Accomplishments

Accomplishments INDX

2007

At the Energy Frontier . . .

  • The CDF and D-Zero detectors at Fermilab have collected over 20 times more data in Run II of the Tevatron collider than that of all of Run I (1992-1996). CDF has reported the world’s first observation of the very rapid particle-antiparticle oscillations of the heavy B mesons that contain a strange quark (called “Bs mesons”). D-Zero has a slightly less sensitive measurement that is in agreement with the CDF result. The results are based on 1.0 fb-1 of integrated luminosity, about two-thirds of the collected data. This result supplies additional information independent of the precision measurements of B-meson mixing done at the B-factory. The measured rate of Bs-meson oscillations is consistent with the Standard Model range of predictions.

At the Intensity Frontier . . .

  • The MINOS collaboration has announced their first observation of the oscillation of muon neutrinos using the NuMI beamline. This result validates the performance of the MINOS detector and the NuMI beam, based on the neutrinos produced by 1 ? 1020 protons colliding with the neutrino production target. The measurement is the most precise in the world, and is consistent with previous measurements, reaffirming the current picture of neutrino masses and oscillations. The experiment is planned to run through 2010 to achieve its ultimate sensitivity, about a factor of two improvement over its current result.
  • In 2007, the SLAC B-factory delivered 90 fb-1 (inverse femtobarns) of which the BaBar detector recorded 86.5 fb-1. The BaBar collaboration analyzed and presented the latest results at the major biennial summer research conference in 2007. The quantum mixing of D-zero particles with their anti-particles was discovered, along with unexpected particle resonances which are challenging the conventional picture of how quarks and gluons form stable bound states.
  • BaBar has made substantial progress on a comprehensive set of measurements for CP-violating asymmetries, a systematic exploration of rare decay processes, and detailed studies to elucidate the dynamics of processes involving heavy quarks. Combined data from BaBar and Belle have continued to explore hints of possible new physics beyond the Standard Model which were present in the early data in a class of B meson decays to particles (such as K mesons) which contain the strange quark. Though most of these hints of new physics have not increased in significance in the interim, neither have they gone away. These detectors will double their current datasets by 2008, which will provide ample opportunities for discovery.

At the Cosmic Frontier . . .

  • First light from the Very Energetic Radiation Imaging Telescope Array System (VERITAS) was observed in 2007, with the telescope installed at the Whipple Observatory in Arizona. This facility is now one of the world’s leading ground-based gamma-ray observatories.
  • The Large Area Telescope (LAT), a DOE and NASA partnership and the primary instrument on NASA’s GLAST mission, was completed in 2006 and is scheduled for launch from Kennedy Space Center in fall 2007. It will begin full data operations in 2008. SLAC led the DOE participation in the fabrication of the LAT and will run the instrument science operations center during the data-taking phase.
  • The DOE contribution to the fabrication of the Very Energetic Radiation Imaging Telescope Array System (VERITAS) was completed in 2006, with the telescope installed on a temporary basis at the Whipple Observatory in Arizona, while NSF is completing the arrangement for a permanent site for the final installation. The array will undergo engineering operations at this site through 2008 before moving to a permanent site by 2009.
  • The Cryogenic Dark Matter Search (CDMS II) experiment completed installation of its full complement of 5 kg-sized towers of silicon and germanium detectors in the Soudan Mine in Minnesota beginning in mid-2005. Preliminary results were reported in 2005 from data-taking with two towers (comprising about 2 kg of active detectors), setting new world-record limits on the existence of massive dark matter particles in our galaxy, entering the realm of supersymmetric masses and interaction cross sections. The full experiment will take data through 2007, setting limits about 10 times more sensitive than its existing ones in the search for dark matter particles, well into the realm where new particles are predicted by many models of supersymmetry.

In Theory . . .

