Guest Lecturer
Dr Michaela Froehlich
Michaela Froehlich has obtained her PhD in chemistry from the University of Vienna in 2011 and has significant experience in radiochemistry. Her measurements demonstrated for the first time that uranium-236 is detectable in the environment.
In 2012, she moved to Australia to accept a Postdoctoral Position at the Australian National University where she continued combining innovative chemistry and Accelerator Mass Spectrometry. She is also part of the Advanced Metrology Team at the ARC Centre of Excellence for Dark Matter Particle Physics where she develops chemical separation techniques to extract radioimpurities such as lead-210 and optimises the AMS measurements to characterise and quantify their background in high-purity detector material.
In 2019, she was awarded the Trevor Ophel Innovation Award and in 2023, the Environmental Chemistry Medal Award by the Royal Australian Chemical Institute in recognition of her work dedicated to developing methods for trace level actinide radionuclides used as environmental tracers. She serves as Associate Editor for the Journal of Environmental Radioactivity and is the Vice-President of the South Pacific Environmental Radioactivity Association.
Michaela is also a STEM Coach as part of the Curious Minds program since 2022. Here, she coaches and mentors female Year 9 and Year 10 students to explore their potential in STEM studies and careers.
Presentation topic: Alpha Spectrometry and Accelerator Mass Spectrometry – A Strong Alliance
This lecture will provide a brief summary about actinides in general and then focus on different procedures separating uranium, plutonium and americium from environmental samples.
Here, the main emphasis is on column chromatography and how methods changed over time, for example the introduction of extraction resins. At the end, two measurement techniques, namely alpha spectrometry and accelerator mass spectrometry, will be introduced to showcase their synergy.
Guest Lecturer
Dr Madison Williams-Hoffman
Dr Madison Williams-Hoffman is a Postdoctoral Research Fellow in the ARC Industrial Transformation Training Centre for Radiation Innovation, aka RadInnovate, at the Australian National University. Her research revolves around the detection and assessment of radionuclides in the Australian environment, while her PhD at Edith Cowan University focussed on the quantification of nuclear-weapon legacies in coastal ecosystems.
She has years of practical experience with alpha spectrometry techniques for the quantification of anthropogenic radionuclides from nuclear activities, as well as 210Po applied to the measurement of sediment dating in aquatic environments. She is a long-time member of both the South Pacific Environmental Radioactivity Association (SPERA) and the Royal Australian Chemical Institute (RACI) and is passionate about helping foster the production of good quality radionuclide measurements and data in Australia now and into the future.
Presentation topic: Sampling and sample preparation for alpha spectrometry
Ensuring representative and accurate alpha spectrometry analyses in environmental samples starts long before the first count. This lecture will cover important considerations to be made across sampling design, sample preparation, digestion and source preparation techniques that should be considered prior to commencing analysis.
This session looks at three phases for environmental alpha spectrometry studies: the pre-sampling phase, the sample preparation phase and the radiochemical phase.
In the pre-sampling phase, we will look at key factors to be explored before samples are taken, including which sampling strategies and study designs are best suited for a given environmental assessment and how sample types and matrices should be carefully considered prior to collection to enable intercomparison of studies, sites and sampling years.
In the sample preparation phase, we will explore the impact of deciding on size fractionation and the definition of bulk soils and sediments, and the run on effects of these decisions. Lastly, we will turn to the radiochemical phase which will primarily address the impact of different digestion processes such as acid leaching, microwave-assisted digestion and fusion systems on environmental studies. We will finish with an overview of autodeposition specifically for plating of 210Po from soil, sediment and biological material.
Peter Medley
Peter Medley obtained his PhD in Research at the Australian National University School of Physics and Engineering, Canberra in 2025, on New techniques to assess 231Pa and 227Ac abundance and transfer in environmental media. He has over 20 years of experience in radiation protection, including environmental radiochemistry, gamma surface surveys, radon monitoring and dose assessment.
Peter works in Radiation Sciences (Queensland Health) with demonstrated specialist expertise in techniques for low-level measurement of environmental radioactivity, alpha and gamma spectrometry, liquid scintillation counting techniques and method development. He has published and presented on practical radiochemical improvements for alpha spectrometry source preparation, including rapid micro-precipitation approaches for 210Po, with an emphasis on robust performance in complex sample matrices. He is currently on a secondment with the Environmental Research Institute of the Supervising Scientist in Darwin.
John Pfitzner
John is an experienced practitioner in environmental radioactivity measurement with the Office of the Supervising Scientist. His diverse technical experience includes laboratory and field instrumentation, with a special focus on HPGe gamma detector calibrations, environmental radon measurements and assessing radon retention in sample containers—experience that strongly complements end-to-end alpha spectrometry training from sample preparation through to defensible results.