[Congressional Record Volume 140, Number 51 (Tuesday, May 3, 1994)]
[Senate]
[Page S]
From the Congressional Record Online through the Government Publishing Office [www.gpo.gov]




            FERMILAB COMPLETES THE BUILDING BLOCKS OF MATTER

  Mr. SIMON. Mr. President, I rise today to recognize a special 
milestone in science and our understanding of nature. Scientists at 
Illinois' own Fermilab have found the first direct evidence of the top 
quark, the sixth and last component of a standard model of matter that 
explains the relationships between subatomic particles.
  Since the fifth quark was seen at Fermilab in 1977, scientists around 
the world have searched for the elusive other half of the pair. I am 
proud to say that the 2,000 men and women of Fermilab have the honor of 
once again claiming the prize. Those in Congress who have supported 
U.S. leadership in science have a right to be proud as well.
  Programs such as that at Fermilab have not only contributed greatly 
to our knowledge, but have provided the tools and skills of our best 
science to their communities and the hundreds of students and 
researchers that carry the scientific vision from Illinois to 
communities across the Nation.
  We congratulate them on their accomplishment and wish them every 
success in their continuing research. I ask unanimous consent that the 
full text of the attached article from the New York Times be included 
in the Record.
  There being no objection, the article was ordered to be printed in 
the Record, as follows:

                [From the New York Times, Apr. 26, 1994]

   Top Quark, Last Piece in Puzzle of Matter, Appears To Be in Place

                         (By William J. Broad)

       The quest begun by philosophers in ancient Greece to 
     understand the nature of matter may have ended in Batavia, 
     Ill., with the discovery of evidence for the top quark, the 
     last of 12 subatomic building blocks now believed to 
     constitute all of the material world.
       An international team of 439 scientists working at the 
     Fermi National Accelerator Laboratory will announce the 
     finding today, bringing nearly two decades of searching to a 
     dramatic conclusion.
       The Fermilab discovery, if confirmed, would be a major 
     milestone for modern physics because it would complete the 
     experimental proof of the grand theoretical edifice known as 
     the Standard Model, which defines the modern understanding of 
     the atom and its structure. The finding is likely to produce 
     waves of intellectual satisfaction for physicists around the 
     world and to give American physics a significant boost.
       The discovery in all likelihood will never make a 
     difference to everyday life, but it is a high intellectual 
     achievement because the Standard Model, which it appears to 
     validate, is central to understanding the nature of time, 
     matter and the universe.
       ``The exciting thing is that this is the final piece of 
     matter as we know it, as predicted by cosmology and the 
     Standard Model of particle physics,'' Dr. David N. Schramm, a 
     theoretical physicist at the University of Chicago, said in 
     an interview, ``It's the final piece of that puzzle.''
       Dr. Hans A. Bethe, a Nobel Laureate in physics at Cornell 
     University, said the finding was ``a very big deal'' that 
     ``makes the whole picture of subnuclear particles much more 
     believable and better established.''
       ``We've needed the top quark,'' he said. ``it figures in 
     all our calculations for further processes, and none of them 
     would be right if it weren't there.''
       If the top quark could not be found, the Standard Model of 
     theoretical physicists would collapse, touching off an 
     intellectual crisis that would force scientists to rethink 
     three decades of work in which governments around the globe 
     had invested many billions of dollars.
       All matter is made of atoms, but nearly a century ago 
     physicists discovered that atoms, long considered to be the 
     smallest units of matter, were themselves composed of 
     smaller, subatomic particles like protons and neutrons. But 
     these particles later showed signs of being made of yet 
     smaller building blocks.
       The field was plunged into confusion for many years until a 
     grand unifying theory pioneered by Dr. Murray Gell-Mann, a 
     physicist at the California Institute of Technology, sought 
     to explain the structure of particles like protons and 
     neutrons in terms of new units that he whimsically named 
     quarks.
       His theory called for the existence of six different kinds 
     of quarks, named up and down, charm and strange, top and 
     bottom. The quark family parallels a six-member family of 
     lighter particles, known as leptons, that includes the 
     electron.
       Various combinations of these 12 particles are thought to 
     make up everything in the material world. In addition to 
     matter, the universe contains potent forces like 
     electromagnetism and gravity, and perhaps many other exotic 
     particles as yet to be discovered.
       Five of the six quarks were eventually found but the sixth 
     remained painfully absent. For nearly two decades rival teams 
     of scientists around the world have sought the top quark by 
     performing ever-more-costly experiments on increasingly large 
     machines that accelerate tiny particles almost to the speed 
     of light and then smash them together in a burst of energy. 
     The resulting fireball can yield clues to nature's most 
     elementary building blocks.
       The team at Fermilab, which includes scientists from the 
     United States, Italy, Japan, Canada and Taiwan, cautioned 
     that the evidence they had gathered over the past year and a 
     half for the top quark would be convincing to many scientists 
     but not definitive. They said further work would be needed to 
     firmly establish the top quark and its attributes.
       ``Some people will say, `Hey, nice piece of physics but you 
     need more data to make sure,' '' said Dr. Melvyn J. Shochet, 
     a physicist at the University of Chicago who worked on the 
     Fermilab experiment and is a spokesman for the discovery 
     team. ``To that I can only agree.''
       ``We don't have a discovery,'' said a senior Fermilab 
     official, who spoke on the condition of anonymity. ``We have 
     evidence. It's good evidence. It's tightening up to where the 
     top quark lives. The next step is to get more events.''
       The experiment was run on Fermilab's Tevatron, a four-mile, 
     circular accelerator in an underground tunnel that hurls 
     counterrotating beams of protons and antiprotons at each 
     other with a combined energy of 1.8 trillion electron-
     volts. It is currently the highest-energy accelerator in 
     the world. The detector that gathered the evidence is the 
     size of a large house and weighs 5,000 tons. A 150-page 
     manuscript describing the work was mailed on Friday to 
     Physical Review, the world's pre-eminent journal of 
     physics.
       Dr. Schochet, the team spokesman, said the mass of the top 
     quark, its most important attribute, was calculated to be 174 
     billion electron-volts, with an uncertainty range of plus or 
     minus 17 billion electron-volts.
       ``That's quite heavy,'' he said. ``It's almost as heavy as 
     an entire gold atom. It's by far heavier than any other 
     elementary particle that's been observed, which is why it's 
     taken so long to find.''
       As Fermilab, which is run by the Federal Department of 
     Energy, reports the finding today, simultaneous announcements 
     are to be made in Rome, Tokyo, Ottawa and Taipei.
       Dr. Gell-Mann took the word quark from a line in 
     ``Finnegans Wake'' by James Joyce: ``Three quarks for Muster 
     Mark.'' So too, Dr. Gell-Mann predicted that quarks in normal 
     matter came in groups of three. Protons would be made of two 
     up quarks and one down quark; neutrons of two down quarks and 
     one up quark. Dr. Gell-Mann's ideas were radical and strongly 
     resisted, partly because the fractional charges of his quarks 
     seemed implausible. But his theories explained much, and were 
     soon partly confirmed by particle discoveries. In 1969 he won 
     the Nobel Prize in Physics.
       Low-mass quarks, the up and down, are the only ones thought 
     to ordinarily exist in this world. Physicists believe that 
     the higher-mass ones, charm and strange, top and bottom, were 
     present naturally only for a tiny fraction of a second at the 
     beginning of time during the Big Bang--the primordial 
     explosion thought to have given rise to the universe. Top 
     quarks, having the highest mass of all, are believed to have 
     vanished from the universe after existing for less than a 
     billionth of a second.
       Thus, a time machine is needed to see most quarks. Particle 
     acclerators slam together tiny bits of matter to create 
     intense fireballs almost as hot as those that existed at the 
     beginning of time, creating streams of nature's most 
     rudimentary particles.
       In 1977, when the bottom quark was discovered at Fermilab 
     in a particle accelerators, physicists calculated that its 
     top-quark companion would have a mass of 13.5 billion 
     electron-volts, making it an easy target for any number of 
     accelerators then planned around the world.
       In July 1984, a European team of 151 scientists headed by 
     Dr. Carlo Rubbia announced that it had confirmed the 
     existence of the top quark, calling it a major breakthrough. 
     That fall, Dr. Rubbia won the Nobel Prize in Physics for 
     other discoveries. But it turned out that his top-quark claim 
     was premature. The particle was far heavier, and more 
     difficult to detect, than had generally been anticipated.


