Final PhD Seminar

Gamma-ray and electron spectroscopy with Solenogam

Mr Matthew Gerathy
Department Nuclear Physics

Solenogam is a recoil spectrometer designed and constructed for use at the ANU Heavy Ion Accelerator Facility. The design enables the study of nuclear excitations populated in the decay of long-lived states such as isomers and radioactive ground states.  A gas-filled superconducting solenoid is used to transport the products of fusion-evaporation reactions to a focal plane where Solenogam is situated; it consists of high-sensitivity gamma-ray and electron detector arrays for singles and coincidence measurements.

This work represent the first on-line measurements using the full Solenogam array and the ability to measure gamma-gamma, electron-electron and gamma-electron coincidences has increased the sensitivity of the array; this enables the study of weak decays and complex level schemes.  A number of nuclear systems have been studied during implementation and testing including the beta-decay of both 190Au and 184Au into 190Pt and 184Pt, respectively. More recently, the decay of the high-spin, T1/2=0.96-μs isomer in the N=83 nucleus, 145Sm, has been studied using the 124Sn(26Mg,5n) reaction at a beam energy of 115 MeV. Microsecond chopped beams were used to isolate the isomeric decay resulting in a (longer) revised lifetime and significant changes to the level scheme. Conversion coefficients were measured to confirm the isomer spin and parity for the first time with the new level scheme interpreted using shell-model calculations.  The new results for 145Sm, as well as other results that demonstrate the measurement capabilities of Solenogam, will be presented.

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