STALKING THE WILD NEUTRINO : In a Subterranean Russian Lab, Scientists Search for Clues to the Making of the Universe.

“HEAR THE MOUNTAIN BREATHING.”

Vladimir Gavrin, a nuclear physicist, stands two miles inside Mt. Andyrchi in southern Russia, listening to underground streams that surge through seams in the rock only a few yards above the tunnel that houses his laboratory. From inside the tunnel, the mountain does seem like a living thing. The walls are warm--105 degrees Fahrenheit--heated by the Earth’s primordial furnace. The pressure of the water flowing through the hidden aquifers constantly threatens to breach the metal walls of the laboratory.

Gavrin is a compact and energetic man with a pugnacious jaw and deep-set eyes. He has a taste for poetry. Sometimes, in the middle of explaining his science in thickly accented English, he will begin to recite Russian verse, going on and on with rolling Rs and sonorous vowels until he reaches the end of his memory. He does not look like a thinker, but rather like a boxer, with combat lines etched deeply into his face.

With extraordinary stamina and guile, Gavrin has assembled an experiment that bucked Soviet apparatchiks and the conventions of particle physics. His groundbreaking lab is the site of the Soviet-American Gallium Experiment (SAGE), an international collaboration of chemists and physicists forged eight years ago when Cold War mistrust was still icy. Each side brought singular assets to the table, making a bargain that withstood the political climate. The Russians dug a cavern out of a mountain of granite and painstakingly amassed a costly rare metal that is the heart of the experiment. The Americans offered computers, fiber optics and high-tech sensors. Together, they built a subterranean telescope to observe a puzzling subatomic particle produced by the sun.

Experiments in subatomic physics usually take place in accelerators, enormous machines that push particles along at unearthly speeds and smash them into targets. But in the paradoxical world of SAGE, the scientists stand still and look, with great care, at what is all around them. This is astrophysics in a hole in the ground.

There were 20 years of battles to finish this laboratory, many tests of new methods that have met with setbacks and some success, Gavrin says. “Some people gave up and stopped believing in the work. I pushed maybe too hard sometimes to finish this laboratory. Sometimes we were pouring concrete for the floor and testing the chemical apparatus at the same time. The theoreticians said I was too impatient. Somehow, I usually got done what was necessary, like a small animal who becomes very fierce in his own territory and frightens animals twice as big.”

The two governments invested in SAGE with no expectation of a practical payback. The experiment is fundamental science, closer to poetry than to technology. It asks not how to make the world better, but poses the question: What is the world? Part of the answer, Gavrin and his colleagues believe, may come to light when they know the hidden nature of a subatomic particle called the neutrino.

Because the neutrino is at a nexus connecting particle physics, astrophysics and cosmology, what SAGE reveals about this elusive particle could produce a missing piece that fits into puzzles across a giant scale of science. At the least, it is a step toward understanding the forces that exist in the subatomic world and toward explaining the elementary particles that those forces control. The search is Gavrin’s passion, and his life’s work.

THE NEUTRINO IS SO SMALL THAT IT HAS BEEN CONsidered by most scientists to be massless, with no heft and no weight, just a packet of energy so elusive that it is like movement glimpsed from the corner of the eye. Look straight at it and it does not appear to be there at all, yet there are more neutrinos in the universe than any other form of matter.

What SAGE found is tantalizing evidence that neutrinos are not just insignificant ghosts but seem to have mass. Should the neutrino prove to have mass, it could very well be the particle that weaves the fabric of the universe, describes its beginning and determines its ultimate fate.

SAGE’s mountain and the sun that shines down on it are vital parts of the machinery of the experiment. The sun acts as a powerful thermonuclear reactor that creates billions of energetic neutrinos as well as light and heat as it burns. The mountain is a thick shield that absorbs almost all the sun’s radiation except the ghost wind of neutrinos. Unlike light, which is stopped cold by matter, neutrinos glide through the mountain as if nothing were there.

These solar neutrinos are extremely hard to catch, but because there are so many of them, there is an infinitesimal chance that one will bump into something. And when that happens, it performs the alchemy of changing one element into another, entering the nucleus of an atom and reacting with a neutron to form a proton.

