LSST
(Large Synoptic Survey Telescope)
Dr. Michael Prouza, Assoc. Prof. Stefan Westerhoff
Recent observations suggest that we live in a Universe made up of
74% dark energy, 22% dark matter, and only 4% ordinary matter.
One of the main future projects to understand the nature of
dark matter and dark energy is the
Large Synoptic Survey Telescope. LSST is a next-generation
ground-based 8.4 meter diameter, 10 square-degree field of view
optical telescope which will produce digital images of the entire
observable sky every three days, thus opening a new window, the
"time window," in astronomy. LSST will produce a "movie-like"
picture of the Universe that will enable us to discover objects
that change or move rapidly: supernovae, asteroids,
Kuiper Belt objects, and ... the unknown.
In addition to providing the traditional images of luminous stars and
galaxies, LSST will "map" the dark matter distribution in the Universe
by measuring the distortion of the shape of remote galaxies via
weak gravitational lensing. Since the signal is small, a large
number of galaxies must be studied in these weak lensing
surveys. The results not only reveal the distribution of mass
(and in particular the dark matter) in the Universe in three
dimensions, but will also allow for precision tests of dark
energy theories.
LSST is currently in the design and development phase. The telescope
is to be built at the existing astronomical site on the El Penon peak
of Cerro Pachon in northern Chile. First light is expected in 2013.
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ATLAS
Dr. Kamal Benslama, Asst. Professor Gustaaf Brooijmans, Dr. Jeremy Dodd, Dr. Mikhail Leltchouk, Dr. Andrew Haas, Professor Emlyn Hughes, Professor John Parsons, Professor Mike Tuts, Professor William Willis
The ATLAS experiment is being designed and built for operation at the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. The LHC is a proton-proton collider which will be the world's highest energy collider and will be the premier experimental HEP facility for many years.
The foremost question of HEP is the source of so-called "electroweak symmetry breaking" (EWSB), related to the issue of the origin of mass. The SM postulates the existence of the Higgs boson to solve this issue. However, many other scenarios (eg. supersymmetry, technicolor, extra dimensions) have been proposed. The LHC and ATLAS are designed to probe an energy scale which should make possible investigation of the source of EWSB. For example, ATLAS should be able to either discover the SM Higgs boson or to definitively rule out its existence. If no SM Higgs is found, we expect to find instead indications of the true source of EWSB.
ATLAS is in the design and construction phase. On-going ATLAS activities at Nevis include development of state-of-the-art electronics for readout of the ATLAS calorimeter, studies of the physics potential of ATLAS, and development of software for the simulation of the calorimeter performance.
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D0
Asst. Professor Gustaaf Brooijmans, Dr. Andrew Haas, Dr. Sabine Lammers, Dr. Michael Mulhearn, Professor John Parsons, Professor Mike Tuts
The Tevatron proton-antiproton collider at Fermilab, near Chicago, is currently the energy frontier for particle colliders. The DØ experiment is currently runnign with an upgraded detector for which the Columbia group made major contributions. We are making important contributions to the study of many of the most interesting questions in physics today. Included in a long list of topics are studies of the top quark (which was discovered by the D0 and CDF experiments), attempts to understand the source of the huge preponderance of matter over antimatter in the universe (by studies of CP violation in b-quarks), probes of the electro-weak and strong forces and searches for the unexpected. Additionally, there is the challenge of operating and understanding a complicated, new detector with more than one million channels of information coming from a variety of technologies.
The Columbia DØ group is involved a wide range of activities on the experiment. We have built cutting-edge electronics for the calorimeter and the level-2 muon trigger and will be analyzing the first data from these devices in the spring and summer. We are also involved in designing and building a precision tracking trigger using information from the DØ silicon tracker. Our physics activities include studies of b-quarks, top-quarks and searches for physics beyond the standard theory.
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e-Bubble
Dr. Jeremy Dodd, Dr. Mikhail Leltchouk, Professor William Willis
For many years neutrino physics and collider detectors have been a major part of the Nevis program. During the last year we have established a new program to move forward on research on new detectors, so that we will be prepared for the next round of experimental needs in these areas. We are focusing on ideas for detectors which utilize the advantages of a cryogenic environment, and in particular on detectors using liquid helium as the detection medium.
