2012 - Finding the Higgs Boson, the Last Piece of the Standard Model of Physics
The Standard Model of physics, which explains how particles interact, was missing a major piece until quite recently. Scientists' difficulty finding it was throwing the entire model into question. In these landmark 2012 papers, scientists described detecting the missing piece, called the Higgs boson. While previous experiments set limits on where scientists should looks, these findings from the ATLAS and CMS experiments at the Large Hadron Collider were the first to identify a specific particle that matched all of the necessary characteristics. These experimental observations led to the 2013 Nobel Prize in Physics. In addition to completing the Standard Model, the presence of the Higgs boson also explains how the building blocks of our universe have mass.
G. Aad, et al. (ATLAS Collaboration), "Observation of a new particle in the search for the Standard Model Higgs Boson with the ATLAS Detector at the LHC." Physics Letters B 716, 1-29 (2012). [DOI: 10.1016/j.physletb.2012.08.020]
S. Chatrchyan, et al. (CMS Collaboration), "Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC." Physics Letters B 716, 30-61 (2012). [DOI: 10.1016/j.physletb.2012.08.021] (Image credit: Lawrence Livermore National Laboratory)
2011 - Setting the Cell in Motion
Getting to the atomic order of incredibly complex structures buried in the fatty membranes of cells isn't easy. In fact, the search for the structure of the G-protein-coupled receptors, which detect chemicals such as adrenaline, has consumed the better part of two decades. This landmark 2011 paper described, for the first time, the atomic structure of a G-protein-coupled receptor at work. This discovery was made possible by DOE's Advanced Photon Source. In this case, the team determined the structure of the receptor in the act of turning on a G-protein inside a cell. The receptor activates a G-protein based on the chemical it detects. That is, it conveys different messages to different cells based on what it detects. The receptors are involved in numerous responses to hormones and neurotransmitters throughout the body. Therefore, the receptors are a popular target for drugs. Research into the receptors earned Brian Kobilka as well as Robert Lefkowitz the 2012 Nobel Prize in Chemistry.
S.G.F. Rasmussen, B.T. DeVree, Y. Zou, A.C. Kruse, K.Y. Chung, T.S. Kobilka, F.S. Thian, P.S. Chae, E. Pardon, D. Calinski, J.M. Mathiesen, S.T.A Shah, J.A. Lyons, M. Caffrey, S.H. Gellman, J. Steyaert, G. Skiniotis, W.I. Weis, R.K. Sunahara, and B.K. Kobilka, "Crystal structure of the β2 adrenergic receptor–Gs protein complex." Nature 477, 549-555 (2011). [DOI: 10.1038/nature10361]. Subscription required: contact your local librarian for access. (Image credit: Adapted by permission from Macmillan Publishers Ltd: Nature, ©2011)
2011 - Creating an Electricity Sponge
Supercapacitors can store electrical energy quickly, release it superfast and last for thousands of recharges. Even with all of these advantages, supercapacitors aren't widely used. Why? They simply don't have as much storage capacity as batteries. This landmark 2011 paper offered a near atomic-resolution view of a new material that let a supercapacitor store more energy – with an energy density nearly equal to a lead-acid battery. This material – called activated graphene – had more surface area than other forms of graphene. The surface area was the result of the formation of a network of tiny pores, some just a nanometer wide. The pore walls were made of carbon just one atom thick. In some ways, the structure resembled inside-out buckyballs. The incredibly detailed view of the activated graphene material was created using microscopes and other instruments at three DOE scientific user facilities.
Y. Zhu, S. Murali, M.D. Stoller, K.J. Ganesh, W. Cai, P.J. Ferreira, A. Pirkle, R.M. Wallace, K.A. Cychosz, M. Thommes, D. Su, E.A. Stach, and R.S. Ruoff, "Carbon-based supercapacitors produced by activation of graphene." Science 323(6037), 1537-1541 (2011). [DOI: 10.1126/science.1200770]. Subscription required: contact your local librarian for access. (Photo credit: Brookhaven National Laboratory)
2010 - Changing up the Sheets and Electrons
In 2010, scientists were starting to build ultrathin sheets of materials. The sheets had far different properties than their larger counterparts. In these landmark 2010 papers, scientists described two properties of an amazing ultrathin sheet made from a layer of molybdenum atoms sandwiched between one-atom-thick sulfur layers. In the tiny sheets, electrons were more easily freed to conduct a current than in a larger block of the molybdenum-based material. This change in electron motion also let the material give off large quantities of light. The work offered new ways to control electrons. It opened doors for solar energy and computers, including making the smallest transistor ever.
