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ISBN 0-7313-9711-8

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AUSTRALIAN INSTITUTE OF NUCLEAR SCIENCE AND ENGINEERING

AINSE'S 40TH ANNIVERSARY CONFERENCE

LUCAS HEIGHTS, SYDNEY, 2 & 3 DECEMBER 1998

CONFERENCE HANDBOOK (containing program, abstracts and list of participants) LIST OF PARTICIPANTS AUSTRALIAN INSTITUTE OF NUCLEAR SCIENCE AND ENGINEERING

AINSE'S 40TH ANNIVERSARY CONFERENCE

AINSE Theatrette, Lucas Heights, Sydney 2 & 3 December 1998

Conference Committee: Professor Helen Garnett, Chief Executive, ANSTO Professor Trevor Ophel, Australian National University Dr John Boldeman, ANSTO Professor Claudio Tuniz, ANSTO A/Professor Ron Cooper, The University of Melbourne Professor Ron McDonald, University of Newcastle Dr Dennis Mather, AINSE

Conference Manager: Mrs Margaret Lanigan, Conference Overload (Australia) Pty Ltd PROGRAM AINSE'S 40TH ANNIVERSARY CONFERENCE

Lucas Heights, 2-3 December 1998 PROGRAM

WEDNESDAY 2 DECEMBER Abstract page no. 0930-1030 Registration/coffee

1030-1100 An historical review and perspective of AINSE Professor Trevor Ophel, President of AINSE

1100-1130 Archaeometry and AINSE Dr Wallace Ambrose

1130-1200 Nuclear physics achievements via AINSE Dr John Boldeman

1200-1230 AINSE - More than 20 years of ion beam analysis Dr David Cohen

1230-1400 Lunch and poster displays

1400-1430 The ever expanding field of ion beam analysis A/Professor John O'Connor 5

1430-1500 The contribution of AMS to geosciences Professor Allan Chivas 6

1500-1530 Future directions of the AMS program at Lucas Heights Dr Claudio Tuniz

1530-1600 Afternoon tea/coffee

1600-1630 Evolution of materials research within the AINSE portfolio Dr Adam Jostsons

1630-1700 The National Centre for Neutron Scattering Dr Trevor Hicks

1700-1730 Neutron scattering in the 21st Century Professor John White 10

1830-2130 Conference Dinner in ANSTO canteen Guest speaker: Professor Max Brennan, AO Australian Science - Past, Present & Future

THURSDAY 3 DECEMBER 0900-0930 Highlights from the past Mr Bill Palmer, OBE: AINSE - the first 30 years -1958-1988 11 Dr Roger Gammon: AINSE - The years between 1988 and 1998 12 Abstract page no.

0930-1000 Nuclear science and a better environment - an oxymoron? Dr Gerald Laurence 13

1000-1030 Getting warmer? Can models predict the future of the earth's climate?

Professor Anne Henderson-Sellers 14 1030-1100 Morning tea/coffee 1100-1130 Diverse applications of radiation chemistry A/Professor Ron Cooper 15 1130-1200 Uses of neutron scattering in supramolecular chemistry Professor Leonard F Lindoy 16

1200-1230 The unique facilities offered by gamma radiolysis to understand polymerisation kinetics Professor Robert G Gilbert 17

1230-1400 Lunch and poster displays

1400-1430 Fusion plasma physics research on the H-1 National Facility Professor Jeffrey Harris 18

The Rotamak - Contributions from ANSTO and 1430-1500 Flinders University Professor Ieuan Jones 19

Low temperature plasmas - from fundamentals 1500-1530 to commercial applications Dr Matthew Fewell 20

1530-1600 Afternoon tea/coffee

1600-1630 Radiolanthanides in therapeutic nuclear oncology Professor J Harvey Turner 21

Fission track modelling and visualisation of the 1630-1700 thermotectonic evolution of Australia Professor Andrew Gleadow 22

Partnerships in nuclear science and technology contributing 1700-1730 to the 'high road' to the future Professor Helen Garnett, Chief Executive, ANSTO 23

1730 Close of Conference POSTER PAPERS Abstract page no. VENUE: Council Room, AINSE

Biogeochemistry of the Ballarat East Goldfield Jackie Stott, Dennis Arne and Helen Waldron 25

Mobility of rare earth elements in hydrothermally altered meta-turbidites associated with mesothermal gold mineralisation in Central Victoria Frank P Bierlein, Helen M Waldron and Dennis C Arne 26

Monte Carlo calculation of synchrotron x-ray beam dose profiles in a lung phantom F Z Company and B J Allen 27

Monte Carlo simulations of the dose characteristics of microplanar photon beams in mammography F Z Company and B J Allen 28

Ferrimagnetism in MNxVj,x alloys L D Cussen, T J Hicks, A J Studer and S J Kennedy 29

Ordering and interactions in MnPS3 D J Goossens and T J Hicks 30

Modification of surfaces following plasma implantation of helium P W Gilberd, P B Johnson, J Y Lazar, A Markwitz, W J Trompetter, K T Short and G A Collins 31

Twenty thousand years of changing obsidian trade in Melanesia J Peter White and Robin Torrence 32

A novel method of radon grab sampling in caves Craig Barnes, Michael Hyde, Julia James, Stewart Whittlestone and Wlodek Zahorowski 33

The crystal and magnetic structure of Nd3Co2^iJS10 Heng Zhang, S J Campbell, E Wu, S J Kennedy, M Hofmann, H-S Li and A J Studer 34

Neutron diffraction studies of mechanochemically synthesized iron oxides E Wu, S J Campbell, W A Kaczmarek, M Hofmann, S J Kennedy and A J Studer 35

Structural influences of substitution into synthetic apatites Jean Y Kim. Ronald R Fenton, Brett A Hunter and Brendan J Kennedy 36

Structural refinement of cis-bis(L-alaninato)copper(II) S M Moussa. R R Fenton, B A Hunter, B J Kennedy and R O Piltz 37

Studies of copper transport in mammalian cells using copper radioisotopes J Camakaris, S Smith, I Voskoboinik, H Brooks, J Mercer and M Greenough 38 Abstract page no.

The Flinders University inductively driven Spherical Tokamak project Lance McCarthy 39

Radioactive disequilibrium in mound spring deposits J R Prescott, M A Habermehl and Henk Heijnis 40

The retention of caesium and strontium in cemented zeolites A S Ray, M G Stevens, R S Knight, K Stevenson and C Mapson 41

Two new solid solutions in calcite-magnesite system identified in a sample from coral reefs in the Northern Perth Basin D Y Li, B H O'Connor, Z R Zhu, L B Collins and B Hunter 42

Contributions of radiation chemistry to research David F Sangster 43

Development of a fast data acquisition and processing system for spectroscopy diagnostic on H-1NF device Shu Zhang and Xuehua Shi 44

Use of neutron diffraction in alumina-matrix ceramics research: a 10 year perspective B H O'Connor, A van Riessen and D Y Li 45

Evidence for cerium mobility in used automotive catalytic converters: a PIXE/PIGME milliprobe investigation D E Angove, N Dytlewski, G M Bailey, N W Cant and D D Cowen 46

VENUE: Function Room, Stevens Hall

Significance of grafting in radiation curing reactions. Comparison of ionising radiation and UV systems Elvis Zilic, John L Garnett, Loo-Teck Ng and Visay Viengkhou 47

Modelling the angular momentum J, of Is, Ip, Id, 2s and If nucleons Peter Norman 48

Electrical and magnetic phases of the layered perovskites Ca^JuaJdnsOw P Goodman, Shane Kennedy, N S Witte, F J Lincoln and R H March 49

The high energy radiation chemistry of some fluorinated elastomers John S Forsythe, David J T Hill and Andrew K Whittaker 50

Inertial confinement fusion and related results H Hora, J C Kelly, P McMillan, T Rowlands, R J Stening, B Boreham, S Newman, F Osman and R Castillo 51

Natural radioactivity in environmental studies Henk Heijnis, Andrew Jenkinson and Robert Chisari 52 Abstract page no.

The effect of MEW A ion implantation on the tribological properties of PVD-TiN films Rafael Manory, Simon Mollica and Peter Evans 53

Study of thin (~2nn) surface oxide layers on silicon using high resolution 2 MeV He RBS-channeling L S Wielunski and M J Kenny 54

Age of the last glaciation of Vestfold Hills and significance for sea level change Damian B Gore and Eric A Colhoun 55

Age estimates of stick-nest rat middens Stuart Pearson and Ewan Lawson 56

SIMS analysis of nitrided austenitic stainless steel P T Burke, K E Prince, M Baldwin, J Priest and M P Fewell 57

The actinide beamline - a new AMS facility at ANTARES MAC Hotchkis, P J Lee and N Mino 58

In-situ cosmogenicI0 Be and 36Cl studies in the earth sciences at the ANTARES AMS facility David Fink, Greg Elliot, David Child and Charles Misfud 59

Recent tree ring analyses at the ANTARES AMS Centre Q Hua, M Barbetti, G E Jacobsen, U Zoppi, E M Lawson, A M Smith and N Lenh 60

The mechanism of copper activation of sphalerite Andrea Gerson, Roger Smart, Angela Lange and Kathryn Prince 61

Neutron scattering applied to environmental waste containment M M Elcombe, A J Studer and C L Waring 62

Neutron beam facilities at the replacement reactor S J Kennedy 63

Oxide research using neutron scattering B A Hunter, C J Howard and B J Kennedy 64

Structural characterisation of 1- and 2-dimensional transition metal polymers using neutron powder diffraction Michael James 65

Applications of the small angle neutron scattering technique - an ANSTO/AINSE collaboration R B Knott 66

Carbon monoxide migratory insertion - a comparison of cationic and neutral palladium(II) complexes Katrina E Frankcombe, Kingsley J Cavell, Brian F Yates and Robert B Knott 67 Abstract page no.

Heavy ion time-of-flight analysis of titanium-oxy-nitride thin films for solar energy applications J Metson, A Bittar, L J Tornquist, I Vickeridge, N Dytlewski and D D Cohen 68

The high energy heavy ion microprobe and its detection systems R Siegele and David D Cohen 69

Neutron diffraction and magnetic studies of Rhomobohedral La1.xSrxMnO3+s T Ersez, C M D'Souza, S J Kennedy and B C Chakoumakos 70

Fine resolution AMS 14C chronology for lunette-lake sediment sequences, Lake Bolac, Victoria Ellyn Cook 71

New developments in plasma nitriding: outcomes of AINSE collaborations G A Collins, M P Fewell and M Samandi 72

Stochastic pattern recognition techniques and artificial intelligence for nuclear power plant surveillance and anomaly detection Leslie G Kemeny 73

The high pressure phase transition of silicon R O Piltz 74

Composition and structural analysis of Sm-Co thin films on (100)Si Muralidhar K Ghantasala, D K Sood, K T Short and S Mohan 75

Application of RBS analysis to investigation of cerium implanted stainless steel as an interconnect material for SOFC S Shamsili, D K Sood, S P S Badwal and P J Evans 76

Axial shortening of fission tracks to response thermally driven volume diffusion of lattice vacancies David X Belton and Roderick W Brown 77

Unstable isotopes in a stable? landscape: untangling southern Africa's geological history with fission tracks and cosmogenic nuclides D X Belton, R W Brown and D Fink 78 ABSTRACTS AU9917967

AN HISTORICAL REVIEW AND PERSPECTIVE OF AINSE

T.R.Ophel, President AINSE

Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra.

AINSE was formed in 1958 as a cooperative venture of modest scope, involving the newly established AAEC (created by the Atomic Energy Act of 1953 with facilities at Lucas Heights being formally opened in 1955) and the eight universities that existed at the time. Research emphasis was very much nuclear, with the two reactors MOATA and HIFAR and possible future nuclear energy developments defining it. Two accelerators, added in the early sixties - the 3 MV Van de Graaff and the 1.3 MV electron machine, were to sustain those original activities of the AAEC. It would probably be true to say that AINSE in those early days placed much importance on the general support of nuclear science throughout Australia, whereas now of course the facilitation of the use of ANSTO facilities has become the main function.

Thereafter, both AINSE and the AAEC have undergone dramatic change. The number of universities expanded to 19 in the late sixties, along with more support and encouragement for research at both the new institutions and the original group of eight. University use of Lucas Heights facilities, through the agency of AINSE, expanded and began to diversify somewhat into other disciplines - a trend that has continued apace ever since. In the nineties, the Dawkins revolution led to a doubling of the number of tertiary institutions, so that once again AINSE experienced a quantum jump in size, with of course matching complexity. In parallel, AAEC broadened its activities to embrace a wide range of nuclear and energy related areas, though basic research began to taper off. Finally, the organization was given a new charter in 1985 and re-named ANSTO.

A much expanded university system, the "new" ANSTO, the rise of economic rationalism and the creation of the ARC have combined to provide a succession of challenges to AINSE. From the original small, club-like beginning with narrow interests, AINSE has emerged with more than a four-fold increase in membership, to foster research within almost all of the Faculties of those members. AU9917968

ARCHAEOMETRY and AINSE

W.R. Ambrose Australian National University Research School of Pacific and Asian Studies Dept. of Archaeology and Natural History

Archaeology, as with all disciplines, has developed into several specialized areas. It is possible to complete a higher degree in archaeology without ever visiting an archaeological site, although most archaeologists would regard this is falling short of the ideal where 'dirt' is encountered at some stage. Archaeology requires redefinition from time to time as a result of these changes in practice, with one of the more demanding recent redefinitions involving the concept of Archaeometry. From its earliest manifestation archaeology as history has been attached to anthropology, natural history and geology. Chronology will always be a major concern so that the astounding success of nuclear science research, with its steady production of new ways to date the past and examine the properties of materials, has opened major new avenues that archaeologists are keen to exploit. Archaeometry is the term that has gained some weight as the field that tries to bind these advances in physics and other sciences to archaeology in a more systematic way. The creation of AINSE provided an excellent opportunity for archaeologists to explore the powerful repertoire of instrumentation and research that others had specifically designed for physics and chemistry purposes. But archaeologists are fairly inconsequential players in these primary fields and must rely on the expertise of others for accessing the facilities at Lucas Heights. This procedure has worked very well for some archaeologists through their association with interested (and generous) personnel at AINSE and Lucas Heights for more than twenty years. As archaeologists we are not always sure that others see a mutual benefit in the arrangement where the very applied nature of archaeology's needs compete with the basic research of other AINSE supported work. A short record of the major advances in the archaeology of our region will underline the very beneficial impact that AINSE has had on our discipline. To some extent this success has encouraged Australian archaeologist to accept a dependency on AINSE that may not be sustainable or satisfactory in the longer term. It may be time to consider the future of this dependency by recalling the words of Professor Rhys Jones who reminded us at an archaeometry conference in 1992 that 'archaeometry is archaeology or it is nothing'. The meaning of this statement is fairly blunt but needs to be seen as the clearest definition of what archaeometry is. It is simply stating that archaeology needs to redefine itself in a way that encourages greater cooperative participation with all the players in the field, and not expect others to be what they are not. When compared with Universities and research centres in Europe and the United States where archaeology is involved, Australia has very limited archaeological science resources. The ANU has closed the centre developing advanced science-based archaeological research despite its assurances of continuity, while conventional radiocarbon dating as a routine procedure is no longer accessible in Australia. It is unreal to expect that AINSE can accommodate even a small fraction of these lost opportunities for archaeology. Any future development of the field will require a realignment of University priorities, but whatever develops it is clear that AINSE should remain an important contributor to the application of nuclear science based research to archaeometry in Australia. AU9917969

Nuclear Physics Achievements Via AINSE

J W Boldeman

Australian Nuclear Science and Technology Laboratory, PMB 1, Menai 2234, New South Wales

From its establishment, the Australian Institute of Nuclear Science and Engineering has supported a strong program in nuclear physics studies. This was especially so in the earliest days of the Institute. The studies made use of the Van de Graaff accelerator, the neutron beams from the HIFAR reactor and more recently the Tandem Accelerator on the Lucas Heights site. There were other studies which used some of the supporting infra structure there. Within the university sector, major facilities such as the Betatron and Pelletron at Melbourne University and the EN Tandem, Cyclotron and 14 UD at the Australian National University were involved in various collaborations.

The activities covered many areas of research. The more prominent were studies of the nuclear fission process, neutron capture and astrophysics. This paper will examine some of this research and endeavour to present several representative highlights. AU9917970

AINSE - MORE THAN 20 YEARS OF ION BEAM ANALYSIS

David Cohen Physics Division, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW, 2234, Australia

AINSE has a strong tradition in people, personalities, scientific training and research spanning over 40 years. From the late 1960's it operated a small but efficient Accelerator Group, attached to the ANSTO Physics Division. This Group assisted in the national promotion of ANSTO's accelerator based capabilities throughout all Australian Universities. It was mainly associated with research related to the use of the 3 MV positive ion Van de Graaff accelerator, the 1.3 MV Van de Graaff electron accelerator and a 3 ns pulsed electron Febetron, together with a range of y irradiation facilities.

During the mid 1970's physicists at ANSTO and AINSE picked up on the world-wide move towards the accelerator based use of ion beam analysis (IBA) methods. These IBA techniques were for the main part fast, non-destructive and able to be applied across an extremely broad range of scientific disciplines. This particularly suited both AINSE's role, with a need to be relevant to as broad a range of Australian universities as possible, and ANSTO's need, at the time, to become more relevant and practical to outside research groups as well as industry.

The growth in the research associated with the applications of accelerator based IBA methods within Australian has been extremely well documented in the Proceedings of the ten national Conferences on Nuclear Techniques of Analysis. These conferences, held every two years, commenced in May 1976 and the eleventh one is due to be held at Lucas Heights in November 1999. They have been sponsored and run by AINSE all of this time and hundreds of papers have been presented by students, lectures, professors and researchers. Most Australian universities have presented research at this Conference at some time.

It has been interesting to note that at the first Conference in 1976 papers were presented on ion channelling, Rutherford backscattering, nuclear micrprobes, ion induced X-rays, ion beam sputtering, ion implantation, forward scattering, charged particle reactions and nuclear reaction analysis. The wide range of samples analysed included, bones, muscles, teeth, glass, rocks, soil, Th/U ores, coal, obsidians, air particulates, solar absorbers, wheat grains, silica and ceramics. At the last Conference in November 1997, some 22 years on, all of these research areas and sample types were still well represented through a range of medium energy accelerators around Australia. However, in more recent times the field has been considerably expanded by the inclusion of both low energy (<100 keV) and high energy (>10 MeV) heavy ion facilities at various institutions around Australia. This includes the world class 10 MV heavy ion Tandem accelerator facility installed at ANSTO in 1989 and the interest, during the 1990's, of the ANU 14 UD heavy ion accelerator in more applied research such as AMS.

The AINSE researchers, at ANSTO, have been involved in 20 to 30 different projects annually since 1976 related to accelerator based IBA methods. Some of these lasted only 12 months, many longer, some have been successfully producing for more than a decade. This talk will attempt to describe the range, depth and scope of AINSE's unique involvement in IBA research with its subsequent benefits to ANSTO and Australian research generally. AU9917971

THE EVER EXPANDING FILED OF ION BEAM ANALYSIS

DJ. O'Connor

University of Newcastle Callaghan, NSW 2308

The field of Ion Beam Analysis has steadily developed over the past forty yields to provide more detailed information for the analyst from a wider range of materials analysis tools. The first technique to be well developed was Rutherford Backscattering Spectrometry which relied on the elastic and inelastic scattering of H and He projectiles to provide composition and structural information in the near surface region. From this grew Ion Channelling which provided a valuable structural tool for the crystallographic location of impurities in solids.

The field expanded to include Proton Induced Xray Emission (PIXE) and Nuclear Reaction Analysis (NRA) which pushed the detection limits beyond the range of RBS for most elements. Apart from different techniques the energy range was extended to develop Medium Energy Ion Scattering (MEIS, 100-500keV) which has been shown to probe the first 3-10 atomic layers with almost layer by layer resolution and Low Energy Ion Scattering (LEIS) which is exceedingly sensitive to the outermost one or two atomic layers.

By pushing the limits of techniques we can push the detection limits. This will be shown for MEIS and for recoils. The use of recoils over a wide range of energies will be discussed to show the range of applications and the versatility of the techniques. At the low energy end this technique has the flexibility to not only detect 10"4 of a mono-layer of O on a clean surface and locate it crystallographically at the low energy end, while at the high energy end it also allows multi-element depth profile analysis with a uniform detection sensitivity over half the periodic table.

The power and capacity of these scattering and recoil methods as well as future developments will provide an insight to the future expansion of techniques and applications. AU9917972

THE CONTRIBUTION OF AMS TO GEOSCIENCES Allan R. Chivas School of Geosciences, the University of Wollongong NSW 2522, Australia The advent of Accelerator Mass Spectrometry (AMS) has heralded investigation of a variety of important problems in the geosciences, previously not considered possible for technical or conceptual reasons. This presentation outlines some of the advances in AMS methods with emphasis on Australian examples and measurements using the accelerators at ANSTO and the Australian National University.

