Tuesday, 22 December 2015

Pioneering nuclear scientist – yet another Kiwi success

Thomas Athol Rafter was born in 1913 in Wellington. After graduating in 1938 at Victoria University College, he started teaching, as there were no jobs as a research scientist available.
In 1940 a position at the Dominion Laboratory became available and he started working on analysing coal ash and uranium bearing minerals from the West Coast beach sands.

Rafter's first radioactive laboratory at the
Institute of Nuclear Sciences in 1948
In 1948, almost a decade later, the New Zealand government decided to establish a group of scientists within the DSIR (Department of Scientific and Industrial Research) to do nuclear research. Rafter’s role in the newly formed group was to further develop the method of radiocarbon dating,

which had been invented three years earlier in the United States by Willard Libby. Rafter’s pioneering work and the resulting publications form a major part of the core literature in radiocarbon dating. In 1959, Rafter became the director of the newly founded Institute of Nuclear Sciences in Gracefield, Lower Hutt. He held this position until he retired in 1978.

Rafter’s legacy was establishing one of the first radiocarbon laboratories in the world in 1951. It still operates today at its original site that is now known as the National Isotope Centre, a part of GNS Science, which makes it the longest continuously operating radiocarbon laboratory in the world. On his 80th birthday in 1993, the laboratory was named ‘Rafter Radiocarbon Laboratory’.

Thomas Athol Rafter passed away in 1996 in Wellington.

Current radiocarbon research applications including 14COas a tracer for fossil fuel emissions, bio product verification, and chronology for Paleoclimatology and aging of shell fish. These topics will be explained in future posts.

Wednesday, 18 November 2015

What do children breathe inside school classrooms?

Bill Trompetter is showing an air sample filter.
Air particulate scientist Bill Trompetter led a project to determine levels of air particulates and their sources inside school classrooms. This was achieved by comparing the air quality from a normal classroom with a classroom that was fitted with a ventilation system, providing heated air through a solar collector. This study is mainly driven by the fact that children are more affected by air pollution than any other age group and very little is known of healthiness at schools, child care centres etc. where children spend a significant amount of their days.

Photo shows the GNS Science sampling
Samplers were installed in two classrooms and an extra one outside. Air particulates PM10 (particulate matter up to 10 micrometres in size [1 micrometre = 0.000001 metre]) are deposited onto a polycarbonate filter and were collected hourly for 3 weeks.
The air sampling campaign was accompanied with a throat swab test for Streptococcal group A, C and G, as well as health related absenteeism quantification and an after test questionnaire.

But where is the link to nuclear science here? Well, it is the measurement technique!

A schematic of ion beam elemental composition analysis.
The technique used for quantifying and qualifying the composition of the air particulate samples is PIXE (Proton Induced X-ray Emission). This method uses accelerated protons (Hydrogen nuclei) hitting atoms on the target filter and resulting in an elemental specific signal (elemental specific X-ray energy) which gets detected.

This study clearly shows that insufficiently ventilated classrooms have a higher concentration of particulates in the ambient air than a ventilated room during school hours. Elemental analysis shows the air particulates are mainly soil dust stirred up from the carpet when the classroom is occupied with the children.

A continuation of this project will look into an improved cleaning regime to reduce dust exposure to children inside classrooms.