ORCID Profile
0000-0003-2321-0222
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Surfacewater Hydrology | Atomic, Molecular, Nuclear, Particle and Plasma Physics | Hydrogeology | Physical Geography and Environmental Geoscience | Astronomical and Space Sciences not elsewhere classified | Synchrotrons; Accelerators; Instruments and Techniques | Physical Oceanography | Particle Physics | Nuclear Physics
ANZSRC Socio-Economic Objective (SEO)
Management of Water Consumption by Mineral Resource Activities | Expanding Knowledge in the Earth Sciences | Expanding Knowledge in the Physical Sciences | Emerging Defence Technologies | Scientific Instruments | Mining Land and Water Management |
Related Links
Publications
Masses and level schemes of 33Si and 34Si
Publisher: Elsevier BV
Date: 07-1985
First 26Al analyses at the ANTARES AMS Centre: uptake via oral ingestion of 26Al in rats
Publisher: Elsevier BV
Date: 06-1994
Measurement of U-233/U-234 ratios in contaminated groundwater using alpha spectrometry
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.JENVRAD.2015.08.013
Abstract: The uranium isotope (233)U is not usually observed in alpha spectra from environmental s les due to its low natural and fallout abundance. It may be present in s les from sites in the vicinity of nuclear operations such as reactors or fuel reprocessing facilities, radioactive waste disposal sites or sites affected by clandestine nuclear operations. On an alpha spectrum, the two most abundant alpha emissions of (233)U (4.784 MeV, 13.2% and 4.824 MeV, 84.3%) will overlap with the (234)U doublet peak (4.722 MeV, 28.4% and 4.775 MeV, 71.4%), if present, resulting in a combined (233+234)U multiplet. A technique for quantifying both (233)U and (234)U from alpha spectra was investigated. A series of groundwater s les were measured both by accelerator mass spectrometry (AMS) to determine (233)U/(234)U atom and activity ratios and by alpha spectrometry in order to establish a reliable (233)U estimation technique using alpha spectra. The Genie™ 2000 Alpha Analysis and Interactive Peak Fitting (IPF) software packages were used and it was found that IPF with identification of three peaks ((234)U minor, combined (234)U major and (233)U minor, and (233)U major) followed by interference correction on the combined peak and a weighted average activity calculation gave satisfactory agreement with the AMS data across the (233)U/(234)U activity ratio range (0.1-20) and (233)U activity range (2-300 mBq) investigated. Correlation between the AMS (233)U and alpha spectrometry (233)U was r(2) = 0.996 (n = 10).
Radionuclides in sea turtles at the Montebello Islands former nuclear test sites: Current and historical dose rates for adults and embryos
Publisher: Elsevier BV
Date: 09-2020
Accumulation of plutonium in mammalian wildlife tissues following dispersal by accidental-release tests
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.JENVRAD.2015.03.031
Abstract: We examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife inhabiting the relatively undisturbed, semi-arid former Taranaki weapons test site, Maralinga, Australia. The accumulation of absorbed Pu was highest in the skeleton (83% ± 6%), followed by muscle (10% ± 9%), liver (6% ± 6%), kidneys (0.6% ± 0.4%), and blood (0.2%). Pu activity concentrations in lung tissues were elevated relative to the body average. Foetal transfer was higher in the wildlife data than in previous laboratory studies. The amount of Pu in the gastrointestinal tract was highly elevated relative to that absorbed within the body, potentially increasing transfer of Pu to wildlife and human consumers that may ingest gastrointestinal tract organs. The Pu distribution in the Maralinga mammalian wildlife generally aligns with previous studies related to environmental exposure (e.g. Pu in humans from worldwide fallout), but contrasts with the partitioning models that have traditionally been used for human worker-protection purposes (approximately equal deposition in bone and liver) which appear to under-predict the skeletal accumulation in environmental exposure conditions.