The telescope at SAGE is actually 60 tons of the metal gallium contained in eight huge vats. The nucleus of an atom of gallium 71 has 40 neutrons; 60 tons of gallium contains 1030(1 with 30 zeros after it) atoms--a big target for neutrinos. When a neutron in a gallium atom engages a passing neutrino and turns into a proton, the new atom is radioactive germanium, which can be chemically separated and counted, atom by atom. SAGE has been looking for germanium atoms, and thus neutrinos from the sun, for about three years. In that time, considerably fewer than half the neutrinos the sun should supply have been found.

Let’s say you walked into a bare room and found a set of children’s blocks scattered on the floor. In the corner is a box marked “blocks.” You pass the time by stowing the blocks in the container, but when you get to the end of the task, you see that the box is not filled. Now you know something significant: You either have the wrong box, or there are more blocks somewhere else.

In Gavrin’s experiment, the size of the “box” has been determined by what we know about solar activity. The sun has been measured in many different ways, and from these measurements have come agreement on how many neutrinos the sun’s reactor core should be producing. So, because the “box” looks to be the correct size, scientists instead began looking for missing neutrinos to fill it to the top.

What happened to all those neutrinos? Current science does not offer a good answer, but there are theories that go beyond the bounds of proven physics. The most elegant explanation of the missing neutrinos predicts that, in their journey through the sun, many will “oscillate,” that is, transmute into other, more exotic species of neutrinos. The gallium at SAGE would not react to these new particles, so the missing neutrinos could be there--but hidden from view, requiring new ways of seeing to find them. Scientists know that, in order to oscillate, a particle must have mass. And that calls for a revolution in physics. If the neutrinos are oscillating, they too must have mass. If that is so, these neutrinos, among the most common stuff of the universe, would seem to have a robust personality that was hardly guessed at, a nature that scientists believe could illuminate the deepest cosmic mysteries.

MT. ANDYRCHI RISES LIKE A DOGTOOTH OUT OF the narrow valley of the Baksan River in the Caucasus Mountains, where Europe shades into Asia. It is a sharp, volcanic range that forms a bridge of land between the Black Sea and the Caspian, a small appendix to the vast Russian Republic.

The Caucasus Mountains seem restless on the surface--the sounds of rockslides often rumble through the night--but deeper down, they are geologically stable. When Gavrin and his mentors at the Institute for Nuclear Research in Moscow were seized with the vision of underground physics, they brought their ambitions here. Where there was nothing but a barren stretch of road, the scientists drilled into the mountain to make their laboratory and, across the river, on the other side of the valley, built Neutrino Village.

“Certain officials could not believe that we would excavate such a huge tunnel just for science,” Gavrin says. “One time the miners were too lazy to fix some lights, and the visitors were certain that the tunnel was where secrets were buried.”

The village itself is a town of concrete block offices and apartment buildings tacked onto a treeless slope. The miners, electricians, carpenters, secretaries and day laborers whose work supports the tunnel and its three laboratories, including SAGE, live there year-round. They number close to 1,000, including about 400 children. Most of the SAGE scientists live in Moscow, but they come to Neutrino Village for two weeks every month to perform the chemistry that extracts germanium from the gallium.

For the scientists coming in from Moscow, the journey to Neutrino is more like an expedition than a business trip. It starts with a crowded, wide-body jet into Mineral Water (Mineral’nyye Vody), an airport where hundreds of passengers, backed up from days of delayed and canceled flights, hunch over their luggage in the cavernous cold of the waiting room. From there, the choice of ground transportation is a five-hour bus ride or a taxi. The road to Neutrino Village, which at some point becomes barely more than a ledge, rises toward Mt. Elbrus, Europe’s unsung highest peak. My driver had the reflexes of a fighter pilot, and he needed them. We swerved past broken trucks, washed-out pavement and a sea of sheep that came spilling off the hillside.

Gavrin cadges gas coupons for months to ensure American visitors such a ride in a private car. His job as director of the gallium laboratory goes far beyond physics. Each month he must organize two weeks of food, airplane tickets, work schedules, tools and materials for his research team.