Perhaps the best known of these techniques is the application of AMS 14C dating which has the advantage of needing much smaller amounts of sample (typically < 1 mg C), and having a potentially somewhat older age limit (to approximately 55,000 yr), than conventional I4C determinations by (3 counting. AMS 14C has been applied to dating an enormous array of materials including archaeological samples and sites, tree rings, ice cores, banding in coals and circulation and ventilation changes in the world's oceans. An exciting application of the measurement of the rare long-lived isotopes I0Be, 26A1 and 36C1 is in the relatively new field of cosmogenic exposure dating. Accumulation of these comogenically produced nuclides formed in-situ in exposed rock surfaces is used to estimate both the time of exposure of the rock surface and mean errosion rates. A large variety of landscape-related processes have been successfully addressed including weathering and sediment-transport rates and the ages of glacial retreat, tectonic uplift and lava erruptions.

In the field of hydrology, 36C1 studies of dissolved chloride have been used to successfully estimate the ages of ground waters and trace their origins. The tracing of atmospheric air masses that deliver rain and the origin of Australian salt lakes and continential salinisation using 36C1 lead to important conclusions on the origin and residence time of chloride in the Australian landscape. The ultimate origin of the bulk of the surficial chloride in Australia is shown to be meteoric, and for the western part of the continent, a mean residence time of about 0.75 Ma pertains. The realisation of the long-term and continuing delivery of salts to the landscape needs recognition in planning strategies to combat salinisations of agricultural areas. AU9917973

FUTURE DIRECTIONS OF THE AMS PROGRAM AT LUCAS HEIGHTS

Claudio Tuniz Australian Nuclear Science and Technology Organisation Private Mail Bag 1, Menai, 2234 NSW, Australia

The research program based on the ANTARES AMS spectrometer involves applications of the long-lived radionuclides 14C, 10Be, 26A1,36C1 and 129I in earth sciences and archaeology. Examples of environmental applications of AMS at Lucas Heights include: use of the 14C bomb pulse to determine the age and age-spread of air trapped in Antarctic ice bubbles, key parameters to study the variability of CO2 and other greenhouse gases in the past [1]; analyses of 14C bomb-pulse curves in tree rings from tropical regions and the southern hemisphere to improve our understanding of the carbon cycle and air-sea interactions, important processes for the global climate [2]; analyses of 10Be and 36C1 produced in-situ in polished glacial bedrock and moraine boulders from Tasmania, New Zealand and Antarctica, as part of a major national project to unravel the timing of glacial cycles in the southern hemisphere [3]. A recent archaeological application has been the radiocarbon dating of charcoal fragments from the rock shelter at Jinmium in the Northern Territory demonstrating that this site was occupied by Aboriginal people only during the late Holocene [4]. In environmental monitoring, the analysis of 1291,14C and 36C1 in water specimens from Mururoa and Fangatauga contributed to an IAEA study regarding residual radioactivity in the Pacific after the French nuclear program [5]. Concerning the future of the AMS program at Lucas Heights, one can forecast the continuous growth of applications in environmental sciences and archaeology. In climatic studies, there is an ongoing collaborative program to determine the fossil contribution to the global methane budget from the analysis of 14CH4 trapped in Antarctic firn before the nuclear age. The program based on in-situ produced radionuclides is expanding with the study of complex processes such as the transport and deposition of eroded material to understand phenomena such as the evolution of desert sands. Less traditional applications are also being developed such as the use of anthropogenic 14C to detect synthetic additives in food products and wine. Biomedicine is set to become a major direction in future AMS applications at Lucas Heights. The most significant advantage of AMS in biomedical applications is that the biological response to toxins can be obtained at environmentally relevant dose levels. In fact, AMS enables the detection of carcinogens labelled with 14C at concentrations of one attomole per milligram of body tissue. Furthermore, the use of long lived radionuclides make negligible the radiation hazards to subjects and researchers. For example, the metabolism of calcium and aluminium in humans can be studied using 41Ca and 26A1, respectively. The capability recently achieved at ANTARES for the AMS detection of actinides could offer exciting possibilities in studies related to the toxicology of plutonium.

I4 [1] V.A. Levchenko et al.: 'The C "bomb spike" determines the age spread and age of CO2 in Law Dome firn and ice', Geophysical Research Letters 23(1996)3345. [2] Hua et al.: 'Atmospheric radiocarbon variations from pinus kesiya tree rings in Thailand from 1952 to 1975 AD', the First International Workshop on Southeast Asian Dendrochronology SEA DENDRO 98, Chang Mai , Thailand, 1998. [3] D. Fink et al.: 'A glacial history of Tasmania in the Quaternary using in-situ 10Be and 36C1', International Conference on Geochronology, Cosmochronology and Isotope Geology, Beijing, China, 1998. [4] R. Roberts et al.: 'Optical and radiocarbon dating at Jinmium rock shelter in northern Australia', Nature 393(1988)258. [5] G.E. Jacobsen et al.: 'AMS measurement of 36C1,129I and 14C in waters from Mururoa and Fangataufa atolls', International Symposium of Marine Pollution, Monaco, 1998. AU9917974

EVOLUTION OF MATERIALS RESEARCH WITHIN THE AINSE PORTFOLIO

Dr Adam Jostsons Director, Materials Division, ANSTO ANSTO PMB1 Menai NSW 2234

The main materials research interactions between ANSTO/AAEC and the AINSE member universities are reviewed and linked to the main thrust of contemporary ANSTO/AAEC programs.

The AINSE portfolio encompasses the previous AAEC research contracts, which represent an earlier example of public sector outsourcing, until re-discovered during the present decade, as well as AINSE studentships and Research and Training Projects. Collectively these mechanisms did much to foster the maintenance of effective materials research teams in Australian universities. Selective examples will illustrate the success of the AINSE family in training to "help provide engineers and scientists of high ability for the future". AU9917975

THE NATIONAL CENTRE FOR NEUTRON SCATTERING

Trevor Hicks Department of Physics, Monash University Clayton 3168, Australia

As neutron scattering can be done nowhere else than at Lucas Heights in Australia, both ANSTO and AINSE have been heavily involved in the support for the past forty years. I will trace the involvement of AINSE, highlighting significant developments in instrumentation and organisation. The prospect of a replacement reactor promises a new era for neutron beam science in Australia. I will outline the present plans with emphasis on the opportunities for new science for participating universities.

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NEUTRON SCATTERING IN THE 21ST CENTURY

Professor John W White, CMG, FAA, FRS Research School of Chemistry Australian National University, Canberra ACT 0200

The watchwords for neutron scattering in the 21st Century will be complementarity and computing. Despite the enormous impact that is coming in condensed matter science, chemistry and biology from synchrotron light sources, the essential complementarity between x-ray and neutron scattering is likely to be not only preserved but enhanced. This will be acheived by current and foreseen investments in new neutron sources of high intensity and by technique developments involving neutron polarisation, neutron optics and neutron detection.

The complementary relationship between neutrons and x-rays - especially using isotopic and spin polarisation contrast will be illustrated along with some challenges which might well be met in the next ten to 15 years. In meeting these challenges it is inevitable that the enormous growth in power of computing systems will play a key part. Computing must be combined very intimately in the design and interpretation of scattering experiments as well as the retention and the retrieval of experimental data. International organisations such as the International Union of Crystallography will play a part in this.

10 AU9917977

AINSE - THE FIRST THIRTY YEARS-1958-1988

Mr E A (Bill) Palmer Former Executive Officer AINSE 1959-1988

The original constitution adopted on 4/12/58 to establish AINSE remained unchanged through three decades during which the number of member universities increased from nine to nineteen, the AAEC became ANSTO (1987), and the wording in the relevant legislation changed from uranium and atomic energy to nuclear science and technology. The agreement on 4/12/58 by representatives of the nine universities and the AAEC to establish the Institute followed discussions initiated in 1957 by Professor J P Baxter then chairman of the AAEC and Vice Chancellor of the University of New South Wales. Adoption of the constitution created AINSE as an independent organisation governed by the Council with funds provided by annual subscriptions from the member organisations and an annual "Contribution for Research and Training" from the Commonwealth Government. The aims were to assist research and training in disciplines relevant to the nuclear field, or requiring use of AAEC facilities at Lucas Heights. Having access to HIFAR and MO AT A, no Australian academic institution found it necessary to locate a research reactor on its own campus. Among many critical actions of the early years were decisions to set up specialist committees in certain disciplines, eventually including nuclear physics, plasma physics, radiation chemistry, radiation biology, neutron diffraction, nuclear techniques of analysis, and relevant aspects of engineering. Council decisions determined the development of AINSE operations, and a critical role was also played by each of the fifteen AINSE Presidents who held office in the first thirty years. Relations with the AAEC were important, and AINSE benefited from the active cooperation of the Commissioners and AAEC staff through these decades. From the early 1960's several series of AINSE conferences were established, one in each of the relevant fields, usually bi-annual. Most series have continued to the present and have played a useful role, particularly in encouraging the reporting work of in progress. Research results arising from AINSE projects were always made available without restriction. AINSE grants originally awarded in 1960 have continued as the major means by which the Institute assists research undertaken by the member universities, often in co-operation with members of Lucas Heights research groups. AINSE studentships (postgraduate) and AINSE Fellowships (post-doctoral) fully funded by the Institute, were successful in attracting able candidates through the three decades, and many moved on to senior appointments in research institutions. All these AINSE activities involved visits and attachment of university staff and students to Lucas Heights, in considerable numbers, and sometimes for extended periods. From 1965 most visitors were accommodated in Stevens Hall. Also important was the appointment of AINSE scientific and technical staff at Lucas Heights to constitute the AINSE Neutron Diffraction Group (4 staff) in 1965, and the AINSE Accelerator group (2 staff) in 1972, together with the provision by the Institute of research equipment at Lucas Heights. These AINSE staff members did much to develop research facilities and to assist university visitors. The AINSE building at Lucas Heights was completed early in 1960 and became the base for the AINSE office, meetings, visitors, lectures and conferences. Some of the female staff members located there were with the Institute for many years and made important contributions to the administration of AINSE activities. Many of the concepts evolved in the first thirty years have survived. New ideas have been introduced in the ten years which have followed and AINSE will continue to build on its original foundations.

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AINSE - THE YEARS BETWEEN 1988 AND 1998

Roger Gammon Ex-AINSE Executive Officer

This paper traces the history of AINSE between the years 1988 and 1998. It was a time of great change for AINSE. At the beginning of this period the Government implemented major structural reforms of the higher education system and new mechanisms for research infrastructure support followed a year later. This culminated in 1993 with a major restructuring of AINSE which had continued with little change since its inception in 1958. This was followed in 1994 with a comprehensive review and reorganisation of ANSTO, which also had a significant effect on AINSE. These events will be described and will include some of AINSE's considerable achievements and successes which saw the organisation, in partnership with ANSTO, in a strong position at the end of this ten year period.

12 AU9917979

NUCLEAR SCIENCE AND A BETTER ENVIRONMENT - AN OXYMORON?

Dr Gerald Laurence The University of Adelaide ADELAIDE 5005

AINSE was born when nuclear science was seen as the source of a better environment of clean and abundant energy, of new techniques for understanding the environment, and the general advancement of the human lot. Despite the threat of nuclear weapons, the world was bullish for nuclear science when the first UNESCO Conference on 'Atoms for Peace' was held in Paris in 1957. Optimism for science in general and nuclear science in particular has decreased since then and nuclear activities of all kinds are seen as particularly environmentally harmful if not catastrophic. The extent to which nuclear science and nuclear techniques have contributed to our understanding of the environment and to reducing the impact of past exploitation is not commonly realised.

The Environmental Specialist Committee of AINSE is a relatively recent addition to the areas of special interest but AINSE and ANSTO have supported environmental research for many years in areas such as environmental engineering studies, insect control, sensitive analytical techniques (which are in many cases at the heart of an improved understanding of environmental processes) and environmental radioactivity and the control of radioactive waste. Such techniques make a direct contribution to the remediation of contaminated industrial and mining sites and to monitoring the continued effect of these sites on the environment.

Recently the spread of quaternary studies with distinct environmental importance has increased the AINSE involvement in supporting the use of AMS techniques involving cosmogenic radionuclides, not only for studies of current processes but also for historic studies designed to reveal past climates and geomorphology. Nuclear science of this kind contributes to a better understanding of patterns of atmospheric circulation, underground water resources and climate change. Even a simple application of nuclear science, the neutron soil moisture probe, improves the efficiency of water use in agriculture and reduces the environmental impact of irrigation.

The environmental impact of development in the third world will have major environmental consequences in the next twenty years. Developments in nuclear science in chemical analysis, the dynamics of environmental processes and in monitoring resources will help in controlling a sustainable and rational use of the environment.

13 AU9917980

GETTING WARMER? CAN MODELS PREDICT THE FUTURE OF THE EARTH'S CLIMATE? A. Henderson-Sellers Director, Environment Division Australian Nuclear Science and Technology Organisation Lucas Heights Science and Technology Centre Private Mail Bag 1 Menai, NSW, 2234

Both of the questions posed in the title of this paper were answered in the Intergov- ernmental Panel on Climate Change (IPCC) Second Scientific Assessment which says, inter alia, "The balance of evidence suggests a discernible human influence on global climate" (Houghton et al, 1996, p4). However, the answers contained in the IPCC 1996 report provide only indications of the impacts likely to arise from and responses demanded by climate change. Scientists must now tease out additional questions and determine answers to them in order to provide policy advice for future climate-related mitigation and adaptation activities. Specifically, whilst it is known that numerical mod- els can predict future climates, their accuracy, regional specificity and policy usefulness remain open to challenge and certainly require further refinement and improvement. Climate modellers are most confident about the radiative heating by greenhouse gases and cooling by industrial, and other, aerosols. We have considerable confidence about our ability to simulate the largescale circulation of the atmosphere and oceans but as yet have little prediction skill for near-surface continental climates, extreme events or knowledge of the sensitivity to socio-economic forcing functions which drive climate change. As yet no formalism exists for validation of coupled climate models but evaluation and confirmation can and must be attempted by examination of the results of fully coupled simulations; model component intercomparisons; and sensitivity studies of interactions between numerical model components (Gates et al., 1996). Modelling and observation communities must jointly strive for improved accuracy (determined by more careful validation against high quality data); enhanced regional to local specificity (gained by model improvements and enhanced validation); and by increasing the skill with which we can detect climate change (observationally driven enhanced by model- based sampling strategies and scenarios). In this paper I consider specific examples of these three challenges to climate pre- diction improvement: better accuracy in terms of continental surface climate prediction (e.g. Qu et al., 1998); enhanced specificity in terms of tropical cyclone predictions (e.g. Henderson-Sellers et al., 1998); and improved detection in terms of increased under- standing of the global carbon cycle (e.g. Schimel et al, 1996). References Gates, W.L., Henderson-Sellers, A. et al., 1996, Climate models — evaluation, Chapter 5 in Climate Change 1995. The Science of Climate Change (eds. J.T. Houghton et al.), Cambridge University Press, Cambridge, 229-284 Henderson-Sellers, A. et al., 1998, Tropical cyclones and global climate change: a post- IPCC assessment, Bulletin of the American Meteorological Society, 79(1), 19-38 Houghton et al, 1996, Climate Change 1995: The Science of Climate Change, Contri- bution of Working Group I to the Second Assessment of the Intergovernmental Panel on Climate Change, Cambridge University Press, 572pp. Qu, W., Henderson-Sellers, A. et al., 1998, Sensitivity of latent heat flux from PILPS land-surface schemes to perturbations of surface air temperature, 3. Atmos. Sci., 55(11), 1909-1927 Schimel, D. et al., 1996, Radiative forcing of climate change, Chapter 2 in Climate Change 1995. The Science of Climate Change (eds. J.T. Houghton et al), Cam- bridge University Press, Cambridge, 65-131

14 AU9917981

DIVERSE APPLICATIONS OF RADIATION CHEMISTRY

Ronald Cooper

School of Chemistry University of Melbourne Parkville Victoria

Radiation Chemistry began as early radiotherapists needed a reliable and appropriate dosimeter. The Iron Sulphate dosimeter, using ferrous iron in sulphuric acid and oxidation by irradiation, was a nasty brew of chemicals but it was sensitive, reliable and conveniently had the same density as human tissue. The full mechanism for its action took almost thirty more years to elucidate. In this time the chemical-physics of the interaction of X rays, y-rays, electrons, protons, a-particles with water was quantitatively worked out. The fundamental species generated in water by radiation can now be utilised with qualitative and quantitative control. Oxidising or reducing conditions can be generated as well as a library of free radicals useable in chemical synthesis. The ability to generate solvated electrons in water enables inorganic coordination chemistry to probe electron transfer processes in transition metal complexes. These molecules are considered as candidates for solar energy conversion systems as well as controlled drug release agents.. Radiation chemistry can quantitatively produce and study the redox forms of these compounds whereas photolysis cannot. Water irradiation chemistry studies were driven by the need to understand the fundamental processes in radiotherapy ; to control the corrosion problems in the cooling/ heat exchange systems of nuclear reactors and to find stable solvents and reagents for use in spent fuel element processing. Common organic liquids, hydrocarbons, alcohols, and aromatics were examined and a new area of free radical and electronic excited state chemistry opened up. The use of scintillation counting techniques in radionuclide assay was significantly enhanced by the radiation chemical studies of the luminescence from a new range of organic scintillators. Chain reactions induced in irradiated unsaturated hydrocarbons enabled profitable commercial production of petroleum additives. The electrical and mechanical stability of materials in high radiation fields stimulated the attention of radiation chemists to the study of defects in solids. The coupled use of radiation and ESR enabled the identity of defect structures to be probed. This research led to the development of the sensitive Thermoluminescent Dosimeters, TLD's and a technique for dating of archaeological pottery artefacts. More recently the ESR detection of free radicals has been used to determine the extent of irradiation in food preservation. The electrical breakdown of insulators has also been a cross discipline study by radiation chemists and solid state physicists. Recently a workshop in the USA examined the use of ultra high purity sapphire (AI2O3) as the electrical insulator and first wall material in a high temperature fusion reactor; measurement of the radiation induced conductivity by pulse radiolysis was a significant factor in this decision. The gas cooled reactors stimulated research into the stability of irradiated gases. Initially carbon dioxide was the prime target but subsequently the field broadened. It has been realised that ionising radiation methods, especially using relatively low energy electrons ~ 1 MeV, were powerful means to produce gas phase ions, free radicals, excited states and low energy secondary electrons; in other words, a PLASMA. The pulsed irradiation technique enabled direct observation of the formation and reaction of species important in atmospheric chemistry. Oxygen atoms forming ozone could be monitored as could the reaction of atmospherically important excited states such as those of nitrogen, oxygen and OH radicals. Flue gas clean up by low energy electron beam treatment is under development in europe. Conductivity methods adapted to nanosecond time resolution can directly measure electron cooling, capture and recombination processes in gases-all crucial processes in describing and modelling electrical discharge phenomena such as is found in lighting, welding, gas lasers, atmospheric electrical storms, surface etching etc. Radiation chemistry in the area of medicine is very active with fundamental studies of the mechanism of DNA strand breakage and the development of radiation sensitisers and protectors for therapeutic purposes. The major area of polymer radiation chemistry is one which australia commands great international respect. It will be the topic of a later presentation in this conference. 15 AU9917982

USES OF NEUTRON SCATTERING IN SUPRAMOLECULAR CHEMISTRY

Leonard F. Lindoy University of Sydney School of Chemistry, University of Sydney, NSW 2006

A major thrust in recent chemical research has been the development of supramolecular chemistry - broadly the chemistry of large multicomponent molecular assemblies in which the component structural units are held together by either covalent linkages or by a variety of weaker (non- covalent) interactions that include hydrogen bonding, dipole stacking, 71 -stacking, van der Waals forces and favourable hydrophobic interactions. Much of the activity in the area has been motivated by the known behaviour of biological molecules (such as enzymes). Thus molecular assemblies are ubiquitous in natural systems but, with a limited number of exceptions, have only recently been the subject of increasing investigation by chemists. A feature of much of this recent work has been its focus on molecular design for achieving complementarity between single molecule "hosts" and "guests".

The use of single crystal neutron diffraction coupled with molecular modelling and a range of other techniques to investigate the nature of individual supramolecular systems will be discussed. By way of example, in one such study the supramolecular array formed by co-crystallisation of 1,2- diaminoethane and benzoic acid has been investigated; the system self-assembles into an unusual layered structure composed of two-dimensional hydrogen bonded networks sandwiched between layers of edge-to-face stacked aromatic systems. The number of hydrogen-bond donors and acceptors is balanced in this structure.

16 AU9917983

THE UNIQUE FACILITIES OFFERED BY y RADIOLYIS TO UNDERSTAND POLYMERIZATION KINETICS

Robert G Gilbert

Chemistry School, Sydney University Sydney, NSW 2006.

