Experimental Elementary Particle Physics

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Particle physics plays an essential role in the broader enterprise of the physical sciences. It inspires U.S. students, attracts talent from around the world, and drives critical intellectual and technological advances in other fields. And it is entering an era of unprecedented potential as a result of new discoveries about matter and energy in the Universe. It seeks to explore, through accelerator experiments, the fundamental nature of matter, energy, space, and time. It asks such questions as: What are the origins of mass? Can the basic forces of nature be unified? How did the universe begin? How will it evolve in the future? What is dark energy? Are there extra dimensions beyond space-time? Formerly separate questions in cosmology (the universe on the largest scales) and quantum phenomena (the universe on the smallest scales) become connected through our understanding that the early universe can be explored through the techniques of particle physics.At the NSF, particle physics is supported by three programs within the Division of Physics: (1), the Theory program which includes fundamental research on the forces of nature and the early history of the universe as well as support for the experimental program by providing guidance and analysis for high energy experiments; (2), the Elementary Particle Physics (EPP) program which supports particle physics at accelerators, and (3) the Particle Nuclear Astrophysics (PNA) program which supports non- accelerator experiments. The EPP program supports, for example, accelerator experiments at the Tevatron at Fermilab, and collider experiments utilizing the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. The challenge of designing detectors for the LHC is unprecedented, as they are required to observe up to 600 million collisions each second. Yet some of the phenomena physicists are searching for will take place at the rate of only a few per day. These include possible discoveries such as a particle called the Higgs that is thought to endow other particles with mass, new forms of matter that explain the mysterious dark matter pervading the cosmos and even phenomena that reveal new dimensions of spacetime.A new generation of neutrino experiments, using beams from Fermilab and other accelerators in Europe and Japan, have set out to study this elusive, quantum-oscillating particles under laboratory-controlled conditions. The new experiments probe high-intensity neutrino beams produced by particle accelerators. The beams travel hundreds of miles through the Earth to underground detectors that measure changes in the composition of the neutrino beam.EPP also supports advances in accelerator physics and detectors at acceleratorsand new methods of utilizing distributed computing in support of collaborative research, for example, grid development, both nationally and internationally. The program also engages K-12 educators, who participate in experiments with University Scientists and Students.

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