[Congressional Record Volume 141, Number 47 (Tuesday, March 14, 1995)]
[Senate]
[Pages S3906-S3907]
From the Congressional Record Online through the Government Publishing Office [www.gpo.gov]


                       DISCOVERY OF THE TOP QUARK

 Mr. D'AMATO. Mr. President, I rise today to congratulate Dr. 
Paul D. Grannis and the New York State D-Zero collaboration members on 
the discovery of the Top Quark.
  Dr. Grannis is a physicist at the State University of New York at 
Stony Brook and is a leader of an international collaboration of 
scientists working at Fermi National Accelerator Lab in Batavia, IL.
  The D-Zero collaboration includes scientists from Brookhaven National 
Laboratory, Columbia University, New York University, and the 
University of Rochester as well as those from the State University of 
New York at Stony Brook. Scientists from Rockefeller University also 
participated in the discovery.
  The discovery of the Top Quark is one of the most important 
achievements in high energy physics this decade. The Top is the last of 
six Quarks to be discovered and is an integral part of the Standard 
Model of modern physics. This Standard Model not only serves as the 
basis for our understanding of physics but defines the fundamental 
building blocks of the Universe.
  Dr. Grannis has headed the D-Zero collaboration at Fermilab for over 
a decade. During this tenure he has commuted to Illinois nearly every 
week while never failing to meet his commitment to academics and 
teaching in New York.
  I commend him on his extraordinary commitment--which I believe 
exemplifies the high standard of dedication to both research and 
education in New York. It is a great credit to New York State 
institutions that their leadership has culminated in this exciting 
discovery.
  Again, I congratulate Dr. Grannis on this tremendous achievement and 
wish him continued success. Dr. Grannis lives in Stony Brook, NY with 
his wife Barbara and has four children: Jennifer, Eliza, Helena, and 
David.
  Mr. President, I ask that the March 3, 1995, New York Times article 
by Malcolm W. Browne describing this discovery be included in the 
Record following the text of these remarks.
                [From the New York Times, Mar. 2, 1995]

              Elusive Atomic Particle Found by Physicists

                         (By Malcolm W. Browne)