  • High precision numerical simulations of the strong interactions of quarks and gluons, Quantum Chromodynamics (QCD), are producing accurate and reliable predictions of strong interaction decay constants and mass differences. These results, which use supercomputer simulations of QCD, include the important but difficult to calculate “virtual quark” effects in the underlying field theory. In some important cases, the agreement between the calculated and experimental values has reached the experimental uncertainty itself. This is a major success of the theory of strong interactions, and is an improvement by nearly an order of magnitude over previous calculations. These breakthroughs have been accomplished by the application of new, highly efficient algorithms combined with the use of today’s supercomputers and dedicated clusters of PC’s.
  • Recently, powerful new techniques have been developed to reliably calculate high-energy strong interaction processes that will be measured at the LHC. These procedures came from studying the most esoteric branch of theoretical high energy physics: “string theory.” In traditional calculations, one calculates only one or two of the largest terms in an infinite series; but these new approaches, some of which are based on analytic methods that had their origins in quantum gravity or string theory, calculate the entire infinite set of terms so that more accurate predictions can be made.

In Advanced Technology . . .

  • There has been significant progress on alternate physical mechanisms of charged particle acceleration. In particular, current experiments at SLAC address the potential feasibility of a particle-driven plasma wakefield “afterburner” that could one day potentially double the energy of a linear accelerator beam in only a few meters of plasma. An accelerating gradient 1,000 times that now possible in conventional accelerators has been measured in an 85 centimeter long plasma channel for a net energy gain in excess of 40 GeV. The acceleration of positrons (anti-electrons) by particle driven plasma wake fields has also been demonstrated, an essential step if the plasma accelerators are to ever be applied to electron-positron colliders.
  • At LBNL, a laser-driven plasma wakefield experiment has successfully trapped a bunch of electrons in a plasma and accelerated them to energies of 1 GeV in a few millimeters. The process creates an electron bunch in which the distribution of individual electron energies is very narrow, within a few percent of the average energy of the bunch. This is an important step forward from the earlier experiments that produced bunches with 100% energy spread and is an essential step in developing a useful accelerator.

2008

At the Energy Frontier . . .

  • Important recent physics results from the CDF and D-Zero detectors at Fermilab include the production of single top quarks, one of the rarest collision processes ever observed at a hadron collider; a new measurement of the top quark mass, which when combined with a new precise measurement of the W mass places increasingly strong bounds on the Standard Model Higgs mass; the first observation of events that simultaneously produce a W boson and a Z boson, an important milestone in the search for the Higgs boson; and the discovery of new particles containing quarks from each of the three different families. The innovative analysis methods employed by CDF and D-Zero scientists, and thorough understanding of detector performance and backgrounds displayed in these results, bode well for future discoveries.

At the Intensity Frontier . . .

  • The MiniBooNE experiment reported its findings and resolved questions about results from the Liquid Scintillator Neutrino Detector (LSND) experiment in the 1990’s. All neutrino oscillation results from around the world could be explained by a simple model of three types of neutrinos oscillating among themselves. MiniBooNE researchers showed conclusively that the LSND results could not be due to simple neutrino oscillations, and that a proposed new type of neutrino does not exist.

At the Cosmic Frontier . . .

  • The Large Area Telescope (LAT), a DOE and NASA partnership and the primary instrument on NASA’s GLAST mission, was tested and integrated into its launch vehicle in 2007 and is scheduled for launch from Kennedy Space Center in mid-2008. It will begin full operations late in 2008 and continue taking data for at least five years. SLAC led the DOE participation in the fabrication of the LAT and will run the instrument science operations center during the data-taking phase.
  • The Pierre Auger cosmic ray detector array in Argentina, a collaboration with the NSF and international partners, completed fabrication of its full array in 2007 and is now in full scale operations. The array covers an area of 3,000 square kilometers and is the largest of its kind in the world. Its purpose is to observe and study the very highest energy cosmic rays in the universe. The Auger experiment announced in November 2007 a major step forward in solving the long-standing mystery of the nature and origin of the highest energy cosmic rays: the collaboration traced the sources of the highest energy cosmic rays to the locations of nearby galaxies that have active galactic nuclei in their centers.

