Australia Keeps Up With Atom Research

Press, Volume XCI, Issue 27666, 24 May 1955, Page 11

Australia Keeps Up With Atom Research

{Australian Information Bureau"]

Work under way at the Research School of Physical Sciences of the Australian National University in Canberra, aims to keep Australia in the vanguard of the world-wide effort to solve the enigmas of nuclear science. The distinguished Australian scientist, Professor Marcus Oliphant; who was associated with Lord Rutherford in much of the groundwork of modern nuclear physics at the Cavendish Laboratory at Cambridge, is the director of the school’s laboratories. There are six departments of the school: astronomy, radiochemistry, geophysics, theoretical physics, particle physics and nuclear physics. Because of Professor Oliphant’s close interest, and the importance of the project in an era whose sweetest fruits may well go to the possessors of advanced atomic power, most headway has been made in the department of nuclear physics, under the guidance of Professor E. W. Titterton. Professor Titterton is a graduate of Birmingham who, during the war, was one of a small group of Englishmen who worked on micro-wave radar devices. Later, he was a member of the British Atomic Commission and worked for three years on the development of the atomic bomb at Los Alamos in the United States. N.Z. Graduates Assist

A team of young Australian graduates, who hitherto would have been forced to go abroad to obtain research training, has been collected at the school while research workers from England, the United States, New Zealand’, Canada, and Asia have also taken advantage of the facilities offered at Canberra.

The buildings of the research school are placed on a gently sloping ridge that fingers out below Black Mountain, one of the three peaks that dominate the beautiful capital city. Here architecture suggesting massive strength is allied with the light airiness of the background of trees and blue sky. Beams and columns of the building are of steel, walls and floors of reinforced concrete. High banks of windows extend the length and almost the height of the walls and flood the interior* with light. A wide passage has been driven deep underground between the laboratory and office wings of the department of nuclear physics to house an atom-smashing machine called an electron synchrotron.

Research rooms, offices, workshops, a lecture theatre, locker and shower rooms have taken shape swiftly since 1949, when the department was founded. The working areas are heavily insulated with pastel-tinted slabs of pressed fibre. In concrete-shielded rooms are futuristicrlooking masses of yellow and brown plastic rings and whorls, or immense steel framework overhung by a crane. Carpenters, engineers, designers, plumbers, and electricians study blueprints and fill the big, echoing main building with their racket. To the visitor, it is vast and confusing. It is difficult to connect all this with the monumental exactness of the studies represented—with the atomic structure of matter, the reactions produced by minutely-designed accelerators and the painstaking examination of the results to be gained from the applied knowledge. To study nuclear physics, it is necessary first to study nuclear reactions. Target materials are bombarded with nuclear particles at terrific speeds. Then the products of disintegration which occurs, or nuclear reaction, are detected and examined by special instruments. It is a wide and fascinating horizon, as no-one knows what momentous secrete may be locked in the constituents of matter not yet .subjected to detailed analysis. Three “Bombarding” Machines The school already possesses three and has under construction two other accelerating machines. The first that was installed, a linear accelerator, is described by Professor Titterton as “a modest piece of equipment.” It speeds up protons, or hydrogen nuclei, to 35,000,000 miles an hour, and developed 1,250,000 volts at its initial trial m December of 1951. This is the highest steady voltage yet achieved in Australia. Manufactured in the Netherlands, it was installed in Canberra with the help of the staff at the National University. It is air insulated, and housed tn a compartment 40 feet high by 40 feet wide by 60 feet long. Atomic “bullets,” the hydrogen nuclei, are fired vertically downwards in a straight line towards the target. The accelerating tube through which they pass must be 14 feet long to withstand the 1,250,000 volts. To prevent sparkover to the room walls—something akin to a minor flash of lightningmore than 10 feet clearance is needed in each direction. This linear accelerator is a conventional seven-stage Cockcroft-Walton multiplying circuit. It has twin 30-feet columns, each one with seven mushroom-like shields, known as corona shields, to minimise spark-over. On operation, the first column gives seven successive high-voltage boosts to seven sites down the length of the second column, where a beam of electrified particles is drawn from top to bottom. In this process the seven boosts endow the particles with more than 1,000,000 volts of energy. A magnet at the base of the column diverts from the vertical and they smash against the target material, shattering some of the atoms composing it. Professor Titterton, using this procedure, disintegrates, among other things, the atoms of tritium—thought to- be a hydrogen bomb ingredient and the rarest form of hydrogen known today. Intense gamma rays are released, which in turn are employed to smash other atoms. Canberra’s Power Affected Fluctuations in the voltage of the city of Canberra’s electricity supply were a factor in causing variations in the beam energies recently, and they were intolerable for some experiments. An electronic control unit, therefore, was designed, built and put to work in November of 1954. It produced a remarkable improvement in the stability of the beam at the target. A second accelerating machine, a 600,000-volt proton and deuteron accelerator, resembling the linear accelerator, went into action at the laboratories in October, 1954. In the next 12 months, it is planned to convert this to operate with selenium rectifiers instead of the present mercury valves; and the same conversion may be carried out on the 1,250,000-volt linear accelerator. A third atom-smasher at the school was a recent gift from the United Kingdom Government. It had been used at the Atomic Research Establishment at Harwell, England. This is a 33,000,000-volt electron synchrotron worth about £55.000. It was dismantled in May and June of 1954 by Professor Titterton during a visit to Britain, and arrived in Canberra in September, 1954. Besides these three machines are intricate installations such as the multichannel pulse height analyser—which can examine electrical pulse spectrums operating at the rate of 1000 impulses a second, and sorting them automatiIcally into 120 groups. Greatest interest at the moment, however, is focused on the fifth of the school’s accelerators, a proton synchrotron, construction of which Is being supervised by Professor Oliphant. This was originally designed to be the most powerful atom-smashing device world; but it may be robbed of this honour by delays in securing its constituent materials. Its potential energy is eight times that of a comparable type of machine installed at Birmingham, and four times greater than the power of a synchrotron operated by America’s Atomic Energy Commission, at Brookhaven. Long Island.