                           a kind of alchemy

       Physicists at Fermilab have been hunting the top quark for 
     nearly two decades, looking at increasingly high energies. 
     The process, they say, is like slamming together two tennis 
     balls and trying to find a bowling ball in the rubble--a hint 
     of the top quark's huge mass. The tennis balls can create 
     things heavier than themselves because of their high 
     energies, a kind of alchemy first suggested by Einstein in 
     his famous law of equivalence between matter and energy.
       The rub is the rarity of collisions that make top quarks. 
     Dr. Shochet, the experiment team's spokesman, said many 
     billions of proton-antiproton collisions were needed to 
     produce just one top quark and that even then, subtle clues 
     to its existence might be lost amid a clutter of spurious 
     signals. The quarks themselves exist for only a fraction of a 
     second, and cannot be detected directly. Their presence is 
     inferred from ghostly showers of particles produced as they 
     perish.
       Dr. Shochet said the team's evidence gathered over a year 
     and a half amounted to 15 clues from 12 collisions. Those 
     results, he added, were about twice as high as expected from 
     false positives in the background noise. He said really 
     nailing down the top quark would require a mass of evidence 
     three or four times above background levels.
       Dr. Claudio Campagnair, a team physicist, said in a 
     Fermilab brochure: ``Rather than one `Eureka!' event, top 
     discovery will come by accumulating a lot of different 
     evidence, bit by bit. You could compare discovering top with 
     what happens in a courtroom in a case where there's no 
     smoking gun and you must convince the jury by the accumulated 
     weight of circumstantial evidence.''
       A separate team of 420 scientists at Fermilab is now using 
     a different detector in an effort to confirm the first team's 
     findings during the Tevatron's current 18-month run. Its 
     work, and that of the original team, should be eased somewhat 
     by recent accelerator improvements that will increase the 
     number of collisions.
       Fermilab is also completing a $230 million upgrade of the 
     Tevatron that should sharply increase the collision rate, 
     perhaps producing hundreds or thousands of top-quark 
     candidates. It should be completed by 1998 or 1999.
       After that, the only other accelerator power enough to join 
     the hunt would be one under consideration at CERN, Europe's 
     premier accelerator laboratory, on the border of France and 
     Switzerland. Known as the Large Hadron Collider, it might be 
     completed by the year 2005.
       If the top quark has indeed been discovered at Fermilab, 
     particle physicists will turn their attention to other 
     enigmas, such as why all matter has mass. In the United 
     States, such questions were to be addressed by the 
     superconducting supercollider, which was to have measured 54 
     miles around and cost up to $11 billion. In October, Congress 
     canceled the half-built machine in Waxahachie, Tex., calling 
     it an inordinate drain on the Federal budget.
       American inventors are now trying to create small, 
     innovative accelerators in lieu of the big machine.
       ``Any new particle that's found'' in the years ahead, said 
     Dr. Schramm of the University of Chicago, ``is going to be 
     exotic in a much greater way than any quark.''

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