The development of a β-decay tape station and the search for vibrations in Ruthenium isotopes

Makhathini, Lucky Maxwell (2021-03)

Thesis (PhD)--Stellenbosch University, 2021.

Thesis

ENGLISH ABSTRACT: This work gives details of the new facility that is introduced to iThemba LABS for nuclear structure studies, called the tape station. The technical description of this device is presented along with an experimental demonstration. A user-friendly control system for this device is developed and it can easily be integrated into the existing beam control system for the iThemba LABS beamline line control systems. Two versions of this device were successfully used to conduct experiments. The versatility of this device is demonstrated by performing multiple experiments, one with a shorter half-life and two with long half-lives. A method to produce "short-lived nuclei (radioactive nuclei)" at iThemba LABS is given. The low-lying states of 98,100Ru were investigated using the γ-ray spectroscopy following the β-decay of 98,100Rh. The source of activity for 162Yb was produced using the 147Sm(19F, 4n) reaction while in 98Ru and 100Ru were produced using the 89Y(12C, 3n)98Rh and 89Y(14N, p2n)100Rh, 89Y(14N, 3n)100Pd reactions at beam energies of 45 MeV and 47 MeV, respectively. The results obtained from experimental data are given and analysed. The 162Yb study demonstrated that this device is capable to be used to probe nuclei with shorter half-lives. While for 100Ru the data confirmed the γ-rays observed in the previous measurement, while in 98Ru new γ-rays were observed. The newly assigned γ and 0+2 bands in 98Ru fit well in the systematics of these excitations assigned in the heavier Ru isotopes while 100Ru differs. Beyond-mean-field calculations employing the self-consistent configuration mixing method suggest that the Ru isotopes are triaxiality deformed and shape coexistence occurs around 98Ru.

AFRIKAANSE OPSOMMING: ’n Nuwe fasiliteit wat gebruik kan word in kern struktuur navorsing is beskikbaar by die iThemba Laboratory of Accelerator Based Sciences (LABS). Hierdie fasiliteit, die sogenaamde bandstasie (tapestation), sal in detail beskryf word, asook ’n tipiese eksperiment. ’n Gebruikersvriendelike beheerstelsel wat maklik geintegreer kan word met die bundel beheerstelsel wat by iThemba LABS gebruik word is ontwikkel. Daar bestaan twee weergawes van hierdie nuwe eksperimentele fasiliteit, en beide is reeds suksesvol gebruik. Hierdie metings, twee waarvan die bestudeerde halfleeftyd lank was en een waarvan die halfleeftyd van belang kort was, toon duidelik die veelsydige aard van die bandstasie. In hierdie tesis word die eksperimentele proses bespreek wat gebruik is om radioaktiewe kerne met ’n kort halfleeftyd te vervaardig. Laagliggende energie toestande van 98,100Ru is bestudeer met behulp van gammastraal spektroskopie asook beta verval metings. Die radioaktiewe kern 162Yb is ook bestudeer, en is verkry deur die 147Sm(19F, 4n) reaksie. Die kerne 98Ru and 100Ru is respektiewelik verkry deur die volgende reaksies: 89Y(12C, 3n)98Rh en 89Y(14N, p2n)100Rh, 89Y(14N, 3n)100Pd. Analise van die eksperimentele data vir die 162Yb studie toon dat die bandstasie effektief gebruik kan word om kerne met ’n kort leeftyd te bestudeer. Bekende waardes vir gamma strale vanaf 100Ru is bevestig in hierdie metings, terwyl nuwe gamma oorgange waargeneem is vir die 98Ru kern. Nuut toegekende waardes vir die and 0+2 bande in 98Ru bevestig bestaande sistematiek soos bekend vir soortgelyke opwekkings in swaarder Ru isotope. Vir die 100Ru kern is die situasie egter anders. Gesofistikeerde teoretiese berekening wat ’n stap verder gaan as die standaard gemiddelde veld aanname, en wat gebruik maak van die eie konsistente konfigurasie menging metode, toon aan dat Ru isotope beskou kan word as drie-as vervormed kerne, en dat 98Ru aspekte van vorm naasbestaan toon.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/110041
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