At Neutrino, the final two miles to the laboratory is by train through a dark, sulfurous tunnel, iron wheels screaming along the rails. At the end of the line is SAGE, slick and clean as a newly minted coin. Steel vessels, like giant Cuisinarts painted red, green and yellow, squat on the floor of the lab. They hold 60 tons of gallium, warmed to a sluggish, gray liquid. Inside the tanks, motorized paddles stir the metal at a constant speed, adjusting to any changes in viscosity. At room temperature, gallium looks and feels like the graphite in a No. 2 pencil, but it melts in the palm of the hand. On the occasions when bricks of gallium are transferred to the vessels, the workers’ skin and clothing are uniformly blackened by the end of the day.

In bricks, the 60 tons of gallium would stack up to the size of a one-car garage. Each month the scientists process the metal chemically to extract about 20 atoms of germanium from the 1030 atoms of gallium, much like hunting for a few specific grains of sand on a Santa Monica beach. The apparatus for the extraction looks like a tabletop chemistry set blown up to gargantuan size. Test tubes six feet tall connected by great elbows of glass hang from a high steel scaffolding. Gavrin calls it “our chemical jungle.” The main room is all business, but in an alcove to the side, where a delicate maze of blown-glass tubing handles the later stages of processing, someone has taped a Beatles poster to the wall.

The instruments are precise and complex, but they merely assist in the experiment. There is an art to drawing the few germanium atoms out into the open. Chemists add what Gavrin describes as “aggressive reagents,” solutions of hydrochloric acid and hydrogen peroxide, to the vats. The reagents take up any germanium and, holding it, rise to the top of the gallium. The timing, the temperature, the proportion of reagents and the speed of the paddles that stir the metal are all critical ingredients of the recipe that has evolved over years of testing.

Igor Knyshenko is one of the chemists who monitors the vats and dials during the extraction. He dashes up the stairs to a loft where a bank of computers registers data. He descends at a run, stopping for a moment to peer through a hatch into the molten gallium, then races over to tap on the tubes, where cascades of liquid wash down the inside of the glass.

The procedure takes 24 hours from beginning to end. The young Russian chemists spell each other through the night. For at least half those hours, Gavrin is at a desk in the middle of the lab, troubleshooting, tracking every nuance of the chemistry.

INSIDE SAGE, THE LIGHT NEVER CHANGES, THE air hardly stirs and 12 hours can pass without notice. More than a mile of mountain separates the sky and the cambered roof of the laboratory, keeping out a barrage of natural radiation from cosmic rays. Cosmic rays are like a gale wind from deep space that strikes the top of the atmosphere, initiating a rain of penetrating subatomic particles. The atoms in all that dirt above the laboratory absorb most of this unruly mob, which would otherwise disrupt the gallium.

Stray radiation can turn gallium into germanium and cause false readings, so the gallium must be kept clean and undisturbed by anything other than the neutrinos. Because another source of trouble is radioactive impurities in the mountain itself, the laboratory, a metal shell fitted into a cavern, is surrounded by a layer of concrete that seals off the room from traces of uranium in the rock.

On a late fall evening, Gavrin sits at the dining table in the scientists’ cozy two-story cottage in Neutrino Village and talks about building the lab. We drink strong tea sweetened with apricot jam. Gavrin has tried but failed to find cheese and cooking oil this week, and one day there is no bread, but the meals are abundant and unhurried. Natasha, the cottage’s general factotum, works around the shortages with ease. She can cook a rabbit 10 different ways.

“The concrete itself could not be radioactive,” Gavrin says, explaining how carefully the lab was constructed to avoid contaminating the experiment. He often paces when he talks, but this night he is tired after spending 12 hours underground. He sits with his knees almost touching mine, leaning forward, as if to be sure that I am listening to every word.

“We investigated many places looking for the right rock and sand. We chose dolomite in the Urals, very old rock. And from the Ukraine very pure quartz sand. But to crush the dolomite, we needed a machine that was completely clean. I found a factory that could spare time on one of their crushers. We cleaned it very thoroughly, and then I posted a man by the machine to see that they did not put any other rock but ours into it.

“Even carrying it into the tunnel, it was necessary to have cleaned carts that would not contaminate the mixture. Many things we carried by hand. We would even wash down the walls of the tunnel--all 3 1/2 kilometers--before we transported our materials. The miners thought we were very strange.”