K.F. Mak, C. Lee, J. Hone, J. Shan, and T.F. Heinz, "Atomically thin MoS2: A new direct-gap semiconductor." Physical Review Letters 105, 136805 (2010). [DOI: 10.1103/PhysRevLett.105.136805]. Subscription required: contact your local librarian for access.
A. Splendiani, L. Sun, Y. Zhang, T. Li, J. Kim, C.Y. Chim, G. Galli, and F. Wang, "Emerging photoluminescence in monolayer MoS2." Nano Letters 10, 1271-1276 (2010). [DOI: 10.1021/nl903868w]. Subscription required: contact your local librarian for access. (Image credit: Claire Ballweg, DOE)
2010 - Trapped Antihydrogen
If you can't contain it, you can't study it. That's the case with antimatter, an elusive substance that may hold secrets to matter, time and the universe. So far experiments, including work at CERN in Switzerland, had failed to confine antihydrogen. In this landmark 2010 paper, Gorm Andresen and his colleagues described the first experiments that trapped 38 antihydrogen atoms. Their work was enabled by plasma physics research and has opened the door to precise measurements of antihydrogen and other antimatter atoms.
G.B. Andresen, et al., "Trapped antihydrogen." Nature 468, 673-676 (2010). [DOI: 10.1038/nature09610]. Subscription required: contact your local librarian for access. (Image credit: Adapted by permission from Macmillan Publishers Ltd: Nature, ©2010)
2010 - Variety Is the Spice of MOFs
It's hard to hold a sparrow in a cage built for an elephant. The size and structure of the cage matter. The same is true when building molecular cages to capture and hold carbon dioxide or other gases. The problem scientists had was that they lacked the building materials necessary to create the right cages. In this landmark 2010 paper, scientists demonstrated new building materials to create molecular cages. These materials were essentially bars of different lengths. The bars, or linkers, were connected together to create intricately shaped cages, or metal-organic frameworks. The change in structure of these porous frameworks yielded impressive results. In one case, a framework made with linkers of different lengths was 400 percent better at capturing carbon dioxide than the best metal-organic framework (MOF) made from just one type of linker and the new framework ignored unwanted carbon monoxide.
H. Deng, C.J. Doonan, H. Furukawa, R.B. Ferreira, J. Towne, C.B. Knobler, B. Wang, and O.M. Yaghi, "Multiple functional groups of varying ratios in metal-organic frameworks." Science 327, 846-850 (2010). [DOI: 10.1126/science.1181761]. Subscription required: contact your local librarian for access. (Image credit: Boasap, Wikipedia [GFDL or CC-BY-SA-3.0] via Wikimedia Commons)
2010 - Search for the "Island of Stability" Passes through Tennessine
"Super heavy" elements are missing near the bottom of the periodic table. The elements aren't lost; they simply haven't been and probably won't be found in nature. Although a challenging task, scientists have created a number of these elements over the years. In this landmark 2010 paper, a U.S./Russian team reports the creation of element 117, called Tennessine. The second heaviest element to date, packed with 117 protons, Tennessine points to an "island of stability." On this isle, a region of the periodic chart, elements with the "magic number" of protons and neutrons become long-lived. While Tennessine, with a half-life of about 50 thousandths of a second, doesn't prove the island exists, its behavior offers encouraging signs as the hunt for the isle continues.
