111 Science 10: A Contextual Approach

Energy

Related chapters:

The structure of matter

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science BIGWith the increasing costs of chemicals and laboratory

equipment, many school laboratories now make use

of microscale techniques where experiments are

carried out on a tiny scale to reduce costs and ensure

safety. When looking at the reactions and structures

of tiny atoms and molecules you would think that

a relatively small laboratory would be enough.

However in 2007 Australia will have a massive

facility, an enormous laboratory that will allow

Australian scientists to have access to technology

that they previously had to use overseas—the

Australian Synchrotron.

BIG SCIENCE 11

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Respondingto change

The restlessEarth

12 Science 10: A Contextual Approach

What is a synchrotron?

The Australian Synchrotron

fi gure bs.1 The 2 km ring of the tevatron particle accelerator.

A synchrotron is a device that generates brilliant beams of light across a range of wavelengths of energy from microwaves to gamma rays. These are used to investigate the structure and composition of substances. The light produced by a synchrotron is much brighter than light from other sources.

Synchrotrons were fi rst constructed in the 1940s. They were developed over time until major use of synchrotron light began in the 1960s. The Australian Synchrotron is a refi nement of earlier versions. Until now Australian scientists have had to make use of synchrotrons situated in other countries. An Australian beamline was even established in the mid-1980s in a synchrotron in Japan known as the ‘Photon Factory’.

In 2001 it was decided to build the Australian Synchrotron in Victoria and construction commenced in 2003. It is expected that, by 2007, 13 out of 30 beamlines will be operational.

The Australian Synchrotron will have a total cost of $206.3 million dollars. It will feature a storage ring with a circumference of 216 m. That might sound like a pretty big piece of laboratory equipment, but it is actually a scaled-down version of some of its predecessors.

Synchrotrons are one type of particle accelerator and some overseas facilities make the Australian Synchrotron look rather humble. The tevatron near Chicago (fi gure bs.1) has a diameter of 2 km and the Stanford Linear Accelerator Center in the USA features a straight-line accelerator 3 km long (fi gure bs.2). In 1993, the United States of America abandoned construction of the Superconducting Supercollider after hundreds of millions of dollars had already been spent, because the cost became too much. The large hadron collider is currently being built in Geneva at a cost of almost US$2.5 billion. It features a facility with a circumference of 27 km!

BIG SCIENCE 13

fi gure bs.2 The 3 km long accelerator at the Stanford Linear Accelerator Center.

fi gure bs.3 The large hadron collider is being built in a tunnel on the border of France and Switzerland.

Would you ever consider measuring the thickness of a book with a trundle wheel? A meaningful measurement wouldn’t be possible. A ruler with millimetre units could be used to measure the thickness of a book and millimetres are also used to provide the specifi cation on a set of house plans. When making measurements, the units need to be around the same size as the object being measured or smaller.

Have you ever wondered why scientists don’t build a really powerful microscope to look at atoms and molecules? Visible light has a wavelength of around 10–6 metres. When we look at something, our eyes and brain can make sense of the messages generated by the light from objects that are larger than the wavelength of light. With powerful microscopes we can use light to look at tiny cells and bacteria, but these are of the order of 10–6 metres in size. Anything smaller than this cannot be examined using visible light. Scientists needed to fi nd methods that used ‘rulers’ with smaller increments. Synchrotrons produce a range of wavelengths of energy that can be used to examine different materials.

How does a synchrotron work?

Section 4.1 Atomic structure describes the subatomic particles that are used in particle accelerators.

The synchrotron starts the process of creating beams of light by generating electrons. Magnetic fi elds are used to contain the beams of electrons and accelerate them. After initial acceleration the electrons pass into the booster ring where they are accelerated further until they reach speeds close to the speed of light. They are then passed into the storage ring from which they can be accessed for experiments.

fi gure bs.4 Radiation such as X-rays, with a smaller wavelength than visible light, can penetrate a sample and provide information about molecules. © Victorian Government 2004

Section 7.3 Radiation describes the different types of energy that make up the electromagnetic spectrum.