In the late 1970s, when the Russian physicists decided to use gallium’s abundant and cooperative neutrons for detecting solar neutrinos, there was not enough of the metal in the world to satisfy the demands of the experiment’s design. Estimates of the cost of purifying 60 tons of gallium were in the range of $30 million to $40 million. But scientists argued that the cost was justified: The neutrons in gallium were a hundred times more likely to capture neutrinos than those in less expensive elements.

It was Gavrin’s job to persuade his government to spend the money.

Talking past midnight, many years after the events, Gavrin’s feelings are still fresh--his resigned sadness about the self-serving nature of mankind, his pleasure in his own cunning. “About something of this importance only the very top of the Communist Party, the Politburo, could make a decision,” he says. “It was the minister of colored metals, in charge of the production of such things as gold and copper, who could order the production of gallium. It was comparable to starting up uranium production, but that had been easy because Stalin had wanted it. Only the physicists wanted gallium.

“Gallium is produced when you refine aluminum. We searched all over the Soviet Union and found a factory where the technique for gallium was very advanced, but they were only making a few kilograms. We had many meetings with technologists and scientists and deputy ministers to campaign for everyone’s support before we went directly to the minister. Everyone was enthusiastic, but I saw two difficulties. At that time, people would advance their careers and earn better money if they fulfilled the party’s plan. Doing something new, doing improvements, did not necessarily bring benefits.

“The second problem was that we were asking to produce just a certain amount of gallium for one purpose and then there would be no future. So I searched for other applications for gallium. One day, I read in a Western newspaper about the capture of Che Guevara. The story was about how American spy planes used infrared optics to see Guevara’s campfire in the Andes. Infrared optics, I knew, need gallium.

“The next meeting with the ministry bureaucrats, there were military men invited to listen to this information about Americans using gallium. They did not introduce themselves; I never knew who they were. I just know that after that meeting, interest in gallium was much greater.”

I found it difficult to associate this methodical diplomacy with Gavrin. He crackles with energy, and his anger and his wit can snap out at any moment. When he is surrounded by his co-workers, I notice that they usually keep their eyes on him, as they would on anything that might be a little dangerous. Apparently, his passion for gallium astrophysics invested him with the necessary patience.

“Then it was finally time to make a presentation to the minister of colored metals. I went to the meeting with my chief and with a very prominent scientist in the Soviet Academy. As we sat before him, I could see on the minister’s face the struggle to make a decision. Would it bring him more power to reject the important scientist or to take the job of gallium production with many possible problems?” The minister went for gallium.

IN THE EARLY 1980s, THE half-dozen American scientists on the SAGE team had been working through their own bureaucracy, trying to get their hands on enough gallium to get the neutrino project moving, but they failed where Gavrin succeeded. The Americans, based at Los Alamos National Laboratory, signed on with the Soviet group in 1986, the first instance of scientists from an American nuclear weapons laboratory collaborating with a Russian experiment. The nuclear physicists are in a separate division not connected to weapons work, but security matters are still an issue.

Tom Bowles, a tidy, bespectacled physicist from Los Alamos who is the leader of the American team, is at SAGE at the same time that I meet with Gavrin. While we talk, he uses a pair of needle-nosed pliers to tinker with the torpedo-shaped box of equipment that makes the final count of germanium.

“Sometimes the equipment we brought over was on the embargo list and we had to get special licenses for the Soviet Union,” he says. “The Department of Energy has audited our records of the collaboration numerous times over the years. Even though they authorized it, the bureaucrats look at all the money and equipment we send over here and they ask what’s going on.”

The device Bowles is repairing, a quartz counter, weighs 1,000 pounds and hangs from a ceiling crane. At one point he has to get down on his knees to reach the part he is fixing. Bowles is as well acquainted with the mechanics of the laboratory as he is with the physics of neutrinos, and, like Gavrin, he never sits still.

“It is not the same as working with an experiment in, say, Western Europe. When we first came, there was only one 15-year-old computer at the lab,” Bowles recalls. “It took days to get phone calls through from Moscow. When you are here, you can’t just go to the store to get the right size nuts and bolts. You have to plan your moves months in advance.