Polymers literally form the stuff of our everyday lives. Improving the ways of making present polymers in industry, and devising new polymeric materials all require better knowledge of the mechanism of polymer formation. One of the most important means of polymer formation involves initiation by free radicals. A subset of this, especially important in industry, is emulsion polymerization, whereby the polymerization process is dispersed in water: an environmentally-friendly "solvent" [/]. yradiolysis as an initiation method for free-radical poly- merization can give unique mechanistic information: it can penetrate opaque media (i.e., produce a uniform flux of radicals) yet can be switched off instantly, thereby enabling radical loss mechanisms to be investigated. It also gives a steady radical flux at any temperature, which is particularly convenient for looking at reactions at low temperatures, thereby giving the means of "tuning out" complications that can oCcur at elevated temperatures. Data will be presented to show that this has enabled rate coefficients for a variety of free-radical processes to be obtained, often for the first time: for example, radical loss in emulsion polymerization by exit [2] and by termination [3]. A new method [4] enables termination rate coefficients to be obtained by two completely independent means (one of which requires y), thereby verifying the results from both. However, care must be taken for certain systems, such as those involving vinyl esters, where evidence has been obtained that unusual species are formed which undergo slow subsequent polymerization but rapid termination, thereby limiting the applications of the technique. The knowledge gained from these studies has been used to develop theories for these free-radical processes [5-7] which are being further refined by testing with further experiments. Moreover, this knowledge has also been used to design new materials [8,9]. Many collaborations with Professor Don Napper and David Sangster are gratefully acknowledged, as is the support of AINSE.

(1) Gilbert, R. G. Emulsion Polymerization: A Mechanistic Approach; Academic: London, 1995. (2) Lansdowne, S. W.; Gilbert, R. G.; Napper, D. H.; Sangster, D. F. J. Chem. Soc. Faraday Trans. 1 1980, 76, 1344. (3) Adams, M. E.; Russell, G. T.; Casey, B. S.; Gilbert, R. G.; Napper, D. H.; Sangster, D. F. Macromolecules 1990, 23, 4624. (4) Clay, P. A.; Christie, D. L; Gilbert, R. G. In Advances in Free-Radical Polymerization; K. Matyjaszewski, Ed.; A.C.S.: Washington D.C., 1998; Vol. 685; p 104. (5) Russell, G. T.; Gilbert, R. G.; Napper, D. H. Macromolecules 1992, 25, 2459. (6) Scheren, P. A. G. M.; Russell, G. T.; Sangster, D. F.; Gilbert, R. G.; German, A. L. Macromolecules 1995,28, 3637. (7) Gray-Weale, A. A.; Henchman, R. H.; Gilbert, R. G.; Greenfield, M. L.; Theodorou, D. N. Macromolecules 1997, 30, 7296 . (8) Subramaniam, N.; Balic, R.; Monteiro, M. J.; Gilbert, R. G., 1997, PCT, Australia "Modified Rubber Polymer Latex". (9) Subramaniam, N.; Balic, R.; Taylor, J. R.; Griffiths, M.; Monteiro, M. J.; Gilbert, R. G.; Ho, C. C; Abdullah, L; Cacioli, P. J. Nat. Rubber Res. 1997,12, 223.

17 AU9917984

FUSION PLASMA PHYSICS RESEARCH ON THE HI NATIONAL FACILITY

Jeffrey Harris Head, Plasma Research Laboratory, RSPhysSE, Australian National University Canberra, ACT

Australia has a highly leveraged fusion plasma research program centred on the H-l National Facility device at the ANU. H-l is a heliac, a novel helical axis stellarator that was experimentally pioneered in Australia, but has a close correlation with the worldwide research program on toroidal confinement of fusion grade plasma. Experiments are conducted on H-l by university researchers from the Australian Fusion Research Group (comprising groups from the ANU, the Universities of Sydney, Western Sydney, Canberra, New England, and Central Queensland University) under the aegis of AINSE; the scientists also collaborate with fusion researchers from Japan and the US. Recent experiments on H-l have focused on improved confinement modes that can be accessed at very low powers in H-l, but allow the study of fundamental physics effects seen on much larger machines at higher powers. H-l is now being upgraded in magnetic field and heating power, and will be able to confine hotter plasmas beginning in 1999, offering greatly enhanced research opportunities for Australian plasma scientists and engineers, with substantial spillover of ideas from fusion research into other areas of applied physics and engineering.

18 AU9917985

THE ROTAMAK - CONTRIBUTIONS FROM ANSTO AND FLINDERS UNIVERSITY

Ieuan R Jones Department of Physics, Flinders University GPO Box 2100, Adelaide, 5001, South Australia

The investigation of plasma/field configurations of the compact torus variety is of current interest in the field of fusion research. Two configurations of this genre are the field reversed configuration (FRC), which does not have an externally applied toroidal magnetic field, and the spherical tokomak (ST) which possesses such a field. Both of these compact torus concepts, as studied outside Australia, suffer from the very serious disadvantage that they are inherently pulsed devices; the toroidal plasma current is not maintained indefinitely.

The rotamak is a compact torus configuration having the unique and distinctive feature that the toroidal plasma current is driven in a steady-state, non-inductive fashion by means of the application of a rotating magnetic field. In its basic form, the rotamak is operated as an FRC. However, by means of a simple modification, a steady toroidal magnetic field can be added to the basic rotamak apparatus and the configuration then becomes that of an ST.

The rotamak concept was conceived and developed in Australia and the bulk of investigations in this field, both theoretical and experimental, have been undertaken at Flinders University (1979-1998) and AAEC/ANSTO (1982-1988). This talk will cover the history of the project in this country, will dwell on the marvellous interaction which flourished between the two research groups and will finish with the news that the rotamak concept has been enthusiastically embraced by fusion research teams in the United States.

19 AU9917986

LOW TEMPERATURE PLASMAS: FUNDAMENTALS TO COMMERCIAL APPLICATIONS

Matthew Fewell Department of Physics University of New England, Armidale, NSW 2350

This paper provides an overview of some selected aspects of low temperature plasmas that have been relevant to the wide variety of activities undertaken at Lucas Heights.

Reference will be made to some early fundamental studies of weakly ionized plasmas. These investigations provided reliable, new and precise information about the spatial and temporal growth of ionization in both static electric fields and combined electric and magnetic fields. The ionization behaviour was determined essentially by electron, ion and photon processes in pure molecular gases but when investigations were extended to a study of the influence of trace impurities on the ionization behaviour, dramatic new influences were revealed. Removal of the impurities demonstrated the influence of excited neutral metastable particles. These are not influenced by electric or magnetic fields but are controlled by the process of diffusion and exert strong effects at metal surfaces. Studies of these metastable particle influences proved to be important in developing new lasers, eg. the high power excimer laser which operates in mixtures of inert gases. Most recently considerable interest has developed in the role played by similar metastable particles in plasmas established in molecular nitrogen. The role of metastable particles generated in pure nitrogen is now being examined exhaustively because strong evidence has emerged that they play an important role in commercial plasma nitriding. The latest developments emerging from the co-operative studies by ANSTO, AINSE and UNE have yielded new information and further investigations are continuing.

20 AU9917987

RADIOLANTHANIDES IN THERAPEUTIC NUCLEAR ONCOLOGY

J Harvey Turner Department of Medicine, University of Western Australia and Department of Nuclear Medicine, Fremantle Hospital

Radiolanthanides such as Holmium-166 (T1/2 26.8h), Samarium-153 (T1/2 46.3h) and Lutetium-177 (T1/2 6.7 days) all have beta emissions suitable for radiopharmaceutical therapy. They also emit gamma photons of energies which permit quantitative imaging on conventional gamma cameras which facilitates calculation of dosimetry in individual patients. The range of half-lives has the potential to match the irradiation of tumour cells to the residence time of the radiopharmaceutical thus minimising radiotoxicity to normal tissues. Relative ease and low cost of production of these radiolanthanides in rectors such as HIFAR at ANSTO render radiolanthanides a practical option for radiopharmaceutical treatment of cancer for patients in whom conventional therapy has failed.

Samarium-153 ethylenediaminetetramethylene phosphonic acid (EDTMP) has been developed in clinical trials over the past decade for pain palliation of disseminated skeletal metastases arising from prostate and breast cancer. Response rates of 87% have been reported with 25% of patients becoming pain- free. Prospective individual dosimetry is performed at Fremantle Hospital using a tracer activity of 153Samarium-EDTMP a new whole body imaging method has been validated against the urine sampling technique which we originally developed to limit the radiation exposure of red marrow to 2 Gy to avoid haematologic toxicity from this bone-seeking radiopharmaceutical. Re-treatment in patients who relapsed following initial pain response to 153Samarium-EDTMP has also produced gratifying results.

Both Samarium-153 and Holmium-166 when chelated with bone seeking chelates (EDTMP and DOTMP respectively) and given in high dose may be used to ablate bone marrow, in combination with chemotherapy, to treat haematological malignancy. We have ablated marrow in experimental animals using a combination of 153-EDTMP and Melphalan, and with subsequent bone marrow transplantation treated murine myeloma with encouraging results. A clinical trial of 153Samarium-EDTMP bone marrow ablation is contemplated at Fremantle Hospital and early clinical data from trials of 166Holmium-DOTMP will be presented.

In experimental studies in pigs we have validated a method for estimating dosimetry in the liver following intra-hepatic arterial administration of 166Homicrospheres. A phase 1 clinical trial of this therapy is in progress at Fremantle Hospital in patients with liver cancer and preliminary results will be reported.

Radioimmunotherapy of cancer using various monoclonal antibodies targeted to specific tumour-cell antigens has been performed with Samarium-153, Holmium- 166 and Lutetium-177-labelled antibodies in human tumour xenografts in nude mice and in clinical trails. The development of a large animal model of human cancer will be described in relation to improving the accuracy of prediction of dosimetry and preclinical evaluation of efficacy and toxicity of radiolanthanides in therapeutic nuclear oncology.

21 AU9917988

Fission Track Modelling and Visualisation of the Thermotectonic Evolution of Australia

AJW Gleadow1'2, BP Kohnu, PB O'Sullivan1-2, RW Brown2 and K Gallagher3 'Australian Geodynamics Cooperative Research Centre 2Department of Earth Sciences, La Trobe University, Bundoora, Victoria 3083 department of Geology, Imperial College, London SW7 2BP England

Thermochronology can provide quantitative constraints on long-term patterns of denudation at the Earth's surface and can resolve alternative models for the tectonic evolution of the crust. One of the most important of these methods is based on the apatite fission track dating system, which is a particularly sensitive low-temperature thermochronometer for studies of the upper crust. Until recently, however, the results of such studies, mostly on a local to regional scale, have been difficult for non-specialists to interpret and the implications have been difficult to visualise over large areas. A major objective within the Australian Geodynamics Cooperative Research Centre has been to develop new methodologies for interpreting and visualising the results of Apatite Fission Track Thermochronology (AFTT) and to apply these, for the first time on a continental scale, to the whole of Australia in a format that can be combined with other continental data sets. The apatite fission track system depends on the accumulation of radiation damage from spontaneous fission of 238U which is only stable over geological time at relatively low temperatures, <~120°C. Such temperatures are characteristic of the upper -3-4 kilometres of the continental crust, so that rock cooling histories reconstructed from the AFTT measurements can quantify cooling through this upper crustal zone. The development of quantitative thermal modelling and regional imaging techniques for large data sets now means that fission track analysis can be accessed in a variety of novel formats, and used to investigate patterns and timing of denudation, and post-orogenic tectonic activity over broad areas of the crust. In addition to the already widespread application of AFTT data in petroleum exploration and sedimentary basin analysis, these new approaches are also expected to find application in exploration programs for commodities where the relative position of deposits to a palaeo-landsurface is an important factor. Fission track imaging can also reveal discontinuities associated with major lineament features, possibly indicating the presence of long-lived fundamental faults.

22 1 III 1 1 1 AU9917989

PARTNERSHIPS IN NUCLEAR SCIENCE AND TECHNOLOGY CONTRIBUTING TO THE 'HIGH ROAD' TO THE FUTURE

Professor Helen Garnett, Chief Executive, Australian Nuclear Science and Technology Organisation, PMB 1, Menai 2234

The focus of this AINSE conference is a celebration of the many contributions that nuclear science and technology have made to the development of knowledge over the past forty years. While understanding and reviewing the past can help us along the road to the future, and in particular help us avoid mistakes of the past, such an historical review cannot determine what the future road will be.

What is possible is to scope possible scenarios taking account of a wide variety of inputs from many and varied sources; to assess the facts and the trends in many fields and then to couple this information with some 'dreaming' and 'what if questioning. We are in a knowledge revolution. The available information is currently doubling every seven years. For socioeconomic development some of the knowledge, currently available and to be generated in the future, must be converted into value, into innovative products, services and solutions which will give rise to wealth creation.

What are the likely sources of wealth creation in the first twenty years of the next century? Economists, engineers and scientists seem to agree that the 'high road' for Australia is likely to involve the exploitation of a range of advanced and emerging technologies for which a reasonable scientific base has been developing over the past twenty years of this century. These include communication technologies, biotechnology, nanotechnology, biomedical engineering, novel resource processing technologies, environmental technologies, advanced transportation technologies and smart food technologies together with participation in large 'infrastructure' projects which will generate a quick start in Asia.

Technological developments require further scientific questions to be answered and a raft of enabling technologies. Underpinning many of the emerging technologies, considered likely to contribute to socioeconomic development, are both materials science and various processing technologies. There is a requirement to understand the structure and function of natural and man-made molecules and changes in the structure of materials during processing steps and/or functional performance in a range of environments. There is a need to better understand natural processes.

An analysis of the structure, function and performance of materials requires the use of the fundamental probes, neutrons, charged particles and X-rays. Understanding natural processes is facilitated by isotopes. The past has delivered a solid knowledge base for understanding the properties of these probes and their potential applications. Each has unique properties and access to all types of probe is required. Recent innovations, in materials development, have themselves resulted in the design of facilities to deliver these probes more efficiently and effectively and in the construction of better detectors to 'visualise' the outcome, thereby allowing a broader range of questions to be answered. The crystal ball cannot forecast specifically what creative ideas will emerge, innovations that will be considered nor what specific questions will require solution. However, trends show that the development cycle for new products is quickening. Access to solutions for materials and processing problems will

23 be required in an ever-decreasing time span for any company wishing to maintain the competitive edge. Nuclear science and technology can and will be an essential component of this innovation cycle, assisting Australian enterprises to be at the leading edge of competitive markets.

AINSE has enabled and fostered projects across scientific disciplines and partnering between institutions has improved. However the effective application of the appropriate nuclear probe/s to solving questions, in materials science and the processing industries, of direct relevance to advancing the emerging technologies and their innovative application to provide high value products and services, will, almost certainly, require different ways of working. It will be up to the scientific community to show that they can make a difference. Multidisciplinary teams, including not only scientists and engineers but consisting of all disciplines involved in a product life-cycle, or value chain, on a scale not common for current AINSE projects, will almost certainly be required; improved communication and genuine inter-institutional teaming for specific projects will be essential. ANSTO and others are attempting to address these issues. However if the benefits of nuclear science and technology are to be captured, embracing such new partnership models will need to become commonplace in the years ahead.

We will plan and commission facilities, we will foster the scientific capabilities but we must not just create knowledge, but also create the opportunities to assist in adding value and thereby make a difference. We must dream about what might be, brainstorm as to what should be and then influence the external environment and create networks to make the 'high road' a. reality. We must share our dreams.

24 AU9917990

BIOGEOCHEMISTRY OF THE BALLARAT EAST GOLDFIELD

Jackie Stott1'2, Dennis Arne1 and Helen Waldron3 Minerals Industry Research Institute, University of Ballarat, Victoria 3353 2 Presently at Posgold Ltd, PO Box 294, Tennant Creek, Northern Territory 0861 3Becquerel Laboratories, PMB 1, Menai, New South Wales 2234

The Ballarat East gold deposit is hosted by Ordovician metaturbidites that have been tightly folded along north-south trending fold axes. Gold occurs in quartz "reefs" on the eastern limbs of faulted anticlines fleatherjacket structures) and subparallel to the axial surfaces of folds (Taylor, 1998). Gold mineralisation is accompanied by arsenopyrite and rare base metal sulphides, and is associated with a primary hydrothermal alteration halo extending tens of metres out from the leatherjacket structures (Bierlein et al, 1997). This primary alteration halo is characterised by a zone of visible bleaching involving sericitisation and carbonatisation with elevated COj, K, Au, As, Sb and S. At surface the primary alteration halo is enhanced by intense kaolinisation, inferred to have resulted from acid produced during oxidation of sulphides. The ore zones and associated alteration halo are exposed at surface along a continuous ridge, the Whitehorse Range, from which the rich alluvial deposits of the Ballarat field are thought to have formed.

The gold deposits along the crest of the Whitehorse Range were extensively worked last century, and the area was revegetated during the 1930s with Monterey Pine (P. radiata). P. Radiata of different ages were sampled at 25m intervals along two east-west traverses roughly perpendicular to the strike of the Ballarat East field. Sampling occurred during the winter of 1995 following heavy rains. Blackwood (Acacia melanoxylon) and Chinese scrub (Cassinia aculeata) were alsq sampled for comparative purposes. A third traverse through a belt of remnant eucalyptus" (Zs. obliqua, E. dives, and E. macrorhyncha) was sampled to the south of the pine plantation in 1996. These samples were washed in de-ionised water. Sample material included either leaves or needles, the tips of twigs, and outer bark. The samples were dried, pulverised and analysed using instrumental neutron activation at Lucas Heights, NSW. Gold and As from Cassinia leaves and twigs, and Eucalyptus bark show a good correlation with extensions of known mineralised trends inferred from aerial photographs, as do Ce, Cr, La, Sm, Sc and Th. Samples of P. radiata needles and bark show only a moderate correlation with mineralised trends for Au and As. Repeat sampling to determine sampling variance has revealed probable contamination of Eucalyptus outer bark by dust. Sequential washing experiments indicate that the dust is difficult to remove from fibrous outer bark. Therefore, while application of biogeochemistry to exploration in the central Victorian Goldfields appears feasible, caution must be exercised in the interpretation of data from outer bark for some Eucalyptus species. References: Bierlein, F.P., Arne, D.C., Fuller, T. and Besanko, J., 1997, Wallrock alteration as an exploration tool of turbidite-hosted gold deposits: Examples from Victoria, Australia: 4th Biennial Meeting of the European Society of Geologists Applied to Ore Deposits, Turku, Finland, August 11-13, p. 149-152. Stott, J.E., 1996, A biogeochemical survey of the Ballarat East gold mine, Ballarat, Victoria: Unpublished honours thesis. University of Ballarat, 67 p. Taylor, D.H., 1998, Ballarat gold deposits: In Geology of Australian and Papua New Guinean Mineral Deposits, D.A. Berkman and D.H. Mackenzie (eds.), The Australasian Institute of Mining and Metallurgy, p. 543-548.

25 AU9917991

MOBILITY OF RARE EARTH ELEMENTS IN HYDROTHERMALLY ALTERED META-TURBIDITES ASSOCIATED WITH MESOTHERMAL GOLD MINERALISATION IN CENTRAL VICTORIA

1 Frank P. Bierlein,2 Helen M. Waldron,' Dennis C. Arne 1 Minerals Industry Research Institute, University of Ballarat, Ballarat Vic 3353 2 Becquerel Laboratories, Lucas Heights Science and Technology Centre, Lucas Heights NSW 2234 Turbidite-hosted mesothermal gold deposits, such as those found in Victoria, were long believed to be characterised by a lack of significant wallrock alteration, due in part to the apparent absence of a diagnostic alteration halo. However, visible wallrock alteration in meta- turbidites may often appear to be absent or only weakly developed simply because the host rock composition did not allow for the extensive development of distinct alteration assemblages, such as those which are recognised within extensive alteration haloes in reactive ultramafic host rocks around Archaean lode gold deposits in Western Australia. Until recently, the perceived lack of wallrock alteration around turbidite-hosted gold deposits generally discouraged comprehensive studies on the significance and extent of wallrock alteration in gold deposits in Victoria and, consequently, both the origin and relative timing of gold mineralisation in many turbidite-hosted deposits have been the subject to some controversy.

It has been recognised that the study of mineralogical and chemical changes within turbidites associated with gold mineralisation can provide invaluable information regarding ore genesis and represents a potentially powerful exploration tool by significantly increasing the magnitude of the exploration target. To this end, a number of detailed petrological and geochemical investigations of wallrock alteration associated with turbidite-hosted gold deposits have been carried out in central Victoria in the last few years. These studies demonstrate that wallrock alteration is much more pervasive and extensive than previously thought. Zones of wallrock bleaching, the development of pyrite and arsenopyrite porphyroblasts in meta-sedimentary rocks, abundant carbonate spotting and broad geochemical haloes all suggest that large quantities of hydrothermal ore-bearing fluids infiltrated and interacted with the host rocks. Chemical changes generally occur within 10 to 100 metres from the auriferous structures and involve enrichment in CO2, I^O, H2O, S, As, and Au as quartz reefs are approached, whereas SiO2 and Na^ are commonly depleted.