14 Science 10: A Contextual Approach

The wide spectrum of beams of light with different wavelengths and energies provides radiation for many different techniques to analyse a large variety of substances.

fi gure bs.5 The steps in generating powerful beams of light in the Australian Synchrotron. The electrons are generated by the electron gun, accelerated in the linac, then they pass into the booster ring where they are accelerated to 99.9999% of the speed of light. Finally the electrons are stored in the storage ring. © Victorian Government 2004

fi gure bs.6 The radiation produced by the Australian synchrotron compared with the range of the electromagnetic spectrum that we normally encounter. © Victorian Government 2004

BIG SCIENCE 15

There are thirteen initial beamlines of the Australian Synchrotron that will be used to perform particular experiments and make measurements. Table bs.1 summarises the functions of the proposed beamlines.

What can be found using a synchrotron?

Some specifi c examples of the uses of a synchrotron follow.

Fighting the infl uenza virusAn Australian team using synchrotrons overseas was able to produce a highly detailed model of an infl uenza enzyme. This allowed a drug to be developed that would interact with the active site of this enzyme. Figure bs.7 shows a model of the structure of an infl uenza virus enzyme (infl uenza neuraminidase) with a molecule of the infl uenza drug Relenza . The drug blocks the proteins of the virus and disrupts its life cycle making it unable to reproduce. Human strains of avian infl uenza—also known as ‘bird fl u’—have been shown to be effectively treated by this drug.

Table bs.1 The 13 beamlines of the Australian Synchrotron will be used for different purposes.

Beamline Use Purpose

1 High-throughput protein To determine the crystal structure of large protein crystallography molecules.

2 Protein microcrystal and small A fi nely focused X-ray beam is used to determine the molecule X-ray diffraction density of electrons and crystal structures of proteins that

are diffi cult to crystallise and of other small molecules.

3 Powder X-ray diffraction To determine high-resolution crystal structures of powdered samples so that compounds can be identifi ed and their quality assured.

4 Small and wide angle X-ray Measurements to determine the shape and structure scattering of complex molecules and materials.

5 X-ray absorption spectroscopy Measurements, including the lengths of bonds between atoms and the arrangement of atoms, to determine the shape of elements with an atomic number higher than 20.

6 Soft X-ray spectroscopy As above for elements with an atomic number less than 20. And to analyse thin fi lms and surfaces.

7 Vacuum ultraviolet (VUV) To determine the arrangement of electrons and surface characteristics of soft, solid materials and gases.

8 Infrared spectroscopy To analyse the bonds within and between complex molecules.

9 Microspectroscopy To produce fi nely detailed maps of the arrangement of (submicron-XAS, XANES, and XRF) atoms in a material, particularly heavy metal elements.

10 Imaging and medical therapy To produce high-contrast images of objects, including small animals and manufactured objects.

11 Microdiffraction and fl uorescence To analyse minerals and manufactured materials. probe (XRD and XRF mapping) This information can be useful in assessing areas of

environmental concern.

12 Circular dichroism To determine the way molecules move and function due to their structure.

13 Lithography To produce components with fi ne detail at a micro level.

fi gure bs.7 A model of the smaller molecules of the infl uenza drug Relenza at the active site of an infl uenza virus enzyme. © Victorian Government 2004

16 Science 10: A Contextual Approach

Fighting air pollutionThe tiny particles found in air pollution can travel vast distances. Soil particles, industrial pollutants and waste materials produced by cars can all contribute to the pollution known as ‘smog’ that hangs over city skies. Scientists can analyse the particles that make up air pollution using synchrotron techniques. This allows the sources of pollutants to be identifi ed so that we can devise strategies to reduce their effects.

