Beyond the God Particle

by Leon M. Lederman

  15. See “Charles-Augustin de Coulomb,” http://en.wikipedia.org/wiki/Charles-Augustin_de_Coulomb, and “Coulomb's law,” http://en.wikipedia.org/wiki/Coulomb%27s_law (sites last visited 3/26/2013).

  16. See “Electric charge,” http://en.wikipedia.org/wiki/Electric_charge. The electric field, which we call E, produces a force on the charge, which we call F, and the relationship between these is very simple, F = eE, or “force equals charge times electric field.” A force causes a particle to accelerate. This was precisely expressed by Newton in his famous equation F = ma, or “force equals mass times acceleration.” So, if we combine these two equations, we see that ma = eE, or a = eE/m, “the acceleration of the particle is proportional to charge times electric field divided by mass.” See “Electric field,” http://en.wikipedia.org/wiki/Electric_field; see also http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elefie.html; http://www4.uwsp.edu/physastr/kmenning/Phys250/Lect03.html (sites last visited 1/23/2013). Quarks have fractional charges, up = +2/3 times e, and down = –1/3 times e, but quarks are always bound into strongly interacting particles, such as protons, neutrons, and π's such that the observed charges are integers (see Appendix).

  17. The direction of an electric field and a conventional electric current always emanates from positive and points toward negative. This convention was adopted before the discovery that the electric charge of the electron is negative. So the actual flow of electrons is opposite to that of the electric field and the conventional current. See “Electric current,” http://en.wikipedia.org/wiki/Electric_current (site last visited 5/4/2013).

  18. Search online for “electron microscopes” and follow links to “images for electron microscopes.” See “Electron microscope” and references therein, http://en.wikipedia.org/wiki/Electron_microscopes (site last visited 1/23/2013). Quoting from this source:

  According to Dennis Gabor, the physicist Leó Szilárd tried in 1928 to convince him to build an electron microscope, for which he had filed a patent. The German physicist Ernst Ruska and the electrical engineer Max Knoll constructed the prototype electron microscope in 1931, capable of four-hundred-power magnification; the apparatus was a practical application of the principles of electron microscopy. Two years later, in 1933, Ruska built an electron microscope that exceeded the resolution attainable with an optical (lens) microscope. Moreover, Reinhold Rudenberg, the scientific director of Siemens-Schuckertwerke, obtained the patent for the electron microscope in May 1931. Family illness compelled the electrical engineer to devise an electrostatic microscope, because he wanted to make visible the poliomyelitis virus. The first practical electron microscope was constructed in 1938, at the University of Toronto, by Eli Franklin Burton and students Cecil Hall, James Hillier, and Albert Prebus; and Siemens produced the first commercial transmission electron microscope (TEM) in 1939. Although contemporary electron microscopes are capable of two million-power magnification, as scientific instruments, they remain based upon Ruska's prototype.

  CHAPTER 8. THE WORLD'S MOST POWERFUL PARTICLE ACCELERATORS

  1. See “Michael Faraday,” http://en.wikipedia.org/wiki/Michael_Faraday (site last visited 3/26/2013). In the “opinion” of Snopes.com (the fact-checking website that has punched so many holes in the many idiotic opines of elected officials and various rancidly political distribution e-mails), this famous quote of Faraday's is undocumented hearsay: http://www.snopes.com/quotes/faraday.asp. However, the recipient of the comment, Gladstone, was supposedly Chancellor of the Exchequer, and not prime minister, according to Wikiquote: http://en.wikiquote.org/wiki/Michael_Faraday (sites last visited 3/26/13): “Faraday's reply to William Gladstone, then British Chancellor of the Exchequer (minister of finance), when asked of the practical value of electricity (1850), as quoted in The Harvest of a Quiet Eye: A Selection of Scientific Quotations (1977), p. 56.” Snopes claims to discredit the quote because Gladstone was allegedly prime minister at the time of the remark, but in fact he did not hold that office until after Faraday's death. The fact that Gladstone was Chancellor of the Exchequer seems to undercut that part of the Snopes argument. Electricity had not developed to the cell phone–video camera stage in Faraday's era, so we'll never know who's right or who's wrong, but we do love the “quote.”

  2. Much more technical detail than we have space for can be found by perusing the Wikipedia entry for “Linear particle accelerator,” http://en.wikipedia.org/wiki/Linear_Accelerator (site last visited 3/26/13).

