Physicists at the Fermi National Accelerator Laboratory near Chicago succeeded yesterday in operating a newly upgraded $300 million atom smasher that is the world's most powerful device of its kind. It is expected to probe deeper into the ultimate nature of matter than anyone has ever gone before.

The success, which was met with champagne-drenched jubilation and a flurry of telegrams to notify scientific colleagues around the world, came after seven years of construction and more than a month of round-the-clock efforts to make the device run properly.

"It finally happened, as usual, at 3 in the morning. It was very tricky, getting all this equipment to work just right, but we did it. We got some very spectacular collisions," said Leon Lederman, director of the lab, Fermilab. "We're looking forward to a period of fantastic discoveries."

Results of the collisions, which were electronically recorded, have not been analyzed, but they are the first of thousands that are expected eventually to reveal more about what atoms are made of at the most fundamental level.

Physicists seek ever more powerful collisions because the more energy they can pack into the tiny space in which particles collide, the more likely it is that the energy will transform itself into new forms of matter that have never been seen before. Thus, the more powerful the machine, the better the chance of finding out what is inside the most tightly bound subatomic particles.

Fermilab's machine, which creates its concentrated energy by hurling particles of subatomic matter at other particles moving in the opposite direction, is the world's most powerful particle collider. Fermilab is funded by the Department of Energy and operated by a consortium of 10 universities and three national laboratories.

Until now, the most powerful collider was in Switzerland, operated by CERN, a consortium of European nations and Fermilab's chief competitor in the world of high-energy physics. Discoveries with the CERN collider won the 1984 Nobel Prize in physics.

"The total energy was 1.6 trillion electron volts, which is about three times higher than Brand X," Lederman said, referring to the CERN collider.

The purpose of such machines and the motive behind a longstanding international rivalry, prizes aside, is to understand at the most fundamental level what the world is made of. The knowledge is not expected to have any practical applications in the foreseeable future, if ever.

Earlier research has shown that the protons and neutrons that clump to make up an atom's nucleus are each made of three smaller particles called quarks. Scientists hope Fermilab's new machine, the largest scientific instrument in the world, will eventually reveal whether quarks are made of still smaller particles.

The Fermilab collider, a souped-up version of an accelerator that has been in operation since 1971, hurls protons at nearly the speed of light into head-on collisions with antiprotons, specially manufactured particles of antimatter, moving in the opposite direction at the same speed.

Antimatter is like matter except that its particles have differing characteristics, such as electrical charge. For every particle of ordinary matter, be it a proton, neutron or electron, there is a corresponding antiparticle. The proton, for example, has a positive charge while the antiproton, although it has the same mass as a proton, carries a negative charge. The known universe is believed to consist of ordinary matter, but antimatter can be created in the laboratory.

When matter and antimatter meet, they annihilate one another in a burst of energy. In this case, the burst is made vastly more powerful because of the energy the particles possess, as they move at more than 99.99 percent of the speed of light.

As Einstein's relativity theory indicates, matter and energy are alternative forms of one another. A hydrogen bomb turns matter into energy. Fermilab turns energy into matter. No one really knows how this happens, but it is as if the energy released in the collision could crystallize or condense into tiny lumps of matter.

The prodigious energy formed in the Fermilab collision -- comparable to the energy that existed in the first trillionth of a second of the Big Bang that is thought to have created the universe -- transmutes itself into sprays of new subatomic particles, most of which are never seen in nature.

"If we can get a good look at those particles, we're hoping they'll teach us some new physics," said Roy Schwitters, a Harvard physicist working at Fermilab. "We don't know what we're going to find, but it'll probably be something we never suspected."

Because the particles of new matter can form only according to the laws of nature, they combine in systematic ways. By studying the variety of new particles, physicists hope to discover how many possible combinations there are in which the fundamental units of matter -- be they quarks or something smaller -- can be put together. From these combinations, they can deduce the properties of the smaller particles that make them up.

"It's all very profound," Lederman said. "We want to know how the Lord made the world."

The new particles, for all the effort needed to make them, do not live long. In less than a trillionth of a second, the unstable combinations die, changing back into dissipated puffs of energy.

