Athol Rafter – nuclear chemist
Athol Rafter – nuclear chemist
- Changing scientific ideas
- Advances in science and technology
- Biography
Rutherford and radioactivity
Ernest Rutherford and Frederick Soddy (pictured) suggest that radioactivity might be used to date minerals and rocks.
Born in Wellington
Full name Thomas Athol Rafter, but becomes known as Athol.
University
Obtains BSc at Victoria University College, Wellington.
More studies
Chemistry MSc at Victoria University College, Wellington. Becomes school teacher.
Marriage
Marries Ruby Valerie Organ, known as Val.
Carbon-14 discovered
University of Waikato
Sam Kamen and Martin Ruben discover C-14, a radioactive isotope of carbon, at University of California, Berkeley.
Beginning research
Becomes research scientist at Dominion Laboratory, analysing coal ash and uranium-bearing minerals.
Carbon-14 in living things?
Willard Libby in America predicts that C-14 exists in living matter.
Prediction proved
Willard Libby (pictured) and Ernie Anderson make first detection of C-14 in biological material
Training in radioactivity
GNS Science
Is sent to America to learn about radioactivity.
1st radiocarbon revolution
Radiocarbon dating becomes one of the most important dating methods in archaeology.
Radiocarbon dating
Willard Libby and colleagues develop radiocarbon dating using radioactive decay of isotopes in solid carbon
Radiocarbon dating
Begins working on new technique of radiocarbon dating.
Improving radiocarbon dating
Rafter improves method of radiocarbon dating, making it more accurate than Libby’s original method.
First New Zealand dates
University of Waikato
Rafter and Gordon Fergusson obtain first radiocarbon dates for moa bones and Taupo ash layers.
Atmospheric radiocarbon
The measurement of C-14 in atmospheric CO2 started at Makara, Wellington
Atom bomb effect
In the 1950s, there is a growing realisation that the proportion of C-14 to C-12 and C-13 in the atmosphere is not uniform over time or space or in its uptake by different types of organic matter. For example, between 1955 and 1963, the use of atomic bombs doubled the amount of C-14 in our atmosphere. With Fergusson, Rafter links a measured increase in radiocarbon in the atmosphere with nuclear weapons testing.
Publication of ‘The Atom Bomb Effect’
Rafter and colleague Gordon Fergusson publish their paper ‘The Atom Bomb Effect' in the New Zealand Journal of Science and Technology. The paper summarises their findings from measurements of C-14 levels in the environment, particularly in the atmosphere and surface ocean. The atmospheric data is collected from Makara.
The results are announced to the wider scientific community when published in Science (USA) Volume 126 on 20 September 1957.
Increased accuracy
Public domain
Calibration curves allow radiocarbon dates to be converted to calendar dates. Across the late 50s and 60s scientists, recognise that C-14 in the atmosphere varies through time and from place to place – for example, the atom bomb testing that skewed C-14 levels in the 50s and 60s.
2nd radiocarbon revolution
Accuracy greatly improved using a calibration curve based on tree ring dating.
Accuracy greatly improved using a calibration curve based on tree ring dating.
Receives OBE
Receives OBE (Officer of the Most Excellent Order of the British Empire) for services to science and education.
New dating facility
Department of Science and Industrial Research (DSIR) Institute of Nuclear Science is set up in Lower Hutt.
Institute of Nuclear Science
GNS Science
Becomes first director of Department of Science and Industrial Research (DSIR) Institute of Nuclear Science in Lower Hutt.
Libby Nobel Prize
Libby receives the Nobel Prize in chemistry for his radiocarbon dating work.
Awarded DSc
Awarded DSc (Honorary doctorate in science) by Victoria University of Wellington for his radiocarbon work and geothermal studies using oxygen isotopes.
Cambridge half-life
It is discovered early on that Libby’s original estimate of the half-life of C-14 – 5,568 years – is out by 162 years. Improved estimates available by the late 1960s set it at 5,730 years. This updated value is known as the ‘Cambridge half-life’.
This means that many calculated dates in papers published prior to this are incorrect. For consistency with these early papers and to avoid the risk of a double correction for the incorrect half-life, radiocarbon ages are still calculated using the incorrect half-life value of 5,568 years.
