Interactive

Athol Rafter – nuclear chemist

Athol Rafter – nuclear chemist

  • Changing scientific ideas
  • Advances in science and technology
  • Biography
1902
1902
Rutherford and radioactivity

Ernest Rutherford and Frederick Soddy (pictured) suggest that radioactivity might be used to date minerals and rocks.

1913
1913
Born in Wellington

Full name Thomas Athol Rafter, but becomes known as Athol.

1935
1935
University

Obtains BSc at Victoria University College, Wellington.

1938
1938
More studies

Chemistry MSc at Victoria University College, Wellington. Becomes school teacher.

1939
1939
Marriage

Marries Ruby Valerie Organ, known as Val.

1940
1940
Carbon-14 discovered

University of Waikato

Sam Kamen and Martin Ruben discover C-14, a radioactive isotope of carbon, at University of California, Berkeley.

1940
Beginning research

Becomes research scientist at Dominion Laboratory, analysing coal ash and uranium-bearing minerals.

1946
1946
Carbon-14 in living things?

Willard Libby in America predicts that C-14 exists in living matter.

1947
1947
Prediction proved

Willard Libby (pictured) and Ernie Anderson make first detection of C-14 in biological material

1948
1948
Training in radioactivity

GNS Science

Is sent to America to learn about radioactivity.

1949
1949
1st radiocarbon revolution

Radiocarbon dating becomes one of the most important dating methods in archaeology.

1949
Radiocarbon dating

Willard Libby and colleagues develop radiocarbon dating using radioactive decay of isotopes in solid carbon

1949
Radiocarbon dating

Begins working on new technique of radiocarbon dating.

1953
1953
Improving radiocarbon dating

Rafter improves method of radiocarbon dating, making it more accurate than Libby’s original method.

1953
First New Zealand dates

University of Waikato

Rafter and Gordon Fergusson obtain first radiocarbon dates for moa bones and Taupo ash layers.

1954
1954
Atmospheric radiocarbon

The measurement of C-14 in atmospheric CO2 started at Makara, Wellington

1957
1957
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.

1957
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.

1958
1958
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.

1958
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.

1958
Receives OBE

Receives OBE (Officer of the Most Excellent Order of the British Empire) for services to science and education.

1959
1959
New dating facility

Department of Science and Industrial Research (DSIR) Institute of Nuclear Science is set up in Lower Hutt.

1959
Institute of Nuclear Science

GNS Science

Becomes first director of Department of Science and Industrial Research (DSIR) Institute of Nuclear Science in Lower Hutt.

1960
1960
Libby Nobel Prize

Libby receives the Nobel Prize in chemistry for his radiocarbon dating work.

1968
1968
Awarded DSc

Awarded DSc (Honorary doctorate in science) by Victoria University of Wellington for his radiocarbon work and geothermal studies using oxygen isotopes.

1969
1969
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.

1972
1972
International conference

The 8th International Radiocarbon Conference is held in Lower Hutt, a sign of the important role played by Rafter and colleagues.

1974
1974
Second lab for NZ

University of Waikato

Waikato Radiocarbon Dating Laboratory is set up at University of Waikato.

1977
1977
3rd radiocarbon revolution

Accelerator mass spectrometry (AMS) counts isotope atoms directly, making radiocarbon dating more accurate and using much smaller samples.

1978
1978
Athol retires

GNS Science

Although retired, Athol continues to be active on science committees. Plays bowls when time allows.

1987
1987
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.

1991
1991
New organisation

GNS Science

Institute of Geological and Nuclear Sciences (GNS), a new Crown Research Institute, is formed.

1992
1992
Athol’s wife, Val dies

Val had been Athol’s wife for 53 years.

1993
1993
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. 

1996
1996
Athol dies

GNS Science

Athol dies aged 83.

Aged 83

2006
2006
Bayesian statistical method

A shift to using the Bayesian statistical method means that radiocarbon dates are even more accurate. 

2006
Another increase in accuracy

Bayesian statistics and modern computers allow radiocarbon date ranges to be narrowed.

2010
2010
Atmospheric C-14 measurement continues

The C-14 measurements started by Rafter in 1954 continue. Longest such record in the world.

2010
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.

2012
2012
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.

2014
2014
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.

2017
2017
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.

Rights: University of Waikato
Published:10 June 2010