Y.T. Oganessian, et al., "Synthesis of a new element with atomic number Z=117." Physical Review Letters 104, 142502 (2010). [DOI: 10.1103/PhysRevLett.104.142502]. Subscription required: contact your local librarian for access. (Image credit: Oak Ridge National Laboratory)
2009 - A CHARMMing Computational Microscope
Tracking atoms and electrons in computer simulations created a tug of war between classical physics, which was simple to calculate but not detailed, and quantum physics, which was slow but detailed. This landmark 2009 paper described a software that married classical and quantum physics to simulate reactions. The result? Faster, higher resolution views of chemical reactions. The software is called Chemistry at Harvard Molecular Mechanics, CHARMM for short. Work began on CHARMM in the 1970s, and the software has had numerous developers and sponsors, including DOE. CHARMM is used on studies ranging from drug discovery to solar panels. Martin Karplus, a key force behind CHARMM, garnered a 2013 Nobel Prize in Chemistry with his colleagues Michael Levitt and Arieh Warshel.
B.R. Brooks, et al., "CHARMM: The biomolecular simulation program." Journal of Computational Chemistry 30(10), 1545-1614 (2009). [DOI: 10.1002/jcc.21287]. Subscription required: contact your local librarian for access. (Image credit: Claire Ballweg, DOE)
2009 - Decay Data and the Laws of the Universe
Since the early 1950s, scientists have been probing the Standard Model that describes the physical laws of our universe, such as magnetism. One way to learn more about our universe and the accuracy of the model is to study how certain atomic nuclei eject electrons via beta decay. The decay is caused by the weak force. The force is an integral part of the Standard Model. This landmark 2009 paper surveyed detailed measurements of 20 different superallowed beta decays. A superallowed decay means that there are more decays per unit time than expected. With these data, scientists tested our understanding of the weak force to unprecedented precision and set limits on the existence of new physics beyond the Standard Model.
J.C. Hardy and I.S. Towner, "Superallowed 0+ ---> 0+ nuclear beta decays: A new survey with precision tests of the conserved vector current hypothesis and the standard model." Physical Review C 79, 05502 (2009). [DOI: 10.1103/PhysRevC.79.055502]. Subscription required: contact your local librarian for access. (Image credit: public domain)
2009 - Things Are Different on the Inside
Scientists thought topological insulators were possible, but couldn't prove it. In this odd state of matter, a material's interior doesn't conduct electrons but the surface does. This landmark 2009 paper showed that a bismuth-and-tellurium-based material (Bi2Te3) was a topological insulator. At rates even better than predicted, this easy-to-make material conducted small amounts of electricity without loss at room temperature. This work sparked new ideas about how to make faster computer chips. Tools at the Advanced Light Source and Stanford Synchrotron Radiation Lightsource, both DOE scientific user facilities, made the work possible.
Y.L. Chen, J.G. Analytis, J.H. Chu, Z.K. Liu, S.K. Mo, X.L. Qi, H.J. Zhang, D.H. Lu, X. Dai, Z. Fang, S.C. Zhang, I.R. Fisher, Z. Hussain, and Z.X. Shen, "Experimental realization of a three-dimensional topological insulator, Bi2Te3." Science 325, 178-181 (2009). [DOI: 10.1126/science.1173034]. Subscription required: contact your local librarian for access. (Image credit: Yulin Chen and Z.X. Shen)
2009 - How to Make Dense, Complex Copolymers
Imagine trying to build a train track without the ties to hold it together. For scientists, that's what creating long, dense polymers was like — the individual pieces (called monomers) were in place, but no method existed to link and secure the structure. This landmark 2009 paper offered insights into a new blueprint to construct such well-organized materials, known as brush block copolymers. The key to success was a ruthenium-based catalyst. It efficiently connected the different monomers and allowed control of the polymer's structure simply based on the proportions of the building blocks and how they assembled. The results from this approach opened doors for the preparation of compact, long-chain polymers, which have potential uses in manipulating light.