Particles inside it are to be excited to an energy of about 10,000.000,000 volts, and they will move at about 180.000 miles a second, or about 6000 miles a second below the speed of light. Its cost, when it is finished in about two years, is expected to be about onetenth the cost of a synchrotron just completed in Berkeley, California, which will lead the way in United States research in this sphere. Th» key of the Canberra m»-

chine may be likened to a facetrack, a system of nine-inch stainless steel tubes arrayed in a rough circle 32 feet in diameter. An enormous magnetic field produced by a current of 1,700,000 amperes is applied to this. Then a supply of billions of proton particles is injected into the tubeway, after they have been manufactured in a nearby proton-cyclotron which 'generates 8,000,000 volts. These particles will hurtle around the tubes in a vacuum, close to the speed of light, but never touching the tube sides because they are guided by magnetic influences. A radio frequency induction accelerator increases the velocity of the particles by giving the two “kicks” a revolution as they speed around on their way. Tn one experiment, for instance, a record of the particles’ behaviour is secured by directing them into photographic emulson on glass perhaps only two square inches of which has been. inserted into the tubeway at a certain point. The protons collide with particles that make up the substance of the emulsion. The tracks of the resultant “chips” which may fly off the particles are later seen as dark lines scored across the photographic plate, which itself may be no more than 1/10,000th of an L nc h Expert observers may need three or four months to trace ana analyse with microscopes the ‘clues’ registered on one of these plates. The prodigious magnetic field which must be fed to the “racetrack” to produce such effects comes from an installation known as a homepolar generator. A model has already been successfully tested. This is a scientific world m itself, housed in a framework of 1400 tons of special steel. Inside it will spin four suspended discs weighing 20 tons each and rotating at nearly 1000 revolutions a minute. A 1000kilowatt motor sets them in motion, and the installation includes an elaborate system of cooling towers, pumps and controls. Fantastic Problems The principle is the same as the plain Faraday disc of schooldays. But the energies dealt with pose some problems of fantastic proportions. The discs, coupled in pairs, will reverse direction of spin twice in a second. Several tons of liquid sodium metal . PP. Projected against them through high velocity jets. These will act as brushes to collect the current T* l ® discharged pulses will then be fed across to the air-cored orbital guiding magnet (the “racetrack ’). The air-cored magnet principle has been used in this Because it can develop a magnetic field five times greater than that obtainable from an iron core. It can be readily imagined that, with such forces unleashed, materials concerned must be carefully chosen—for under these conditions many metals would melt in an instant. But the design and construction engineers at the school have overcome these obstacles. All these machines and the research workers’ skills will enable the execution of experiments for examining what holds together the particles of a nucleus; they will convert energy into matter, and continue the study of newly-found entities called mesons, which in recent years have been detected in cosmic radiation. The Department of Nuclear physics at the Australian National University has followed the policy of pursuing its research on a basis of as much selfsufficiency as possible. Attached to the laboratories are workshops which can produce anything from delicate glassware to huge steel castings. It is possible that research at the ■ school will provide crucial pieces in the jig-saw that will one day explain some of the deepest of nature’s mysteries. Methods are elaborate in the extreme, yet their purpose is simple—to lay bare new vistas of the atom’s > amazing world just as the Mount Palo- • mar (California) telescope laid bare t for exploration undreamed-of fields of » space and power in the .universe.