In Theory . . .

  • Another recent development is the discovery of a correspondence between string theory in multi-dimensional space and conventional field theories in four dimensions. This insight enables completion of many previously intractable model calculations, which in turn illuminate physics related to quark-gluon plasmas and high energy scattering processes.

In Advanced Technology . . .

  • At LBNL, a laser-driven plasma wakefield experiment has successfully trapped a bunch of electrons in a plasma and accelerated them to energies of 1 GeV in a few millimeters. The process creates an electron bunch in which the distribution of individual electron energies is very narrow, within a few percent of the average energy of the bunch. This is an important step forward from the earlier experiments that produced bunches with 100% energy spread and is an essential step in developing a useful plasma-based accelerator.

2009

At the Energy Frontier . . .

  • For the first time since the Large Electron-Positron (LEP) collider at CERN last operated in 2000, researchers are again treading on unexplored Higgs territory with the Tevatron Collider experiments at Fermilab. Recently, combined results from the Tevatron Collider experiments have started to exclude a region of Higgs mass between 170 and 181 times the mass of the proton. As more data is collected at the Tevatron, either this exclusion region will expand or the first possible hints of the Higgs boson will appear.
  • The Tevatron Collider experiments, CDF and D-Zero, have observed rare Standard Model processes such as double Z boson production, simultaneous W and Z boson production, and single top quark production. The observation of these rare processes is a necessary precursor for the discovery of the Higgs boson. In addition, the Tevatron has also recently produced the most precise measurements of top quark and W boson parameters, which are used to further constrain new physics theories. The innovative analysis methods employed by CDF and D-Zero scientists and the thorough understanding of detector performance and backgrounds displayed in these results also support future discoveries.

At the Intensity Frontier . . .

  • A groundbreaking ceremony was held in May 2009 at the site of the NO?A neutrino detector in northern Minnesota. The NO?A project will fabricate the NuMI Off-Axis Electron Neutrino Appearance (NO?A) detector near the Ash River, about 40 miles southeast of International Falls. This 14,000-ton particle detector is optimized to identify electron-type neutrinos and, using the NuMI beam from Fermilab, will observe for the first time the transformation of muon-type neutrinos into electron-type neutrinos. Fabrication of the NO?A detector was initiated in 2007, and is planned to be complete in 2014. Operations are planned to begin with a partially completed detector in 2013.
  • Operations of the Large Hadron Collider (LHC) began in late 2009 after a year-long shutdown to repair electrical problems discovered in its initial start-up. The energy of the machine was ramped up to a center-of-mass energy of 2.36 TeV, surpassing the Tevatron Collider as the world’s highest energy accelerator, although initial luminosity is very low as the machine is being carefully commissioned. Both the ATLAS and CMS large detectors have observed events and are taking data with fully functional detectors. The LHC is expected to increase its energy and accumulate much more data in 2010 with its first physics run.
  • Over the past several years, the B-factories in the U.S. and Japan have discovered several unexpected new particles which contain a charm quark and a charm antiquark. However, the masses and decay patterns of these new states do not fit within the theoretical expectations from Quantum ChromoDynamics (QCD) for standard strongly bound quark-antiquark states, and the evidence for some of these new states is controversial and in need of independent confirmation. These recently discovered exotic particles may be hybrid quark-antiquark-gluon states, loosely bound “molecules” of conventional charmed mesons, or four quark states. The exploration of this unforeseen new spectroscopy is an essential step towards fully understanding QCD. Studies of these exotic hadrons with the full B-factory datasets are ongoing.

At the Cosmic Frontier . . .

