Research Areas
Non-Accelerator-Based Physics
Supporting Information
Early in the 20 th century, the study of cosmic rays—highly energetic, charged particles from space—provided the first evidence for the richness of particle physics. By discovering the positron, the antiparticle of the electron, these first observations revealed the first existence of antimatter. Cosmic rays also enabled physicists to discover the muon, the unexpected heavier cousin of the electron.
As high energy particle accelerators became increasingly capable of producing exotic particles in a controlled laboratory setting, scientists migrated from the cosmic frontier, using natural sources, to the energy frontier, using powerful beams of electrons and protons. With an increasingly set of sophisticated techniques that complement the accelerator-based research, the cosmic frontier is experiencing a resurgence, creating a diverse program of experiments.
A number of experiments aim to solve the mystery of dark matter and dark energy. These mysterious elements of the universe do not shine like stars and galaxies though. Thus, scientists have only indirect evidence of their existence through gravitational influence on both the motion of galaxies as well as the light they emit. The direct detection of dark matter might be possible by searching for weakly interacting massive particles. Physicists consider these WIMPs to be the leading candidates for the constituents of dark matter.
Fermilab’s Cryogenic Dark Matter Search experiment hopes to discover WIMPs half a mile below ground where the detector is shielded from background noise. High-energy gamma ray observations from the Large Array Telescope using GLAST, a NASA space telescope, and VERITAS, a ground-based telescope in Arizona, present another approach for shedding light on dark matter.
In the case of dark energy, measurements of its properties rely on the impact it has on how distant galaxies move over large amounts of space and time. Such measurements require telescopes capable of surveying large portions of the sky in great detail. The Dark Energy Survey will map the distances of 300 million galaxies, helping chart the geometry of the universe. The Joint Dark Energy Mission, a planned space-based observatory in collaboration with NASA, will be able to map the universe using multiple methods, possibly addressing that it has changed over time.
Neutrinos present another research area on the cosmic frontier. Though trillions of neutrinos pass through our bodies each second, they hardly leave a trace. Thus, the neutrino earned the title of most mysterious of the known particles in the universe. Observations of neutrinos can provide windows into both the physics governing their astrophysical sources as well as the nature of the mysterious particles themselves. The physics of neutrinos may actually hold clues to even deeper mysteries such as where has all the antimatter gone and do all the forces become one.
Earlier this decade, physicists at the Sudbury Neutrino Observatory in Canada and the Super-K observatory in Japan discovered the first evidence for neutrino mixing. Scientists are still analyzing data from these observatories, but these results demonstrate a breakdown in the Standard Model of physics. The Standard Model states that neutrinos do not have mass. Scientists believe that neutrino mixing, however, most likely involves mass, opening up a whole new set of questions for experiments to tackle. When combined with the results of new, highly precise experiments designed to observe neutrinos from controlled sources including accelerators as well as nuclear reactors such as Daya Bay in China, scientists hope to get some of the answers that they are searching for on the cosmic frontier.