The ANTARES AMS facility at ANSTO
Publisher: Elsevier BV
Date: 08-2004
Ground-state mass excesses and low-lying levels of the neutron-rich nuclei 36P, 35P and 34P
Publisher: Elsevier BV
Date: 07-1985
Using sedimentary prokaryotic communities to assess historical changes in the Gippsland Lakes
Publisher: Wiley
Date: 10-10-2023
DOI: 10.1111/FWB.14182
The ANTARES AMS Centre at the Lucas Heights Research Laboratories
Publisher: Elsevier BV
Date: 06-1994
High-precision radiocarbon measurements at the ANTARES AMS Centre
Publisher: Elsevier BV
Date: 06-1996
A study of 25Ne via the 26Mg(13C, 14O)25Ne reaction
Publisher: Elsevier BV
Date: 04-1985
Research and measurement program at the ANTARES AMS facility
Publisher: Elsevier BV
Date: 03-1997
Observations of 20n via the heavy-ion transfer reaction 48Ca(18O, 20N)46Sc
Publisher: Elsevier BV
Date: 1989
60 Fe deposition during the late Pleistocene and the Holocene echoes past supernova activity
Publisher: Proceedings of the National Academy of Sciences
Date: 24-08-2020
Abstract: Nearby supernova explosions shape the interstellar medium. Ejecta, containing fresh nucleosynthetic products, may traverse the solar system as a transient passage, or alternatively the solar system may traverse local clouds that may represent isolated remnants of supernova explosions. Such scenarios may modulate the galactic cosmic-ray flux intensity to which Earth is exposed. Varying conditions of the traversed interstellar medium could have impacts on climate and can be imprinted in the terrestrial geological record. Some radionuclides, such as 60 Fe, are not produced on Earth or within the solar system in significant quantities. Their existence in deep-sea sediments demonstrates recent production in close-by supernova explosions with a continued influx of 60 Fe until today.
14C in uranium and thorium minerals: a signature of cluster radioactivity?
Publisher: Springer Science and Business Media LLC
Date: 06-1999
Plutonium and other radionuclides persist across marine-to-terrestrial ecotopes in the Montebello Islands sixty years after nuclear tests
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.SCITOTENV.2019.06.531
Abstract: Since the 1956 completion of nuclear testing at the Montebello Islands, Western Australia, this remote uninhabited island group has been relatively undisturbed (no major remediations) and currently functions as high-value marine and terrestrial habitat within the Montebello/Barrow Islands Marine Conservation Reserves. The former weapons testing sites, therefore, provide a unique opportunity for assessing the fate and behaviour of Anthropocene radionuclides subjected to natural processes across a range of shallow-marine to island-terrestrial ecological units (ecotopes). We collected soil, sediment and biota s les and analysed their radionuclide content using gamma and alpha spectrometry, photostimulated luminescence autoradiography and accelerator mass spectrometry. We found the activity levels of the fission and neutron-activation products have decreased by ~hundred-fold near the ground zero locations. However, Pu concentrations remain elevated, some of which are high relative to most other Australian and international sites (up to 25,050 Bq kg
Examining the response of an eastern Australian mangrove forest to changes in hydro-period over the last century
Publisher: Elsevier BV
Date: 08-2020
Certified reference material for radionuclides in seawater IAEA-381 (Irish Sea Water)
Publisher: Springer Science and Business Media LLC
Date: 2002
The 40Ar(13C, 14O)39S reaction and the ground-state mass of 39S
Publisher: Elsevier BV
Date: 06-1989
Measurement of 236U in environmental media
Publisher: Elsevier BV
Date: 10-2000
Radioactive particles from a range of past nuclear events: Challenges posed by highly varied structure and composition
Publisher: Elsevier BV
Date: 10-2022
Accelerator Mass Spectrometry on SIRIUS: New 6 MV spectrometer at ANSTO
Publisher: Elsevier BV
Date: 09-2017
The ansto isotope cycling system
Publisher: Cambridge University Press (CUP)
Date: 2013
Characterization of deep-level defects in GaAs irradiated by 1 MeV electrons
Publisher: AIP Publishing
Date: 15-01-1993
DOI: 10.1063/1.353375
Abstract: Deep level transient spectroscopy has been employed to determine the defect energy levels, capture cross sections, and trap densities in Si-doped vapor phase epitaxy GaAs both before and after irradiation by 1 MeV electrons at room temperature for electron fluence ranging from 1.1×1014 to 5.0×1015 e cm−2. The results indicate that the irradiated s les have an electron trap at Ec-0.334 eV(EL6) in addition to the two electron traps at Ec-0.815 eV(EL2) and Ec-0.420 eV(EL3) which are present in the nonirradiated s le. The density of the EL6 trap increases monotonically with irradiation fluence from 6.7×1013 to 24.4×1013 cm−3 as electron fluence is increased from 1.1×1014 to 3.1×1014 e cm−2. In contrast, both the EL2 and EL3 trap densities were found to be only moderately affected by electron irradiation with trap densities slightly greater than the nonirradiated s le. These results, along with the fact that the EL6 trap was not observed in the nonirradiated s le, strongly suggest that this trap is created by the electron irradiation. In addition to creating the EL6 trap, electron irradiation results in a nonexponential transient for the EL2 deep level at Ec-0.815 eV which can be resolved into the sum of two exponential transients arising from two closely spaced deep levels at Ec-0.815 eV and Ec-0.843 eV.
