Japan joins world hunt for elusive quark

Press, 23 September 1987, Page 34

Japan joins world hunt for elusive quark

NZPA-AP Tsukuba, Japan In silver tunnels beneath Japanese pines, scientists spin atoms at close to the speed of light. They are in a worldwide, multi-billion-dollar race to find a particle that has eluded the best minds and machines in the United States, Europe, China and the Soviet Union.

The particle sought in Japan’s SUS7OO million ($1134 million) Super collider and super colliders elsewhere is the last of the six sub-atomic particles.

Whoever finds it first can expect a glimpse of a tidbit locked inside the structure of the atom, more insight into Nature’s blueprint and, just perhaps, a Nobel Prize in physics.

“Our senses delve smaller and smaller,” said physicist Sadaharu Uehara. “Now we can recognise the smallest units of matter in nature. We

want to know why they exist, and what forces govern them.” Scientists say all matter is made up of quarks and leptons, which make up atoms that combine to become oceans, stars, human beings. They have found the leptons and think nature made six quarks, but so far have discovered only five.

Scientists name each quark according to its characteristics. Those who found the fourth quark, the charm, won the Nobel physics prize. But the discoverers of the fifth, the bottom, went unnoticed by the Nobel committee. With a worldwide hunt on for the sixth, top quark, it is difficult to say whether discovery will bring the prize. Uehara is part of the 350-man team that monitors Tristan, which began running in May. The 3km ring lies 10m under the countryside an hour from Tokyo on the outskirts of the Government’s science

enclave. Tsukuba Science City is home to 6000 scientists and 46 research laboratories, but its prime attraction is the accelerator and complex of offices and labs built to service it '

About as big around as a roll of paper towels, the accelerator ring runs through a subway-size tunnel, surrounded by particle-guiding magnets. Its main job is to unleash elementary particles by smashing electrons and positrons head-on from opposite directions at 99.99 per cent the speed of light. Nearby, a “particle factory” makes electrons and positrons and injects them into a smaller ring, where they whirl around, building up to millions of electron volts of energy before being pulsed into Tristan - electrons in one direction and positrons in the other.

Magnets draw the beams on until they crash

at 25 billion electron volts each, producing a 50-bil-lion electron volt collision. Uehara and others watch the screens for 8 hour stretches, 24 hours a day, hoping for hints of undiscovered tidbits. It takes greater and greater energies to create successive quarks. If at some energy level the rate of events suddenly rises, they will know they have found the sixth quark. The Japanese have reason to hurry. Tristan is now the world’s pre-emi-nent electron-positron collider, but it will soon be eclipsed by other, stronger machines. In about a year, Stanford University in California will complete a more powerful electron-positron accelerator, and the European Organisation for Nuclear Research in Geneva a stronger one by 1989.

Fermilab in Batavia, Illinois, -is the world’s most powerful proton col-

lider, with energies higher than Tristan’s, but the research director for Tristan, Ken Kikuchi, says detecting quarks in the greater debris of protonantiproton collisions is “like trying to find a diamond In a huge amount of junk." >

Within 10 years, pending approval from Congress, the United States plans the absolute giant among the world’s atom smashers — the 53>mile superconducting super collider (S.S.C.), to be built at a cost of SUS 4.4 billion ($7.1 billion). The S.S.C. will be a proton smasher capable of energy levels reaching 20 trillion electron volts, 20 times more powerful than Fermilab.

Scientists say collisions of such Incredible intensity will approximate the Big Bang, the explosion that created the universe, and inevitably produce the sixth quark and other new particles.