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    Bevatron

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    Gilberto Manhattan
    The Bevatron was a particle accelerator at Lawrence Berkeley National Laboratory that began operating in 1954. It was capable of accelerating protons to energies of billions of electronvolts, allowing researchers to discover the antiproton in 1955. The Bevatron required a large 10,000 ton iron magnet and vacuum system to accelerate protons to 6.2 GeV, the minimum energy needed to create antiprotons through proton-nucleon collisions. Extracted particle beams from the Bevatron were passed through liquid hydrogen bubble chambers to study particle interactions via automated tracking and computer analysis of the bubble chamber photographs. The Bevatron was decommissioned in 1971 but continued operating as an injector for the SuperHILAC until 1993.

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    Bevatron

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    Gilberto Manhattan
    137 views4 pages
    The Bevatron was a particle accelerator at Lawrence Berkeley National Laboratory that began operating in 1954. It was capable of accelerating protons to energies of billions of electronvolts, allowing researchers to discover the antiproton in 1955. The Bevatron required a large 10,000 ton iron magnet and vacuum system to accelerate protons to 6.2 GeV, the minimum energy needed to create antiprotons through proton-nucleon collisions. Extracted particle beams from the Bevatron were passed through liquid hydrogen bubble chambers to study particle interactions via automated tracking and computer analysis of the bubble chamber photographs. The Bevatron was decommissioned in 1971 but continued operating as an injector for the SuperHILAC until 1993.

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    Bevatron

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    The Bevatron was a particle accelerator at Lawrence Berkeley National Laboratory that began operating in 1954. It was capable of accelerating protons to energies of billions of electronvolts, allowing researchers to discover the antiproton in 1955. The Bevatron required a large 10,000 ton iron magnet and vacuum system to accelerate protons to 6.2 GeV, the minimum energy needed to create antiprotons through proton-nucleon collisions. Extracted particle beams from the Bevatron were passed through liquid hydrogen bubble chambers to study particle interactions via automated tracking and computer analysis of the bubble chamber photographs. The Bevatron was decommissioned in 1971 but continued operating as an injector for the SuperHILAC until 1993.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    137 views4 pages

    Bevatron

    Uploaded by

    Gilberto Manhattan
    The Bevatron was a particle accelerator at Lawrence Berkeley National Laboratory that began operating in 1954. It was capable of accelerating protons to energies of billions of electronvolts, allowing researchers to discover the antiproton in 1955. The Bevatron required a large 10,000 ton iron magnet and vacuum system to accelerate protons to 6.2 GeV, the minimum energy needed to create antiprotons through proton-nucleon collisions. Extracted particle beams from the Bevatron were passed through liquid hydrogen bubble chambers to study particle interactions via automated tracking and computer analysis of the bubble chamber photographs. The Bevatron was decommissioned in 1971 but continued operating as an injector for the SuperHILAC until 1993.

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    of 4

    Bevatron

    nized that parity was not conserved in the weak interactions, which led to resolution of the tau-theta puzzle, the
    understanding of strangeness, and the establishment of
    CPT symmetry as a basic feature of relativistic quantum
    eld theories.

    2 Requirements and design


    In order to create antiprotons (mass ~938 MeV/c2 ) in
    collisions with nucleons in a stationary target while conserving both energy and momentum, a proton beam energy of approximately 6.2 GeV is required. At the time
    it was built, there was no known way to conne a particle
    beam to a narrow aperture, so the beam space was about
    four square feet in cross section.[4] The combination of
    beam aperture and energy required a huge, 10,000 ton
    iron magnet, and a very large vacuum system.

    Edwin McMillan and Edward Lofgren on the shielding of the


    Bevatron. The shielding was only added later, after initial operations.

    The Bevatron was a particle accelerator specically, a


    weak-focusing proton synchrotron at Lawrence Berkeley National Laboratory, U.S., which began operating in
    1954.[1] The antiproton was discovered there in 1955,
    resulting in the 1959 Nobel Prize in physics for Emilio
    Segr and Owen Chamberlain.[2] It accelerated protons
    into a xed target, and was named for its ability to impart
    energies of billions of eV. (Billions of eV Synchrotron.)