Time-of-flight system for a heavy ion magnetic spectrometer
Publisher: Elsevier BV
Date: 10-1987
Measurements of the 14CO2 bomb pulse in firn and ice at Law Dome, Antarctica
Publisher: Elsevier BV
Date: 03-1997
Radiocarbon detection by ion charge exchange mass spectrometry
Publisher: Elsevier BV
Date: 06-2007
Scavenger hunt: Searching for the optimal target material for low-level 210Pb accelerator mass spectrometry
Publisher: Elsevier BV
Date: 10-2022
SIRIUS – A new 6 MV accelerator system for IBA and AMS at ANSTO
Publisher: Elsevier BV
Date: 03-2016
AMS at ANTARES – The first 10 years
Publisher: Elsevier BV
Date: 10-2000
Equipment and methodology for high precision, high throughput 14C AMS analyses at ANTARES
Publisher: Elsevier BV
Date: 06-1994
The Antares AMS Centre: A Status Report
Publisher: Cambridge University Press (CUP)
Date: 1995
DOI: 10.1017/S0033822200031180
Abstract: The ANTARES accelerator mass spectrometry facility at Lucas Heights Research Laboratory is operational and AMS measurements of 14 C, 26 Al and 36 Cl are being carried out routinely. Measurement of 129 I recently commenced and capabilities for other long-lived radioisotopes such as 10 Be are being established. The overall aim of the facility is to develop advanced programs in Quaternary science, global climate change, biomedicine and nuclear safeguards.
60Fe and244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-05-2021
Abstract: The rapid neutron capture process (r-process) produces many of the heavy chemical elements, but the astrophysical settings where it occurs remain unclear. Leading candidates are neutron star mergers and some types of supernovae. Wallner et al. analyzed the plutonium content of a deep-sea crust s le, identifying a few dozen atoms of the r-process isotope plutonium- 244 that were delivered to Earth within the past few million years. There was a simultaneous signal of iron-60, which is known to be produced in supernovae. Comparing the ratios of these isotopes constrains the relative contributions of supernovae and neutron star mergers to r-process nucleosynthesis. Science , this issue p. 742
Sulphur hexafluoride as a stripper gas for tandem accelerators
Publisher: Elsevier BV
Date: 05-2013
Untangling geochronological complexity in organic spring deposits using multiple dating methods
Publisher: Elsevier BV
Date: 02-2018
Ionisation efficiency improvements for AMS measurement of actinides
Publisher: Elsevier BV
Date: 04-2010
Investigation of gas stripping at 4.1MeV for high mass negative ions
Publisher: Elsevier BV
Date: 2013
The mass and low-lying levels of 40Cl
Publisher: Elsevier BV
Date: 04-1984
14C analyses at the ANTARES AMS Centre: Dating the log coffins of northwest Thailand
Publisher: Elsevier BV
Date: 06-1994
A record of fallout 239Pu and 240Pu at World Heritage Bathurst Harbour, Tasmania, Australia
Publisher: Elsevier BV
Date: 10-2021
From carbon to actinides: A new universal 1MV accelerator mass spectrometer at ANSTO
Publisher: Elsevier BV
Date: 10-2015
The 26Mg(18O, 17F)27Na and 26Mg(18O, 15O)29Mg reactions and the level schemes of 27Na and 29Mg
Publisher: Elsevier BV
Date: 04-1985
Actinides AMS on the VEGA accelerator
Publisher: Elsevier BV
Date: 2019
The mass of 18C from a heavy ion double-charge-exchange reaction
Publisher: Elsevier BV
Date: 09-1982
Plutonium in wildlife and soils at the Maralinga legacy site: persistence over decadal time scales
Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1016/J.JENVRAD.2013.10.014