The relative mobility of so-called 'immobile' elements such as rare earth elements (REE) and high-field-strength elements (HFSE) in hydrothermal systems is influenced by a number of factors which include fluid-rock interaction, pH, Eh, /O2, changes in temperature and pressure, and fractionation processes during alteration. Thus, these elements are useful in understanding the processes that lead to the genesis of a given ore deposit, as they can provide constraints on the nature, source and composition of ore-forming hydrothermal fluids, when used in conjunction with petrographical information, fluid inclusion data, and isotopic signatures. Alteration traverses across and away from auriferous structures in six deposits (Ballarat West, Ballarat East, Fiddlers Reef, Fosterville, Maldon, Tarnagulla) sampled during previous studies provided an ideal opportunity to investigate possible systematic variations in REE distributions in hydrothermally altered meta-sedimentary rocks. Most noticeably, systematic trends (i.e., from most altered to least altered samples) cannot be identified in any of the traverses. Aside from some variations in the total REE content, all samples display chondrite-normalised REE signatures very similar to Post-Archaean Average Shale (PAAS) with general REE enrichment relative to chondrite values, and particular enrichment in light REE (LREE). (La/Yb)n ranges from 7.11 to 11.93, they are moderately depleted in Eu (Eu/Eu* 0.48-0.69) and have relatively flat heavy REE (HREE) patterns with (Tb/Yb)n approximating 1.1. These REE signatures, which suggest that REE and HFSE remained practically immobile throughout hydrothermal alteration, rule out high-temperature, strongly reducing or strongly acidic fluid compositions and further support the argument that REE remain relatively immobile during sericitisation and carbonatisation of siliclastic sediments, notwithstanding relatively high fluid-rock ratios.

26 AU9917992

MONTE CARLO CALCULATION OF SYNCHROTRON X-RAY BEAM DOSE PROFILES IN A LUNG PHANTOM

F Z Company1 and B J Allen2 School of Science, University of Western Sydney, Nepean, Kingswood 2747, NSW 2St George Cancer Care Centre Gray Street, Kogarah 2217, NSW, Australia

Recent advances in synchrotron generated X-ray beams with high fluence rate permit investigation of the application of an array of closely spaced, parallel or converging microplanar beams in radiotherapy. The proposed technique takes advantage of the hypothesised repair mechanism of capillary cells between alternate microbeam zones, which regenerates the lethally irradiated endothelial cells.

The lateral and depth doses of 100 keV microplanar beams are investigated for different beam dimensions and spacings in a tissue, lung and tissue/lung/tissue phantom. The EGS4 Monte Carlo code is used to calculate dose profiles at different depth and bundles of beams (up to 20x20 cm square cross section). The maximum dose on the beam axis (peak) and the minimum interbeam dose (valley) are compared at different depths, bundles, heights, widths and beam spacings.

Relatively high peak to valley ratios are observed in the lung region, suggesting an ideal environment for microbeam radiotherapy. For a single field, the ratio at the tissue/lung interface will set the maximum dose to the target volume. However, in clinical application, several fields would be involved allowing much greater doses to be applied for the elimination of cancer cells. We conclude therefore that multifield microbeam therapy has the potential to achieve useful therapeutic ratios for the treatment of lung cancer.

27 AU9917993

MONTE CARLO SIMULATIONS OF THE DOSE CHARACTERISTICS OF MICROPLANAR PHOTON BEAMS IN MAMMOGRAPHY

F Z Company1 and B J Allen2 School of Science, University of Western Sydney, Nepean, Kingswood 2747, NSW 2St George Cancer Care Centre Gray Street, Kogarah 2217, NSW, Australia

Synchrotron generated x-ray beams with small divergence and sharply defined microbeam margins permit investigation of the application of an array of closely spaced, parallel microplanar beams in diagnostic.

The depth absorbed dose and lateral dose in a breast phantom (p = 1.0 g/cm3) of a single microplanar beam is investigated with 20-200 kev photons.

The EGS4 Monte Carlo code is used to calculate dose profiles at different depths and different beam widths (2jtim-5mm). The maximum dose on the beam axis (Peak) and the minimum interbeam dose (Valley) are compared at different beam energies and widths.

It was found that a bundle of Synchrotron microplanar x-ray beams can improve the image quality in mammography.

28 AU9917994

FERRIMAGNETISM IN MNXV,.X ALLOYS

L.D. Cussen*, T.J. Hicks*, AJ. Studer+ and SJ. Kennedy+

School of Communications and Informatics, Victoria University of Technology PO Box 14428, MCMC, Victoria 8001, Australia Department of Physics, Monash University, Clayton, Victoria 3168, Australia ANSTO, PMB 1, Menai, NSW 2234, Australia

ABSTRACT The magnetic properties of MnV alloys near the equiatomic concentration have been investigated using magnetic susceptibility and neutron powder diffraction. Rapidly cooled body centred cubic alloys near the equiatomic concentration are confirmed as very weakly ferrimagnetic with average local moment of the order of 0.05 }1B per atom and average ordered moments of order 0.02 ^B per atom. The degree of atomic and magnetic order can be greatly enhanced by annealing these alloys supporting the view that the ordered moments are associated with CsCl type atomic short range order. Evidence is presented that the moment is not associated with impurities or any of the multitude of magnetically ordered mixed manganese vanadium oxides.

29 AU9917995

ORDERING AND INTERACTIONS IN MnPS3

D. J. Goossens and T. J. Hicks Physics Department, Monash University Clayton VIC 3168

Manganese thiophosphate, MnPS3, is a quasi-two-dimensional closely Heisenberg antiferromagnet in which the Mn atoms lie in planes and alternate with P2 pairs, so that the Mn atoms form a honeycomb lattice. These layers are sandwiched between sulphur layers, and these three-layer structures are bonded by van der Waals forces, giving the material strong magnetic interactions in the plane but weak interactions between planes. The magnetic moments, at low applied magnetic field, point perpendicular to the planes. However, a strong field applied along the spin direction gives rise to a spin flop phase transition in which the spins rotate and lie in the plane. We have examined the magnetic behaviour of the material in terms of exchange, single- ion and magnetic dipole-dipole interactions. All interactions are found to be significant, with the long range ordering of the material depending on both weak interplanar coupling and the net anisotropy due to dipolar and single ion effects.

The effect of magnetic dilution, through the production of samples of MncZn1.xPS3, has been explored experimentally using a SQUID magnetometer and magnetic neutron scattering. The concentration and temperature dependence of the Neel temperature, TN, can be explained by that of the dipolar anisotropy, and these results allow an estimate of the single ion anisotropy. This anisotropy, which is due to the electric field symmetry at the moment site, is found to be significant, and may explain critical neutron scattering results found in the literature. These results show that the critical scattering is of a planar, or XY, universality class rather than an Ising class, although the latter is what would be expected from the zero field, low temperature magnetic order. Also, the change in orientation of the magnetic moments with dilution agrees with a model of competing dipolar and single-ion anisotropies. We conclude that dipole-dipole interactions provide the dominant anisotropy mechanism in MncZn1.xPS3. In conjunction with exchange and single-site effects, this anisotropy explains much of the observed behaviour.

30 AU9917996

MODIFICATION OF SURFACES FOLLOWING PLASMA IMPLANTATION OF HELIUM

P W Gilberd a>b, P B Johnson a, J Y Lazar a, A Markwitz b, W J Trompetter b, K T Shortc and G A Collins c

a School of Chemical and Physical Sciences, Victoria University of Wellington, P O Box 600, Wellington, New Zealand b The Institute of Geological and Nuclear Sciences Ltd, P O Box 31-312, Lower Hurt, New Zealand c ANSTO Materials Division, Private Mail Bag 1, Menai, NSW 2234, Australia

The surface and sub-surface regions of silicon and a range of titanium- and vanadium-based metals have been modified by implantation of helium at energies of 20-50 keV, using the Plasma Immersion Ion Implantation (PI3) facility at ANSTO. In the case of silicon, the resulting structure has been altered further, either by thermal annealing, or by thermal annealing following the application of a thin, sputtered, film of gold onto the surface. For the metals, the implanted structure has been oxidised in several ways; thermally, anodically, and by plasma implantation.

Surfaces modified in these ways might be expected to have unique chemical and physical properties. They have been investigated by a range of techniques including electron microscopy, Raman spectroscopy, Rutherford backscattering spectrometry, and nuclear reaction analysis.

Implanted silicon has a thin amorphous layer at the surface, containing bubbles of helium. On annealing, the material crystallises and the bubbles grow into faceted voids up to —30 nm across. The application of a surface film of gold prior to annealing gives rise to plate- like inclusions of Au-Si alloy on heating, and also filling, partial-filling and surface decoration of the voids.

The structure and phases of oxides developed on plasma-implanted metals are compared with those on unimplanted, but otherwise identically treated, metals. Corresponding results for helium-ion implantation at higher energies are also presented. It is shown that implantation can affect the blend of oxide phases at the surface and the degree of oxidation.

31 AU9917997

TWENTY THOUSAND YEARS OF CHANGING OBSIDIAN TRADE IN MELANESIA

J. Peter White and Robin Torrence Archaeology, University of Sydney, NSW 2006; Anthropology, Australian Museum, 6-8 College Street, Sydney NSW 2000

This research demonstrates the value of extensive collaboration between physics and archaeology in using PIXE-PIGME analysis to study ancient trade in Papua New Guinea. Obsidian has been recorded as a major exchange item in the Bismarck Archipelago since European contact and has been found in archaeological sites in levels dating from 20,000 years ago. Initial investigations of artefacts from a range of sites in the Pacific region using PIXE-PIGME showed that these traded items came from two major obsidian source regions in West New Britain — Willaumez Peninsula and Mopir. Archaeological investigations in these areas identified four well separated obsidian flows which varied in terms of their spatial scale, ease of extraction of raw material, and quality of obsidian for artefact manufacture. Extensive deposits of the by-products from quarrying and artefact manufacture were associated with each flow. Using enhancements in PIXE-PIGME, a finer discrimination was achieved that has allowed each artefact to be assigned to one of the four sub-regions in the Willaumez Peninsular group. These results have led to a better understanding of ancient trade practices. Further analyses of archaeological materials from multiple sites in the Bismarck Archipelago have shown: 1. During the Pleistocene (20,000 - 10,000 years ago) obsidian from both major source regions was repeatedly moved to New Ireland, a distance of some 600 km. The Mopir source predominated. 2. In the period 3500-1500 years ago Mopir was very rare probably because the source was cut off due to a massive volcanic eruption. 3. Although proximity to outcrop is usually the major factor in determining which obsidian was used, one excellent sub-source, Baki on Garua Island, was almost never traded and was not always even the preferred source locally.

32 AU9917998

A NOVEL METHOD OF RADON GRAB SAMPLING IN CAVES

Craig Barnes1, Michael Hyde2, Julia James1, Stewart Whittlestone2, and Wlodek Zahorowski2

1 School of Chemistry, The University of Sydney 2 Environmental Division, ANSTO

Jenolan caves, located 100 km west of Sydney, are the premier tourist caves in Australia and are visited by over 250,000 tourists each year. To accommodate such large numbers of visitors, there are many guides and maintenance workers at the Caves. For these workers, radon is a workplace hazard, so studies of radon levels within the caves are essential for their well being.

Various methods of detection and measurement of radon levels have been used at Jenolan Caves over recent years, including those based on track etch films, scintillation cells, ionisation chambers and solid state detectors. These were excellent for measurement of long-term averages or for intensive surveys. However, an additional technique was required that provided cheap, quick, accurate, spot radon concentrations with equipment rugged and portable enough to be taken anywhere within the cave and simple enough to be used by untrained personnel.

First it was confirmed that a cave air sample taken in one litre plastic bottle could be analysed with sufficient sensitivity for cave work. A vial containing a small amount of charcoal is put into the bottle, which is then sealed for six hours. The radon absorbed by the charcoal can be measured subsequently in the laboratory using a liquid scintillation technique. The lower detection limit for the method is 10 Bq m"3. Radon results evaluated by the new method agree well with those obtained by an ionisation chamber detector. It has been shown that commercially available vials with a mixture of charcoal and a hydroscopic agent developed for radon screening in houses can be used thus avoiding the time consuming preparation of the charcoal mixture.

Data have been collected using this method over a period of two years, at different times and from several different sites within the Jenolan cave system. Indeed, this method allowed simultaneous collection at several sites, and was used to collect samples from twenty different locations within a period of 40 minutes each time sampling was undertaken. The results obtained from the twenty sites for this two-year period are presented.

By comparing results from the same site taken at different times of the day and year, it has proved possible to observe both diurnal and seasonal variations in the radon levels. Further, the comparison of the results between sites has allowed a determination of the spatial distribution of the radon levels within the caves and the characterisation of radon behaviour at the various sites. Consequently, the new method has proved to be an accurate and extremely useful method of measuring radon levels.

33 AU9917999

THE CRYSTAL AND MAGNETIC STRUCTURE OF Nd3Co29Si4B]0

Heng Zhang, S. J. Campbell, E. Wu, S. J. Kennedy \ M. Hofmannb, H.-S. Lic and A. J. Studera

School of Physics, University College, The University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600 'Neutron Scattering Group, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 b Hahn-Meitner-Institut GmbH, Abteilung NE/Uni, Glienickerstr 100, D-14109 Berlin, Germany 'School of Physics, The University of New South Wales, Sydney, NSW 2052

The crystal and magnetic structure of the compound Nd3Co29Si4B10has been investigated by neutron powder diffraction (room temperature and 1.5 K) and Rietveld refinement. The crystal structure has been established as tetragonal (space group P4/nmm) with Nd3Ni29Si4B10 structure [1] of lattice constants a = 11.2394(2) A and c = 7.8911(2) A. AC magnetic susceptibility measurements reveal magnetic transitions at ~200 K and ~40 K. The enhanced magnetic diffraction from the neutron diffraction pattern at 1.5 K is consistent with ferromagnetic ordering. The Rietveld refinement indicates that Nd3Co29Si4B10 has a commensurate magnetic structure with a magnetic unit cell of the same dimensions as the chemical unit cell. The magnetic ordering at 1.5 K is mainly associated with the rare-earth sites. The magnetic moment of Nd in the 2b site is likely to lie in the basal plane, while the moment of 4d site exhibits a complex structure.

This work is supported in part by a grant from AINSE. SJC acknowledges the support received from AINSE over the years with initial contact stemming from 1970.

[1] Heng Zhang, E. Wu, S. J. Campbell, S. J. Kennedy , H.-S. Li, A. J. Studer, S. R. Bulcock and A. D. Rae, J. Alloys and Compounds (in press).

34 AU9918000

NEUTRON DIFFRACTION STUDIES OF MECHANOCHEMICALLY SYNTHESIZED IRON OXIDES

E. Wua, S.J. Campbell3, W.A. Kaczmarek5, M. Hofmann0, S.J. Kennedy" and A.J. Studerd

aSchool of Physics, University College, The University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600, Australia bDepartment of Applied Mathematics, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia cHahn-Meitner-Institut GmbH, Abteilung NE/Uni Glienickerstr. 100, D-14109 Berlin, Germany dNeutron Scattering Group, Australian Nuclear Science and Technology Organization " Private Mail Bag 1, Menai, NSW 2234, Australia

Mechanochemically synthesized magnetite has attracted considerable interest due to its interesting structural and magnetic properties [1,2,3]. The neutron diffraction measurements have been carried out on a series of mechanochemically synthesized iron oxide samples (haematite milled for 24h, 48 h, 72 h, 96 h, 144 h) at room temperature. The diffraction patterns of normal haematite, magnetite and maghemite (y-Fe2O3) have also been collected for comparison. Refinement of the neutron diffraction patterns indicates a continuous transformation of haematite to magnetite during the milling process and after 144 h of milling, the diffraction pattern of the sample shows a spinel-type, magnetite structure. The lattice parameters and the site occupancies reveal that there are vacancies in both the octahedral and tetrahedral sites of the spinel structure of the mechanochemically synthesized magnetite with a formula of Fe3.x(Vac)xO4 where x~0.3. Based on the analysis, the crystal and magnetic structure of the mechanochemically synthesized product exhibit features similar to both magnetite and y-Fe2O3. The patterns have been refined in terms of diffraction refinement models allowing for the possible presence of randomly distributed vacancies in both the octahedral and the tetrahedral sites of the spinel structure.

This work is supported in part by a grant from AINSE. SJC acknowledges the support received from AINSE over the years with initial contact stemming from 1970.

[1] W.A. Kaczmarek and B.W. Ninham, IEEE Trans. Magn. 30 (1994) 732. [2] SJ Campbell, W.A. Kaczmarek and G-M. Wang, NanoStructured Mat. 6 (1995) 735. [3] M. Hofmann, S.J. Campbell and W.A. Kaczmarek, Mater. Sci. Forum 228-231 (1996) 607.

35 AU9918001

STRUCTURAL INFLUENCES OF SUBSTITUTION INTO SYNTHETIC APATITES

Jean Y. Kim \ Ronald R. Fenton \ Brett A. Hunter2 and Brendan J. Kennedy1

1 School of Chemistry, University of Sydney, N.S.W., 2006, Australia 2 ANSTO, PMB 1 Menai, N.S.W., 2234, Australia

Hydroxy apatite, Cai0(PO4)6(OH)2, is a major mineral component of calcified tissues, including bones and teeth. It is a good model system for natural apatites, having a structure which can easily accommodate a great variety of anionic and cationic substitutions. Consequently, hydroxyapatite acts as a natural sink to heavy metals, especially Pb and Cd, in biological systems. The incorporation of foreign ions affects such properties as the crystallinity, morphology and more importantly, the stability of the apatite structure. It is known that, in nature, the hydroxy ion is partially replaced by other anions and one aim of the present work is to establish how such substitutions influence the ability of the natural complexes to sequest and immobilise heavy metals. The determination of the precise structures of these materials is therefore of considerable importance. We have used a combination of high resolution powder neutron and synchrotron X-ray diffraction methods for our structural studies.

In our work, not only have various halide ions (F, Cl and Br) been substituted for the OH ion, but in addition, Pb ions have also been incorporated in place of the Ca ion in the various apatite compounds. It has been found that the replacement of the OH group with the halides alters the rejiative distribution of Pb over the two possible sites in these compounds. It has also been determined that for the Ca compounds, the F, Cl and the OH are all positioned at (0, 0, z), where z « 0.2 - 0.6 A. The Br, however, is positioned at (0, 0, 0). For the Pb compounds, only the OH is positioned at (0, 0, z), where z « 0.1 A. The F, Cl and Br are located at the (0, 0, 0) position. Neutron scattering methods have been essential in determining the positional parameters of the lighter elements (H, F, O etc.) in the presence of the heavy Pb atom. In this paper we present both the experimental results and discuss the possible reasons for the observed differences.

36 AU9918002

STRUCTURAL REFINEMENT OF C/5-BIS(L-ALANINATO)COPPERai)

S.M. Moussa,1 R.R. Fenton,1 B.A. Hunter,2 B.J. Kennedy1 and R.O. Piltz.2

1 School of Chemistry, University of Sydney, N.S.W., 2006, Australia 2ANSTO, PMB 1 Menai, N.S.W., 2234, Australia

This work is part of the ongoing investigations into the structures and hydrogen-bonding networks of divalent metal(II) amino-acidato complexes. Studies of these types of complexes are of considerable interest due to their significant roles in many biological systems and in the possibility that they may enhance our understanding of the more complicated metalloproteins.

The structure of c/s-bis(L-alaninato)copper(II) {d5-[Cu(L-ala)2]} was determined using single crystal neutron diffraction techniques at both low (7 K) and ambient temperature. The cell was found to be orthorhombic, space group Y1{1{1\. The unit cell parameters obtained at ambient temperature were a = 11.645(4) A, b = 8.772(3) A and 3 c = 8.444(2) A, V = 862.6(5) A while at low temperature a = 11.564(4) A, b = 8.709(3) A and c = 8.406(3) A, V = 846.6(5) A3. The final measures of fit were, Rl = 2.3% and wR2 = 4.2% for 982 unique reflections and GOF 1.1; Rl = 2.2% and wR2 = 4.5% for 1145 unique reflections and GOF 1.2 using the ambient and low temperature data set respectively.

At both temperatures the coordination sphere around the copper atom is best described as square pyramidal, where the fifth position is occupied by a weakly bonded carbonyl oxygen from an adjacent alanine unit. The alanine ligands coordinate to the divalent copper atom in an approximately square planar ds-arrangement. The significant difference between the two structure determinations is the contraction of the apical carbonyl oxygen - copper bond distance from 2.372(4)A to 2.326(2) A upon cooling.

The structure was also refined using powder neutron diffraction techniques. During refinement of the structure a second phase was detected and was subsequently included. The cell parameters obtained were a = 11.6273(5) A, b = 8.7580(4) A and c = 8.4358(4) A and final measures of fit were Rp = 1.27 %, Rwp = 1.55 %, Rexp = 0.93 % and Rbiagg = 0.92 % and GOF = 2.75.