International conference
The 8th International Radiocarbon Conference is held in Lower Hutt, a sign of the important role played by Rafter and colleagues.
Second lab for NZ
University of Waikato
Waikato Radiocarbon Dating Laboratory is set up at University of Waikato.
3rd radiocarbon revolution
Accelerator mass spectrometry (AMS) counts isotope atoms directly, making radiocarbon dating more accurate and using much smaller samples.
Athol retires
GNS Science
Although retired, Athol continues to be active on science committees. Plays bowls when time allows.
A southern hemisphere first
Lloyd Homer, GNS Science
An accelerator mass spectrometer at the Institute of Nuclear Science, Lower Hutt, is the first for radiocarbon dating in southern hemisphere.
New organisation
GNS Science
Institute of Geological and Nuclear Sciences (GNS), a new Crown Research Institute, is formed.
Athol’s wife, Val dies
Val had been Athol’s wife for 53 years.
Rafter Laboratory
GNS Science
To mark Rafter’s 80th birthday, the Institute of Geological and Nuclear Sciences names their dating facility the Rafter Radiocarbon Laboratory.
Athol dies
GNS Science
Athol dies aged 83.
Aged 83
Bayesian statistical method
A shift to using the Bayesian statistical method means that radiocarbon dates are even more accurate.
Another increase in accuracy
Bayesian statistics and modern computers allow radiocarbon date ranges to be narrowed.
Atmospheric C-14 measurement continues
The C-14 measurements started by Rafter in 1954 continue. Longest such record in the world.
New accelerator mass spectrometer opens
GNS Science Limited
19 May, Rafter Radiocarbon Laboratory gets new accelerator mass spectrometer, the only facility of its kind in the southern hemisphere. View the Rafter Laboratory AMS facility at GNS Science in this video.
Resetting the carbon clock
National Land Image Information (Color Aerial Photographs), Ministry of Land, Infrastructure, Transport and Tourism, Japan.
The sediment of Lake Suigetsu in Japan has preserved a time capsule of radioactive carbon dating back to 52,800 years ago.
Present calibration of radioactive curves for C-14 are based on only 12,550 years of terrestrial data, leaving approximately three-quarters of the timescale calibrated via less-secure marine records. Cores from this lake are expected to provide more precise terrestrial data that will make the process of carbon dating more accurate, refining estimates by hundreds of years.
The recalibrated clock won’t force archaeologists to abandon old measurements wholesale, but it could help to narrow the window of key events in human history.
Refining radiocarbon dating
Professor Tom Higham, University of Oxford
Professor Thomas Higham lead a team who re-tested a number of Upper Palaeolithic bone samples from across Europe. Higham used improved ultrafiltration to pre-treat the samples in order to refine the radiocarbon dating. The results, published in August 2014, showed a number of the past dates were inaccurate or wrong. This has provided new insights into Neanderthal distribution and extinction and has implications for other radiocarbon dates for ancient bone samples.
Present day and into the future
Radiocarbon dating was expected to establish an empirical foundation for absolute chronologies. However, refining of sample processing and calibration curves, the anomalies in some replicability of results and differing cultural inferences around dates are highlighting that scientists and archaeologists must continue to use multiple lines of evidence and robust networks when interpreting radiocarbon data and drawing subsequent conclusions.
Transcript
Changing scientific ideas
Each specialised field of science has key ideas and ways of doing things. Over time, these ideas and techniques can be revised or replaced in the light of new research. Most changes to key science ideas are only accepted gradually, tested through research by many people.
Advances in science and technology
All scientists build their research and theories on the knowledge of earlier scientists, and their work will inform other scientists in the future. A scientist may publish hundreds of scientific reports, but only a few are mentioned here.
Biography
This part of the timeline outlines just a few events in the personal life of the featured person, some of which influenced their work as a scientist.
CHANGING SCIENTIFIC IDEAS
Rutherford and radioactivity – 1902
Ernest Rutherford and Frederick Soddy (pictured) suggest that radioactivity might be used to date minerals and rocks. Acknowledgement: Public domain.