Section 10.4 Changes in the atmosphere describes factors that alter the Earth’s atmosphere, including pollutants.

fi gure bs.8 Three images of a fi nger joint using: (a) conventional X-ray, (b) synchrotron X-ray, and (c) synchrotron phase contrast X-ray. Note the improved detail of each image. © Victorian Government 2004

(a) (b) (c)

Examining soft tissuesX-rays for medical purposes can only be used to observe hard body substances like teeth and bone. Synchrotron X-ray images have much higher resolution and can be used to create fi nely detailed images of soft tissue such as heart muscle and brain tumours. These images are also used to detect cancer in breast tissue. The aerospace industry has used these X-ray techniques to detect fl aws in the materials used to build aeroplanes and spacecraft.

Section 3.2 Disease describes the body’s response to infectious diseases, including those caused by viruses.

Section 3.2 Disease describes diseases, some of which may be diagnosed by using X-rays.

fi gure bs.9 By fi nding out where pollutants are produced, anti-pollutant strategies can be developed.

BIG SCIENCE 17

Making smoother chocolateScientists at the UK synchrotron were enlisted by Cadbury to follow the process of making chocolate at a molecular level. The information that the scientists obtained allowed them to work out the optimum conditions for chocolate. The outcome was that Cadbury lowered the temperature at which the chocolate was produced. This resulted in better quality chocolate and energy savings for the company.

Searching for gold depositsCSIRO has been using synchrotron techniques to analyse the solutions trapped in ancient underground rock in order to determine the likely location of gold-ore deposits. X-ray fl uorescence is the name of the technique that has been used.

Making more absorbent baby nappiesDow chemicals wanted to investigate the use of more absorbent materials in disposable nappies. Researchers used synchrotron X-ray techniques to observe the effectiveness of the super-absorbent polymer beads that are used. Dow now has a manufacturing plant which produces absorbent polymer gels, adhesives and other materials for a range of uses. They even manufacture a synthetic soil for potted plants.

Future use of the Australian SynchrotronIt is expected that research performed at the new Australian Synchrotron will result in new products and new processes for industry, which will generate income for the nation. The present practice of Australian scientists using overseas synchrotrons has its limitations. Biological substances are often fragile, have a short life span, and are subject to quarantine restrictions when being taken into other countries.

The commissioning of the Australian Synchrotron is expected to result in Australian scientists using a larger range of synchrotron techniques over a broader range of science areas. The interactions and collaboration of various scientists at the facility are expected to enhance the level of Australian scientifi c research.

Section 4.4 Molecular substances describes the structure of polymers.

fi gure bs.11 Synchrotron light can be used in the detailed manufacture of tiny mechanical parts. © Victorian Government 2004

fi gure bs.10 Super-absorbent polymer beads have replaced the cellulose paper material once used in disposable nappies.

The Australian InternationalGravitational Observatory

Section 7.3 Radiation describes the different types of energy of the electromagnetic spectrum.

Chapter 11 In a fraction of a bang! describes events that may have caused gravitational waves.

The Australian International Gravitational Observatory is another facility in development. It is a project of the University of Western Australia being built 80 km north of Perth. The fi rst laser interferometer detector in the southern hemisphere is being built in an effort to discover gravitational waves. The 80 m detector being fi tted will be used to detect waves in the microwave to optical frequency range in an attempt to measure the tiny vibrations caused by gravitational waves.

This facility will work in cooperation with other detectors around the world. Each will detect movement or vibrations in the surrounding Earth but if all the detectors identify the same disturbance simultaneously then gravity waves from somewhere away from the Earth must have caused the movement. The use of several detectors allows cosmic events to be distinguished from local events such as earthquakes.

Albert Einstein predicted the existence of gravitational waves in 1916 in his theory of relativity. They are ripples in the fabric of space–time produced by catastrophic events such as exploding supernovae and collisions between black holes. Electromagnetic waves such as visible light and X-rays are produced by accelerating charges. Gravitational waves are predicted to be caused by the acceleration of masses, and the larger the masses, the more powerful the waves, and the more easily they will be detected. Gravitational waves are much weaker than electromagnetic waves, which is the major reason that they have avoided detection so far. While evidence of gravitational waves has been collected, direct measurement of them has not been possible.