37 AU9918003

STUDIES OF COPPER TRANSPORT IN MAMMALIAN CELLS USING COPPER RADIOISOTOPES

J. Camakaris1, S. Smith2,1. Voskoboinik1, H. Brooks1, J. Mercer3 and M. Greenough1 'Department of Genetics, University of Melbourne, Parkville, Victoria 3052, Australia 2Radiopharmaceuticals Division, ANSTO, Lucas Heights, NSW 2234, Australia 3Centre of Cellular and Molecular Biology, Deakin University, Rusden Campus, Clayton, Victoria 3168, Australia

The trace element copper poses a major problem for all organisms. It is essential as a number of vital1 enzymes require it. Copper deficiency can lead to neurological disorders, osteoporosis and weakening of arteries. However Cu is also highly toxic and homeostatic mechanisms have evolved to maintain Cu at levels which satisfy requirements but do not cause toxicity. Toxicity is mediated by the oxidative capacity of Cu and its ability to generate toxic free radicals. There are several acquired and inherited diseases due to either Cu toxicity or Cu deficiency. The study of these diseases facilitates identification of genes and proteins involved in copper homeostasis, and this in turn will provide rational therapeutic approaches. Using the copper M 67 radioisotopes Cu (tV2 = 12.8 hr) and Cu (tV2 = 61 hr) we have developed a number of systems for studying copper transport in mammalian cells. These include investigation of copper uptake, copper efflux and ligand blot assays for Cu-binding proteins. Our studies have focused on Menkes disease which is an inherited and usually lethal copper deficiency disorder in humans. We have demonstrated that the Menkes protein is directly involved as a copper efflux pump in mammalian cells. Using cells overexpressing the Menkes protein we have provided the first biochemical evidence that this functions as a Cu translocating (across the membrane) P-rype ATPase (Voskoboinik et ah, FEBS Letters, in press). These studies were carried out using purified plasma membrane vesicles. We are now carrying out structure- function studies on this protein using targeted mutations and assaying using the radiocopper vesicle assay. Recently we have commenced studies on the role of amyloid precursor protein (APP) in copper transport and relationship of this to Alzheimers disease.

38 AU9918004

THE FLINDERS UNIVERSITY INDUCTIVELY DRIVEN SPHERICAL TOKAMAK PROJECT

Lance McCarthy Physics Department, Flinders University, South Australia

The Flinders University inductive start up Spherical Tokamak (ST) program is designed with two major functions: first a target plasma for a definitive test of rotating magnetic field (RMF) current drive, and secondly as a target plasma to be used in development of diagnostics for the collaboration between Flinders University and the Australian National Fusion Facility. A third goal is to maintain an Australian link to the international ST community at a time when this ST approach to plasma fusion is entering a "second generation" phase of larger machines, following the demonstration of resilience to major disruptions on START and MEDUSA, and excellent confinement properties, and /3. Modelling of the optimum operating regime consistent with power supplies available at Flinders University, and comparisons of plasmas prepared by RMF alone with ohmically heated plasmas such as START, are presented to support the need for the design of this OH hot confined target plasma approach to RMF current drive as an alternative to that of pure RMF current drive at higher powers being attempted elsewhere, should that approach not prove successful. Progress on the experiments, which now includes successful tests of the toroidal field system and the OH coil system, is reported. The RMF facility will not be available till late in 1998. The case is made for retaining the valuable equipment resources of the Flinders University plasma research group and negotiating for the transfer of these to the Australian National Fusion Facility at the completion of this project at the end of 1999.

39 AU9918005

RADIOACTIVE DISEQUILIBRIUM IN MOUND SPRING DEPOSITS

J.R. Prescott* Physics & Mathematical Physics, University of Adelaide, SA 5005 M.A. Habermehl Australian Geological Survey Organisation, Canberra, ACT 2601 Henk Heijnis Environmental Radiochemistry, ANSTO, Menai NSW 2243

The AINSE-supported programme, Radioactive disequilibrium in low level uranium and thorium determinations, had its genesis in the luminescence dating programme at the University of Adelaide, because of the need to assess uranium and thorium in the environment at the ppm level, and it has continued in a variety of contexts. The present paper is chosen as it is our most comprehensive from this programme; it also exemplifies the general role of collaboration between the University, external organisations and ANSTO. Much of it is unpublished.

The problem to be resolved was the age of the mound spring sediments on the margin of the Great Artesian Basin to the south and south-west of Lake Eyre. Nine samples from six springs and two from neighbouring dune fields were collected. The parent and daughter nuclides for the uranium and thorium decay chains have been comprehensively measured by a variety of techniques: DNA, thick-source alpha particle counting, field scintillometry, high resolution gamma spectrometry and high resolution alpha spectrometry. Gross radioactive disequilibrium in the uranium chain is found for the spring samples. The activity, in Bq kg"*, for the uranium chain at and below radium, compared with the parent uranium and its immediate daughters, ranges from an excess factor of two to a factor of six, depending on the age of the spring mound deposit. This is interpreted as evidence that radium is being carried up into the springs with artesian groundwater and deposited in the spring mound sediments. There is also evidence for a small excess of thorium.

The ages of the spring mound deposits have been successfully found by thermoluminescence. They range from about 20ka to 500ka. The disequilibrium suggests why attempts to use uranium series dating have not been successful.

* Corresponding author tel (08) 8303 4747 fax (08) 8303 4380 email: [email protected]

40 AU9918006

THE RETENTION OF CAESIUM AND STRONTIUM IN CEMENTED ZEOLITES

A.S. Ray, M.G. Stevens, R.S. Knight, K. Stevenson and C. Mapson University of Technology, Sydney and L.P. Aldridge Austtralian Nuclear Science and Technology Organisation (ANSTO)

Cemented zeolite cured at different temperatures were studied to determine whether or not there significant changes between the retention of caesium or strontium. A 65% pure clinoptilolite zeolite, a 90% pure clinoptilolite zeolite and a synthetic A type zeolite were used in the study. Two different Portland cements were chosen to immobilise the zeolites which were ion exchanged with caesium and strontium prior to immobilisation. The cemented zeolites were cured for 28 days at room temperature, and for 7 days at 70°C and 150°C. They were then leached in pure water at 25°C and 40°C for 28 days without replacement of the leachate solutions. Leachate aliquots were collected every 3, 7, 14, 21 and 28 days. Zeolite additions in cements improved the retention of both caesium and strontium the level of retention being dependent on the type of zeolite, the type of cement and the temperature of leaching.

41 AU9918007

TWO NEW SOLID SOLUTIONS IN CALCITE-MAGNESITE SYSTEM IDENTIFIED IN A SAMPLE FROM CORAL REEFS IN THE NORTHERN PERTH BASIN

D.Y. Li, B.H. O'Connor, Z.R. Zhu and L.B. Collins

Curtin University of Technology GPO Box U1987, Perth 6845 WA

B. Hunter

Australian Nuclear Science and Technology Organisation Private Mail Bag 1, Menai NSW 2234

Dolomite, CaMg(CO3)2, is an economically important mineral, being of particular significance in petroleum geology. Carbonate rocks have long been a focus of investigation because these rocks contain an estimated 60 percent of the world's recoverable petroleum, and include most of the world's largest reservoirs. Correct phase identification in carbonates has concerned sedimentologists and petroleum geologists for decades. A new type of solid solution in the calcite (CaCOa) - magnesite (MgCOs) system has been identified at Curtin University by Rietveld XRD and neutron diffraction data analysis in a sample from late Pleistocene reefs in the northern Perth Basin. It is known that the structure of calcite (space group R3C) will be transformed to dolomite (R3), which has an ordered distribution of Ca and Mg in the structure, if 50% of its Ca atoms are substituted by Mg in terms of the Ca-Mg atomic ratio. However, the upper limit of Mg substitution for Ca in calcite under sedimentary-geological conditions without there being a change in structure to dolomite is still unknown. Two carbonates examined at Curtin showed Mg substitution for Ca in calcite under coral reef sedimentary conditions of 18.1% and 37.7%, whereas Bragg peak shifts for a 'dolomite' line for these samples were interpreted by geologists as indicative of dolomite with a certain extent of order-disorder distribution between Ca and Mg atoms. The observations have provided an opportunity to re-examine the origins of dolomite and aspects of dolomitization in a coral reef environment in the Quaternary.

42 AU9918008

CONTRIBUTIONS of RADIATION CHEMISTRY to RESEARCH

David F Sangster, Hon. AINSE Fellow Chemistry School Fl 1, University of Sydney, NSW, 2006, Australia

Many chemical processes involve free radical species. Radiolysis of water produces three very reactive free radicals, the solvated electron, the hydroxyl radical and the hydrogen atom. These undergo interesting reactions and have been the subject of many studies. However, in the presence of selected solutes, they will react to give a range of free radicals which may be used to investigate a series of free radical reactions. Research fostered by AINSE over the last 40 years, using the gamma sources, the pond, GATRI and the shielded cells, and the steady beam and the pulse radiolysis faciliies associated with the 1.3 MeV electron accelerator and with the 0.5 MeV Febetron at Lucas Heights, has enabled insights to be gained which would not have been possible otherwise. Answers can be given to the two questions what is the reaction and how fast is it. Particularly valuable has been the determination of reaction rate constants and one finds these quoted extensively in the chemical literature. Although most of the work has been carried out on aqueous systems, there have been some studies on solutions in non-aqueous solvents and in the gas phase. Examples will be given from the fields of metal/organic, excited state, biological and polymer chemistry. Metal ions of unusual valence states can be made readily and their reactions studied. The stability of ligand cages containing these metal ions points up rules for the more common compounds. The puzzling reactions of powerful oxidants with azido CoDI compounds were explained when an unexpected long lived transient was found from reaction with hydroxyl radicals. Reactions involving hydrated electrons were found to be much faster than those involving outer sphere reductants. Rhenium compounds were studied in order to obtain an insight into the reactions of technitium compounds. With alcohol/alkane mixtures some measure of the degree of association of the alcohol molecules could be obtained from the ability to solvate radiolytic electrons. The radiolysis of cryogenic ice gave excited water molecules and the experimental parameters controlling their decay could be evaluated. Rate constants for reactions of the superoxide ion with quinones and with the enzyme myeloperoxidase were evaluated in order to test the possibility of some proposed in vivo reactions. Free radicals are being recognised increasingly as being important in biological systems and some of these can be made by radiolysis. Radiation initiation of polymerisation can be controlled and very precisely stopped and started. Radical production is almost independent of temperature. The biocompatible polymer poly(N-vinyl pyrrolidone) was made in this way free of initiator decomposition fragments. The optimum conditions for radiation grafting of monomer to polymeric substrates were determined. Some recent investigations on polymer-surfactant mixtures have shown that it is possible to make a novel polyelectrolyte with unusual properties. Under irradiation the surfactant moiety is grafted by covalent bonds onto the polymer chains and these are held together within the expanded latex particles by entanglements. The particle becomes an open structure in which 96% or more of its bulk is the interstitial solution. The unchanged surfactant can be removed by dialysis leaving only the sodium counter-ions and the open structure remains. The successful use of the radiation facilities at Lucas Heights under the auspices of AINSE can be attributed to many factors - the assistance given to university research workers and the servicing of the equipment by the resident AAEC/CSIRO/ANSTO staff, the provision of auxilliary peripherals and of travel and accommodation by AINSE, the opportunity to meet and discuss at AINSE Conferences, and above all the ever-helpful attitude of AINSE staff.

43 AU9918009

DEVELOPMENT OF A FAST DATA ACQUISITION AND PROCESSING SYSTEM FOR SPECTROSCOPY DIAGNOSTIC ON H-INF DEVICE

Shu Zhang and Xuehua Shi School of Advanced Technologies and Processes Faculty of Engineering and Physical Systems Central Queensland University, Rockhampton 4702

This paper describes the development of a fast data acquisition, processing and display system for the plasma spectroscopy diagnostic on H-INF at Australian National University. The system consists of a custom-designed interface and control unit, a Digital Signal Processor (DSP) card as a main processing unit, and a PC as a host server for the DSP card, to provide a development environment, and to be a control, display and storage unit. Currently, two fast data acquisition channels are provided, however, the interface section in the system can be easily duplicated to handle multi- channel spectroscopy data.

The paper shall start with a brief introduction to the spectroscopy diagnostics on H-INF and the algorithms used to derive ion temperature and ion flow velocity of an argon plasma from the spectroscopy data. This is followed by an overview of the data acquisition, processing and display system. The hardware design of the interface and control unit, the function of the DSP card and the software development to handle the interactions between the DSP card, the PC and the interface shall be discussed in detail. In the end of this paper, experimental results processed by the system shall be presented.

44 AU9918010

USE OF NEUTRON DIFFRACTION IN ALUMINA-MATRIX CERAMICS RESEARCH: A 10 YEAR PERSPECTIVE

B H O'Connor, A van Riessen and D Y Li

Materials Research Group, Department of Applied Physics, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia.

The Materials Research Group at Curtin University has made extensive use of the Lucas Heights neutron powder diffraction facilities over the last decade. There have been two substantial research programs on the processing of alumina-matrix ceramics - that conducted by the authors of this presentation and their students, and a second program by our colleague Dr Jim Low and students. The paper will summarise the following neutron diffraction experiments all of which involved high-temperature, real-time measurements with the MRPD diffractometer: • Microstructure development in zirconia-dispersed aluminas (van Riessen, 1997) in which phase composition changes and residual strain development were examined as the material cooled to room temperature following sintering. • Calcination of gibbsite to a-alumina (Gan, 1996). A highlight of this study was the observation of co-existing tetragonal and cubic polymorphs of y-alumina. • Study of the liquid-phase-sintering of an alumina-matrix ceramic composition (Latella, 1995; Latella et al, 1998). Here the influence of the post-sintering cooling rate on phase composition was examined with particular reference to wear-resistant behaviour. All of the experiments were supported by the Australian Institute of Nuclear Science and Engineering.

References Gan, B.K. (1996). Crystallographic transformations involved in the decomposition of gibbsite to a-alumina. PhD thesis. Curtin University of Technology. Latella, B.A. (1995). Development of debased alumina wear-resistant ceramics. PhD thesis. Curtin University of Technology. Latella, B.A., O'Connor, B.H. and Hunter, B.A. (1998). In situ high temperature neutron diffraction study of a liquid-phased-sintered alumina ceramic. Journal of Materials Science Letters, J7, 349-353. van Riessen, A. (1997). Depth-profile character of zirconia-dispersed aluminas. PhD thesis. Curtin University of Technology.

45 AU9918011

EVIDENCE FOR CERIUM MOBILITY IN USED AUTOMOTIVE CATALYTIC CONVERTERS: A PIXE/PIGME MILLIPROBE INVESTIGATION

D E Angove*, N Dytlewski, G M Bailey, N W Cant* and D D Cowen *School of Chemistry, Macquarie University, NSW 2069

A comparison was made between used and unused three-way automotive catalysts using the milliprobe facility at ANSTO. These catalysts were constructed commercially by applying a Pt/Rh/Al2O3/CeO2 washcoat to a cordierite honeycomb support. In the fresh sample the expected elements Al, Si and Ce were readily observed. In the used sample the contaminants P, K, Ca, and Zn were observed along with Ce but, unexpectedly, Al was not observed. This observation has been interpreted as being caused by the migration of Ce from the washcoat into the contaminant layer deposited on the washcoat during vehicle use. X-ray diffraction studies indicated that CePO4 is present in the used sample. Further studies are planned to confirm tis observation using alternative instrumental techniques.

46 AU9918012

SIGNIFICANCE OF GRAFTING IN RADIATION CURING REACTIONS. COMPARISON OF IONISING RADIATION AND UV SYSTEMS

Elvis Zilic' John L. Garnett", Loo-Teck Ng and Visay Viengkhou1

'School of Civic Engineering and Environment, University of Western Sydney Nepean, Kingswood, N.S.W., 2747. ^Radcure Australia Inc, University of Western Sydney Nepean, Kingswood, N.S.W., 2747.

Radiation curing is now an accepted commercial technology where both ionising radiation (electron beam) and ultra violet light (UV) sources are used. Grafting is essentially the copolymerisation of a monomer/oligomer to a backbone polymer whereas curing is the rapid polymerisation of a monomer/oligomer mixture onto the surface of the substrate. There is no time scale theoretically associated with grafting processes which can occur in minutes or hours whereas curing reactions are usually very rapid, occurring within a fraction of a second. An important difference between grafting and curing is the nature of the bonding occurring in each process. In grafting, covalent carbon-carbon bonds are formed, whereas in curing, bonding usually involves weaker Van der Waals or London dispersion forces. The bonding properties of the systems are important in determining their use commercially. Thus the possibility that concurrent grafting during curing could occur in a system is important since, if present, grafting would not only minimise delamination of the coated product but could also, in some circumstances, render difficulties recycling of the finished product especially if it were cellulosic. Hence the conditions for observing the occurrence of concurrent grafting during radiation curing are important. In the present paper, this problem has been studied by examining the effect that the components used in radiation curing exert on a typical reaction. Instead of electron beam sources, the spent fuel element facility at Lucas Heights is used to simulate such ionising radiation sources. The model system utilised is the grafting of a typical methacrylate to cellulose. This is the generic chemistry used in curing systems. The effect of typical additives from curing systems including polyfunctional monomer and oligomers in the grafting reactions have been studied. The ionising radiation results have been compared with analogous data from UV experiments. The significance of the work in curing processes is discussed.

47 AU9918013

MODELLING THE ANGULAR MOMENTUM J OF Is, lp, Id, 2s, AND If NUCLEONS

Peter Norman Monash University Clayton, Victoria

Norman (1), (2) has shown that if alpha particles are densely packed as spheres then not only are nuclide sizes, densities, quadrupole moments and binding energy data satisfied but so too are the requirements of the energy levels of the "shell models of nuclear structure. The magnitude of the angular momentum J of a nucleon is defined as VjO+1) h/27i where j is the quantum number and h is the Planck constant. It will be assumed that J = mvr where m = 1.67x10-27 kg is the nucleon mass, v = nucleon velocity about the nuclide centre of mass distant r from the nucleon. For each Is nucleon in an alpha particle n = 0.86 fin and Ji = 0.86 h/2n so that vi = 0.21 c. In the liquid drop model of 4 alpha particles representing an oxygen 16 nuclide. each lp nucleon is distant n = 2.18 fin from the centre of the nuclide. Because J2 =1.94 h/2n it follows that V2 = 0.19 c ~ vi. By using the liquid drop model of 14 alpha particles representing a nickel 56 nuclide it can be shown that the mean distance of each of the Id and 2s nucleons is n = 2.85 fin from the nuclide centre. Because J3 = 2.96 h/2ii it follows that V3 ~ V2 ~vi. A similar situation holds for the lf7/2 nucleons for which » = 3.95 fin and h = 3.96 h/27i so that vt ~ vi. That is, the velocity of all nucleons is the same and is independent of the energy level. This implies that the de Broglie wavelength of all nucleons isw = h/mv=6.3fin~27t fin. Therefore for n ~ 1 fin there is one w per orbit; for n ~ 2 fin there are 2 w per orbit and so on. This implies that in the first magic number closed shell of nucleons there are 2 orbits each containing 2 standing wave maxima representing 1 proton and 1 neutron. The second closed shell consists of 3 orbits each containing 2 proton and 2 neutron standing wave maxima. While the third closed shell consists of 4 orbits each containing 3 protons and 3 neutrons the fourth closed shell consists of only 2 orbits each containing 4 protons and 4 neutrons. The Bemal liquid drop alpha particle models of nuclear structure appear to accord quite well with the quantum mechanical prescriptions of nucleon angular momentum and de Broglie wavelength.

References:

(1) Norman P.D. (1993) "Models of the meson bond structure of the most abundant products of stellar nucleosynthesis" Eur. J. Phys. 14,36.

(2) Norman P.D. (1995) "Liquid drop alpha particle models of some common nuclides" Proc. A.N.A. 95, 125.

48 AU9918014

ELECTRICAL AND MAGNETIC PHASES OF THE LAYERED PEROVSKITES Ca(4x)LaxMn3O10

!P Goodman, 2Shane Kennedy, 3N S Witte, 4F J Lincoln and 5 R H March 'National Key Centre for Microscopy and Microanalysis, University of Sydney, FO9, NSW Australia 2006 2ANSTO, Dept of Physics Private Mail Bag 1, Menai NSW 2234 3School of Physics, University of Melbourne, Parkville, Victoria 3052 4Director, Research Centre for Advanced Mineral and Materials Processing, Department of Chemistry, University of Western Australia, Nedlands, WA 6907 department of Physics, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 315

We analyse magnetic susceptibility, resistivity and neutron diffraction measurements of the electron doped triple layered perovskite, or Ruddleston-Popper class of Manganates 2+ 3+ 3M+ Ca La Mn O]0, where the CaO component is doped by small quantities of La, thus oxidising the compound. In the resulting phase diagram, near the undoped region, a paramagnetic insulator to antiferromagnetic insulator transition is observed with decreasing temperature and a concomitant change in the conduction process from thermal activation to Mott-type hopping. For larger doping, with a Mn valence of 3.97, there is a transition from the paramagnetic insulator to a canted antiferromagnetic insulator, which exhibits a more dramatic change in the conduction mechanism. The undoped magnetic structure is a collinear Antiferromagnet with moment reversal along all axes, and the moment is approximately aligned along the c-axis.