“It took a while, but we are getting used to the differences between the two styles of science and are making the most of them. Russians have long-term planning, steady resources. Americans are more opportunistic. We react more quickly to contingencies. Russians have a hierarchy of responsibility, a step-by-step approach.

“We had argued that the Russians should move the equipment from the test lab in Moscow to the Baksan (valley) sooner than the plan called for. The Americans wanted to get started, to get the equipment running so we could find the problems and solve them. They finally went along with us. And, of course, we relied on their ability to acquire the gallium and maintain the lab.

“Neither group could have carried this out so well on their own. We have made the most of each other’s strengths.”

For the first two years of the collaboration, there was always one American at the site. Now, Bowles and his associates make the two-day trek from New Mexico to the Baksan valley three times a year to work on upgrades. The scientists constantly tweak the system, trying to get the data, which they share on computers through a satellite linkup, closer to certainty. They upgrade the hardware and hone the mathematics in their efforts to identify and count the germanium created by solar neutrinos, and to disregard any germanium atoms that might arise from other causes.

Distinguishing the meaningful signal--the neutrino-made germanium--from all the noise of the background radiation is a heroic job, refined but never perfected. The task is something like standing by the railroad tracks, listening for a violinist playing in the dining car as the train roars by. It takes a lot of equipment and a lot of effort to filter out all sounds but the Beethoven.

“We are turning this into a clean room for the quartz counter that registers the germanium,” Bowles says, standing up to tap the intricate package of wires and semiconductors that is the object of his attention. “That means the air will be filtered and pressurized to keep out dust, and it will be electrostatically protected. When it is finished, you will pass through a foyer and put on protective clothing before you come in.”

Tom Bowles is careful with his enthusiasm, smiling but almost solemn when he tells me, “I never thought I would be this lucky. You always expect to get ambiguous answers. I was shocked as hell that the results were so clear cut. The exciting part is that the experiment sheds light on the very smallest and the very largest phenomena in the universe.”

IT IS AN ARTICLE OF FAITH in physics that the world’s bewildering complexity hides an ultimate simplicity. The Greek philosopher Democritus first proposed the idea that the world was made of very small, identical, irreducible bits of matter: atoms, from the Greek word for unbreakable.

Scientists have searched for this singular grain of matter, but nature has not cooperated. Atoms are too complex, with two kinds of working parts--quarks and leptons. Quarks are the units that combine to make protons and neutrons. The lepton family includes electrons and neutrinos. And inside the tiny confines of the atom, there are no less than three separate forces in action.

Atoms seem as complicated as a game of chess, their pieces odd-sized and moving across the board with different, staggered gaits. Yet even when confronted with this proliferation of nuclear particles and nuclear forces, physicists refuse to abandon the ideal of simplicity.

Theorists choose to see all the mismatched parts of the subatomic world as the shattered, cold remains of an earlier unity. They look back to the time of the Big Bang, when the universe was so hot that particles and forces were merged into one reality where they were not distinct, but identical to one another.

The idea of temperature transmuting matter has an everyday counterpart. With enough heat, water appears only as steam, a single, uniform substance. With a bit of cooling, steam condenses to liquid, which has startlingly different properties. Get it cold enough, and water turns to ice, which seems to have no connection to the original steam, and is certainly not at all like liquid.

Most physicists believe that the whole universe was simple at its superheated birth, but fractured into multiple parts and forces when it cooled. Grand Unified Theories, or GUTs, are mathematical pictures of how three nuclear forces ought to blend into a single force at high temperatures. The elementary bit of matter Democritus postulated is an artifact of the most distant past, and Grand Unified Theories are like artists’ renderings of the creation of the universe.

But a theory without laboratory evidence is just a guess. The theories need to be fed with facts. GUTs require that at some deep level, quarks and leptons must share an identity that connects them to their common past. This kinship is possible if neutrinos have mass and therefore share that property with quarks. Data from SAGE provides the first solid clue that can verify a Grand Unified Theory. Without results such as SAGE’s, GUTs are acts of informed imagination. Afterward, they are measures of reality.

Theories, of course, are open to differences of interpretation. When I mention Grand Unified Theory and the beginning of time to Gavrin, he says, “You can discuss this topic only with God.”