Y. Xia, B.D. Olsen, J.A. Kornfield, and R.H. Grubbs, "Efficient synthesis of narrowly dispersed brush copolymers and study of their assemblies: The importance of side chain arrangement." Journal of the American Chemical Society 131, 18525-18532 (2009). [DOI: 10.1021/ja908379q]. Subscription required: contact your local librarian for access. (Image credit: Reprinted with permission, ©2009: American Chemical Society)
2005 - The Blueprints for the Cell's Protein Factory
At the beginning of this century, the chemical assembly line that cells use to form life's building blocks – proteins – wasn't well defined. Understanding that assembly line is key to combatting disease, by disabling the ribosomes in bacteria. This landmark 2005 paper, which used two DOE light sources, shed light on the assembly line. The scientists defined how a ribosome, the cell's protein factory, quickly connects amino acids to create proteins. Yale University professor Thomas Steitz received the 2009 Nobel Prize in Chemistry for his contributions to ribosomal research.
T.M. Schmeing, K.S. Huang, D.E. Kitchen, S.A. Strobel, and T.A. Steitz, "Structural insights in the roles of water and the 2' hydroxyl of the P site tRNA in the peptidyl transferase reaction." Molecular Cell 20, 437-448 (2005). [DOI: 10.1016/j.molcel.2005.09.006]. (Image credit: Protein by Emw (own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons. Modified by Claire Ballweg, DOE)
2005 - Higher Levels of Carbon Dioxide Led to Greater Tree Growth
How forests would respond to higher levels of carbon dioxide was one of the biggest uncertainties in early climate models. This landmark 2005 paper gave researchers far more confidence in those models by providing data from actual forests. Researchers examined how increasing levels of carbon dioxide in the air influence tree growth. Using a shared framework, they showed a 23 percent average increase in how much carbon trees took up at the levels of carbon dioxide estimated in 2050. In addition, it showed these results were consistent across forests with different structures and growth rates.
R.J. Norby, et al., "Forest response to elevated CO2 is conserved across a broad range of productivity." Proceedings of the National Academies of Sciences 102, 18052-18056 (2005). [DOI: 10.1073/pnas0509478102]. Subscription required: contact your local librarian for access. (Image credit: Oak Ridge National Laboratory)
2005 - Speeding Up Searches through Giant Datasets
Like trying to find a particular sentence in a thick book, finding exactly the right pieces of data in a vast collection can be extremely time-consuming. However, huge, complex datasets with numerous characteristics are far easier to search with a unique indexing technology called FastBit. This landmark 2005 paper described how researchers and programmers from DOE's Lawrence Berkeley National Laboratory developed the FastBit software. When it was first released in 2005, FastBit analyzed read-only scientific datasets 10 to 100 times faster than comparable commercial software. Originally designed to help particle physicists sort through billions of data records to find a few key pieces of information, FastBit has since been used to develop applications that analyze everything from combustion data to Yahoo!'s web content to financial data.
K. Wu, "FastBit: An efficient indexing technology for accelerating data-intensive science." Journal of Physics: Conference Series 16, 556 (2005). [DOI: 10.1088/1742-6596/16/1/077]. (Image credit: U.S. Department of Energy)
2005 - Free Quarks and Gluons Make the "Perfect Liquid"
Just after the Big Bang, quarks and gluons – the fundamental building blocks of atomic nuclei – were free and unrestricted. Only a few microseconds later, they started forming into the protons and neutrons that (with electrons) make up atoms today. While scientists theorized that this free "quark-gluon plasma" was a weakly interacting gas, results published in this landmark 2005 paper contradicted that idea. Scientists reported that when the Relativistic Heavy Ion Collider replicated these early conditions, the free quarks and gluons interacted strongly. They created a "perfect" liquid that flowed with almost zero resistance. In addition to revealing information about the universe's earliest moments, this discovery gave scientists insight into other forms of matter, including ordinary solids.
STAR Collaboration, J. Adams, et al., "Experimental and theoretical challenges in the search for quark gluon plasma: The STAR Collaboration's critical assessment of the evidence from RHIC collisions." Nuclear Physics A 757, 102 (2005). [DOI: 10.1016/j.nuclphysa.2005.03.085]. Subscription required: contact your local librarian for access.
