Free The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World by Sean Carroll Page B
Authors: Sean Carroll
electron volts, while the kinetic energy of a flying mosquito is a trillion eV. (It takes many atoms to make a mosquito, so that’s very little energy per particle.) The amount of energy you can release by burning a gallon of gasoline is more than 10 27 eV, while the amount of nutritional energy in a Big Mac (700 calories) is about 10 25 eV. So a single eV is a small amount of energy indeed.
Since mass is a form of energy, we also measure the masses of elementary particles in electron volts. The mass of a proton or neutron is almost a billion electron volts, while the mass of an electron is half a million eV. The Higgs boson that the LHC discovered is at 125 billion eV. Because one eV is so small, we often use the more convenient unit of GeV, for giga– (1 billion) electron volts. You’ll also see keV for kilo– (1,000) electron volts, MeV for mega– (1 million) electron volts, and TeV for tera– (1 trillion) electron volts. In 2012, the LHC collided protons with a total energy of 8 TeV, and the eventual goal is 14 TeV. That’s more than enough energy to make Higgs bosons and other exotic particles; the trick is to detect them once they’re produced.
We can even measure temperature using the same units, because temperature is just an average energy of the molecules in a substance. From this perspective, room temperature is only two-hundredths of an electron volt, while the temperature at the center of the sun is about 1 keV. When the temperature rises above the mass of a certain particle, that means that collisions have enough energy to create that particle. Even the center of the sun, which is pretty hot, isn’t nearly high enough to produce electrons (0.5 MeV), much less protons or neutrons (about 1 GeV each). Back near the Big Bang, however, the temperature was so high that it was no problem.
The easiest way for nature to hide a particle from us is to make it so heavy that we can’t easily produce it in the lab. That’s why the history of particle accelerators has been one of reaching for higher and higher energies, and why accelerators get names like Bevatron and Tevatron. Reaching unprecedented energies is literally like visiting a place nobody has ever seen.
Energizing Europe
The official name of CERN, the Geneva laboratory where the LHC is located, is the European Organization for Nuclear Research, or in French Organisation Européenne pour la Recherche Nucléaire. You’ll notice that the acronym doesn’t work in either language. That’s because the current “Organization” is a direct descendant of the European Council for Nuclear Research, Conseil Européen pour la Recherche Nucléaire, and everyone agreed that the old abbreviation could stick even after the name was officially changed. Nobody insisted on switching to “OERN.”
The council was established in 1954 by a group of twelve countries that sought to reenergize physics in postwar Europe. Since that time, CERN has been at the forefront of research in particle and nuclear physics, and has served as an intellectual center for European science, as well as an important component of Geneva’s identity. In the second-largest city in Switzerland, a world center of finance, diplomacy, and watchmaking, one out of sixteen passengers passing through Geneva airport is somehow associated with CERN. When you land there, chances are there’s a physicist or two on your airplane.
Like most major particle physics labs, the story of CERN has been one of bigger and better machines reaching ever-higher energies. In 1957, there was the Synchrocyclotron, which accelerated protons to an energy of 0.6 GeV, and in 1959, saw the inauguration of the Proton Synchrotron, which reached energies of 28 GeV. It still operates today, providing beams that are accelerated further by other machines, including the LHC.
A major step forward came in 1971 with the Intersecting Storage Rings (ISR), which attained 62 GeV in total energy. The ISR was a proton collider as well
Since mass is a form of energy, we also measure the masses of elementary particles in electron volts. The mass of a proton or neutron is almost a billion electron volts, while the mass of an electron is half a million eV. The Higgs boson that the LHC discovered is at 125 billion eV. Because one eV is so small, we often use the more convenient unit of GeV, for giga– (1 billion) electron volts. You’ll also see keV for kilo– (1,000) electron volts, MeV for mega– (1 million) electron volts, and TeV for tera– (1 trillion) electron volts. In 2012, the LHC collided protons with a total energy of 8 TeV, and the eventual goal is 14 TeV. That’s more than enough energy to make Higgs bosons and other exotic particles; the trick is to detect them once they’re produced.
We can even measure temperature using the same units, because temperature is just an average energy of the molecules in a substance. From this perspective, room temperature is only two-hundredths of an electron volt, while the temperature at the center of the sun is about 1 keV. When the temperature rises above the mass of a certain particle, that means that collisions have enough energy to create that particle. Even the center of the sun, which is pretty hot, isn’t nearly high enough to produce electrons (0.5 MeV), much less protons or neutrons (about 1 GeV each). Back near the Big Bang, however, the temperature was so high that it was no problem.
The easiest way for nature to hide a particle from us is to make it so heavy that we can’t easily produce it in the lab. That’s why the history of particle accelerators has been one of reaching for higher and higher energies, and why accelerators get names like Bevatron and Tevatron. Reaching unprecedented energies is literally like visiting a place nobody has ever seen.
Energizing Europe
The official name of CERN, the Geneva laboratory where the LHC is located, is the European Organization for Nuclear Research, or in French Organisation Européenne pour la Recherche Nucléaire. You’ll notice that the acronym doesn’t work in either language. That’s because the current “Organization” is a direct descendant of the European Council for Nuclear Research, Conseil Européen pour la Recherche Nucléaire, and everyone agreed that the old abbreviation could stick even after the name was officially changed. Nobody insisted on switching to “OERN.”
The council was established in 1954 by a group of twelve countries that sought to reenergize physics in postwar Europe. Since that time, CERN has been at the forefront of research in particle and nuclear physics, and has served as an intellectual center for European science, as well as an important component of Geneva’s identity. In the second-largest city in Switzerland, a world center of finance, diplomacy, and watchmaking, one out of sixteen passengers passing through Geneva airport is somehow associated with CERN. When you land there, chances are there’s a physicist or two on your airplane.
Like most major particle physics labs, the story of CERN has been one of bigger and better machines reaching ever-higher energies. In 1957, there was the Synchrocyclotron, which accelerated protons to an energy of 0.6 GeV, and in 1959, saw the inauguration of the Proton Synchrotron, which reached energies of 28 GeV. It still operates today, providing beams that are accelerated further by other machines, including the LHC.
A major step forward came in 1971 with the Intersecting Storage Rings (ISR), which attained 62 GeV in total energy. The ISR was a proton collider as well
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