G5 Doctoral dissertation (article)
Combined γ-ray and electron spectroscopy : study of shape coexistence in 186Pb (2023)

Ojala, J. (2023). Combined γ-ray and electron spectroscopy : study of shape coexistence in 186Pb [Doctoral dissertation]. University of Jyväskylä. JYU dissertations, 604. http://urn.fi/URN:ISBN:978-951-39-9288-0

JYU authors or editors

Publication details

All authors or editors: Ojala, Joonas

eISBN: 978-951-39-9288-0

Journal or series: JYU dissertations

eISSN: 2489-9003

Publication year: 2023

Number in series: 604

Number of pages in the book: 1 verkkoaineisto (84 sivua, 10 numeroimatonta sivua)

Publisher: University of Jyväskylä

Place of Publication: Jyväskylä

Publication country: Finland

Publication language: English

Persistent website address: http://urn.fi/URN:ISBN:978-951-39-9288-0

Publication open access: Openly available

Publication channel open access: Open Access channel

Abstract

Structures in 186Pb have been under extensive investigation for several decades. 186Pb is the system having a low-lying triplet of zero-spin states, which are assigned with different shapes (spherical, prolate and oblate). This nucleus has been previously studied using α-decay and in-beam γ-ray spectroscopic methods but the transitions near the ground state remained a mystery due to the large conversion coefficient. In this thesis, the low-lying structure of 186Pb was experimentally investigated by combined γ-ray and electron spectrometer, SAGE, and utilising the recoil-decay tagging method. As a result, the E0 2+2 → 2+1 and 4+ 2 → 4+1 interband transitions could be assessed. Also, the feeding of the first excited 0+ 2 state was observed for the first time. Results allowed for reassigning the shapes of 0+ states in 186Pb, which provide input for new theoretical calculations. Recent developments for in-beam γ-ray spectroscopy at the Accelerator Laboratory of Jyväskylä forms part of this thesis work. The properties of the JUROGAM 3 germanium array, such as energy resolution, add-back factor and photopeak detection efficiency, can be found in the fifth chapter. Also, the sum-peak method to determine the absolute photopeak detection efficiency of a germanium array is explained in this chapter. The issue with pile-up marking in the DAQ system is also raised to notify other potential users.

Keywords: spectroscopy; gamma radiation; electrons; doctoral dissertations

Free keywords: shape coexistence; conversion electron spectroscopy; γ-ray spectroscopy; SAGE; JUROGAM 3

Contributing organizations

Ministry reporting: Yes

VIRTA submission year: 2023