PHENIX Collaboration, K. Adcox, et al., "Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration." Nuclear Physics A 757, 184-283 (2005). [DOI: 10.1016/j.nuclphysa.2005.03.086]. Subscription required: contact your local librarian for access. (Image credit: Brookhaven National Laboratory)
2002 - The Asymmetry Between Matter and Antimatter
Physics aims to determine the laws of the universe that everything should reliably follow. Except sometimes, things don't follow the rules. In charge-parity violation, particles and their antiparticles (same particle but opposite charge) don't act the same, even though the laws of physics in the early 1960s predicted that they should. While an experiment in 1964 showed the first evidence for charge-parity violation for a single type of particle, this landmark 2002 paper showed that charge-parity violation was more widespread by observing it in another particle, the B meson. This experimental observation paved the way for the 2008 Nobel Prize in Physics and played an important role in exploring why the early universe favored matter over antimatter.
B. Aubert, et al., "Measurement of the CP Asymmetry Amplitude sin2β with B0 mesons." Physical Review Letters 89, 201802-1-7 (2002). [DOI: 10.1103/PhysRevLett.89.201802]. Subscription required: contact your local librarian for access. (Image credit: Peter Ginter, SLAC)
2002 - Discovery that Solar Neutrino s Change Type Shows Neutrino s Have Mass
Neutrino experiments in the 1960s detected fewer neutrinos from the sun than expected. Although originally thought to be massless, a theory proposed in 1985 suggested that if neutrinos had mass they could also change between three types as they travel. In 1998, the Super-Kamiokande experiment showed that neutrinos created in the atmosphere changed type as they traveled. This changing of neutrino types could explain the apparent deficit of solar neutrinos for detectors only sensitive to one of the three types. The Sudbury Neutrino Observatory was built to solve this problem by being sensitive to all neutrino types. This landmark 2002 paper, which contributed to the 2015 Nobel Prize in Physics, described the discovery that neutrinos produced by the sun change type as they travel and therefore must have mass. This process, called neutrino oscillation, continues to be studied and may provide insight into why matter dominates the universe today even though the Big Bang produced matter and antimatter in equal amounts.
Q.R. Ahmad, et al., "Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory." Physical Review Letters 89, 011301 (2002). [DOI: 10.1103/PhysRevLett.89.011301]. Subscription required: contact your local librarian for access. (Image credit: Brookhaven National Laboratory)
2001 - Sequencing the Human Genome
One hundred years ago, lacking knowledge of our genetic code, the medical field simply didn't understand a major influence on health and illness. Today scientists regularly sequence DNA, leading to the ability to adapt medical treatments to individuals' genetics and analyze genomes of many other species. This 2001 blockbuster paper reported the initial sequencing of the vast majority (94 percent) of human genetic material (DNA). Because the Human Genome Project made the data available to the scientific community without restriction, it spurred a broad range of discoveries, creating an estimated $800 billion in economic impact. The Human Genome Project, conceived and initiated by DOE in 1985, has had far-reaching implications for energy, manufacturing, environmental and medical science, and the establishment of the scientific field of genomics.
E.S. Lander, et al., "Initial sequencing and analysis of the human genome." Nature 409, 860-921 (2001). [DOI: 10.1038/35057062]. Subscription required: contact your local librarian for access. (Image credit: Jonathan Bailey)
1999 - Supernovae Provide Evidence the Expansion of the Universe is Speeding Up
Until the dawn of the 21st century, scientists assumed the universe's expansion was slowing down as gravity pulled debris from the Big Bang back together. But now scientists know that the universe's expansion is speeding up, driven by an unknown cause referred to as "dark energy." This landmark 1999 paper reported measurements from Type la supernovae – which all reach the same maximum brightness when they explode – that indicated expansion is speeding up. These observations found that distant Type la supernovae were 25 percent less bright than they "should" be if the universe's expansion is slowing down. The discovery of the accelerating expansion of the universe was recognized with the 2011 Nobel Prize in Physics.
