Uses Of Isotopes

Solar wind sheds light on early solar system

In 2004 NASA’s Genesis space mission made an unplanned crash landing, damaging its precious cargo of solar-wind particles. Now, after years of painstaking work, two independent groups of scientists have managed to measure the relative abundances of nitrogen and oxygen isotopes in the solar wind. Their studies reveal that the isotopic compositions on Earth are very different from in the Sun. The result could prove important to understanding the conditions in the early solar system, when the Earth was forming.

While scientists know a great deal about the isotopic abundance of elements on the Earth, Moon and meteorites, very little is known about the Sun. Fortunately, the Sun spews out a steady stream of ions called the solar wind, which can be captured by spacecraft. Although mostly hydrogen, the wind does contain small amounts of heavier elements and their isotopic composition is believed to be similar to the material from which the solar system formed.

Genesis collected the particles over about two years using a solar-wind concentrator, which uses electric fields to accelerate the oxygen and nitrogen ions and focus them on a number of ultra-pure silicon-carbide targets. Despite boosting the number of ions hitting the targets by a factor of 20, the concentrations of the isotopes in the targets was still very small when the mission returned to Earth and would therefore require careful analysis.

But tragedy struck in 2004 when the mission’s sample-return capsule failed to deploy its parachute as it fell towards Earth. The capsule overheated and smashed into the ground, breaking open and shattering much of its contents, including many of the solar-wind targets.

What remained of the targets was contaminated by a range of materials (including a mysterious oily film) and scientists embarked on a painstaking process to clean the samples. This cleaning was difficult because the oxygen and nitrogen ions reside about 100 nm below the surface of the targets and could easily be scrubbed away.

Now, the silicon carbide targets have been cleaned sufficiently to have their oxygen and nitrogen contents analysed. One study has been undertaken by Kevin McKeegan and colleagues at the University of California, Los Angeles and other universities in the US, UK and Japan. They used an instrument specially designed for Genesis called MegaSIMS, which is a secondary ion mass spectrometer coupled to an accelerator mass spectrometer. An important feature of the instrument is that it can analyse tiny regions of the sample about 2 µm across in order to find regions of the surface that are not contaminated.

Joint Venture announced to expand the use of molecular imaging in ...

CanProbe, a joint venture unique, not-for-profit to advance the use of medical isotopes to diagnose and treat cancer and other serious diseases, was announced today by the Centre for the development and commercialization (CPDC) and the University Health Network (UHN).

The joint-venture, officially Molecular Imaging Probe Canadian Consortium (CanProbe), combines the strengths of both organizations to create a new centre of excellence of Toronto to develop and manufacture Imaging probes molecular. These probes are part of advanced imaging technology that uses medical isotopes to assess the health of the patients at the cellular level. With the help of molecular probes, physicians can diagnose disease earlier and more specifically, monitor the effectiveness of treatments and deliver targeted therapies, often without the need for biopsy or surgical procedures.

CanProbe will establish a new centre for research, production and distribution of Toronto to provide important probes, often saving lives, molecular to support research and programs for UHN affiliated hospitals and the global community of nuclear medicine clinical imaging. The centre will work also to introduce new molecular imaging probes of Ontario through its own research and development and the approval for the manufacture of probes for imaging that are used successfully in other parts of the world. CanProbe will provide complete concept-to-clinic services in the development of the probe which include research and development, regulatory approvals, clinical, manufacturing and distribution tests.

UHN and SCDC researchers have already started their first project with CanProbe at the new molecular imaging probes which will help to diagnose and treat certain rare medical conditions in children and adults. In many cases, these patients have few options for care and often get medical care outside of Ontario or the Canada. By enabling hospitals to offer services of Ontario, CanProbe may help to reduce costs to the health care system, to improve access to services and to alleviate the financial difficulties and emotional patients feel when they travel outside their province or territory for medical care.

Beneficial uses and production of isotopes, 2000 update

Nuclear Development Beneficial Uses and Production of Isotopes, 2004 Update

Isotopic Tracers in Surface Water

Isotope tracers in catchment hydrology

Earth, evolution of a habitable world