    A large motor/generator system was used to ramp up the


    magnetic eld for each cycle of acceleration. At the end
    of each cycle, after the beam was used or extracted, the
    large magnetic eld energy was returned to spin up the
    motor, which was then used as a generator to power the
    next cycle, conserving energy; the entire process required
    about ve seconds. The characteristic rising and falling,
    wailing, sound of the motor-generator system could be
    heard in the entire complex when the machine was in operation.

    Antiprotons

    In the years following the antiproton discovery, much pioneering work was done here using beams of protons extracted from the accelerator proper, to hit targets and generate secondary beams of elementary particles, not only
    protons but also neutrons, pions, "strange particles", and
    many others.

    At the time the Bevatron was designed, it was strongly


    suspected but not known, that each particle had a corresponding anti-particle of opposite charge, identical in
    all other respects, a property known as charge symmetry.
    The anti-electron, or positron had been rst observed in
    the early 1930s, and theoretically understood as a consequence of the Dirac equation at about the same time.
    Following World War II, positive and negative muons and
    pions were observed in cosmic-ray interactions seen in
    cloud chambers and stacks of nuclear photographic emulsions. The Bevatron was built to be energetic enough
    to create antiprotons, and thus test the hypothesis that
    every particle has a corresponding anti-particle.[3] The
    antineutron was discovered soon thereafter by Oreste Piccioni and co-workers, also at the Bevatron. Conrmation
    of the charge symmetry conjecture in 1955 led to the Nobel Prize for physics being awarded to Emilio Segr and
    Owen Chamberlain in 1959.

    3 The liquid hydrogen bubble


    chamber

    The extracted particle beams, both the primary protons


    and secondaries, could in turn be passed for further study
    through various targets and specialized detectors, notably
    the liquid hydrogen bubble chamber. Many thousands
    of particle interactions, or events, were photographed,
    measured, and studied in detail with an automated system of large measuring machines (known as Frankensteins) allowing human operators (typically the wives of
    Shortly after the Bevatron came into use, it was recog- graduate students) to mark points along the particle tracks
    1

    REFERENCES

    5 End of life
    The next generation of accelerators used strong focusing, and required much smaller apertures, and thus much
    cheaper magnets. The CERN PS (Proton Synchrotron,
    1959) and the Brookhaven National Laboratory AGS
    (Alternating Gradient Synchrotron, 1960) were the rst
    next-generation machines, with an aperture roughly an order of magnitude less in both transverse directions, and
    reaching 30 GeV proton energy, yet with a less massive
    magnet ring. For comparison, the circulating beams in
    the Large Hadron Collider, with ~11,000 times higher energy and enormously higher intensity than the Bevatron,
    are conned to a space on the order of 1 mm in crosssection, and focused down to 16 micrometres at the intersection collision regions, while the eld of the bending
    magnets is only about ve times higher.
    The demolition of the Bevatron began in 2009 by Clauss
    Construction of Lakeside CA and completed in 2011.

    6 See also
    First tracks observed in liquid hydrogen bubble chamber at the
    Bevatron

    and punch their coordinates into IBM cards, using a foot


    pedal. The cards decks were then analyzed by earlygeneration computers, which reconstructed the threedimensional tracks through the magnetic elds, and computed the momenta and energy of the particles. Computer programs, extremely complex for their time, then
    tted the track data associated with a given event to estimate the energies, masses, and identities of the particles
    produced.
    This period, when hundreds of new particles and excited
    states were suddenly revealed, marked the beginning of
    a new era in elementary particle physics. Luis Alvarez
    inspired and directed much of this work, for which he
    received the Nobel Prize in physics in 1968.