Carbon-14 discovered – 1940
Sam Kamen and Martin Ruben discover C-14, a radioactive isotope of carbon, at University of California, Berkeley. Acknowledgement: The University of Waikato.
Prediction proved – 1947
Willard Libby (pictured) and Ernie Anderson make first detection of C-14 in biological material. Acknowledgement: Public domain.
1st radiocarbon revolution – 1949
Radiocarbon dating becomes one of the most important dating methods in archaeology.
Atom bomb effect – 1957
In the 50s, there is a growing realisation that the proportion of C-14 to C-12 and C-13 in the atmosphere is not uniform over time or space or in its uptake by different types of organic matter. For example, between 1955 and 1963, the use of atomic bombs doubled the amount of C-14 in our atmosphere. With Fergusson, Rafter links a measured increase in radiocarbon in the atmosphere with nuclear weapons testing. Acknowledgement: Public domain.
Increased accuracy – 1958
Calibration curves allow radiocarbon dates to be converted to calendar dates. Across the late 50s and 60s scientists, recognise that C-14 in the atmosphere varies through time and from place to place – for example, the atom bomb testing that skewed C-14 levels in the 50s and 60s. Acknowledgement: Public domain.
Cambridge half-life – 1969
It is discovered early on that Libby’s original estimate of the half-life of C-14 – 5,568 years – is out by 162 years. Improved estimates available by the late 1960s set it at 5,730 years. This updated value is known as the ‘Cambridge half-life’.
This means that many calculated dates in papers published prior to this are incorrect. For consistency with these early papers and to avoid the risk of a double correction for the incorrect half-life, radiocarbon ages are still calculated using the incorrect half-life value of 5,568 years.
Bayesian statistical method – 2006
A shift to using the Bayesian statistical method means that radiocarbon dates are even more accurate.
Present day and into the future – 2017
Radiocarbon dating was expected to establish an empirical foundation for absolute chronologies. However, refining of sample processing and calibration curves, the anomalies in some replicability of results and differing cultural inferences around dates are highlighting that scientists and archaeologists must continue to use multiple lines of evidence and robust networks when interpreting radiocarbon data and drawing subsequent conclusions.
ADVANCES IN SCIENCE AND TECHNOLOGY
Carbon-14 in living things? – 1946
Willard Libby in America predicts that C-14 exists in living matter.
Radiocarbon dating – 1949
Willard Libby and colleagues develop radiocarbon dating using radioactive decay of isotopes in solid carbon.
Improving radiocarbon dating – 1953
Rafter improves method of radiocarbon dating, making it more accurate than Libby’s original method. Acknowledgement: The University of Waikato.
First New Zealand dates – 1953
Rafter and Gordon Fergusson obtain first radiocarbon dates for moa bones and Taupo ash layers.
Atmospheric radiocarbon – 1954
The measurement of C-14 in atmospheric CO2 started at Makara, Wellington.
2nd radiocarbon revolution – 1958
Accuracy greatly improved using a calibration curve based on tree ring dating.
New dating facility – 1959
Department of Science and Industrial Research (DSIR) Institute of Nuclear Science is set up in Lower Hutt.
Libby Nobel Prize – 1960
Libby receives the Nobel Prize in chemistry for his radiocarbon dating work.
Second lab for NZ – 1974
Waikato Radiocarbon Dating Laboratory is set up at University of Waikato. Acknowledgement: The University of Waikato.
3rd radiocarbon revolution – 1977
Accelerator mass spectrometry (AMS) counts isotope atoms directly, making radiocarbon dating more accurate and using much smaller samples.
A southern hemisphere first – 1987
An accelerator mass spectrometer at the Institute of Nuclear Science, Lower Hutt, is the first for radiocarbon dating in southern hemisphere. Acknowledgement: Lloyd Homer, GNS Science.
New organisation – 1991
Institute of Geological and Nuclear Sciences (GNS), a new Crown Research Institute, is formed. Acknowledgement: GNS Science.
Another increase in accuracy – 2006
Bayesian statistics and modern computers allow radiocarbon date ranges to be narrowed.