  • In 2009, the Large Area Telescope (LAT), the primary instrument on NASA’s Fermi Gamma-ray Space Telescope (FGST) mission, performed outstandingly delivering data that has resulted in over 35 peer reviewed publications and motivated a week-long workshop to present and discuss what these results mean for astronomy, astrophysics, and particle physics. The initial results from FGST were selected by the editors of Science magazine as the runner-up “Breakthrough of the Year” for 2009, noting, “The Fermi Telescope has … revealed, with unprecedented detail, a very restless high-energy universe, and it is solving old mysteries while making new, unexpected discoveries.” The international LAT collaboration released an all-sky survey which shows the universe as seen in high-energy gamma rays (see the figure below). The LAT was a joint DOE and NASA project. SLAC led the DOE participation in the fabrication of the LAT and operates the instrument science operations center while data are taken. Fermi Gamma-ray Space Telescope image of the night sky as seen in high-energy gamma rays
  • The Cryogenic Dark Matter Search (CDMS) experiment announced in late 2009 the final results of the first phase of their experiment, based on several years of data taking with a few kilograms of ultra-sensitive silicon and germanium detectors that can detect extremely rare dark matter interactions. They found two events in their signal region, but this could be a statistical fluctuation of the expected background due to naturally-occuring radioactivity. An upgraded 15 kg detector with improved background rejection is in fabrication (SuperCDMS) and will be installed and operated in 2010 to confirm or deny the tantalizing initial results. Other experiments using different techniques are also actively exploring this region.

In Theory . . .

  • The 2008 Nobel Prize in Physics, announced in October 2008, was shared by Yoichiro Nambu for his theoretical work discovering how symmetry breaking can manifest itself in nature. His work was supported by HEP.
  • High precision numerical simulations of the strong interactions of quarks and gluons, Quantum Chromodynamics (QCD), are producing accurate and reliable predictions of strong interaction decay constants and mass differences. These results, which use supercomputer simulations of QCD, include the important but difficult to calculate “virtual quark” effects in the underlying field theory. In some important cases, the agreement between the theoretical and experimental values has reached the level of the experimental uncertainty itself. This is a major success of the theory of strong interactions and is an improvement by nearly an order of magnitude over previous calculations. These breakthroughs have been accomplished by the application of new, highly efficient algorithms combined with the use of today’s supercomputers and dedicated clusters of personal computers. The support for these research breakthroughs has come from ongoing efforts in the core HEP theory research program, as well as the SciDAC program for high-performance software, and investments in dedicated computing hardware to enable fast and reliable calculations.

In Advanced Technology . . .

  • A collaboration of laboratories, universities, and small businesses has significantly advanced the state of the art for accelerating gradients in normal-conducting accelerating cavities, which is approximately 50 MeV per meter. This effort is directed towards reducing the size and cost of future TeV-scale lepton colliders. At ANL, an intense pulse of electrons was used to excite a microwave field of 100 MeV per meter in a dielectric-loaded accelerating structure. An MIT-designed photonic band-gap accelerating structure also achieved 100 MeV per meter. SLAC has demonstrated 150 MeV per meter in a single-cell, standing-wave copper structure.
  • An example of a novel detector technology that was recently developed with DOE support is a large-area single photon sensor with extremely low radioactivity. These new photodetectors will enable cost-effective scale-up of highly sensitive photon detectors (such as dark matter detectors) that require large active volumes along with extremely low backgrounds from naturally-occurring radioactivity. This technology has a patent application pending and is being commercialized.


2010

At the Energy Frontier . . .

• The Tevatron Collider experiments, CDF and D-Zero, continue to observe rare Standard Model processes such as double Z boson production, simultaneous W and Z boson production, and single top quark production. As more data is collected and better techniques are developed, Tevatron researchers continue to refine their measurements of top quark and W boson parameters, which are used to further constrain new physics theories. The innovative analysis methods employed by CDF and D-Zero scientists and their thorough understanding of detector performance and backgrounds are opening new opportunities for discoveries. For example, the D-Zero collaboration announced in the spring of 2010 indications of a possible anomalous CP violation in the mixing of neutral B mesons.

