On July 4, scientists working with data from ongoing experiments at the Large Hadron Collider (LHC) announced the discovery of a new particle "consistent with" the Higgs boson -- a subatomic particle also colloquially referred to as the "God particle." After years of design and construction, the LHC first sent protons around its 27 kilometer (17 mile) underground tunnel in 2008. Four years later, the LHC's role in the discovery of the Higgs boson provides a final missing piece for the Standard Model of Particle Physics -- a piece that may explain how otherwise massless subatomic particles can acquire mass. Gathered here are images from the construction of the massive $4-billion-dollar machine that allowed us peer so closely into the subatomic world.
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View of the Compact Muon Solenoid (CMS) Tracker Outer Barrel in the cleaning room on January 19, 2007. The CMS is a general-purpose detector, part of the Large hadron Collider (LHC), and is capable of studying many aspects of proton collisions at 14 trillion electronvolts. (Maximilien Brice/© 2012 CERN) 
One module of the ALICE (A Large Ion Collider Experiment) photon spectrometer. There are 3,584 lead tungstate crystals on the first module for the ALICE photon spectrometer. Lead tungstate crystals have the optical transparency of glass combined with much higher density, and can serve as scintillators, lighting up when when struck by an incoming particle. (Maximilien Brice/© 2012 CERN) #
A scientist performs maintenance in the CERN LHC computing grid center in Geneva, on October 3, 2008. This center is one of the 140 data processing centers, located in 33 countries, taking part in the grid processing project. More than 15 million Gigabytes of data produced from the hundreds of millions of subatomic collisions in the LHC should be collected every year. (Reuters/Valentin Flauraud) #
Precision work is performed on the semiconductor tracker barrel of the ATLAS experiment, on November 11, 2005. All work on these delicate components must be performed in a clean room so that impurities in the air, such as dust, do not contaminate the detector. The semiconductor tracker will be mounted in the barrel close to the heart of the ATLAS experiment to detect the path of particles produced in proton-proton collisions. (Maximilien Brice/© 2012 CERN) #
A major milestone in the assembly of the ATLAS experiment's inner detector. The semiconductor tracker (SCT) and transition radiation tracker (TRT) are two of the three major parts of the ATLAS inner detector. Together, they will help determine trajectories of particle collisions produced when the LHC is switched on. February 22, 2006. (Maximilien Brice/© 2012 CERN) #
The electromagnetic calorimeter, completely assembled, is a wall more than 6 m high and 7 m wide, consisting of 3,300 blocks of scintillator, fibre optics and lead. This huge wall will measure the energy of particles produced in proton-proton collisions at the LHC when it is started in 2008. Photons, electrons and positrons will pass through the layers of material in these modules and deposit their energy in the detector through a shower of particles. May 17, 2005. (Maximilien Brice/© 2012 CERN) #
The Linac2 (Linear Accelerator 2) at the European Organization for Nuclear Research, CERN, in Meyrin, near Geneva, Switzerland, on Thursday, October 16, 2008. The current accelerator Linac2, built in 1978 which will be replaced in 2013 by Linac4, separates hydrogen gas into electrons and protons and provides protons beams to the LHC. (AP Photo/Keystone, Martial Trezzini) #
The first half of the Compact Muon Solenoid inner tracker barrel is seen in this image consisting of three layers of silicon modules which will be placed at the center of the CMS experiment. Laying close to the interaction point of the 14 TeV proton-proton collisions, the silicon used here must be able to survive high doses of radiation and a powerful magnetic field without damage. October 19, 2006. (Maximilien Brice/© 2012 CERN) #
One of the end-cap calorimeters for the ATLAS experiment is moved using a set of rails. This calorimeter will measure the energy of particles that are produced close to the axis of the beam when two protons collide. It is kept cool inside a cryostat to allow the detector to work at maximum efficiency. February 16, 2007. (Claudia Marcelloni/© 2012 CERN) #
Michel Mathieu, a technician for the ATLAS collaboration, is cabling the ATLAS electromagnetic calorimeter's first end-cap, before insertion into its cryostat. Millions of wires are connected to the electromagnetic calorimeter on this end-cap that must be carefully fed out from the detector so that data can be read out. Every element on the detector will be attached to one of these wires so that a full digital map of the end-cap can be recreated. August 12, 2003. (Maximilien Brice/© 2012 CERN) #
Switches in the Control Room of the Large Hadron Collider at the European Organization for Nuclear Research (CERN) near Geneva, on April 5, 2012. On this day, the LHC shift crew declared "stable beams" as two 4 TeV proton beams were brought into collision at the LHC's four interaction points. The collision energy of 8 TeV set a new world record, and increased the machine's discovery potential considerably. (Reuters/Denis Balibouse) #
This image made available by CERN shows a typical candidate event including two high-energy photons whose energy (depicted by red towers) is measured in the Compact Muon Solenoid electromagnetic calorimeter. The yellow lines are the measured tracks of other particles produced in the collision. The pale blue volume shows the CMS crystal calorimeter barrel. To cheers and standing ovations, scientists at the world's biggest atom smasher claimed the discovery of a new subatomic particle on July 4, 2012, calling it "consistent" with the long-sought Higgs boson -- popularly known as the "God particle" -- that helps explain what gives all matter in the universe size and shape. (AP Photo/CERN) #
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