Edward O'Sullivan
About
My research project
Complete Decay Spectroscopy of Terbium-152The terbium theragnostic quartet is a group of four radioactive terbium isotopes with potential applications in personalised cancer treatments. Terbium-152 emits positrons in its decay, making it suitable for positron emission tomography (PET) imaging. However the decay is not well studied, limiting the ability of clinicians to calculate the radioactive dose to patients. Sources of terbium-152 were produced at CERN-ISOLDE in May 2023 and taken to ILL Grenoble for measurement. High-resolution detectors were used to correlate gamma rays emitted within nanoseconds of each other, providing insights into the excited nuclear states populated in the decay. Supported by angular correlation of gamma rays and a parallel electron-gamma spectroscopy experiment, the completed project aims to fully map the levels populated in the decay, providing clinicians with the nuclear data needed to support use of terbium-152 in cancer treatments.
Supervisors
The terbium theragnostic quartet is a group of four radioactive terbium isotopes with potential applications in personalised cancer treatments. Terbium-152 emits positrons in its decay, making it suitable for positron emission tomography (PET) imaging. However the decay is not well studied, limiting the ability of clinicians to calculate the radioactive dose to patients. Sources of terbium-152 were produced at CERN-ISOLDE in May 2023 and taken to ILL Grenoble for measurement. High-resolution detectors were used to correlate gamma rays emitted within nanoseconds of each other, providing insights into the excited nuclear states populated in the decay. Supported by angular correlation of gamma rays and a parallel electron-gamma spectroscopy experiment, the completed project aims to fully map the levels populated in the decay, providing clinicians with the nuclear data needed to support use of terbium-152 in cancer treatments.
Publications
Mean lifetime measurements of low-lying yrast positive- and negative-parity states of Gd 150 have been performed with the ROSPHERE array using the Ce 140 ( C 13 , 3 n ) fusion-evaporation reaction and the recoil distance Doppler shift method. Precise branching ratios have been obtained from a complementary electron capture decay experiment of both the isomer and ground state of Tb 150 . Reduced E 1 , E 2 , and E 3 transition probabilities were extracted and compared with the corresponding observables in the neighboring isotopes and isotones. The experimental data are compared to the predictions of various theoretical models: quasiparticle random phase approximation, time-dependent Hartree-Fock calculations, the quadrupole-octupole collective Hamiltonian, the mean-field mapped interacting boson model, and the triaxial projected shell model. We find that a complete description of both quadrupole and octupole collectivity, from ground and excited states, is currently lacking, and such measurements of transition strengths are crucial for constraining present and future calculations.
The radionuclide 152Tb, decaying by β+ emission and electron capture to 152Gd with T1/2= 17.8784(95) h, has been shown in its first-in-human use to be suitable for positron emission tomography (PET) imaging. As a member of the terbium theragnostic quartet, this radionuclide has potential applications in personalised cancer treatments. Sources of 152Tb were produced by proton-induced spallation of a tantalum target followed by on-line mass separation at CERN-ISOLDE. The sources were delivered to ILL Grenoble, where gamma–gamma coincidence spectroscopy of excited states populated in 152Gd following the decay was carried out using the Fission Product Prompt γ-ray Spectrometer (FIPPS). Preliminary analysis has resulted in the identification of multiple previously unreported excited states in 152Gd, thirteen of which are reported here at excitation energies up to 3746 keV. Angular correlation analysis has been used to provide initial spin and parity assignments to excited states. The result of the completed spectroscopy will be a revised gamma-ray and β+ dose to patients compared to the current expected values.