49 AU9918015

THE HIGH ENERGY RADIATION CHEMISTRY OF SOME FLUORINATED ELASTOMERS

John S. Forsythe, David J.T. Hill and Andrew K. Whittaker Polymer Materials and Radiation Group, Department of Chemistry, The University of Queensland, Brisbane, Australia 4072.

INTRODUCTION

Fluorinated polymers are characterized by their excellent resistance to chemical attack and good thermal stability. Therefore they have found applications where resistance to harsh chemical and thermal environments is a fundamental requirement. One such application of poly- (tetrafluoroethylene-co-perfluoropropylene), TFE/PMVE, is in the microelectronics industry as an O-ring material for applications where oxygen atom processing is used. For this application the polymer is radiation crosslinked. In this paper the radiation chemistry of TFE/PMVE will discussed and the radiation chemical yields for new structure formation will be reported.

EXPERIMENTAL

The TFE/PMVE copolymer was obtained from the Du Pont Co. and used without further purification. The polymer was amorphous with a Tg of 276 K and a molecular weight of approximately 60 000 g mol"1. The polymer samples were irradiated at ambient temperature using ^Co radiation at a dose rate of 20 kGy hr"1. After irradiation the samples were placed in a vacuum oven at 373 K for 12 hr to remove evolved gases. The solid state 13C and 19F NMR spectra were obtained on a Bruker MSL200 spectrometer. The I3C spectra were obtained employing CP MAS and high power decoupling, with 10 000 scans per spectrum. The 19F spectra were obtained at 420 K using a n/2 pulse-decay and a 5 us recycle time.

RESULTS AND DISCUSSION

The solid state 19F NMR spectrum of TFE/PMVE consisted of three major resonances arising from O-CF3, -52.4 ppm; -CF2, -110 to -120 ppm and -CF-, -130 to -136 ppm, with intensities consistent with the composition of the copolymer being 1:2 TFE to PMVE. The spectrum following irradiation to a dose of 5.2 MGy at room temperature featured several new fluorine resonances, and the line widths of the -OCF3, -CF2- and -CF- peaks also increased. The increase in the line widths of these peaks can be attributed to limited motional averaging resulting from formation of a cross linked network during radiolysis. The major new resonances were assigned to: -CF2-CF3, -CF2-O-CF3, -CF=CF2, -CF2-COOH and crosslinks which appeared at -179 to -185 ppm. The -CF2-COOH groups are believed to be formed by hydrolysis of new -CF2-COF chain ends on exposure of the irradiated sample to moisture in the air following radiolysis.

Thus the NMR studies confirm TFE/PMVE undergoes both scission and crosslinking. Analysis of the results for radiolysis at room temperature gave G(new structures) = 3.3, G(S) = 1.4 and G(X) = 0.9. Thus the value of G(S)/G(X) =1.5, which is consistent with the polymer undergoing network formation on irradiation. The latter result is in approximate agreement with that obtained from sol/gel analyses assuming a Y-linking mechanism for crosslinking, which gave G(S)/G(X) = 0.8. However, the values of G(S) and G(X) are higher than previously reported values based on less reliable FTIR analyses of the volatile radiolysis products.

50 AU9918016

INERTIAL CONFINEMENT FUSION AND RELATED RESULTS

H.Hora1, J.C.Kelly1, P.McMillan1, T.Rowlands1 and R.J.Stening1 B.Boreham2, S.Newman2, F.Osman3, R.Castillo3

Centre for Fusion Energy Research (IAEA) 'School of Physics, University of New South Wales 2052. department of Applied Physics, Central Queensland University, Rockhampton 4700. department of Physics, University of Western Sydney Macarthur, Campbelltown 2560.

The continuous work on inertial confinement fusion supported by ARGC and AINSE as reported via ANSTO to the IAEA and presented to AINSE-conferences concentrated on fusion gain computations at volume ignition, and the theory of laser plasma interaction phenomena. Volume compression at inertial confinement, as calculated since 1963 led to the discovery of volume ignition where the alpha reheat leads to a characteristic increase of the temperature, of the DT-plasma from few KeV to more than lOOKeV. A drop of the optimised initial temperature considerably below 4.5KeV results to a reabsorption of bremsstrahlung radiation. The priority of this ignition process was admitted by competitors where the model of self similarity compression is the basis which fully fit the highest measured laser fusion gains (2x 1014 neutrons per laser pulse with 30% core gain) and similar results of leading large scale experiments. Contrary to the most complicated spark ignition, the volume ignition is very robust in agreement with experiments on volume compression with about the same net gains and provides a feasible basis for a laser fusion reactor using present days technology. The theory of relativistic self-focusing is being explored theoretically from the very first publication by Hora, and applied to a possible scheme where the internal electric fields and double layer effects indicate an energy deposition spread over the whole precompressed high- density plasma which produces its fusion energy by volume ignition. The basic laser plasma interaction processes are studied, which include the development of the nonlinear force of ponderomotion where the revealing discovery of the few-picosecond stochastic pulsation as measured by Maddever and Luther-Davies is recognised as the main source of negativity in laser plasma interaction, contrary to parametric effects. This can be explained by ripples generating the Laue-Bragg lattices known since 1974. The evaluation with our genuine two fluid hydro-code reproduced the experiments and shows how smoothing techniques eliminate the pulsation. This result proves that direct driver laser fusion with very low reflectivity and high-energy input into the plasma for ICF compression is an available solution for laser fusion. This is also applicable for the use of longer wavelengths (eg. the fundamental wavelength of neodymium glass lasers) with 3 times higher pulse energy than with third harmonics being constructed with the multi-megajoule lasers. Further fundamental studies about the initial ionisation and subsequent acceleration process of the emitted electrons by the nonlinear (ponderomotive) forces was initiated in 1979 and are now under worldwide studies, eg. the correspondence principle of electromagnetic interaction. A further field of work is devoted to the acceleration of electrons by lasers in vacuum (contrary to plasma mechanisms as the beat wave or wake field process) leading to very high energy and large numbers of accelerated electrons.

51 AU9918017

NATURAL RADIOACTIVITY IN ENVIRONMENTAL STUDIES.

Henk Heijnis, Andrew Jenkinson and Robert Chisari. Environment Division ANSTO Lucas Heights NSW 2234

The use natural radioactivity in environmental studies has proven a very powerful tool to determine the dynamics of both natural and antrophogenic processes in our environment. The use of 14C in archeology and past climate studies has led to many scientific discoveries (i.e. shroud of Turin & Utze "the ice-man from Austria).

The use of the 238U-decay series is of at least equal value to studies in archeology and past climates. Some of the Isotopes studied supplement 14C (which is limited to 40,000 years) up to 350,000 years and others can be utilized to date very young sediments, which can't be dated by 14C. The so-called 210Pb dating method has been used over the past 3 decades to date recent sediment. The method uses the disequilibrium in the 238U decay chain, caused by the escape of the intermediate daughter 222Rn (a noble gas) from the earth's crust. In the atmosphere the 222Rn decays via short-lived daughter isotopes to 210Pb. This 210Pb with a very convenient half-life of 22,3 years decays to stable 206Pb.

By measuring the surface activity of a sediment core and subsequent samples at regular intervals one can establish a chronology for the sediment core. By studying the trace metals in these cores, one could deduce a contamination history for the region. Examples of studies supported by AINSE & ANSTO will be given on the poster Dr Henk Heijnis, Senior Research Scientist, Leader Environmental Radiochemistry Group Environment Division

52 AU9918018

THE EFFECT OF MEWA ION IMPLANTATION ON THE TRIBOLOGICAL PROPERTIES OF PVD-TiN FILMS

Rafael Manory1, Simon Mollica1 and Peter Evans2 'Department of Chemical and Metallurgical Engineering, RMIT University POB 2476V, Melbourne, Vic 3001 2ANSTO, Private Mail Bag 1, Menai, NSW 2234

This work deals with some effects of metal evaporation vacuum (MEWA) ion implantation into commercially deposited TiN films. Overall the work attempts to improve the wear performance of hard deposited coatings used for cutting tools. TiN coatings used in the cutting tools industry can be classed into main categories according to their deposition method, PVD or CVD. For PVD-deposited TiN coatings, previous works (-13) have shown that 'conventional' ion implantation with species such as carbon, argon or nitrogen leads to improvements in tribological properties and in cutting performance. The MEVVA implantation technique has been previously used for studies on CVD type TiN, and has also led to improvements in the tribological properties of the films (4). The present work is the first study in which the effects of MEVVA implantation are studied on TiN of the PVD type which is commercially available in Australia. (The MEVVA ion implanter differs from the 'conventional' type of ion implanter in the fact that it has a high throughput of metal ions which are not mass analysed and therefore has more potential for industrial non-electronic applications).

TiN-coated steel samples have been implanted with two types of species - one light and one heavy - C+ and W+ respectively. The samples were analysed by Rutherford backscattering (RBS) and x-ray diffraction (XRD). The tribological performance was assessed by pin-on-disc and microhardness.

The results show that carbon implantation was very effective in improving the friction coefficient by the formation of a carbonaceous layer on the surface. XRD also shows formation of TiC in the near surface region. W implantation does not improve the friction coefficient but improves the lifetime of the coating. Unimplanted films fail in the pin-on-disk test after 7000 cycles, whereas implanted films are still well adhered after 18000 cycles.

This work was performed under AINSE grant 98/045P.

References 1. R Manory et al. Mater. Science and Engineering (in press - 1998). 2. L J Liu, D K Sood, R R Manory and W Zhou, Surface and Coat. Technol., 71, 159-166 (1995). 3. R Manory, D K Sood, L J Liu, M Braun and C Kylner, Surface and Coat. Technol. 70, 1-7 (1994). 4. A J Perry, R R Manory, R Nowak and D Rafaja, Vacuum, 49, 89-95 (1998).

53 AU9918019

STUDY OF THIN (~2nn) SURFACE OXIDE LAYERS ON SILICON USING HIGH RESOLUTION 2 MeV He RBS-CHANNELING

L.S. Wielunski and M.J. Kenny CSIRO, Division of Telecommunications and Industrial Physics PO Box 218, Lindfield NSW 2070, Australia

Silicon surface oxide composition and stability are important parameters in modern silicon device production. The use of silicon as a 1 kg ultra pure single crystal silicon sphere for determination of the Avogadro constant requires very precise knowledge about composition and stability of the surface oxide layer. The current definition of the kilogram in terms of a Pt/Ir artefact can be replaced by an atomic definition in terms of the Avogadro constant if the final uncertainty in sphere volume (diameter) and mass measurement is less than ixlO"8 . A mono layer of silicon oxide on the sphere surface can contribute uncertainties of this order.

In this work we demonstrate how the silicon surface oxide layer can be measured with very high resolution RBS in channelling mode using a 2MeV He ion beam. This method uses very high RBS depth resolution in the glancing angle detection geometry (93°) and channelling background reduction in order to obtain the desired sensitivity to surface layer components. Results will be presented for the analysis of a 2 nm thick silicon oxide layer on a silicon single crystal substrate showing well resolved RBS signals from carbon, oxygen and silicon from the surface layer.

This work is part of an ongoing international collaborative effort involving several national metrological laboratories.

54 AU9918020

AGE OF THE LAST GLACIATION OF VESTFOLD HILLS AND SIGNIFICANCE FOR SEA LEVEL CHANGE

Damian B Gore1 and Eric A Colhoun2 'School of Earth Science, Macquarie University department of Geography and Environmental Science, University of Newcastle

The Vestfold Hills form the second largest deglaciated oasis area in East Antarctica. The last time that the oasis was submerged by the East Antarctic ice sheet as it extended onto the continental shelf has been termed the "Vestfold Glaciation" (Adamson & Pickard 1986). To date the Vestfold Glaciation has been assumed to correlate with the late Wisconsin Glaciation on the basis of Holocene radiocarbon dates obtained from marine deposits in the inlets and from derived sediments ice-proximal to the margin of the Sorsdal Glacier (Adamson & Pickard 1986; Fitsimons & Domack 1993). Since radiocarbon dates on Holocene marine shells can only be minimum ages for the Vestfold Glaciation other approaches to dating are required. Fabel et al 1997 have obtained exposure age dates on erratics within 5km of the present ice edge and conclude that the ice margin retreated around 9-12k yr BP. Gore and Colhoun (1997) suggested from observations on weathering features that it could be possible the oasis was not ice covered during the late Wisconsin. Gore et al 1994 also show from the widespread presence of derived shell fragments and iron-rich granules of a former weathering surface in the regionally distributed Vestfold till that the ice of the Vestfold Glaciation was not highly erosive and may have been of limited thickness.

Radiocarbon dating of shell fragments from Vestfold till deposits distributed throughout the southern and seaward parts of the oasis have given assays from 31.1 to .43.7k yr BP. If the assays represent true ages of the time of growth of the marine shells then it would appear that the Vestfold Glaciation ice expansion onto the continental shelf post-dates 31 k yr and the glaciation is equivalent to the late Wisconsin. Similarly, if the range of assays represents true ages then the fjords must have been occupied by the sea during late middle Wisconsin time, presumably when the continental margin was isostatically depressed below present level. There is, however, the possibility that the assays are minimal, and being derived into till from older marine deposits they could have true greater and mixed ages. This alternative is being explored.

55 AU9918021

AGE ESTIMATES AND STICK-NEST RAT MIDDENS

Stuart Pearson1 and Ewan Lawson2

1 Dept of Geography and Environmental Science Uni of Newcastle,2 Physics Division, ANSTO

A total of 112 radiocarbon analyses on stick-nest rat middens gathered from published and grey literature show (see figure) that the middens of stick-nest rats have a positively skewed distribution. The average of all the estimates is ca. 2967 BP with the oldest midden dated at around 10870 BP. Over 75% of the results are younger than -4480 BP. Possible explanations for this pattern include; sample S> bias, rate of midden and cave decay, a real pattern of Tenpotal dstribiiion cf stick-rest tat midden age distribution and development of techniques. mctfenajp estimates Researchers seeking minimum dates from the tops of middens (n=28) provide termination dates on many middens (average 925 BP, median 330 BP). These dates ' •"** probably over-represent larger middens that have been selected to provide a long continuous record. The start of midden accumulation is frequently the key date for e identifying the value of a stick-nest rat midden. As a result maximum dates (average 4052 BP, median 3430 BP) are over-represented in the radiocarbon analyses. This has the effect of increasing the frequency of older midden age estimates - an outcome in common with American packrat studies. The spatial distribution of midden ages shows no latitudinal or longitudinal pattern although the only middens over 6000 BP have been consistently found in the Flinders Ranges area. The rock types that create the protective caves do differ between sites. Most of the caves are breakaway overhangs under silcrete hardcaps. The Flinders Ranges middens are in harder rock types so similar vhard' rock types were searched in central Australia however middens were relatively young. This suggests rock type is not necessarily an important control. Midden decay appears to be relatively slow if the material is protected from moisture and large animals. The age distribution of middens does not appear to relate to accessibility of the cave - often middens near the mouth of caves are contemporaneous with middens in very low overhangs. The components of the midden being used for radiocarbon analysis has been remarkably uniform. This reflects the small number of researchers in the field and the experience of the American packrat midden research. Early researchers using conventional methods used charcoal and large mixtures of material whereas AMS now allows individual scats to be analysed. In fact 37% of analyses have been on scats as these provide direct evidence of midden occupation and are plentiful in the midden matrix. 66% of analyses used AINSE's AMS method and 23% used conventional methods - the distribution of results using the two methods are similar. A number of dates have incomplete laboratory or methods information. Similar analysis of packrat midden dates in the United States identified both ecological and systematic bias in the age patterns (Webb 1986). The efficacy of midden analysis in Australia, as in America, is limited by the cost of age estimates. Reference: Webb, R.H., 1986. Spatial and Temporal Distribution of Radio-carbon Ages on Rodent Middens from the South- Western United States. Radiocarbon, 28:1-8.

56 AU9918022

SIMS ANALYSIS OF NITRIDED AUSTENITIC STAINLESS STEEL

P.T. Burke1, K. E. Prince1", M. Baldwin5, J. Priest§ and M. P. Fewells ^Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai NSW 2234, Australia § Division of Physics and Electronics Engineering, University of New England, Armidale NSW 2351, Australia

Increasing the hardness and wear resistance is of practical importance to many different materials, including stainless steel. Human prostheses and products subject to continual abrasive mechanical contact require materials that will last a substantial time with negligible damage. One method of increasing the hardness of stainless steel is through incorporation of nitrogen (nitriding). However, austenitic stainless steels have proved difficult in the past to nitride without degradation of their corrosion resistance. Through the use of the Plasma Immersion Ion Implantation (PI3) technique at ANSTO, it is possible to introduce a nitrided layer to the stainless steel. Secondary Ion Mass Spectrometry (SIMS) was then performed to characterise the nitrogen profile in the stainless steels.

The samples used were AISI-316 austenitic stainless steels, implanted by PI3. SMS was performed using a Cs+ primary beam to determine the nitrogen distribution after implantation. The secondary species were monitored either as an MCs+ adduct or alternatively as negative species.

Figure 1 shows the nitrogen profile of an AISI-316 stainless steel sample. It is clear that there is a ~2|im nitrided layer in the sample. MCs+ was found to be the most appropriate SIMS technique for these samples, giving better depth resolution and a reduction in matrix effects.

UNE22

01 234567 Depth (urn)

Figure 1: MCs+ Depth profiles of nitrided AISI-316 stainless steel.

57 AU9918023

THE ACTINIDE BEAMLINE - A NEW AMS FACILITY AT ANTARES

MAC Hotchkis, P J Lee and N Mino Australian Nuclear Science and Technology Organisation PMB 1, Menai, NSW 2234

At the ANTARES accelerator a new beamline has been commissioned, incorporating new magnetic and electrostatic analysers, to optimise the efficiency for Actinides detection by Accelerator Mass Spectrometry. The detection of Actinides, particularly the isotopic ratios of uranium and plutonium, provide unique signatures for nuclear safeguards purposes. We are currently engaged in a project to evaluate the application of AMS to the measurement of Actinides in environmental samples for nuclear safeguards. Measurement of 236U is of particular interest as a means of tracing the anthropogenic component of uranium. 236U is expected to be present in natural samples at an extremely low level (236U:238U ratio ~10~10). It has recently been demonstrated1 that AMS has sufficient sensitivity to detect 236U at this level. Other applications of ultra-sensitive detection of Actinides are also under consideration. The principal components of the new beamline are: 1. electrostatic quadrupole in the accelerator tank to focus high-mass beams; 2. 12° electrostatic deflector (radius 5m, gap 25mm, E/q = 16MeV); 3. 90° electrostatic analyser (radius 2.5m, gap 25mm, E/q = 8MeV); 4. 90° magnet (radius 2m, gap 50mm, ME product = 250); 5. multi-isotope detection system including ion counters and Faraday cups. The design considerations which have led to the above choices of specification include (1) sufficient bending power to allow selection of charge states close to the peak charge state with argon gas stripping in the accelerator terminal; (2) energy resolution sufficient to separate molecular interferences such as 235UH from 236U; (3) matched magnetic deflection, capable of clean resolution of neighbouring masses at mass ~ 240. The beamline was completed in September 1998 and tests are currently underway. Initial tests have been performed with iodine samples, which we have previously measured and have 10 12 i29j.i27j jsotOpjc ratjos jn the range 10~ to 10~ . Figure 1 shows a scan of the 90° magnet for I29I at 36 MeV, with a 4mm slit width, illustrating the high resolving power of the system.

150

1.0065 1.007 1.0075 1.008 1.0085 1.009 Magnet field (T) Figure 1.