The Australian International Gravitational Observatory facility will be used to collect information about a variety of phenomena. When large stars explode and then collapse into black holes cosmological gamma-ray bursts are produced and are expected to result in strong gravitational waves. It is expected that gravitational wave measurements will provide information on the formation of supernovae and allow models to be produced that simulate the production of gravitational waves caused by different kinds of events and processes that take place in the Universe. A better understanding of these may give us insight into how the Universe began and how it will progress in the future.

Other possible applications of the AIGO facility include the detection of surface waves caused by the ocean, their geographic beginnings and how they vary with the seasons. Vibrations due to mine blasts, earthquakes and other local sources of vibration may also be detected and interpreted.

fi gure bs.13 An artist’s impression of gravitational waves emitted by a disturbed black hole.

18 Science 10: A Contextual Approach

fi gure bs.14 The detection of gravitational waves from events such as the formation of a supernova may give us a better idea of how the Universe functions.

fi gure bs.12 The Australian International Gravitational Observatory in Western Australia.

BIG SCIENCE 19

ProjectsThere are many applications of synchrotron techniques to be found on the website of the Australian Synchrotron. Each member of your class could select a different application, conduct research from this website and other sources, and make a presentation to the whole class. Your presentation could be a spoken task, a PowerPoint slide show or a detailed poster.

With knowledge of the uses of synchrotron technology, propose an area that could benefi t from further research. Which type of beamline do you think could be used? What outcome would you expect from this research? Present your fi ndings in the form of a submission request for government funding.

The Australian International Gravitational Observatory has a website with links to current research. Select an area of research and fi nd out about the possible applications that may result.

Do you think it is morally right for governments around the world to spend such large amounts of money on scientifi c equipment? What else might the money be spent on? Is it likely that the money would be spent on the other things you can suggest? Make a list of reasons for and against spending money on these machines in preparation for a class debate.

You should be able to fi nd some more information about particle accelerators, synchrotrons and other expensive devices. Scientifi c magazines are a good place to look for up-to-date events. Your teacher or librarian may be able to help you. Once you have decided which side you want to argue, write a short essay explaining your point of view. It may be helpful to fi nd someone on the other side who can tell you what they are writing about.

In class, a few essays from both sides can be read out, and people can have their say. When the debate is over, hold a vote to see what your class has decided.

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120 Science 10: A Contextual Approach

Suppose you decided to become more ‘environmentally

friendly’, just how far would you go to avoid using

materials that come from unrenewable resources or

that require a lot of manufacturing processes?

How normal would your life be if you only relied on

natural renewable materials?

A MATERIAL WORLD 20

Think about your home; your own bedroom. Let’s

strip away all the plastics to start with since they are

made from our dwindling oil reserves. That means the

computer, television and sound system are the fi rst

things to go, but you can also say goodbye to your

carpet, curtains and even the paintwork. Plastics, many

fi bres and paints are chemically manufactured. You can

keep your wooden bed, but the foam mattress is gone

as well as the pillow. Cotton sheets are fairly natural,

but rare these days. Most are made from a blend of

cotton and polyester, a polymer fi bre. Most of your

clothes are gone, but the ones that remain aren’t that

interesting without the use of chemical dyes. Some of

your shoes are leather, well the uppers anyway. They

just don’t have a sole anymore. Your tennis racquet

(carbon fi bre)—gone, football (synthetic not leather)—

gone and wetsuit (nothing natural there)—all gone.

Glass is hardly natural so you don’t have any windows

or anything else made of glass. Highly manufactured

metals and alloys disappeared with the electrical

items, but then again, without plastic insulation you

don’t have electricity anyway.

How heavily do you rely on manufactured materials?

a materialworld

The structure of matter

Related chapters:

Inheritance and change

2

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Electricity

Energy

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