In their brief life span, however, the particles travel several feet through a new, $64 million, 4,500-ton device, called a detector, that tracks their paths. It was built jointly by the United States, Italy and Japan. It is the shape and direction of those paths that tell physicists what kinds of particles have formed.

Although Fermilab's accelerator -- actually a chain of several accelerators -- is one of the most complex pieces of technology ever built, the work that it does is relatively simple. It makes protons and antiprotons and throws them as fast as it can at each other.

Because protons are so small and must be accelerated to such high velocities, special equipment is required to make them move fast enough. The main accelerating device is a chamber in which radio waves are beamed. Because protons and antiprotons have a natural electrical charge, they can be pushed by radio waves.

A proton in a radio-wave chamber will be pushed forward, rather like a surfer riding an ocean wave. If the pushed proton then moves into another radio-wave chamber, it will get an additional push to a faster speed. Fermilab scientists call their radio-wave chamber "the kicker."

To build the speed up high enough, however, would require a row of kickers stretching hundreds of miles. Instead, the kicked protons are guided around a circle and back into the same kicker for another boost of energy.

The protons do not slow down because they travel inside a hollow tube from which the air has been pumped.

Making the protons' path curve, however, is not easy and gets harder with each kick, just as it is harder to keep a fast car on a curve than a slow car. Powerful electromagnets surrounding the beam tube to do the steering.

The protons are derived from hydrogen gas. Hydrogen atoms, the simplest in nature, consist of a nucleus of one proton orbited by one electron.

In a series of steps, the hydrogen atoms are stripped of their electrons, leaving naked protons that are fed into a small ring-shaped accelerator about 500 yards around. Needle-thin batches about a yard long and containing about 20 billion protons go around about 50,000 times, getting a boost in speed on each pass through a kicker.

When the protons are going fast enough, they are beamed into the main ring -- four miles around -- to be accelerated further. Then they are diverted to a more powerful four-mile ring just under the previous one which gives the protons still more energy.

At the peak, the maximum energy in each proton is measured as 1 trillion electron volts, or 1 TeV. Thus the entire device is called the Tevatron.

At this point, the protons can be held in the ring, circling indefinitely, waiting to be collided with antiprotons. Antiprotons are manufactured at Fermilab by diverting some of the protons from the main ring into a newly built facility where they collide with a bar of tungsten metal. The energy of the collision is transmuted into a variety of new particles, including antiprotons.

The antiprotons are pulled into a special ring of magnets that collects them until there are enough to send back into the main ring. Because they have an opposite charge, the antiprotons move in the opposite direction through the main ring, kicked in the opposite direction by the radio waves.

When the antiprotons are going fast enough, they are sent to join the protons in the lower ring. Three evenly spaced batches of protons circle clockwise as three evenly spaced batches of antiprotons move counterclockwise.

Because the particles are all in the same track, the batches fly through each other. There is no way to aim the particles individually, so the physicists must rely on chance collisions. Preliminary calculations indicate there should be about 50,000 collisions every second.

Because the antiprotons have an energy equal to that of the protons, the total released in a collision can be as high as 2 TeV. The collisions yesterday were at a somewhat lower energy, 1.6 TeV.

Although collisions take place at six points around the ring, the effects of the impacts are recorded at only one, where the detector is installed.

Yesterday's collisions came none too soon. Since Oct. 1, earth-moving machines have been poised to dig up part of the ring and begin construction of a second detector facility at another collision point. The scientists had hoped to achieve collisions before then and shut down the accelerator for a year of construction.

When efforts to get the Tevatron running met repeated setbacks, the construction was postponed day by day. Once the first few collisions proved that the machine had been properly built and that scientists had learned how to operate it, the Tevatron was shut down. Construction of the second dectector was to start today and be finished next summer, allowing the machine to be restarted in September 1986.

Now that the bugs have been worked out, it should be easier to get the machine running again. That's when physicists expect dramatic new findings about the nature of matter to emerge.

"If you want to be a high-energy physicist," one Fermilab scientist said, "you learn to be patient.