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Find out here 'Who's who' of Science
Organisations and Institutes in Africa
 June
Showcase: The National Accelerator Centre.
May
Showcase: Living with Elephants Foundation: an organisation in Botswana
dedicated to improving human- elephant relationships.
April
Showcase: Committee for Science and Technology in Developing Countries (COSTED)
March
Showcase: Sasol Scifest: The National Festival of Science, Engineering
and Technology, South Africa
February's
Showcase: The National Research Foundation, South Africa
January's
Showcase: International Institute of Tropical Agriculture, Nigeria
The National Accelerator Centre, South Africa
The National Accelerator Centre, situated 20km from Cape Town is a multidisciplinary research centre, established in 1977 under the control
of the Council for Scientific and Industrial Research (CSIR). Since 1988 it has been one of the four National Facilities administered by the
National Research Foundation (NRF), and provides facilities for
· basic and applied research using particle beams
· particle radiotherapy for the treatment of cancer
· the supply of accelerator-produced radioactive isotopes for nuclear
medicine and research.
 The National Accelerator Centre (NAC) is intended to bring together
people working in medical, biological and physical sciences who are interested in using accelerated particle beams, by providing
opportunities for research and postgraduate training in these separate disciplines, and also by stimulating mutual interest in the inter-disciplinary areas.
The accelerators now operated by NAC are a 6 MeV Van de Graaff accelerator, and 8 MeV injector cyclotron which provides light ions for
a 200 MeV cyclotron, a second injector cyclotron which provides heavy ions and polarised light ions for the 200 MeV machine, and the 200 MeV
separated-sector cyclotron itself. There are plans in the no-so-distant future for a dedicated 230 MeV Protontherapy Accelerator.
The Van de Graaff accelerator was commissioned in 1963. The Van de Graaff accelerator is a high-precision, variable-energy machine, capable
of accelerating light ions to energies of between 0.5 and 20 MeV with an energy spread of less than one part in 10 000. The accelerator can also
produce pulsed beams of particles with 0.2-nano-second pulses every 500 nanoseconds, which makes it particularly useful for research with
neutrons.
The NAC Van de Graaff accelerator is used almost exclusively for materials research and for solid-state physics. This work is done in
close collaboration with universities and technikons throughout South Africa, as well as with overseas laboratories. Research projects include
the use of accelerated particles for identification and quantification of elements and isotopes as well as trace-elements in such diverse
fields as microelectronics, superconducting materials, optical layers, new materials and geological samples. Radioactive tracers and nuclear
techniques are also utilized in basic and applied investigations.
Laboratory facilities exist for X-ray diffraction, target manufacture, surface preparation and radioactivity counting. Data taking and analysis
are fully computerized.
Another special feature is a high-brightness scanning proton microprobe with a resolution of 1 micron. Dynamic analysis can be done with a true
elemental imaging system. The scanning microprobe is used with the accelerator for investigations in the life sciences and biology, as well
as in archaeology, geology and in materials research.
The Separated-Sector Cyclotron (SSC) is a variable-energy machine capable of accelerating protons to a maximum energy of 200 MeV, which
means in effect that the protons (nuclei of hydrogen atoms) are accelerated by voltages totalling 200 million volts. This gives the
protons sufficient velocity to travel a distance equivalent to four times around the earth in only one second! Protons of 200 MeV can just
pass through the human body, making them especially suitable for cancer therapy.
Two small conventional cyclotrons, designed and constructed by NAC, are
used as injectors (pre-accelerators) for the much larger separated-sector cyclotron. The first injector uses an internal ion
source to produce the intense beams of light ions required for radiotherapy and radioisotope production. The second is designed both
for heavy ions, such as those of carbon, argon and krypton, and for polarised proton and deuteron beams, and has therefore been provided
with two external ion sources. It also provides an alternative source of protons for therapy.
The SSC has been in routine operation since February 1987. It was completely designed and assembled by NAC staff, although a number of the
larger components were manufactured overseas. The SSC has a diameter of 13.2 metres and a height of 7 metres. The four sector magnets together
weigh 1400 tons, and are positioned to an accuracy of one-tenth of a
millimetre. The final machining of the magnet pole-pieces as well as the manufacture of many other components was undertaken by South African
firms.
