometer.
Angular distribution measurements were carried out and used to assign spins to the newly
and previously observed levels. In the current work 64 new or revised transitions were
placed in the 195Tl decay scheme. The analysis of the data from iThemba LABS did not
only lead to a considerable revision and extension of the previously known decay scheme
but also proposed a new chiral system different from the previous.