School Seminar Program

Trapping energy traps: mass spectrometry of nuclear isomers

Matthew Reed
Thursday 19 September 2013 4–5pm
Leonard Huxley Theatre

Dr Matthew Reed
Nuclear Physics

The structure of a nucleus can lead to excited states that have lifetimes much longer than the average nuclear state. These interesting metastable excited states are called nuclear isomers [1] and are useful probes for many different aspects of nuclear structure. The conventional way to examine isomers is by observing their decay via a γ-ray or particle emission, indirectly measuring the isomer’s energy. However, if the state is particularly long-lived it becomes increasingly hard to observe its decay and associate it with a specific isotope. A way to measure the isomer in a direct fashion is required; high-precision mass spectrometry enables this.

The use of mass spectrometry to measure the mass of a nucleus in its groundstate is a well-studied avenue of research and in itself gives interesting structural information [2]. In recent years, these instruments have reached the level of precision where it is possible to resolve masses of single ions with an accuracy of 10 keV. With this unprecedented level of precision, it is now possible to resolve isomers independently from their associated groundstate, a direct proof of E=mc2.

This presentation will review the techniques of Schottky Mass Spectrometry (SMS) and Isochronous Mass Spectrometry (IMS) for measurements of groundstate masses and isomer excitation energies [4] as well as present recent results obtained for neutron-rich isomers [5, 6]. These results contribute to the current understanding of nuclear structure, of conditions in supernovas where isomer properties affect isotope production and/or survival in nature, and for the possible development of novel energy storage devices.

[1] P. M. Walker and G. D. Dracoulis, Nature (London) 399, 35 (1999).

[2] D. Lunney, J.M. Pearson and C. Thibault, Rev. Mod. Phys. 75 (2003) 1021.

[3] Yu. A. Litvinov, et al., Nucl. Phys. A 756, 3 (2005).

[4] F. Bosch et al., J. Phys. B 36, 585 (2003).

[5] M. W. Reed et al., Phys. Rev. Lett. 105, 172501 (2010).

[6] M. W. Reed et al., Phys. Rev. C 86, 054321 (2012).

Dr Matt Reed received a masters in physics from the University of Leicester (U.K.) in 2007. Moving to the Centre for Nuclear and Raditation Physics at the University of Surrey (U.K.), he completed his Ph.D. in 2012. His investigations into excited states in heavy neutron-rich nuclei received the Institute of Physics early career researcher, nuclear physics prize. He is currently working as a postdoctoral research fellow researching shape transitions in exotic nuclei using γ-ray spectroscopy.

Refreshments will be held in the Tea Room after the Seminar (around 5pm)

ALL WELCOME

Contact

Professor Hoe Tan
Hoe.Tan@anu.edu.au
(02)61250356

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