• Operations of the LHC began in late 2009 after a year-long shutdown to repair electrical problems discovered in its initial start-up. The energy of the machine was ramped up to a center-of-mass energy of 7 TeV in March 2010, surpassing the Tevatron Collider as the world’s highest energy accelerator, although initial luminosity was very low as the machine is being carefully commissioned. Both the ATLAS and CMS large detectors are collecting data with full functionality. Results from first data have already been published, and the LHC experiments presented their first Standard Model “re-discovery” results showing observation of expected W and Z boson and top quark events during summer 2010. The LHC has increased its luminosity dramatically over the course of 2010 and is expected to accumulate much more data in 2011 during its first physics run.

At the Intensity Frontier . . .

• Two Fermilab neutrino experiments, MINOS and MiniBooNE, have collected data with an antineutrino beam and reported first results. Although statistically limited, an initial analysis of the data offers tantalizing hints regarding the fundamental properties of neutrinos, which may be an indication of new physics in the neutrino sector.

At the Cosmic Frontier . . .

• In FY 2010, the Large Area Telescope (LAT), the primary instrument on NASA’s Fermi Gammaray Space Telescope (FGST) mission, continued to perform outstandingly. In March 2010, the LAT collaboration showed that less than a third of gamma-ray emission arise from black-hole powered jets from active galaxies, previously suspected as the primary source. Instead it could come from particle acceleration in star-forming galaxies or clusters of galaxies that are merging. Another possibility, which would need much more work to determine, is that it comes from gamma ray production from dark matter particle interactions.

• The FGST identified stringent limits on Lorentz invariance violations (LIV) predicted by some quantum gravity and string models. Lorentz invariance—the idea that the laws of physics are the same to observers everywhere in the universe—is one of the bedrock principles of physics. On May 9, 2009, the FGST observed a gamma-ray burst (GRB) about 10 billion light-years away with a 30 GeV gamma-ray arriving 0.8 seconds after the initial X-ray burst. Since linear LIV models predict a measurable variation of light speed with photon energy, the short delay time between the beginning of the GRB and the gamma-ray arrival severely constrains these models.


In Theory . . .

• Theorists continue to improve simulation tools for LHC experiments. In particular, calculations of next-leading-order Standard Model processes using BlackHat (software primarily developed at SLAC and University of California, Los Angeles) and those using other calculation tools primarily developed at Fermilab show excellent agreement with each other.

• In collaboration with their experimental colleagues, theorists at Rutgers University developed a technique for detecting a particle whose decay chain produced only hadronic final states. The search algorithm was tested successfully with top quark data from the Tevatron. This method may prove useful for new particle searches at the LHC.

• Harvard theorists identified a variable called “jet pull” which may be used to distinguish the color flow in jets. If successful, this will make it possible to distinguish b-jets produced in Higgs (color singlet) decay from the b-jets produced in gluon (color octet) decay, thus making it easier to identify a Higgs signal from the vast background.

In Advanced Technology . . .

• An example of a novel technology developed in 2010 with DOE support is the water based liquid scintillator. By sulfonating linear alkyl benzene, a common chemical used to make detergent, to linear alkylbenzene sulfonate, a water-soluble biodegradable surfactant detergent, a water based scintillator can be created. The characteristics of this scintillator are now being studied at BNL for possible future applications for large scintillator detectors in high energy physics.

• As part of the ILC R&D effort, a consortium of DOE laboratories successfully increased the quality of superconducting radiofrequency (SRF) accelerator cavities, with production accelerator gradients now commonly approaching the benchmark level of 35 MeV per meter. This program also successfully initiated lab-industry partnerships to develop the production of cavities in U.S. industry and improve processing of the cavities at DOE laboratories. SRF is the technology of choice for a number of future accelerator projects and the increasingly higher yields will improve performance and reduce cost for these next generation accelerators.

Last modified: 5/29/2014 9:30:01 AM