S. Perlmutter, et al., "Measurements of omega and lambda from 42 high-redshift supernovae." The Astrophysical Journal 517, 565-586 (1999). [DOI: 10.1086/307221]. (Image credit: NASA)
1999 - The Sounds and the Energy
In 1816, Scottish minister Robert Stirling devised a way to use sound to drive an engine. But the design was too expensive to produce at the time. Over the years, scientists reconsidered Stirling's ideas but with limited success. Enter Scott Backhaus, a postdoctoral fellow at DOE's Los Alamos National Laboratory, and engineer Greg Swift. In this landmark 1999 paper, they described a simple, energy-efficient engine with no moving parts. The engine used heat and compressed helium to produce intense sound waves, or acoustic energy. The acoustic energy can be used in certain types of refrigerators or to produce electricity. The device was more efficient than similar heat engines and was comparable to combustion engines. This work led to significant interest in using sound waves to produce energy.
S. Backhaus and G.W. Swift, "A thermoacoustic Stirling heat engine." Nature 399, 335-338 (1999). [DOI: 10.1038/20624]. (Image credit: Adapted Claire Ballweg, DOE, by permission from Macmillan Publishers Ltd: Nature (see citation), ©1999)
1998 - Tracking Down the Ghosts of the Universe
When this paper was written in 1998, the Standard Model wasn't complete. Ghost-like neutrinos – particles that mostly pass through all matter, move at near light speed and have no charge – weren't behaving as scientists expected because fewer were seen from the sun than predicted. This landmark 1998 paper, which contributed to the 2015 Nobel Prize in Physics, answered a conundrum about neutrinos produced in Earth's atmosphere. Specifically, this result from the Super-Kamiokande experiment proved that the type of neutrinos produced in the atmosphere were changing into other types of neutrinos as they traveled. In doing so, the scientists also showed that neutrinos must have mass. This process of neutrinos changing type, called neutrino oscillation, provided a way to help understand the dramatic difference between the numbers of predicted and observed solar neutrinos. In 2002, the Sudbury Neutrino Observatory experiment provided the remaining pieces of the solar neutrino puzzle.
Y. Fukuda, et al., "Evidence for oscillation of atmospheric neutrinos." Physical Review Letters 81, 1562-1567 (1998). [DOI: 10.1103/PhysRevLett.81.1562]. (Image credit: Nathan Johnson, PNNL)
1997 - Math Wins the Heart of an Atom
For years, determining the interactions involving individual protons or neutrons required intense calculations based on a series of assumptions about the particles and fields involved. This landmark 1997 paper offered a more sophisticated approach that took advantage of increasing computational power to answer questions about the reactions and structures at the heart of an atom. The new computational approach, quantum Monte Carlo, allows researchers to see the splendor of the nuclear shell structure emanating directly from the interactions between protons and neutrons. This theoretical work and related advanced computer algorithms opened the doors for scientists using computer simulations to examine and predict the energy levels of some atomic nuclei.
B.S. Pudliner, V.R. Pandharipande, J. Carlson, S.C. Pieper, and R.B. Wiringa, "Quantum Monte Carlo calculations of nuclei with A<~7." Physical Review C 56, 1720 (1997). [DOI: 10.1103/PhysRevC.56.1720]. Subscription required: contact your local librarian for access. (Image credit: Argonne National Laboratory, CC BY-NC-SA 2.0)
1997 - Simplifying Speed
While supercomputers have split up the work and assigned it to different processors since 1982, coding these systems was time-consuming, error-prone, and required a high level of expertise. This landmark publication describes the PETSc 2.0 software, or the Portable, Extendable Toolkit for Scientific Computation. It made it easier to program networks using parallel processing, whether in supercomputers or conventional computers networked together. The toolkit brought together fundamental routines needed to run scientific models that use multiple unknown variables. Thousands of models have used the PETSc suite, including ones that describe air movement over airplane wings, water flowing across the Everglades.
S. Balay, W.D. Gropp, L.C. McInnes, and B.F. Smith, "Efficient management of parallelism in object-oriented numerical software libraries." Chapter 10 in E. Arge, A.M. Bruaset and H.P. Langtangen (Eds), Modern Software Tools in Scientific Computing, pp. 163-202 (1997). Contact your local librarian for access. (Image credit: National Energy Research Scientific Computing Center)
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