    Particle accelerator: Generalities on various types


    Alternating Gradient Synchrotron: 33 GeV strongfocusing synchrotron, next step after Bevatron
    Tevatron: Fermi Lab accelerator, 1 TeV protonantiproton collider, largest current US machine
    Large Hadron Collider: CERN machine, the worlds
    most powerful when it became operational in December 2009.

    7 References
    [1] UC Radiation Lab Document UCRL-3369, Experiences
    with the BEVATRON, E.J. Lofgren, 1956.
    [2] The History of Antimatter - From 1928 to 1995.
    CERN.(The cited page is noted as 3 of 5. The heading on the cited page is 1954: power tools.)
    [3] Segr Nobel Lecture, 1960
    [4] E.J. Lofgren, 2005

    BEVALAC

    The Bevatron received a new lease on life in 1971,[5]


    when it was joined to the SuperHILAC linear accelerator
    as an injector for heavy ions.[6] The combination was conceived by Albert Ghiorso, who named it the Bevalac.[7] It
    could accelerate a wide range of stable nuclei to relativistic energies.[8] It was nally decommissioned in 1993.

    [5] Bevalac Had 40-Year Record of Historic Discoveries Goldhaber, J. (1992) Berkeley Lab Archive
    [6] Stock, Reinhard (2004).
    Relativistic nucleus
    nucleus collisions: from the BEVALAC to RHIC.
    Journal of Physics G: Nuclear and Particle Physics
    30 (8):
    S633S648.
    arXiv:nucl-ex/0405007.
    Bibcode:2004JPhG...30S.633S.
    doi:10.1088/09543899/30/8/001.
    [7] LBL 3835, Accelerator Division Annual Report,
    E.J.Lofgren, October 6, 1975

    [8] Barale, J. (June 1975). Performance of the Bevalac (PDF). IEEE Transactions on Nuclear Science
    22 (3): 16721674. Bibcode:1975ITNS...22.1672B.
    doi:10.1109/TNS.1975.4327963.

    External links
    History of the Bevatron
    The Bevatron E.J. Lofgren historical retrospective
    account; excellent early pictures.
    Pictures of the Bevatron
    Shutdown of the Bevatron
    Bevatron Building Slated for Demolition
    Historic Atom Smasher Reduced to Rubble and
    Revelry

    Coordinates: 375239N 1221503W / 37.877392N


    122.250811W

    9 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

    Text and image sources, contributors, and licenses

    9.1

    Text

    Bevatron Source: https://en.wikipedia.org/wiki/Bevatron?oldid=709215687 Contributors: Maury Markowitz, Azazello, Radiojon, Securiger, Xezbeth, Bender235, Viriditas, Egg, Ceyockey, Falcorian, Ashmoo, Ae77, Strait, FlaBot, YurikBot, Conscious, SCZenz, Dhollm,
    Closedmouth, Allens, Derdeib, Gilliam, Droll, Backspace, TJJFV, Protron, CmdrObot, Headbomb, Erfa, Omeganian, Schmieder, R'n'B,
    J.delanoy, Captain panda, MrBell, Mercurywoodrose, KP-Adhikari, Thunderbird2, Jdaloner, Lightmouse, Wwheaton, Wanderer34, DumZiBoT, Addbot, LaaknorBot, Luckas-bot, Yobot, PianoDan, Taupositron, Materialscientist, LilHelpa, Glenmark, Ceraniic, Citation bot 1,
    Jonesey95, Trappist the monk, EmausBot, Werieth, ZroBot, Ketme, Bibcode Bot, Technical 13, Regulov and Anonymous: 15

    9.2

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    File:Bevatron.jpg Source: https://upload.wikimedia.org/wikipedia/en/d/d7/Bevatron.jpg License: Fair use Contributors:


    http://www.lbl.gov/Publications/Currents/Archive/Mar-17-2006.html#story4 Original artist: ?
    File:Liquid_hydrogen_bubblechamber.jpg Source:
    https://upload.wikimedia.org/wikipedia/commons/7/76/Liquid_hydrogen_
    bubblechamber.jpg License: Public domain Contributors: ? Original artist: ?

    9.3

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