Abstract: The mobility of plutonium (Pu) in soils, and its uptake into a range of wildlife, were examined using recent and ∼25 year old data from the Taranaki area of the former Maralinga weapons test site, Australia. Since its initial deposition in the early 1960s, the dispersed Pu has been incorporated into the soil profile and food chain through natural processes, allowing for the study of Pu sequestration and dynamics in relatively undisturbed semi-arid conditions. The data indicate downward mobility of Pu in soil at rates of ∼0.2-0.3 cm per year for the most mobile fraction. As a result, while all of the Pu was initially deposited on the ground surface, approximately 93% and 62% remained in the top 0-2 cm depth after 25- and 50-years respectively. No large-scale lateral spreading of the Taranaki plume was observed. Pu activity concentrations in 0-1 cm soils with biotic crusts were not elevated when compared with nearby bare soils, although a small number of in idual data suggest retention of Pu-containing particles may be occurring in some biotic crusts. Soil-to-animal transfer, as measured by concentration ratios (CRwo-soil), was 4.1E-04 (Geometric Mean (GM)) in mammals, which aligns well with those from similar species and conditions (such as the Nevada Test Site, US), but are lower than the GM of the international mammal data reported in the Wildlife Transfer Database (WTD). These lower values are likely due to the presence of a low-soluble, particulate form of the Pu in Maralinga soils. Arthropod concentration ratios (3.1E-03 GM), were similar to those from Rocky Flats, US, while values for reptiles (2.0E-02 GM) were higher than the WTD GM value which was dominated by data from Chernobyl. Comparison of uptake data spanning approximately 30 years indicates no decrease over time for mammals, and a potential increase for reptiles. The results confirm the persistence of bioavailable Pu after more than 50 years since deposition, and also the presence of larger-sized particles which currently affect CRwo-soil calculations, and which may serve as an ongoing source of bioavailable Pu as they are subjected to weathering into the future.
O
Publisher:
American Physical Society (APS)
Date:
11-1984
Publisher: American Physical Society (APS)
Date: 11-1984
14C AMS measurements of the bomb pulse in N- and S-hemisphere tropical trees
Publisher: Elsevier BV
Date: 03-1997
Measurement of fallout radionuclides, Pu-239,Pu-240 and Cs-137, in soil and creek sediment: Sydney Basin, Australia
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.JENVRAD.2015.06.015
Abstract: Soil and sediment s les from the Sydney basin were measured to ascertain fallout radionuclide activity concentrations and atom ratios. Caesium-137 ((137)Cs) was measured using gamma spectroscopy, and plutonium isotopes ((239)Pu and (240)Pu) were quantified using accelerator mass spectrometry (AMS). Fallout radionuclide activity concentrations were variable ranging from 0.6 to 26.1 Bq/kg for (137)Cs and 0.02-0.52 Bq/kg for (239+240)Pu. Radionuclides in creek sediment s les were an order of magnitude lower than in soils. (137)Cs and (239+240)Pu activity concentration in soils were well correlated (r(2) = 0.80) although some deviation was observed in s les collected at higher elevations. Soil ratios of (137)Cs/(239+240)Pu (decay corrected to 1/1/2014) ranged from 11.5 to 52.1 (average = 37.0 ± 12.4) and showed more variability than previous studies. (240)Pu/(239)Pu atom ratios ranged from 0.117 to 0.165 with an average of 0.146 (±0.013) and an error weighted mean of 0.138 (±0.001). These ratios are lower than a previously reported ratio for Sydney, and lower than the global average. However, these ratios are similar to those reported for other sites within Australia that are located away from former weapons testing sites and indicate that atom ratio measurements from other parts of the world are unlikely to be applicable to the Australian context.
New measurements of the masses of 15B and 19N
Publisher: Elsevier BV
Date: 04-1983
Quantifying sources of fine sediment supplied to post-fire debris flows using fallout radionuclide tracers
Publisher: Elsevier BV
Date: 02-2012
Recent developments at the ANTARES AMS centre
Publisher: Elsevier BV
Date: 11-1996
Related Organisations
No related organisations have been discovered for Michael Hotchkis.
Related Funding Activities
ARC Centres Of Excellence - Grant ID: CE200100008
Start Date: 08-2020
End Date: 08-2027
Amount: $35,000,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE160100027
Start Date: 06-2016
End Date: 12-2018
Amount: $600,000.00
Funder: Australian Research Council
View Funded Activity