Atmospheric C-14 measurement continues – 2010
The C-14 measurements started by Rafter in 1954 continue. Longest such record in the world.
New accelerator mass spectrometer opens – 2010
19 May, Rafter Radiocarbon Laboratory gets new accelerator mass spectrometer, the only facility of its kind in the southern hemisphere. View the Rafter Laboratory AMS facility at GNS Science in this video. Acknowledgement: GNS Science Limited
Resetting the carbon clock – 2012
The sediment of Lake Suigetsu in Japan has preserved a time capsule of radioactive carbon dating back to 52,800 years ago. Present calibration of radioactive curves for C-14 are based on only 12,550 years of terrestrial data, leaving approximately three-quarters of the timescale calibrated via less-secure marine records. Cores from this lake are expected to provide more precise terrestrial data that will make the process of carbon dating more accurate, refining estimates by hundreds of years. The recalibrated clock won’t force archaeologists to abandon old measurements wholesale, but it could help to narrow the window of key events in human history. Acknowledgement: National Land Image Information (Color Aerial Photographs), Ministry of Land, Infrastructure, Transport and Tourism, Japan.
Refining radiocarbon dating – 2014
Professor Thomas Higham lead a team who re-tested a number of Upper Palaeolithic bone samples from across Europe. Higham used improved ultrafiltration to pre-treat the samples in order to refine the radiocarbon dating. The results, published in August 2014 showed a number of the past dates were inaccurate or wrong. This has provided new insights into Neanderthal distribution and extinction and has implications for other radiocarbon dates for ancient bone samples.
BIOGRAPHY
Born in Wellington – 1913
Full name Thomas Athol Rafter, but becomes known as Athol.
University – 1935
Obtains BSc at Victoria University College, Wellington.
More studies – 1938
Chemistry MSc at Victoria University College, Wellington. Becomes school teacher.
Marriage – 1939
Marries Ruby Valerie Organ, known as Val.
Beginning research – 1940
Becomes research scientist at Dominion Laboratory, analysing coal ash and uranium-bearing minerals.
Training in radioactivity – 1948
Is sent to America to learn about radioactivity. Acknowledgement: GNS Science.
Radiocarbon dating – 1949
Begins working on new technique of radiocarbon dating.
Treating cancer – 1951
Starts encouraging hospitals to use radioactive isotopes to treat cancer and supplies them with the isotopes.
Publication of ‘The Atom Bomb Effect’ – 1957
Rafter and colleague Gordon Fergusson publish their paper ‘The Atom Bomb Effect' in the New Zealand Journal of Science and Technology. The paper summarises their findings from measurements of C-14 levels in the environment, particularly in the atmosphere and surface ocean. The atmospheric data is collected from Makara.
The results are announced to the wider scientific community when published in Science (USA) Volume 126 on 20 September 1957.
Receives OBE – 1958
Receives OBE (Officer of the Most Excellent Order of the British Empire) for services to science and education.
Institute of Nuclear Science – 1959
Becomes first director of Department of Science and Industrial Research (DSIR) Institute of Nuclear Science in Lower Hutt. Acknowledgement: GNS Science.
Awarded DSc – 1968
Awarded DSc (Honorary doctorate in science) by Victoria University of Wellington for his radiocarbon work and geothermal studies using oxygen isotopes
International conference – 1972
The 8th International Radiocarbon Conference is held in Lower Hutt, a sign of the important role played by Rafter and colleagues.
Athol retires – 1978
Although retired, Athol continues to be active on science committees. Plays bowls when time allows. Acknowledgement: GNS Science.
Athol’s wife, Val dies – 1992
Val had been Athol’s wife for 53 years.
Rafter Laboratory – 1993
To mark Rafter’s 80th birthday, the Institute of Geological and Nuclear Sciences names their dating facility the Rafter Radiocarbon Laboratory. Acknowledgement: GNS Science.
Athol dies – 1996
Athol dies aged 83. Acknowledgement: GNS Science.
Useful links
Learn more about the sediments of Lake Suigetsu and how it is helping in refining radiocarbon dating and resetting the carbon dating clock.