1 X.-L. Zhao, M.-J. Nadeau, L.R. Kilius and A.E. Litherland, Nucl. Instr. & Meth. B92 (1994) 249.

58 AU9918024

IN-SITU COSMOGENICI0Be AND "Cl STUDIES IN THE EARTH SCIENCES AT THE ANTARES AMS FACILITY

David Fink, Greg Elliot, David Child and Charles Misfud Physics Division, ANSTO, Sydney, 2234, Australia

14 10 In parallel with a successful C AMS program, routine measurements of Be (T1/2 = 1.5 Ma), 26A1 (0.7Ma) and 36C1 (0.3Ma) have been demonstrated at the ANTARES AMS facility. With this capability, ANSTO is coordinating and funding a comprehensive program in the application of in-situ cosmogenic radioisotopes for Southern Hemisphere Quaternary climate change. The sub-projects within the program are based on strong university collaboration in the Earth Sciences and with the Australian Antarctic Division. The build-up in concentration of these long lived radioisotopes in exposed surfaces and rocks due to cosmic ray bombardment (although only a few tens of atoms per year per gram) can be utilised to elucidate the exposure history (or age) of geomorphic formations and surfaces. Alternatively, if exposure is sufficiently long for the in-situ signal to reach equilibrium, an average surface erosion rate can be determined. Accordingly, we have focussed our applications in two directions. The first deals with a unified study of Quaternary glacial chronology in the Southern Hemisphere based on sites throughout Tasmania, New Zealand and Antarctica. As the antiquity of the Australian landscape generally precludes the application of the in-situ technique for exposure age dating, the second direction centres on studies of surface denudation and landscape evolution in central arid Australia. In order to successfully complete the difficult task of chemically processing rock samples for AMS measurement, a fully equipped geochemistry laboratory for sample processing has been completed and is now operational. In addition a variety of analytical techniques for sample assay (NAA, ICP-MS, XRF, XRD, etc ) are available through the Environment Division at ANSTO. Research projects in glacial chronology : (a) Southern and Northern Prince Charles Mnts at Lambert Glacier, and Larsmann Hills, Antarctica (with Univ of New England and New South Wales). Our preliminary I0Be exposure ages (12 samples) at Lambert Glacier range from 0.7 to 2.0 Ma and support the concept of a more dynamic East Antarctic Ice Sheet through the Pliocene. (b)Glaciation in Tasmania (Central Plateau ice-cap, outlet valleys, West Coast Ranges) (Univs of Tasmania and Newcastle). 36C1 (8 samples) and I0Be (20) ages on the Central Plateau show the Last Glacial Maximum was at 15-18ka. 10Be exposure ages throughout the West Coast (25 samples) are consistent with estimated Oxygen Isotope Stages of deglaciation over the past 750 ka. A search for a Younger Dryas signal is also being conducted. (c) Glacial terrace sequence Te Anau, Fiordland, New Zealand and the Younger Dryas (Univs of Auckland and Victoria). This involves determination of exposure ages and uplift rates of the Southern Alps. Studies relating to landscape geomorphology : (a) Denudation rates of the Ashburton Plateau, central Australia (Latrobe Univ). Comparison of apatite fission track denudation rates averaged over the past 100 Ma compared with erosion rate estimaytes obtained from in-situ !0Be averaged over the past 1 Ma.. (b) Coastal escarpments, Victorian Plateau, southwest Western Australia (Murdoch Univ, WA). Two cores of 4 meters depth to bedrock of sand regolith along the escarpments have provided profiles of in-situ 10Be (12 samples) to determine the dominant process of escarpment formation. Preliminary modelling of the in-situ lOBe profile indicates transport and deposition of external material over the past few 100 ka, in contrast to suggestions of local subsurface weathering and laterization (c) Sand dunefields at the Simpson Desert and Cape Flattery (Southern Cross and James Cook Univs). We are testing an idea that a survey of the relative concentrations of in-situ 10Be measured over the surface and in cores of sand dunes of different types and positions can lead to information on sanddune turnover rates, history and mobility.

59 AU9918025

RECENT TREE RING ANALYSES AT THE ANTARES AMS CENTRE

Q. Hua1, M. Barbetti2, G.E. Jacobsen1, U. Zoppi1, E.M. Lawson1, A.M. Smith1 and N. Lenh 1 Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia 2 The NWG Macintosh Centre for Quaternary Dating, Madsen Building F09, University of Sydney, NSW 2006, Australia

We have examined the atmospheric 14C excess after 1955 AD resulting from atmospheric thermonuclear testing using two sets of cross-dated tree rings at two widely separated sites having different air mass trajectories. One set is from a medium-sized Pinus kesiya (three-leaf pine) with clear ring structure (D'Arrigo et al., 1997) grown in northwestern Thailand (19°N, 99°25'E). The outer rings, from 1944 AD onwards, are entirely sapwood and typically about 2 mm wide. The other set is Lagarostrobos franldinii (Huon pine) grown in northwestern Tasmania (41°45'S, 145°24'E) (Buckley et al., 1997). The Huon pine rings are typically only 1 mm wide.

A total of 48 annual tree rings (24 pairs) from 1952 to 1975 AD have been carefully split, milled and pretreated to alpha-cellulose, the most reliable component of wood for dating. Due to the small amount of material available in each ring, accelerator mass spectrometry (AMS) rather than the conventional method (radiometry) has been used for the determination of the 4C content in tree rings. Pretreated material was combusted to CO2 and then converted to graphite for the 14C measurement in ANTARES, the tandem accelerator at ANSTO.

Excellent matching between our measured 14C tree-ring data and atmospheric 14C records at the same latitude has been found. Our data can therefore be used for: • extension of atmospheric 14C bomb-pulse curves in tropical regions and the Southern Hemisphere back to the early stage of the nuclear age in the 1950's, for which few direct atmospheric records are available. This is needed to gain a better understanding of global carbon cycle and air-sea interactions; • determination of the growth rate of trees in tropical regions (Murphy et al., 1997); and • dating of modern organic material in tropical regions and the Southern Hemisphere (in combination with C atmospheric data).

References

Buckley B.M., Cook E.R., Peterson M.J. and Barbetti M. 1997. A changing temperature response with elevation for Lagarostrobos franklinii in Tasmania, Australia. Climatic change 36: 477-498

D'Arrigo R.D., Barbetti M., Watanasak M., Buckley B.M., Krusic P., Boonchirdchoo S. and Sarutanon S. 1997. Progress in dendroclimatic studies of mountain pine in northern Thailand. IAWA Journal 18 (4): 433-444

Murphy J.O., Lawson E.M., Fink D., Hotchkis M.A.C., Hua Q., Jacobsen G.E., Smith A.M. and Tuniz C. 1997. 14C AMS measurements of the bomb pulse in N- and S-hemisphere tropical trees. Nuclear Instruments and Methods in Physics Research 123B: 447-450

60 AU9918026

THE MECHANISM OF COPPER ACTIVATION OF SPHALERITE

Dr. Andrea Gerson*, Roger Smart, Angela Lange and Kathryn Prince (ANSTO)

Ian Wark Research Institute, University of South Australia, The Levels, South Australia, 5095. Fax: 61-8-8302-3683, Ph: 61-8-8302-3044, Email: Andrea.Gerson @ unisa.edu.au

The activation mechanism in which sphalerite is conditioned with Cu(II), prior to adsorption of xanthate and flotation, is not well understood. In particular, the nature of the copper species formed on the surface of sphalerite has been the subject of some controversy. Several experimental observations require explanation in any feasible mechanism: • XPS identifies this copper on the sphalerite surface as Cu(I) in all conditions except at relatively high concentrations and high pH where both Cu(I) and Cu(II) are observed (strongly associated with adsorbed hydroxide species). • The uptake of Cu by the sphalerite lattice results in a 1:1 release of Zn(II) implying an ion exchange mechanism. • Ion exchange of Cu(I) into the sphalerite lattice is not expected due to the resulting charge imbalance and the larger ionic radius of Cu(I) compared to Zn(II).

Thus Cu may be present in many different forms, namely: • adsorbed Cu ions (Cu+ or Cu2+) possibly associated with hydroxide ions on the surface; • colloidal Cu(OH)2 particles at high pH and high Cu concentration, • Cu(II) substituted for Zn(II) in the sphalerite lattice; 2 • Cu(I) substituted for Zn(H) in the sphalerite lattice with compensating Sn " species; • as new CU2S or CuS surface phases; • or as a mixed Cu(I) hydroxide/sulphide product in which the copper is bonded to both species.

We propose a mechanism based on the existing XPS literature data and new SIMS and XAFS measurements. SIMS measurements demonstrate that the adsorbed Cu is not solely located in sites of low coordination and is spread relatively evenly across the surface of sphalerite particles. XAFS measurements have indicated that the Cu is located in a distorted trigonal planar conformation in both bulk and surface sphalerite sites. The proposed mechanism accounts for the final oxidation states of Cu and S as observed by XPS. In addition the proposed mechanism of activation accounts for the slight shift to a lower oxidation state of bulk Cu as compared to surface adsorbed Cu as observed from the Cu(ls) binding energies.

61 AU9918027

NEUTRON SCATTERING APPLIED TO ENVIRONMENTAL WASTE CONTAINMENT

M.M. Elcombe, A.J. Studer, C.L. Waring Australian Nuclear Science and Technology Organisation Private Mail Bag 1, Menai, NSW 2234 Australia

A major environmental problem in Australia occurs at mine sites, where rock dumps and tailings dams are still causing problems many years after the mines have ceased operation. ANSTO has developed a method of producing a neutral barrier in-situ, which reduces water flow through the waste material. This in turn prevents water carrying waste products out into the wider environment. Both the loose grained sand substrate and the Neutral Barrier produced are crystalline and therefore amenable to diffraction techniques. In recent laboratory experiments neutron scattering has been used to confirm the presence of the barrier and measure the amount of calcite forming the barrier, at centimetre depths below the surface. The results of these measurements will be presented.

62 AU9918028

NEUTRON BEAM FACILITIES AT THE REPLACEMENT REACTOR

S.J. Kennedy Australian Nuclear Science and Technology Organisation Private Mail Bag 1, Menai NSW 2234

It is now more than year since the Federal government announced the decision to replace the HIFAR research reactor. The planned start up date of the replacement reactor is 2005, and HIFAR will continue to operate until that time. It is to be a multipurpose reactor with improved capabilities for neutron beam research and for the production of radioisotopes for pharmaceutical, scientific and industrial use. The neutron beam facilities are intended to cater for Australian scientific needs well into the 21sl century.

In the first stage of planning the neutron Beam Facilities at the replacement reactor, a Consultative Group was formed (BFCG) to determine the scientific capabilities of the new facility. Members of the group were drawn from academia, industry and government research laboratories. The deliberations of the BFCG, covering a wide range of issues, consisted of regular meetings and a one-day open workshop, drawing input from many Australian and overseas authorities. The BFCG submitted their report in April, outlining the scientific priorities to be addressed and providing a conceptual layout of the facility. Cold and hot neutron sources are included, and cold and thermal neutron guides will be used to position most of the instruments in a neutron guide hall outside the reactor confinement building. This will provide a very low background for the facilities and, with close supporting laboratories, a more practical working area for users than is possible at HIFAR. In 2005 it is planned to have eight instruments installed with a further three to be installed by 2010. A further seven spare instrument positions are included for development of new instruments over the life of the reactor. Provision for a second neutron guide hall to be installed in the future was also recommended.

A beam facilities technical group (BFTG) was then formed to prepare the engineering specifications for the tendering process. The group consisted of some members of the BFCG, several scientists and engineers from ANSTO, and scientists from leading neutron scattering centres in Europe, USA and Japan. The BFTG looked in detail at the key components of the facility such as the thermal, cold and hot neutron sources, neutron collimators, neutron beam guides and overall requirements for the neutron guide hall. The report of the BFTG, which was submitted in August, has been incorporated into the specifications for the reactor project. Planning for the initial suite of instruments is now under way. The latest technological advances will be used wherever possible to ensure that world class facilities are constructed. The details of the facility will be presented, highlighting some new technologies which will be used, and indicating the scientific capabilities that are to be developed.

63 AU9918029

OXIDE RESEARCH USING NEUTRON SCATTERING

B. A. Hunter1, C. J. Howard1 and B. J. Kennedy2 !Neutron Scattering Group, ANSTO, PMB 1, Menai, NSW 2234 2Chemistry Dept, University of Sydney, Sydney, NSW 2001

Oxide materials form a large group of technologically and scientifically important materials, and research on these types of materials is on the forefront of scientific research. The important properties of these materials, such as the electronic, magnetic and mechanical properties, are related to the structure and chemical composition of those materials. As the structure is so important in the understanding of the properties, neutron scattering is playing a key role due to its advantages in characterising the role of the oxygen. We present here some examples of the latest oxide structures studied by neutron powder diffraction at ANSTO.

64 AU9918030

STRUCTURAL CHARACTERISATION OF 1- AND 2-DIMENSIONAL TRANSITION METAL POLYMERS USING NEUTRON POWDER DIFFRACTION.

Dr Michael James Australian Nuclear Science and Technology Organisation Private Mail Bag 1, Menai NSW 2234

The structures of several 1- and 2-dimensional transition metal polymers have been determined using neutrons from the HIFAR reactor at ANSTO and the powder diffractometers HRPD and MRPD along with Rietveld profile refinement techniques. The vast majority of transition metal polymers are formed as insoluble powders and until recently, notions of their connectivity have been gleaned only via elemental analyses, spectroscopic and thermal decomposition studies. The microcrystalline morphology of the powders investigated in this study tended to be needle-like or sheet-like which led to substantial preferred orientation effects in X-ray diffraction data collected in the standard flate-plate Bragg-Bretano geometry. Modelling of these effects using the Dollase preferred orientation function proved inadequate, leading to divergent structural refinements.

Powder neutron diffraction provides an alternate technique for the structural study of transition metal polymers and finds utility over standard X-ray methods in two significant ways. A different instrument geometry means that preferred orientation effects are removed from the system and H atoms in the sample contribute much more to the scattering of neutrons, allowing their atomic position to be accurately determined.

The structures of the linear chain complexes Ni(thiazole)2Cl2 and Co(thiazole)2X2 (X = Cl and Br) were found to be essentially isostructural and composed of pseudo-octahedral transition metal centres doubly linked by halide-bridges. This linear structural motif was also found to be present in the complexes Fe(4,4'-bipyridyl)X2 (X = Cl and Br), however a sheet-like polymer was formed by bridging in the second dimension by bidentate 4,4'-bipyridyl ligands.

65 AU9918031

APPLICATIONS OF THE SMALL ANGLE NEUTRON SCATTERING TECHNIQUE - AN ANSTO/AINSE COLLABORATION

R B Knott Australian Nuclear Science and Technology Organisation Private Mail Bag l,Menai NSW 2234

The Small Angle Neutron Scattering (SANS) technique has wide application in a range of fields in scientific and industrial research and development. In recognition of this, ANSTO and AINSE entered a partnership to develop a SANS instrument that would be optimised to the HIFAR neutron source, and respond to the largest possible user base. At the outset it was recognized that since a cold neutron source had not been installed in HIFAR, innovative design would pay measurable dividends in terms of (i) neutron beam quality at the sample position and (ii) general instrument utility.

The SANS instrument on HIFAR is essentially a conventional 10 metre design with a number of unique features. The monochromator and detector in particular were identified as key elements of the design and extensive evaluation was undertaken. A double multilayer monochromator in reflection geometry provided the brightest option for producing a neutron beam tailored to the requirements of the widest variety of experiments. With an appropriate multilayer monochromator, the neutron wavelength and wavelength spread can be independently selected over a broad range, and harmonic rejection and y-radiation reduction are efficiently achieved in this configuration. Future developments in multilayer monochromators will enable beam focussing, polarised beam production and additional wavelength spread control. These developments will enhance instrument performance.

In order to optimise the performance of the detector and provide long term support to the device, the 2D detector system was designed and manufactured in-house. The detector is a multi wire proportional counter with an active area of 64 x 64 cm2, greater than 70% detection efficiency and a spatial resolution of 5mm, well suited to the instrument resolution.

A program of scientific and industrial research is being constructed with many problems in soft condensed matter under consideration. At present, emphasis is on the investigation of polymeric, colloidal and porous materials.

Acknowledgments: The contribution of many within ANSTO, AINSE and our international collaborators is gratefully acknowledged. Capital funds were provided by ANSTO and AINSE, and supplemented with a joint ARC Major Equipment Grant that funded the major portion of the 2D detector development.

66 AU9918032

CARBON MONOXIDE MIGRATORY INSERTION - A COMPARISON OF CATIONIC AND NEUTRAL PALLADIUM(II) COMPLEXES

Katrina E Frankcombe, Kingsley J Cavell, Brian F Yates and Robert B Knott University of Tasmania, Hobart, Australia Radiopharmaceuticals R&D, ANSTO, Menai, Australia

With the use of ANSTO's resources and expertise and with support from AINSE, we have carried out extensive computer modelling on the mechanism of the palladium catalysed carbonylation reaction, a process which is used industrially in the conversion of carbon monoxide into biodegradable polymers. In this project, experimental and theoretical work has focussed on using Pd(II) complexes containing pyridine carboxylate ligands (NC5H4COO-) to explore the fundamental mechanistic steps. At the MP2 level of theory for a prototype system, we found that the lowest energy pathway involved the following steps: n

PH3

We have calculated the potential energy surfaces for both cationic and neutral complexes and found that there is a difference of over 30 kJ/mol in the key migration reaction (3 -> 4): +6.0 0.0 kJ/mol

Lowest energy pathways for carbonylation of the neutral (dashed) and cationic (solid) systems

The lower activation energy for the migration step in the cationic complex is due to an increased G-donation from the phosphine to the metal, accompanied by a decrease in the metal-carbonyl Tiback-donation. We will present results for subsequent steps in the catalytic cycle and discuss their implication for the design of more efficient catalysts.

We acknowledge generous support for this project from AINSE. Katrina Frankcombe was awarded the AINSE Graduate Student Gold Medal for 1998.

67 AU9918033

HEAVY ION TIME-OF-FLIGHT ANALYSIS OF TITANIUM-OXY-NITRIDE THIN FILMS FOR SOLAR ENERGY APPLICATIONS

J.Metson\ A.Bittar", LJ. Tornquistb, I. Vickeridgec, N. Dytlewskid and D.D. Cohend a University of Auckland, New Zealand b Industrial Research Ltd, Lower Hutt, New Zealand c The Institute of Geological and Nuclear Sciences Ltd, Lower Hutt, New Zealand d Australian Nuclear Science and Technology Organisation

Heavy ion time-of-flight elastic recoil spectrometry and SIMS have been used to determine the elemental depth profiles of TiOxNy selective solar absorbers before and after high temperature anneals. The results of the profiling of samples annealed at 250°C and 300°C have shown that the films on silicon substrates do not suffer any measurable degradation due to annealing. Films on copper substrates on the other hand show significant change in their optical properties and in their depth profiles. The results obtained have enabled us to identify the degradation mechanism and attribute it to copper migration into the thin TiOxNy films and through to the front surface, where it appears to form a thin copper oxide layer. The surface structure is complex, with a nitrogen rich layer overlying a thin copper oxide layer.

Nitrogen rich TiOxNy films with N:O ratios higher than 1.5 show significantly less degradation than films with N:O ratios close to 1. Since the latter is preferred for solar selectivity, this suggests the use of oxygen poor films between the copper substrate and the selective film, as a barrier to copper diffusion in these materials.

68 AU9918034

THE HIGH ENERGY HEAVY ION MICROPROBE AND ITS DETECTION SYSTEMS

R. Siegele and David D. Cohen Australian Nuclear Science and Technology Organisation, PMB 1, Menai 2234, NSW, Australia

The construction of new high energy, heavy ion microprobe on the ANT ARES accelerator has recently been completed. At the moment the microprobe is undergoing rigorous testing. The microprobe is designed to not only focus light ions at low energy, but also heavy ions at energies in excess of 100 MeV. Tests have shown that maximum mass energy (ME/q2) product that can be focused is well in excess of the specification of 100. So far wide range of spot sizes for different ions have been achieved. The microprobe has been extensively tested using 20 MeV and 36 MeV C ions as well as 35 MeV Cl and spot sizes as small as 7 (im have been achieved.

At the moment the microprobe is equipped with a surface barrier detector in a backscattering geometry and pin diode x-ray detector. These detectors allow Rutherford backscattering analysis (RBS) and heavy ion PIXE. Both have X-ray detection systems have been successfully tested with a variety of samples.

In the near future these detectors will be completed with a large surface area dE-E gas detector, under construction at the moment. This detector will complement RBS and PIXE technique, because it will allow the detection of light elements such as H, C and O.

Examples of microanalysis of diffusion of Strontium into a cement paste are shown. The example demonstrates the capability of the microprobe in analysing compositional changes in the cement pastes as well as the diffusion profile of strontium.

As further example the mineral sand grain of 300 (im diameter is analysed. We show that compositional changes in these grains can easily be measured. The maps of Ti and Fe show small inclusions in the grains that most likely are composed of silicates.

69 AU9918035

NEUTRON DIFFRACTION AND MAGNETIC STUDIES OF RHOMOBOHEDRAL

La1.ISriMnO3+5

T. Ersez*, CM. D'Souza*, S.J. Kennedy* and B.C. Chakoumakos+ "Neutron Scattering Group, ANSTO, PMB 1, Menai, NSW 2234, Australia. *Department of Physics, Monash University, Clayton, Victoria, 3168, Australia. "Neutron Scattering Section, Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6393, USA.

The structural and magnetic properties of rhombohedral La,JSrJMnO^g compounds (x=0.125 and 0.175) were studied using powder neutron diffraction and magnetisation techniques. The magnetic behaviour was found to be closely related to the unit cell volume and the refinements indicate that the contraction of the unit cell with decreasing temperature is achieved almost totally by the shortening of the Mn-O bond length. In addition to the Bragg scattering, the presence of diffuse scattering in the neutron diffraction patterns was noted, which increases as the temperature approaches Tc and continues to increase above Tc. Our results closely correspond and show similar behaviour to previous reports which described the development of a quasielastic spin diffusion component observed from neutron inelastic scattering measurements on various perovskite manganites. The coexistence of the diffuse scattering with spin-wave excitations and spin diffusion may be a common feature in these materials. Further studies employing polarised neutron scattering techniques are underway to establish its nature, short-range magnetic order indicated by coherent diffuse scattering could support the idea of the existence of magnetic polarons in these compounds.

