Speaker
Description
The study of $\beta$-decay properties of neutron-rich nuclei in the A $\approx$ 120 region provides key insights into nuclear-structure evolution and serves as a critical benchmark for modern theoretical models, as well as for astrophysical r-process simulations. In this context, the $\beta$-decay of $^{118}$Pd ($Z$ = 46, $N$ = 72), populating excited states in $^{118}$Ag, has been investigated at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyväskylä.
The $^{118}$Pd isotope was produced via proton-induced fission of uranium and subsequently purified and mass-separated using the JYFLTRAP system to ensure high isotopic purity. The decay spectroscopy setup consisted of three high-purity germanium detectors for $\gamma$-ray detection, a plastic scintillator for β tagging, and a movable tape-transport system for activity collection and removal.
A comprehensive analysis of $\beta-\gamma$ and $\gamma-\gamma$ coincidence data has led to a substantial revision of the previously established decay scheme of $^{118}$Pd [1]. Several new γ transitions and previously unreported excited states in $^{118}$Ag have been identified. Furthermore, a cascade of transitions indicative of a new isomeric state [2] has been proposed.
Ongoing work focuses on the extraction of $\beta$-feeding intensities and log ft values, which are essential for constraining spin–parity assignments and refining theoretical descriptions of $\beta$-decay strength distributions in this mass region.
The presented results contribute to the systematic investigation of neutron-rich palladium and silver isotopes, offering improved understanding of nuclear structure in the vicinity of N ≈ 70 and providing valuable experimental input for r-process nucleosynthesis models. A summary of the latest findings will be presented and discussed.
[1] Z. Janas, J. Äystö, K. Eskola, P.P. Jauho, A. Jokinen, J. Kownacki, M. Leino, J.M. Parmonen, H. Penttilä, J. Szerypo, J. żylicz,
Gamow-Teller decay of 118Pd and of the new isotope 120Pd,
Nuclear Physics A,
Volume 552, Issue 3,
1993,
Pages 340-352,
ISSN 0375-9474,
[2] B. van den Borne, M. Stryjczyk, R. P. de Groote, A. Kankainen, D. A. Nesterenko, L. Al Ayoubi, P. Ascher, O. Beliuskina, M. L. Bissell et al.
Binding energies, charge radii, spins, and moments:
Odd-odd Ag isotopes and discovery of a new isomer