More than thirty years ago it was learned that the stable state of an electron in liquid helium is a bubble of about 2 nm diameter, with nothing but the electron inside. Electron bubbles ('eBubbles') can also exist in liquid neon and liquid hydrogen. These eBubbles have properties that appear to be well-suited to detecting particle interactions where the relevant energies are small, where good position and energy resolution are required, and where a large detection volume is needed. We anticipate that this technology may open up new possibilities for next-generation neutrino detectors, and may also have applications in detecting 'dark matter' particles and in future collider detectors.
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HiRes
Dr. John Boyer, Dr. Bruce Knapp, Dr. Eric Mannel, Asst. Prof. Stefan Westerhoff
One of today's great scientific mysteries is the origin of cosmic ray particles with energies beyond 1020 eV (about 20 Joules), the highest energy particles observed in the Universe. The existence of particles at these energies continues to challenge our imagination: where do they come from, how do astrophysical objects produce them or accelerate them to these energies, and how can they travel astronomical distances without substantial loss of energy?
The goal of the High Resolution Fly's Eye (HiRes) Experiment is to measure the energy spectrum and the composition of cosmic rays above 1018 eV. At these energies, the particles cannot be observed directly, but only by measuring the huge particle cascade ("air shower") they induce in the Earth's atmosphere.
Earth-bound air fluorescence detectors like HiRes make use of the fact that the particle cascade of an air shower dissipates much of its energy exciting and ionizing air molecules. The excited Nitrogen molecules fluoresce in the near UV with an emission line spectrum. The fluorescence light is emitted isotropically and its intensity is proportional to the number of charged particles in the shower. Air fluorescence detectors consist of arrays of telescopes that image fluorescence light from distant air showers onto arrays of photomultiplier tubes.
The HiRes experiment operates two sites seperated by a distance of 12.6 km on the US Military's Dugway Proving Ground in Utah. The construction of the sites is completed, and HiRes is in the data-taking mode.
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Mini-BooNE
Professor Janet Conrad, Dr. Jonathan Link, Professor Michael Shaevitz, Dr. Geralyn "Sam" Zeller
Neutrino physics is currently one of the most active areas of research in modern particle physics. One of the main reasons for such heightened activity is the continued mystery regarding some of the basic properties of this elusive particle. Do neutrinos have mass? If so, can it be measured in current experiments? What does our knowledge about neutrinos imply about the evolution of galaxies and the visible universe?
The BooNE neutrino experiment at Fermilab is designed to address these questions. The BooNE experiment uses a muon-neutrino beam to determine whether muon neutrinos oscillate to electron neutrinos. An experiment at Los Alamos National Laborotories (LSND) indicates that this oscillation may indeed occur, but the results are not conclusive. Neutrinos could oscillate only if they have mass. The low energy neutrino beam is aimed at the BooNE detector -- a 40-foot-diameter tank filled with mineral oil. The neutrinos interacting with the oil will either release a muon or an electron, depending on the incoming neutrino flavor. The observation of electron production in the detector would indicate neutrino oscillations. In addition to neutrino oscillations, BooNE is also sensitive to other phenomena, such as supernova explosions and the decay of exotic particles.
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Neutrino Factory & Muon Collider
Professor Janet Conrad, Dr. Stefan Schlenstedt, Professor Michael Shaevitz
The neutrino factory / muon collider collaboration currently consists of about 100 physicists from 27 institutions. The primary goal of the collaboration is to assess the feasibility and potential of high energy high luminosity muon colliders operating at a center-of-mass energy in the range 100 GeV - 4 TeV. The high intensity muon source needed for muon colliders can also be used to feed a muon storage ring neutrino source (neutrino factory). Neutrino factories provide a possible path towards a muon collider
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NuTev
Profesor Janet Conrad, Dr. Jonathan Link, Professor Michael Shaevitz, Dr. Geralyn "Sam" Zeller
NuTeV was designed to observe millions of interactions of the highest energy, highest intensity neutrinos ever produced. Fermilab , the world's highest energy accelerator, generated this beam from just five micrograms of protons. These were special protons, each given the entire energy of motion of a fruit fly in flight, concentrated into a single sub-atomic particle. This proton beam had a power of 100 million Watts.