  3. And, thankfully, in the limit when particles have very large energies, the relationship between their quantum wavelength and energy becomes very simple: E = h /2π λ where λ is the wavelength and h is Planck's constant. This simple formula explains everything about the largest accelerators in the world, from the Fermilab Tevatron, to the SLAC Linac, to LEP, to the Large Hadron Collider—in order to halve the size of λ we must double E—ergo high-energy particle accelerators are big.

  4. Radio frequency cavities are another marvel of modern technology that was spun off from particle accelerator R&D. See “Microwave cavity,” http://en.wikipedia.org/wiki/Microwave_cavity, “Klystron,” http://en.wikipedia.org/wiki/Klystron (site last visited 3/26/13).

  5. Widerøe's cavities were just spaces in a vacuum pipe between tubes of copper that were alternately charged plus and minus by an oscillating electric circuit. When the particles were between the tubes, they were in phase with an electric field (e.g., if an electron, the tube ahead would be charged positive, while the one behind would be negative). As they entered the tubes, the tubes changed polarity while the electrons merely drifted. See “Linear particle accelerator,” http://en.wikipedia.org/wiki/Linear_particle_accelerator.

  6. See the SLAC site: http://www6.slac.stanford.edu/research/ (site last visited 3/26/13).

  7. “Fermilab Linac,” http://www-ad.fnal.gov/proton/linac.html, and for the history: http://history.fnal.gov/linac.html (sites last visited 1/27/2013).

  8. See, e.g., http://www.hep.ucl.ac.uk/~jpc/all/ulthesis/node15.html. See “International Linear Collider,” http://en.wikipedia.org/wiki/International_Linear_Collider; see also http://www.linearcollider.org/ILC/GDE/Director%27s-Corner/2008/1-May-2008---The-art-of-decision-making---STF-phase-2-cavity-choice (sites last visited 3/26/2013).

  9. See “Technetium-99,” http://en.wikipedia.org/wiki/Technetium-99 (site last visited 3/26/2013).

  10. “Magnetic Field Basics,” http://www.physics4kids.com/files/elec_magneticfield.html (site last visited 3/26/2013). Digested from the article:

  Magnets and magnetism were known to ancients. The magnetic field on the surface of a spherical magnet was mapped using iron needles in 1269 by Petrus Peregrinus de Maricourt. He coined the term “poles” in analogy to Earth's poles where the field lines converged at two points on the sphere. In 1600 in a publication, De Magnete, William Gilbert of Colchester demonstrated explicitly that Earth is a magnet, helped to establish magnetism as a science. In 1819, Hans Christian Oersted discovered that an electric current generates a magnetic field encircling it. André-Marie Ampère in 1820 showed that parallel wires having currents in the same direction attract one another. Jean-Baptiste Biot and Félix Savart discovered the force law in 1820 which correctly predicts the magnetic field around any current-carrying wire.

  Extending these experiments, Ampère published his own successful model of magnetism in 1825…. Further, Ampère derived both Ampère's force law describing the force between two currents and Ampère's law which, like the Biot–Savart law, correctly described the magnetic field generated by a steady current. Also in this work, Ampère introduced the term “electrodynamics” to describe the relationship between electricity and magnetism.

  In 1831, Michael Faraday discovered electromagnetic induction when he found that a changing magnetic field generates an encircling electric field. He described this phenomenon in what is known as Faraday's law of induction. Later, Franz Ernst Neumann proved that, for a moving conductor in a magnetic field, induction is a consequence of Ampère's force la
w. In the process he introduced the magnetic vector potential which was later shown to be equivalent to the underlying mechanism proposed by Faraday.…

  Between 1861 and 1865, James Clerk Maxwell developed and published Maxwell's equations which explained and united all of classical electricity and magnetism. The first set of these equations was published in a paper entitled On Physical Lines of Force in 1861. These equations were valid although incomplete. He completed Maxwell's set of equations in his later 1865 paper, A Dynamical Theory of the Electromagnetic Field, and demonstrated the fact that light is an electromagnetic wave. Heinrich Hertz experimentally confirmed this fact in 1887.