The site of the new accelerator complex was chosen to be within easy reach of the two local teaching hospitals, Groote Schuur and
Tygerberg, both of which have major radiotherapy departments. The present site was
selected after detailed examination of a number of others. Piles had to be sunk 30 metres to reach bedrock to support the cyclotron magnets and
the thick shielding walls. The cyclotron is housed in a vault surrounded by concrete walls more than 4 metres thick to provide shielding against
neutrons. The entire facility contains over 30 000 cubic metres of concrete in the form of floor slabs, shielding
walls or removable shielding roof beams.
The accelerated particle beams are guided to specific areas within the shielded building for radiotherapy, radioisotope production or for basic
research in a number of disciplines, including nuclear physics and radiobiology.
Radiotherapy facilities are provided by the NAC Medical Radiation Division, together with the 30-bed Faure Hospital which is now also part
of NAC. Patients from other centres are referred to either Groote Schuur or Tygerberg Hospital for particle radiotherapy at NAC, and a patient
may then be admitted to the Hospital or may be treated as an out-patient. The facilities at NAC are specifically designed to provide
beams of high-energy protons and neutrons for radiotherapy and for related radiobiological experiments.
Neutrons are potentially more effective in controlling certain types of tumour than the radiation from linear accelerators which are routinely
used in radiotherapy. Protons have the advantage that much more of the dose delivered can be accurately localised within the tumour volume,
which minimises damage to surrounding healthy tissue. Since February 1989, cancer patients have regularly received treatment with neutron
therapy, while the first facilities for proton therapy were commissioned in 1993. For proton therapy a computerised system has been developed
which uses video cameras to locate the patient automatically, and then precisely positions the patient for therapy by using a motor-driven
treatment couch.
Radioisotopes have been manufactured in South Africa since 1965. This
started at the old CSIR cyclotron in Pretoria, and since its closure in 1988 the radioisotope production programme has been continued with the
SSC, supported by a strong research and development programme. The higher energy of the SSC and its superior facilities now make it
possible to produce a wider variety of short-lived isotopes, such as 18F, 81Rb/81mKr, 87Ga, 111In, 123I and 201Tl, as well as radio-actively
labelled compounds for medical purposes. In addition, long-lived radioisotopes such as 22Na, 55Fe and 57Co are manufactured for
non-medical use, and are also exported overseas. The short-lived radioisotopes and labelled compounds are supplied to more than 30
hospitals, clinics and research institutes throughout the country, for use as tracers for diagnostic and research purposes. So-called gamma
cameras are used at these establishments to obtain images showing the radio-active tracer uptake and distribution within the human body. Such
images permit physicians trained in nuclear medicine to monitor various body functions, and to obtain unique diagnoses of a variety of diseases
of, for example, the human brain, heart, lungs, kidneys and thyroid, or to detect certain tumours, thus benefiting thousands of patients every
year.
Nuclear physics with the SSC makes use of the most modern facilities. These include a large scattering chamber for the detection of scattered
particles or nuclear reaction products, a multi-purpose gamma-ray detector array, a well-collimated mono- energetic neutron beam, and a
large 160-ton QDD magnetic spectrometer. In addition, sophisticated computerised data-taking and analysis systems are available.
NAC is one of the few Science and Technology institutions to have an “open door” policy to training postgraduates and in-service trainees
with hands-on experience to modern apparatus and technologies. Whilst postgraduates from universities all over SA use the facilities, NAC
proactively participates in the building of research and postgraduate capacity at historically disadvantaged institutions.
Open days for the general public are held on the last Wednesday of every month. School visits occur on an almost daily basis. Local communities
are also encouraged to make use of NAC’s modern auditorium facilities at
no charge.
For further information contact:
Science & Technology Awareness Program
National Accelerator Centre
P O Box 72
Faure, 7131 South Africa
Tel: (021) 8431000 / Fax: (021) 8433525 / Email: stone@nac.ac.za
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