       Batavia, Il., March 2--Culminating nearly a decade of 
     intense effort, two rival groups of physicists announced 
     today that they had found the elusive top quark--an ephemeral 
     building block of matter that probably holds clues to some of 
     the ultimate riddles of existence.
       The announcements brought sustained applause and a barrage 
     of questions from an overflow audience of physicists at the 
     Fermi National Accelerator Laboratory, where the work was 
     done. Fermilab has the world's most powerful particle 
     accelerator.
       The two competing scientific teams, each with about 450 
     scientists and each using a separate detection system, 
     reported that after a long chase in which there had been 
     several false sightings of the top quark, this monstrously 
     heavy but elusive particle has finally been cornered and 
     measured. The results of the two groups' independent 
     measurements differed somewhat, but when margins of error 
     were taken into account, the scientists agreed that the 
     results were consistent.
       One of the teams, the CDF Collaboration (standing for 
     Collider Detector at Fermilab) reported last April that it 
     had found evidence of the quark's existence. But at the time, 
     the group lacked enough statistical evidence to claim 
     discovery, and the competing group, the D0 (for D-Zero) 
     Collaboration, which had even less evidence of its own, 
     branded the CDF announcement as premature.
       The achievement claimed today by both teams leaves 
     virtually no room for doubt, however, and the discovery was 
     hailed as a landmark in science. Hazel O'Leary, who as 
     Secretary of Energy heads the Federal agency providing most 
     of the money for research at Fermilab, called the discovery a 
     ``major contribution to human understanding of the 
     fundamentals of the universe.''
       The finding confirms a prediction based on a theory known 
     as the Standard Model that nature has provided the universe 
     with six types of quarks; the other five, the up, down, 
     strange, charm and bottom quarks had all been known or 
     discovered by 1977. Since the infancy of the universe shortly 
     after the Big Bang--estimated at 10 billion to 20 billion 
     years ago--only
      the up and down quarks have survived in nature, and the 
     protons and neutrons that make up the nuclei of all atoms 
     are built from combinations of these two quarks; the other 
     quarks disappeared 
     [[Page S3907]] from the observed universe, but have been 
     recreated by modern particle accelerators.
       Dr. Leon M. Lederman, a winner of the Nobel Prize in 
     Physics and the former director of Fermilab, said at today's 
     meeting that he doubted there could be any more quark types 
     but that ``we know there's a lot of dark matter out in the 
     universe that we can't identify.''
       ``We're still in for a lot of surprises,'' he added.
       But more important than merely completing the table of 
     quarks predicted by theory, the top quark may now begin to 
     shed light on a deep philosophical question: everything in 
     the universe, from the most distant galaxy to a rose petal, 
     is made of quarks. Were the masses and other properties of 
     these particles determined by random chance, or by some 
     fundamental unifying plan? If so, what is that plan, and how 
     might gravity, the least understood of the four forces of 
     nature, be related to it?
       ``This monster, compared with all the other quarks, is like 
     a big cowbird's egg in a nest of little sparrow eggs,'' said 
     Dr. Paul D. Grannis, a leader of the DO group. ``It's so 
     peculiar it must hold clues to some important new physics.''
       ``The top quark has turned out to be so heavy,'' added Dr. 
     John Peoples, director of Fermilab, ``that it's kind of a 
     laboratory in itself, from which many new experiments will 
     certainly yield important insights.''
       It may be, scientists believe, that quarks (and the higher 
     forms of matter they make up) are endowed with mass by 
     interacting with an all-pervading universal ``field,'' with 
     which they communicate through a hypothetical particle called 
     the Higgs boson. To find and measure the Higgs boson would be 
     as exciting for a physicist as the creation of life in a test 
     tube would be for a biologist.
       One of the questions high-energy physicists regard as 
     fundamental is whether there is a single type of Higgs boson, 
     or several types. Theory predicts that if it is possible to 
     accurately measure the masses of two known particles--the top 
     quarks and the W particles that transmit the weak nuclear 
     force--it will be possible to determine whether there are one 
     or more than one Higgs bosons.
       ``We're so elated by the discovery of the top quark that we 
     haven't yet begun to sift all the data,'' said Dr. Boaz Klima 
     of Fermilab, one of the leaders of the successful search. 
     ``But this particle is so astonishingly heavy that its decay 
     may give us hints of a lot of other things, perhaps even of 
     supersymmetric particles.''
       The quest for supersymmetric particles by the world's most 
     powerful accelerators during the last decade has failed to 
     turn up any evidence that they exist, but according to some 
     theories, they may be so heavy they are beyond reach of 
     present-day accelerators. If supersymmetric particles could 
     be shown to exist, they might offer scientists a tool for 
     learning how gravity is related to the other forces of 
     nature: the electromagnetic force and the strong and weak 
     nuclear forces.
       Even when trillions of protons and antiprotons are made to 
     collide in Fermilab's huge accelerator at combined energies 
     of two trillion electron-volts, the creation of top quarks by 
     the miniature fireballs remains a rare event.
       Dr. Grannis of the D0 collaboration said today that his 
     group, which has been running its detector on and off since 
     1992, has found 17 collisions resulting in evidence of the 
     creation of a top quark. The team was able to calculate the 
     mass of the particle as 199 billion electron-volts, give or 
     take about 30 billion electron-volts. (Particle physicists 
     measure mass in terms of its energy equivalent, because the 
     units are more practical. Einstein's famous equation 
     E=mc2 defines the equivalency of mass and energy.)
       For their part, according to Dr. William Carithers Jr., a 
     leader of the rival CDF Collaboration, two separate counting 
     techniques using the CDF detector have turned up a total of 
     about 21 top quark events. The group calculates the mass of 
     the top quark as about 176 billion electron-volts, give or 
     take about 13 billion.
       These results, the competing teams say, are in reasonably 
     close agreement. At any rate, they agree that they have found 
     the quark, and that there is only one chance in about one 
     million that the results could have been caused by anything 
     besides the decays of pairs of top and antitop quarks.
       One of the main difficulties in identifying the top quark 
     is that it cannot be seen directly. When one is created from 
     the immense pool of energy formed in the collisions of 
     protons and antiprotons accelerated by
      Fermilab's Tevatron, its lifetime is so brief that no 
     detector could sense it. But the top quark disintegrates 
     into hundreds of daughter particles, which in turn decay 
     into cascades of other particles.
       From the patterns of ``jets,'' particle types and other 
     characteristics of these decays, theorists have learned to 
     identify the parent particles like the top quark which cannot 
     be detected directly. A jet is a spray of particles moving in 
     the same general direction away from a collision.
       High-energy physics is expensive. The Fermilab Tevatron 
     accelerator, a ring of superconducting magnets four miles in 
     circumference, cost about $250 million to build, and each of 
     the two detectors built into the accelerator cost about $60 
     million. An upgrade of the Tevatron called a main injector, 
     costing $228 million, is scheduled for completion by 1999.
       The Superconducting Supercollider, a project that would 
     have been Fermilab's successor, would have cost more than $8 
     billion if Congress had not canceled it last year. For the 
     foreseeable future, Fermilab will remain America's most 
     powerful particle accelerator, and scientists say that the 
     machine has at least 15 more years of useful life.
       The stakes for the high-energy physics community are 
     enormous, in terms of job security, the risks of failure and 
     the promise of great prestige for leaders of successful 
     experiments. Competition between physicists is often intense 
     and sometimes bitter.
       The CDF and D0 detector collaborations have gone to great 
     lengths to avoid even looking at each others' experiments--a 
     policy that persisted even today minutes before their joint 
     seminar began.
       ``We know that some of the younger physicists on both sides 
     have been exchanging pirated copies of our reports, but we've 
     tried to suppress such exchanges,'' one physicist said. ``Of 
     course there is friction, but that's a healthy aspect of 
     science. This way, we know that our results are in no way 
     influenced by those of our competitors, and when both our 
     versions of the top quark are published side by side, 
     scientists will be able to judge for themselves.''
       Despite a joking undertone of bickering between the two 
     collaborations, which include scientists from a dozen 
     nations, a holiday mood today eclipsed old rivalries and the 
     collective anxiety about future financing of high-energy 
     physics.
       ``We're ecstatic about this discovery,'' Dr. Peoples said. 
     ``Non-scientists often ask me what the point of all this may 
     be. I say it's important because it makes the universe 
     knowable, in the same sense that our discovery of DNA has 
     made the nature of life knowable. We have a long, long way to 
     go, but it's one of the most intellectually satisfying 
     pursuits there is.''
     

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