  Although implicit in Ampère's force law the force due to a magnetic field on a moving electric charge was not correctly and explicitly stated until 1892 by Hendrik Lorentz who theoretically derived it from Maxwell's equations. With this last piece of the puzzle, the classical theory of electrodynamics was essentially complete.

  Mapping the magnetic field of an object is simple in principle. First, measure the strength and direction of the magnetic field at a large number of locations. Then, mark each location with an arrow (called a vector) pointing in the direction of the local magnetic field with a length proportional to the strength of the magnetic field.

  A simpler method to map the magnetic field is to “connect” the arrows to form magnetic field lines. On a magnetic field line diagram, the direction of the magnetic field at any point is represented by the direction of nearby field lines. Further, if drawn carefully, a higher density of nearby field lines indicates a stronger magnetic field.

  Magnetic field lines are like the contour lines (constant altitude) on a topographic map in that a different mapping scale would show more or fewer lines. An advantage of using magnetic field lines, though, is that many laws of magnetism (and electromagnetism) can be stated completely and concisely using simple concepts such as the “number” of field lines through a surface. These concepts can be quickly “translated” to their mathematical form. For example, the number of field lines through a given surface is the surface integral of the magnetic field.

  Various phenomena have the effect of “displaying” magnetic field lines as though the field lines are physical phenomena. For example, iron filings placed in a magnetic field line up to form lines that correspond to “field lines.” Magnetic fields’ “lines” are also visually displayed in polar auroras, in which plasma particle dipole interactions create visible streaks of light that line up with the local direction of Earth's magnetic field.

  Field lines can be used as a qualitative tool to visualize magnetic forces. In ferromagnetic substances like iron and in plasmas, magnetic forces can be understood by imagining that the field lines exert a tension (like a rubber band) along their length, and a pressure perpendicular to their length on neighboring field lines. “Unlike” poles of magnets attract because they are linked by many field lines; “like” poles repel because their field lines do not meet, but run parallel, pushing on each other.

  The twentieth century extended electrodynamics to include relativity and quantum mechanics. Albert Einstein, in his paper of 1905 that established relativity, showed that both the electric and magnetic fields are part of the same phenomena viewed from different reference frames.

  11. Note that acceleration is the time rate of change of a velocity. Velocity is a vector, meaning it has both magnitude (speed) and direction. If the speed is constant but the direction varies in time, as is the case for uniform circular motion, then the particle is being accelerated.

  12. See “André-Marie Ampère,” http://en.wikipedia.org/wiki/Andr%C3%A9-Marie_Amp%C3%A8re (site last visited 3/26/2013).

  13. This is called “direct current,” or DC, not the “alternating current,” or AC, which oscillates in the wires in your home; the oscillating current also produces magnetic fields, but the forces will oscillate and average to zero, so you won't see the wires deflecting one another

  14. The magnetic property of iron is a consequence of the intrinsic spin of electrons in the iron atoms and is a rather complex quantum phenomenon. See “Ferromagnetism,” http://en.wikipedia.org/wiki/Ferromagnetism (site last visited 1/26/2013).

  15. Magnetic monopoles would in principle exist if certain conditions in particle physics were realized. Such objects would be extremely heavy (at least many TeV in mass, probably higher); there is to date no evidence, other than various theories, of their existence See “Magnetic monopole,” http://en.wikipedia.org/wiki/Magnetic_monopole (site last visited 1/26/2013).

  16. See iron filings revealing the magnetic field lines at http://en.wikipedia.org/wiki/Magnetism#History; see also http://www.wired.com/wiredscience/2011/09/magnetic-invisibility-cloak/ (sites last visited 3/26/2013), or search online for keywords “iron filings magnetic.”

  17. See “Cyclotron,” http://en.wikipedia.org/wiki/Cyclotron and illustrations therein, (site last visited 1/26/2013).

  18. See “Strong focusing,” http://en.wikipedia.org/wiki/Strong_focusing and “Synchrotron,” http://en.wikipedia.org/wiki/Synchrotron (sites last visited 1/26/2013).

  19. “Synchrotron radiation,” http://hyperphysics.phy-astr.gsu.edu/hbase/particles/synchrotron.html; http://www.hep.ucl.ac.uk/~jpc/all/ulthesis/node15.html; http://physik.uibk.ac.at/~emo/physics/synchrotron.html (sites last visited 1/26/2013).