Slamming this immense power in protons into a target produces tens of billions of neutrinos every minute, along with a plethora of other high energy by-products. To protect the NuTeV detector from this onslaught of particle energy, experimenters shielded it with a half kilometer of lead, steel and dirt. Only the weakly interacting neutrinos could travel through such a shield. Observing millions of these neutrinos not only required a lot of neutrinos, but also a lot of detector. The detector itself was a a 700-ton sandwich with over a hundred slices of alternating steel and particle detectors. Even with 700 tons of target material to hit, only one in a billion neutrinos in the NuTeV beam interacted as it went from the first to the last slice. The NuTeV detector can see neutrinos because, on their way through the sandwich, they slam into a nucleus and break it apart. After the collision, the neutrino may stay a neutrino or turn into a muon. If they see a particle leaving the scene, it's a muon. If they see nothing leaving, they know that a neutrino has come and gone. Experimenters count the number of times that the neutrino stays a neutrino and the number of times it changes into a muon. The ratio of these numbers is very accurately predicted from our theories of the Universe, which have been verified to a part per thousand accuracy in the interactions of particles other than neutrinos. Surprise! The number of times that a neutrino stayed a neutrino was not as high as expected. It's very close though; only about 1% of the interactions were missing. To explain the discrepancy between their very precise findings and their expectations, NuTeV experimenters wonder if their neutrinos have felt a new force previously unobserved in nature, or if there is some hitherto undiscovered particle influencing neutrino interactions. Physicists in the United States, Japan and Europe are planning a next generation of neutrino experiments which may solve the puzzles we've discussed here, or they may find even more puzzles!
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Pierre Auger Observatory
Dr. Brian Connolly, Dr. Michael Prouza, Assoc. Prof. Stefan Westerhoff
One of today's great scientific mysteries is the origin of cosmic ray particles with energies beyond 1020 eV (about 20 Joules), the highest energy particles observed in the universe. The existence of particles at these energies continues to challenge our imagination: where do they come from, how do astrophysical objects produce them or accelerate them to these energies, and how can they travel astronomical distances without substantial loss of energy?
The Pierre Auger Observatory in Malargue, Argentina (http://www.auger.org) measures the energy spectrum, arrival direction and composition of cosmic rays above 1018 eV. At these energies, the particles cannot be observed directly, but only by measuring the huge particle cascade ("air shower") they induce in the Earth's atmosphere.
The Auger Observatory is a "hybrid detector," employing two independent methods to detect and study high-energy cosmic rays. One technique is ground-based and detects high energy particles using an array of 1,600 water tanks that cover a large section of the Pampa Amarilla. When a shower particle crosses a water tank, it produces Cherenkov light which can be measured by photomultiplier tubes mounted in the tanks.
The charged particles in an air shower also interact with atmospheric nitrogen, causing it to emit ultraviolet light via a process called fluorescence, which is observed by the Auger Observatory's optical detectors. The observatory's second detection method uses these detectors to observe the trail of nitrogen fluorescence and track the development of air showers by measuring the brightness of the emitted light.
The Pierre Auger Observatory is currently under construction and will be completed in the summer of 2006. At this point, it is already the world's largest cosmic ray experiment. Data taking began in January 2004.
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ZEUS
Dr. William Schmidke, Professor Frank Sciulli
ZEUS is an experiment at the world's only electron-proton collider, HERA, operating at the DESY laboratory in Hamburg, Germany. The ZEUS detector is a sophisticated tool for studying the particle reactions provided by the high-energy beams of the HERA accelerator.
ZEUS is a high resolution microscope looking inside the proton at distances as small as 10-16cm, or 1000 times smaller than the proton size. The high energies offered by HERA permit one to probe deep inside the proton in order to study the distribution of its constituents, the quarks and gluons. The HERA accelerator, after a successful eight-year running period, is currently being upgraded in order to deliver higher numbers of electron-proton collisions (Luminosity) in a second running period starting this summer. The main goal of ZEUS during this new run is to test the Standard Model of electroweak interactions at the highest possible momentum transfer.
The ZEUS group at Nevis is currently leading the construction of a new detector for ZEUS, the Luminosity Spectrometer which will accurately monitor the luminosity provided by HERA. Accurate knowledge of the luminosity is essential for all physics measurements performed by ZEUS. The luminosity measurement is based on the reaction ep -> ep+photon. The goal of the Luminosity Spectrometer is to measure the rate of high-energy photons from this reaction.
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