Heritage scientist timeline – Athol Rafter
Athol Rafter was a pioneer of radiocarbon dating – the Rafter Radiocarbon Laboratory at GNS Sciences, Lower Hutt, is named after him. Rafter played a part in the early development of what became one of the most important dating tools in archaeology. Even now, more than 60 years after the technique was first developed, improvements continue to be made to give greater accuracy and reliability.
Athol Rafter, nuclear chemist
Athol Rafter (1913–1996) pioneered the technique of radiocarbon dating in New Zealand and began the long-term measurement of 14CO2 in the atmosphere.
The technique, first developed in America in 1949, created a revolution in the dating of archaeological material. Radiocarbon dating uses the carbon-14 isotope in organic material to work out the ages of once-living things. Rafter and colleagues immediately saw uses for the technique in New Zealand and tried it out. The new method proved to be a bit unreliable, so Rafter and his team set about solving some of the problems. Their improvements had a lasting impact on the worldwide use of the technique.
...the guiding principle must be ‘you must never give up’.
Athol Rafter
Rafter went on to run the Institute of Nuclear Science in Lower Hutt, and the dating facility was renamed the Rafter Radiocarbon Laboratory to mark his 80th birthday in 1993. Radiocarbon dating has continued to improve. The original method counted radioactive particles given off by carbon-14 atoms. Since 1977, the isotope atoms have been counted directly, making the dating much more accurate. As part of Rafter’s scientific legacy, New Zealand continues to play an important role in these developments and now has two radiocarbon dating laboratories that receive samples from all over the world.
Athol Rafter retires
To mark Athol Rafter’s 80th birthday, the Institute of Geological and Nuclear Sciences named their dating facility the Rafter Radiocarbon Laboratory.
Another aspect of Rafter’s work has also left a lasting legacy. He and Gordon Fergusson were the first to notice an increase in radiocarbon in the atmosphere as a result of nuclear weapons testing in the 1950s. Measurements of radiocarbon in carbon dioxide in the atmosphere were started at Makara, near Wellington, in 1954. Data is still being collected by NIWA and is the longest running record of its kind in the world. Data from the programme plays an important part in recording increased carbon dioxide in the atmosphere, which is causing widespread concern due to its involvement in global warming.
The timeline below lets you see aspects of Athol's life and work, and how his findings changed scientific thinking. A full timeline transcript is here.
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.
Athol Rafter – nuclear chemist
This timeline lets you see aspects of Athol's life and work, and how these fit into a wider science picture of radiocarbon dating. A full transcript is underneath.