  20. See “Quadrupole magnet,” http://en.wikipedia.org/wiki/Quadrupole_magnet (site last visited 1/26/2013).

  21. The “FODO” lattice is discussed in D. Edwards and M. Syphers, An Introduction to the Physics of High Energy Accelerators (Wiley Series in Beam Physics and Accelerator Technology) (Wiley, 1992). For information on the Brookhaven AGS, see http://en.wikipedia.org/wiki/Alternating_Gradient_Synchrotron (site last visited 1/26/2013).

  22. Lillian Hoddeson, Adrienne Kolb, and Catherine Westfall, Fermilab: Physics, the Frontier, and Megascience (University of Chicago Press, 2011); see also “Tevatron,” http://en.wikipedia.org/wiki/Tevatron (sites last visited 3/26/2013). From the source:

  December 1, 1968 saw the breaking of ground for the linear accelerator (linac). The construction of the Main Accelerator Enclosure began on October 3, 1969 when the first shovel of earth was turned by Robert R. Wilson, NAL's director. This would become the 6.4 km circumference of Fermilab's Main Ring.

  The linac's first 200 MeV beam started on December 1, 1970. The booster's first 8 GeV beam was produced on May 20, 1971. On June 30, 1971, a proton beam was guided for the first time through the entire National Accelerator Laboratory accelerator system including the Main Ring. The beam was accelerated to only 7 GeV…

  A series of milestones saw acceleration rise to 20 GeV on January 22, 1972 to 53 GeV on February 4 and to 100 GeV on February 11. On March 1, 1972, the then NAL accelerator system accelerated for the first time a beam of protons to its design energy of 200 GeV. By the end of 1973, NAL's accelerator system operated routinely at 300 GeV.

  On 14 May, 1976 Fermilab took its protons all the way to 500 GeV. This achievement provided the opportunity to introduce a new energy scale, the Tera electron volt (TeV), equal to 1000 GeV. On 17 June of that year, the European Super Proton Synchrotron accelerator (SPS) had achieved an initial circulating proton beam (with no accelerating radio-frequency power) of only 400 GeV.

  The old copper magnet accelerator was shut down on August 15, 1977 for superconducting magnets to be mounted “piggy-back” on the main ring magnets. The “Energy Doubler,” as it was known then, produced its first accelerated beam—512 GeV—on July 3, 1983. Its initial energy of 800 GeV was achieved on February 16, 1984. On October 21, 1986 acceleration at the Tevatron was pushed to 900 GeV, providing a first proton–antiproton collision at 1.8 TeV on November 30, 1986.

  The Main Injector, which replaced the Main Ring, was the most substantial addition, built over six years from 1993 at a cost of $290 million. Tevatron collider Run II began on March 1, 2001 after successful completion of that facility upgrade. From then, the beam had been capable of delivering an
energy of 980 GeV.

  On July 16, 2004 the Tevatron achieved a new peak luminosity, breaking the record previously held by the old European Intersecting Storage Rings (ISR) at CERN. That very Fermilab record was doubled on September 9, 2006, then a bit more than tripled on March 17, 2008, and ultimately multiplied by a factor of 4 over the previous 2004 record on April 16, 2010 (up to 4 × 1032 cm−2 s−1).

  By the end of 2011, the Large Hadron Collider (LHC) at CERN had achieved a luminosity almost ten times higher than Tevatron's (at 3.65 × 1033 cm−2 s−1) and a beam energy of 3.5 TeV each (doing so since March 18, 2010), already ~3.6 times the capabilities of the Tevatron (at 0.98 TeV).

  The initial design luminosity of the Tevatron was 1030 cm−2 s−1, however the accelerator has following upgrades been able to deliver luminosities up to 4 ×1032 cm−2 s−1.

  The Booster is a small circular synchrotron, around which the protons pass up to 20,000 times to attain an energy of around 8 GeV. From the Booster the particles pass into the Main Injector, which was completed in 1999 to perform a number of tasks. It can accelerate protons up to 150 GeV; it can produce 120 GeV protons for antiproton creation; it can increase antiproton energy to 120 GeV, and it can inject protons or antiprotons into the Tevatron. The antiprotons are created by the Antiproton Source. 120 GeV protons are collided with a nickel target producing a range of particles including antiprotons which can be collected and stored in the accumulator ring. The ring can then pass the antiprotons to the Main Injector.