Beyond the God Particle Read Online Free Page B

machine nevertheless made remarkably detailed precision measurements of the properties of the Z 0 boson that have had major impact on our detailed understanding of the Standard Model. LEP was even upgraded for a second operation phase, toproduce and study W particles, but the energy of the machine still limited the reach for a Higgs boson to a mass scale of less than about 115 times that of the proton. It still did not, even with the higher energies, find the Higgs boson. In the meantime, the SSC was canceled in the US, and CERN saw a golden opportunity to convert the LEP collider to a much higher-energy proton–proton collider. The LHC project was born.
    The LEP collider was closed down in November 2000 to make way for the construction of the Large Hadron Collider (LHC) within the same tunnel. The LHC was built and commissioned, and it is, today, the world's most powerful particle accelerator, the most deeply penetrating tool we have into the inner workings of matter and energy.
    COMMISSIONING THE WORLD'S LARGEST PARTICLE COLLIDER ISN'T EASY
    Einstein said you should always drill through the thick part of the wood. Progress can only be made by extraordinary effort. Extraordinary effort often implies overcoming extraordinary setbacks. Particle physics drills deeper into the wood than any other human endeavor. It must necessarily have major setbacks from time to time.
    The Large Hadron Collider at CERN spans the border between Switzerland and France, sitting about 300 feet underground in the LEP tunnel, a large circle with a circumference of about 17 miles. The LHC is the world's most powerful microscope and is used by physicists to study the smallest known particles and processes—the fundamental building blocks of all things. Two beams of protons travel in opposite directions inside the circular accelerator, gaining energy with every lap. Particles from the two beams collide head-on at very high energy within the centers of the two enormous detectors (“eyepieces”) called ATLAS and CMS. Teams of physicists from around the world then analyze the collisions. Two additional medium-size experiments, ALICE and LHCb, have specialized detectors that analyze the LHC collisions for a wide assortment of other phenomena. 8
    Fermilab, with many US universities, collaborates mainly with CMS, and many US university physicists work with ATLAS. Fermilab built the LHC Remote Operations Center for the CMS experiment within its mainbuilding, Wilson Hall. Here US scientists can be part of the action and play a vital role in actually managing the operation of the experiment without having to hop on a transatlantic flight.
    On September 10, 2008, 1:30 a.m. in Fermilab's Remote Operations Center, the first circulating proton beam in the LHC in Geneva was celebrated by a partying audience of dozens of scientists, who were pulling an all-nighter, many clad in robes and pajamas. The mood was confident and exuberant. A new age for particle physics was dawning.
    As the particle energy in the LHC is increased, the magnetic field strength in the accelerator beam pipe must also increase to hold the protons in fixed circular orbits within the machine. This is accomplished with 1,232 special “dipole magnets” (and thousands of other magnets that serve effectively as “correcting and focusing lenses” in the system; the system has about 5,000 magnets in total 9 ). These magnets use electrical current to generate controlled magnetic fields. This can be varied to sweep over the required field strengths needed to maintain the delicate particle orbits, as their energies increase during acceleration (this process is called the “ramp”). Each LHC dipole magnet is a massive steel structure, about 50 feet in length. Their magnetic field ranges from zero to 100,000 times that of the earth's magnetic field. When the maximum field strength is reached, each magnet contains the potential energy of about one-quarter of a ton of TNT. This energy would be