70 AU9918036

FINE RESOLUTION AMS14C CHRONOLOGY FOR LUNETTE-LAKE SEDIMENT SEQUENCES, LAKE BOLAC, VICTORIA

Ellyn Cook Centre for Palynology and Palaeoecology Department of Geography and Environmental Science Monash University Clayton, 3168 [email protected]

Lunette-lakes have the potential to provide palaeoenvironmental records which are two-fold - the palaeoecological record from lake sediments and the somewhat independent geomorphological and sedimentological record from lunettes. However, it is possible that while the lake sediment sequences present palaeoecological records which cover extensive periods of time, these sequences may also contain discontinuities indicative of deflation of sediments from the lake floor to the dune during periods of aridity. If detected, such hiatuses are useful indicators of dry lake phases, and in turn of effective precipitation, and may be interpreted as specific lunette building episodes. Hiatuses may be identified in lake sediment records by the presence of pedogenic zones which are unfavourable for pollen deposition and/or fossilisation, or more accurately, by fine-resolution dating.

This study aims to provide a fine-resolution chronology for lake sediment records from Lakes Bolac and Turangmoroke, located within the drier part of the Western Plains, Victoria. These lakes are expected to be sensitive to subtle climate and vegetation variability and have long been recognised as archaeologically rich, bearing stone tools, hearth and other cultural materials dated to the late Pleistocene (Horton, 1984; former Victorian Aboriginal Survey, unpublished data). Fine-resolution chronological control has rarely been attempted in this sedimentary and (semi-arid) climatic context owing to the paucity of material available for conventional 14C dating. However, pollen and microscopic charcoal in the lake sediments at Bolac and Turangmoroke are suitable for AMS age determination with the most important sedimentary section well within the range of 14C making them ideal records for such a study. The project is supported by a AESfSE Postgraduate Award Special Grant and recent dating results have substantially increased chronostratigraphic interpretation of concurrent palaeoecological and sedimentological work in progress.

Reference: Horton, D.R. (1984) 'Red Kangaroos: Last of the Megafauna' in Martin, P.S. and Klein, R.G. (eds) Quaternary Extinctions University of Arizona Press, Tuscan.

71 AU9918037

NEW DEVELOPMENTS IN PLASMA NITRIDING: OUTCOMES OF AINSE COLLABORATIONS

G.A.Collins1, M.P.Fewell2 and M.Samandi3 1 ANSTO Materials Division, Private Mail Bag 1, Menai NSW 2234 2 University of New England, Armidale NSW 2351 3 Surface Engineering Research Centre, University of Wollongong NSW 2522

As a hardening process, the attractiveness of nitriding lies in its low treatment temperature. Although the thickness of the case is less than that obtained by higher temperature processes such as carburising, there are a range of alloys and applications for which nitriding is the only possible alternative. Indeed, there are some alloys and applications for which even the normal nitriding temperatures (between 500°C and 600°C for ferrous alloys) are too high. In this paper, we report on developments, specifically the use of low pressure plasmas and high energy ion bombardment, which can extend the benefits of nitriding to lower temperatures. A number of workers have investigated the use of low pressure plasmas as a nitriding environment. At pressures around 0.1 Pa (three orders of magnitude lower than those used in conventional plasma nitriding), a dc glow discharge cannot be used. Plasma is generated by radio-frequency (rf) excitation, microwaves or energetic electrons produced by heated filaments. In a collaborative project involving ANSTO and the Division of Physics and Electronics Engineering at the University of New England, we have investigated the nitriding effectiveness of an rf plasma produced by an immersed single-loop antenna excited at 13.56 MHz with powers up to 300 W. The plasma diffuses throughout the treatment chamber and contains a large number of active species which increase the nitriding efficiency. With a separate plasma generation mechanism, it is possible to apply an arbitrary bias to the workpiece. This results in energetic ion bombardment which can also enhance the nitriding efficiency. The ion and neutral fluxes are generally lower than those at higher pressure so the temperature can be kept low. At low pressures, ion energy is not lost by gas collisions, so it is possible to apply large negative voltages and obtain high energy nitrogen ion bombardment in which case nitrogen mass transfer is not just by thermochemical absorption but also by implantation to depths of approximately 0.1 um. This allows "nitriding" temperatures to be brought down further, even below 200°C where the very shallow case is still capable of producing improvements in wear performance of some components. The low temperature process is generally called Plasma Immersion Ion Implantation (PHI or Pp ™) and is not restricted to nitrogen plasmas or to the nitriding of metals. However, because high concentrations of nitrogen can be produced in the surface of a metal, independently of thermochemical absorption processes, Pp is being used to nitride a range of alloys at temperatures between 200° and 500°. The characterisation of these treated materials has been the subject of collaborative research between the Department of Material Engineering at the University of Wollongong and ANSTO. In this poster, we will present results from these collaborative projects, concentrating on the nitriding of austenitic stainless steel at temperatures below 450°C. In this temperature range, the hardness and wear resistance of the surface can be improved without compromising the corrosion resistance of the stainless steel which is reduced by the precipitation of chromium nitride at higher temperatures. A nitrogen rich phase is formed, whose nature is still not known but provides a fruitful area for research.

72 AU9918038

STOCHASTIC PATTERN RECOGNITION TECHNIQUES AND ARTIFICIAL INTELLIGENCE FOR NUCLEAR POWER PLANT SURVEILLANCE AND ANOMALY DETECTION

Leslie G Kemeny Visiting Academic Research Fellow Consulting Nuclear Physicist and Engineer Australia

In this paper a theoretical and system conceptual model is outlined for the instrumentation, core assessment and surveillance and anomaly detection of a nuclear power plant. The system specified is based on the statistical on-line analysis of optimally placed instrumentation sensed fluctuating signals in terms of such variates as coherence, correlation function, zero-crossing and spectral density.

The normal operation of nuclear power plant is characterised by a series of correlated vibrations or fluctuations ranging from flow induced structural vibrations to fluctuations in the neutron or gamma photon population density. The identification in time or frequency associated with these fluctuations gives rise to elegant power plant surveillance and control techniques and the computation of pattern recognition algorithms and anomaly detection and emergency procedures by artificial intelligence.

The project objective is to make available to nuclear plant operating staff a free standing control room cabinet with "user friendly" display operating on up to twenty channels of near to real time parallel data. The channels include neutron and gamma density, reactivity, void fraction, temperature, flow induced vibration and local and global coherence patterns between the stochastic variates. The shape of coherences is continually scanned and compared with the "base-line" condition of a cold critical core to demonstrate anomalies and if necessary, initiate shut down procedures.

The experimental part of the project has progressed under the author's supervision on nuclear plant in the United Kingdom, the United States and Australia. The paper discusses the instrumentation and computing techniques utilised and the results obtained.

73 AU9918039

THE HIGH PRESSURE PHASE TRANSITION OF SILICON

R.O. Piltz Australian Nuclear Science and Technology Organisation Private Mail Bag 1, Menai NSW 2234

At a pressure of 10 GPa silicon undergoes a phase transition from the four-fold coordinated diamond structure to a six-fold coordinated [}-Sn structure. This phase transition is first order and corresponds to a 25% volume reduction. Several atomic mechanisms have been suggested for this transition but none have explicitly included the effects of macroscopic strain induced in the crystal by such as dramatic volume collapse. I will present results of a computational study which indicates an atomic mechanism is possible which has a low energy barrier while preserving strain in the (111) plane of the diamond structure.

74 AU9918040

COMPOSITION AND STRUCTURAL ANALYSIS OF Sm-Co THIN FILMS ON (100)Si

Muralidhar K Ghantasala, D K Sood*, K T Short** and S Mohan# Department of Electrical Engineering, *Department of Communication and Electronic Engineering, RMIT University, 124 La Trobe Street, Melbourne, 3000, Australia **Australian Nuclear Science and Technology Organisation, Lucas Heights Research Laboratory, Private Mail Bag 1, Menai, NSW 2234, Australia ^Central Scientific Instruments Organisation Sector-30 Chandigarh - 160 020, India

The necessity of integration of magnetics with silicon processing technology became essential with the advent of Micro Electromechanical Systems (MEMS). The need to control the crystalline and magnetic properties of the magnetic thin films on silicon substrates has been the primary motivation for this work. The major objective of this work is to prepare the stoichiometric and crystalline SmCo5 thin films with good magnetic properties on single crystal silicon substrate. We have prepared the SmCo think films on single crystal(lOO) silicon substrates using DC magnetron sputtering. Films have been prepared in pure argon as the sputter media at two different pressures 2 x 10.2 torr and 2 x 103 torr with the substrates kept at room temperature, 500 and 700°C separately. These films have been characterised using RBS, XRD and SEM. RBS analysis showed that the films are nearly stoichiometric (1:4.9) and have significant amounts of oxygen as impurity. But XRD studies indicated that the as deposited films (at all substrate temperatures) are yet to form the crystalline structure. Some of the films have been subjected to rapid thermal annealing at two different temperatures at 800 and 1000°C for 30 sees in an effort to crystallise the films. RBS analysis of these films indicated that the room temperature and post annealed films at 1000°C resulted in considerable interdiffusion characteristics, whereas the high temperature deposited (500 and 700°C) and annealed films showed relatively very stable characteristics with minimal diffusion between the film and the substrate. XRD and SEM analysis of the films is in progress. The detailed results of these investigations will be presented.

This work is supported by an AINSE grant and an ARC small grant.

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APPLICATION OF RBS ANALYSIS TO INVESTIGATION OF CERIUM IMPLANTED STAINLESS STEEL AS AN INTERCONNECT MATERIAL FOR SOFC*

S Shamsili, D K Sood Microelectronics and Materials Technology Centre Department of Communication and Electronic Engineering RMIT University 124 La Trobe Street, Melbourne 3001, Australia S P S Badwal Ceramic Fuel Cells Limited 170 Browns Road, Noble Park, Vic 3174 PJ Evans ANSTO, Menai NSW 2234

Solid Oxide Fuel Cells (SOFC) convert gaseous fuels directly into electricity via an electrochemical process. To achieve workable power output, several single cells are combined to multicell units. In this concept, interconnect plates are placed between two electrode/electrolyt/electrode cells, connecting the cathode side of one cell to the anode side of the other. SOFC operate in the temperature range of 800-900°C. Chromia forming alloys offer the best protection mechanism against corrosion and are commonly used as interconnects. The major drawback of using these alloys is the formation of the volatile Cr-oxide and -hydroxide species which cause long-term cell degradation.

This paper presents results of an investigation on doping of chromia forming stainless steel with a reactive element Ce by an ion implantation to improve its high temperature oxidation resistance. Ferritic stainless steel TP 446 (72.37% Fe, 26.16% Cr, 0.77% Mn, 0.51% Si) specimens were polished to 2400 mesh grit SiC paper and thoroughly cleaned. Ions of Ce were implanted on steel samples using MEVVA ion implanter at an extraction voltage of 40 kV, to doses of 5xlO15, lxlO16, 5xlO16 and lxlO17 at/cm2 at nominal room temperature. After implantation, samples were heat treated in air at 800°C and at 900°C for 0.5-100h. Heating rate was 100°C/h. Specimens were characterised by Rutherford Backscattering Spectrometry (RBS). Secondary Ion Mass Spectrometry (SIMS), Scanning Electron Microscopy (SEM/EDX) and Glancing Angle X-Ray Diffraction (GAXRD).

The results show that Ce implantation produces: 1) substantial improvement in oxidation behaviour, 2) reduction in oxide grain size, 3) three types of oxide morphology. Results on oxidation kinetics and their temperature dependence will be presented.

*Work supported by an AINSE and an ARC grant.

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AXIAL SHORTENING OF FISSION TRACKS TO RESPONSE THERMALLY DRIVEN VOLUME DIFFUSION OF LATTICE VACANCIES

David X. Belton and Roderick W. Brown School of Earth Sciences, La Trobe University, Melbourne Victorian Institute of Earth and Planetary Sciences

Fission track analysis is a well established analytical methodology used by geologists to determine the range of temperatures a rock has experienced in the past. The technique has been calibrated against an extensive suite of empirical data on the kinetics of fission track annealing. However, despite the techiniques widespread use within the earth sciences, there is still no quantitative physical description of the phenomenon of thermally driven track shortening. We have developed a preliminary physical model of fission track annealing based on thermally driven bulk diffusion of vacancies within the crystal lattice.

The model is based on current understanding of ion track formation in solids. The initial distribution of lattice defects along the ion trajectory is predicted using current ion-lattice interaction models. The lattice defect density along the track is effectively modelled by defining the initial volume density/concentration of lattice vacancies. Thermal annealing is then modelled by allowing thermally activated volume diffusion of lattice vacancies between the bulk crystal and the damaged region or track. Given the geometry of the ion track (typically 16 urn in length & 10 nm diameter) this diffusion problem is treated as a series of infinite cylinders, thus simplifying the calculation. Diffusion is allowed to proceed until the concentration of vacancies within the track zone equals the concentration of vacancies expected in the undamaged host mineral. Since the initial defect density (ie. vacancy concentration) and the radial dimension of the damage zone varies along the track, the nett result of continuous vacancy diffusion is axial shortening of the track. Using realistic parameters the model describes the annealing of a track in response to changes in both time and temperature and the results are comparable with the annealing determined in laboratory experiments. Future work will attempt to calibrate the model parameters against independent estimates of the various lattice properties and attempt to account for the variations in the diffusion mechanism caused by variations in crystal chemistry.

77 AU9918043

UNSTABLE ISOTOPES IN A STABLE LANDSCAPE? - UNTANGLING SOUTHERN AFRICA'S GEOLOGICAL HISTORY WITH FISSION TRACKS AND COSMOGENIC NUCLIDES

David Belton1, Roderick Brown1 and David Fink2 'VIEPS School of Earth Sciences, La Trobe University, Melbourne 2Physics Division, ANSTO, Lucas Heights, Sydney

In the absence of direct evidence for burial and subsequent exposure of the land surface in the interior of Africa, researchers have argued for surface ages of several hundred million years. The proposition that landforms may have persisted at the surface for these extensive periods of time has a number of important implications. It suggests that the processes of tectonics and geomorphic evolution have been essentially absent for a period of up to 500 Ma. As a consequence, the persistence of these landscapes would require extremely low rates of weathering and erosion. Although this view of continental evolution has been widely held for several decades, recent studies suggest that continental interiors in Africa, Australia, Brazil and north America, have been subject to denudation in the order of several kilometres during the last 60 Ma.

This study applies the complimentary techniques of apatite fission track and cosmogenic nuclide analysis, in an effort to measure both the long-term crustal-scale denudation and the short-term erosion rates, of which denudation is a function. We present preliminary data from the Zimbabwe Craton that illustrates the utility of such techniques in addressing both local and regional geological questions. The study provides a detailed picture of complex tectonic responses.as well as large scale denudation over extended periods of time.

78 AU9918044

ADFA/ANU 150keV RADIOACTIVE ION IMPLANTER

J X Wei1, A P Byrne2-3, D H Chaplin1, W D Hutchison1 and G A Stewart1

'School of Physics, University College, UNSW, Australian Defence Force Academy, ACT 2600, Australia department of Nuclear Physics, RSPhysSE, Australian National University, ACT 0200, Australia department of Physics, The FAculties, Australian National University, ACT 0200, Australia

As foreshadowed at the 10th Australian Conference on Nuclear Techniques of Analysis (Byrne et al1), the collaborative project to build a radioactive ion implanter, within the custom designed Radiation Laboratories at ADFA, has recently led to the initial commissioning tests of the instrument described in that report. Primary aims are to serve the hyperfine interactions community interested in Materials Science with particular emphasis on magnetic and semiconductor materials. 2.8 day inIn will be the first radioactive probe implanted following optimization of beam transport with stable indium. The implanted niIn samples will be prepared for both time-differential, gamma-gamma, PAC studies at ANU and bruteforce NMRON spectroscopies using the top loading dilution refrigerator at ADFA. In this paper we provide further information on the capabilities of the instrument and the results of the initial commissioning tests. Potential users of the instrument beyond the immediate ADFA/ANU collaboration are strongly encouraged to bring forward their interest at this poster paper presentation.

Reference

1 A P Byrne, D H Chaplin, J X Wei, W D Hutchison, Proceedings of the 10th Australian Conference on Nuclear Techniques of Analysis, pi.5. LIST OF PARTICIPANTS (as at time of printing) Abstract page no.

Airey, Dr P ANSTO Ambrose, Mr W Australian National University 2 Angove, Dr D Macquarie University Arne, Dr D University of Ballarat 25, 26 Barnes, Dr C The University of Sydney 33 Belton, D La Trobe University 77, 78 Boldeman, Dr J ANSTO 3 Brennan, Prof M Camakaris, A/Prof J The University of Melbourne 38 Campbell, A/Prof S University College UNSW ADFA 34, 35 Carlson, Mr R Castillo, Dr R University of Western Sydney Macarthur 51 Cheetham, A/Prof A University of Canberra Chivas, Prof A University of Wollongong 6 Cohen, Dr D ANSTO 4, 68, 69 Collins, Dr G ANSTO 31,72 Collins, Mr M University of Western Sydney Company, Dr F University of Western Sydney Macarthur 27, 28 Cook, Ms E Monash University 71 Cooper, A/Prof R The University of Melbourne 15 Cussen, Dr L Victoria University 29 Drewer, Dr R Avondale College Dytlewski, Dr N ANSTO 46, 68 Elcombe, Dr M ANSTO 62 Elliott, Dr G ANSTO Ersez, Dr T ANSTO 70 Evans, Dr P ANSTO 53 Fallon, Mr J ANSTO Fenton, Dr R The University of Sydney 36, 37 Fewell, Dr M University of New England 20, 57, 72 Field, Mr M The University of Sydney Fink, Dr D ANSTO 59, 78 Gammon, Dr R Former AINSE Executive Officer 12 Ghantasala, Dr M RMIT University 75 Garnett, Prof H ANSTO 23 Garrett, Dr R ANSTO Gilberd, Dr P Victoria University of Wellington 31 Gilbert, Prof R The University of Sydney 17 Gleadow, Prof A La Trobe University 22 Goodman, Dr P The University of Melbourne 49 Goossens, Mr D Monash University 30 Hardy, Dr C Australian Nuclear Association Harris, Prof J Australian National University 18 Henderson-Sellers, Prof A ANSTO 14 Hicks, Dr T Monash University 9, 29, 30 Abstract page no.

Hill, Dr D University of Queensland 50 Hirka, Mr I ANSTO Hora, Prof H University of New South Wales 51 Hotchkis, Dr M ANSTO 58 Hua, Mr Q ANSTO 60 Hunter, Dr B ANSTO 36, 37, 42, 64 Jacobson, Dr G ANSTO 60 James, Dr J The University of Sydney 33 James, Dr M ANSTO 65 Johnson, A/Prof P Victoria University of Wellington 31 Jones, Prof I Flinders University 19 Jostsons, Dr A ANSTO 8 Kaczmarek, Dr W Australian National University 35 Kemeny, Dr L International Nuclear Energy Academy 73 Kennedy, Dr B The University of Sydney 36, 37, 64 Kennedy, Dr S ANSTO 29 34, 35, 49, 63, 70 Kim, Ms J The University of Sydney 36 Knott, Dr R ANSTO 66, 67 Laurence, Dr G University of Adelaide 13 Lawson, Dr E ANSTO 56, 60 Lee, Mr P ANSTO 58 Leitch, Prof E University of Technology, Sydney Lindoy, Prof L The University of Sydney 16 Macquart, Mr R The University of Sydney Mather, Dr D AINSE Scientific Secretary Moussa, Ms S The University of Sydney 37 Mumme, Dr I HRCMC Ng, Dr L University of Western Sydney Nepean 47 Norman, Dr P Monash University 48 O'Connor, A/Prof J University of Newcastle 5 Ophel, Prof T Australian National University 1 Osman, Dr F University of Western Sydney Macarthur 51 Palmer, Mr B Former AINSE Executive Officer 11 Parry, A/Prof D Northern Territory University Pearson, Dr S University of Newcastle 56 Pegg, A/Prof G Central Queensland University Piltz, Dr R ANSTO 37, 74 Prescott, ProfJ University of Adelaide 40 Roberts, Dr P Institute of Geological & Nuclear Sciences, Auckland Sangster, Mr D The University of Sydney 43 Siegele, Dr R ANSTO 69 Smith, Dr A ANSTO 60 Sood, Prof D K RMIT University 75,76 Studer, Dr A ANSTO 29, 34, 35, 62 Tuniz, Prof C ANSTO 7 Turner, Prof J H Fremantle Hospital 21 Van Riessen, Dr A Curtin University 45 Abstract page no.

Vyas, Mr S University of Western Sydney White, Prof J Australian National University 10 White, Dr P The University of Sydney 32 Wielunski, Dr W CSIRO - TIP 54 Wu, Dr E University College UNSW ADFA 34, 35 Zhang, Mr H University College UNSW ADFA 34 Zhang, Mr S Central Queensland University 44 Zilic, Mr E University of Western Sydney 47 Zoppi, Dr U ANSTO 60 Znidersic, Dr J Beta & Gamma Services