A neutrino with mass hints at profound truths about the quantum world of the atom and about the Big Bang, but that is not the end of its possibilities. This particle might help us measure the cosmos. Astronomers understand that the great mass of the universe is completely invisible to us. We actually do not know what most of the universe is made of; the stars are just the raisins in the cake.

Scientists have deduced that the seemingly empty stretches of space are full of matter by observing the movement of radiant objects in space. The clockwise whirling of the galaxies cannot be explained unless the stars we see are embraced by a cloud of matter we cannot see. Suppose you watch a movie of a brick falling off a wall, and the brick drifts slowly to the ground. You will probably conclude that the brick has dropped through some heavy, transparent medium, such as water. Likewise, stars move as if they are swimming in an unseen ocean.

The invisible stuff is called dark matter. If the halo of dark matter that surrounds each galaxy were luminous, the night sky would glow with 1,000 full moons. Nobody knows what dark matter is. But a neutrino with mass is an attractive candidate to explain at least some of the mystery.

When we understand dark matter, we can begin to comprehend how stars and galaxies pulled themselves together and resisted the relentless force of the explosive outward expansion of the universe as a whole. Dark matter is more than a small technical problem associated with the birth of galaxies. At least 90% of the universe is dark matter, and when we figure out what it is, we will know exactly how much mass there is in the universe. With that number in hand, we can predict which way the universe will come to an end.

The prophecies are not comforting, but all have grandeur. At or below a certain critical mass, the universe will continue to expand for eternity, growing colder, thinning out to a black, meaningless vapor. Above that critical mass, the universe will expand only to a point, and then gravity will pull it back together. Galaxies will collide. Stars will collapse into black holes. The universe will speed inward, in a hot, tumultuous implosion, a reverse of the Big Bang, finally reaching a point where the laws of physics collapse. The neutrino may hold the power of cosmic annihilation.

SCIENTISTS ARE CONSERVAtive. They do not accept startling conclusions until the proofs have been minutely examined and the facts established through repeated testing.

“Statistics take time,” says Gavrin. If the data is good, he can leave it to others to build monuments with the numbers. But for Gavrin, time is no longer a reliable commodity. Negotiating around the Cold War was easier than muddling through the breakup of the Soviet Union.

“We have to take great care with our supplies. If anything is lost, it cannot be replaced,” Gavrin says. “Every month we need two tons of chemicals for the extraction. The reagents are brought in by trucks that need gasoline. It is more than 100,000 rubles each time.”

“Gavrin used to call to some ministry and ask for tools and chemicals, and now the ministry is lost in confusion,” says Bowles, who spent this March in Russia. “Even if he can find the bureaucrat who used to order the materials, the guy never knew himself where the goods were coming from. There is no natural system of distribution to replace the centralized methods that existed. No one knows quite what should be done.”

I saw Gavrin again in early May. He was with his small crew from Moscow drinking Mexican beer and eating carry-out fried chicken in a hotel room in Los Alamos. They had all slipped their shoes off, as Russians do at home, and were watching “Star Trek” on television. Tanya Knudel, the only woman on the science team, was making tea in the kitchenette.

The group was in the United States to hash over recent results from Baksan and put that set of data into final form, and on his way west, Gavrin had stopped in Washington. Americans, he discovered, weren’t optimistic about their economy either.

“I met with an official of the National Science Foundation, to give him information about a grant application that would benefit SAGE,” Gavrin recounts. “He took two hours to tell me his own difficulties with money. Like the Russian saying, I went to buy wool and came back with no hair.”

In order to assemble the equipment necessary for a final calibration of the SAGE experiment, Gavrin and Bowles have to beat the erratic clock of the Russian economy and a surprising curve thrown them by the end of the Cold War. They are hoping to begin work with artificially produced neutrinos that are generated by a highly radioactive source, in this case chromium 51.

But to do this they need permission to use a shuttered breeder reactor that was part of the Soviet weapons production complex but has been shut down since the end of the arms buildup. The artificially produced neutrinos will then be tested on the gallium to check the earlier neutrino measurements.

“If we can hang on about one more year,” Bowles says, “we will accomplish what we hope for.”