Scientists using the world’s largest atom smasher have created some of the hottest and densest matter ever achieved on Earth achieving a state of matter called a quark gluon plasma that existed in the milliseconds after the big bang 13.7 billion years ago.
Physicists using the Large Hadron Collider (LHC) at CERN, the European Centre for Nuclear Research, smashed heavy lead ions together at close to the speed of light, generating temperatures of more than 1.6 trillion degrees Celsius, 100,000 times hotter than the center of the Sun.
In the process they recreated the densest material ever observed – only black holes are denser.
The results were announced at the Quark Matter Conference recently held in Annecy, France – helping scientists to understand the evolution of the early universe recreating the conditions at the Big Bang.
In its infancy, just microseconds after the Big Bang, the universe was so hot and dense these quarks -the fundamental building blocks of matter- and gluons existed freely and unbound. The new results confirm that quark gluon plasma acts almost like a fluid, with minimal viscosity. The results are based on analysis of data collected during the last two weeks of the 2010 LHC run, when the atom smasher switched from colliding hydrogen protons to lead-ions.
The LHC heavy-ion program builds on experiments conducted more than a decade earlier at CERN’s Super Proton Synchrotron accelerator, which saw hints that a quark gluon plasma could be created and studied in the laboratory.
Then, in 1999, the US Brookhaven National Laboratory’s Relativistic Heavy-Ion Collider established that a quark gluon plasma could be created on a miniscule scale.
“This state of matter doesn’t exist anywhere naturally on Earth and is thought to only now occur during the collision of two neutron stars,” reported Professor Geoffrey Taylor, from the University of Melbourne and part of the scientific team involved with the Large Hadron Collider’s Atlas Detector, “This will help our understanding of the dynamics of the astrophysical processes taking place as a star collapses.
“Looking at how particle jets and subatomic particles like W and Z bosons are created in heavy lead ion collisions compared to lighter hydrogen proton collisions gives us an insight into the conditions that existed in a quark gluon plasma when the universe was just milliseconds old,” Taylor added.
“These collisions are also generating antimatter, which will help us try to understand why we live in a stable universe of matter when equal amounts of matter and antimatter were created in the big bang,” he concluded. “It takes our understanding of things that are happening in the cosmos one step further.”
CERN Large Hadron Collider is once again smashing protons, taking data
May 11, 2016
Following its annual winter break, the most powerful collider in the world has been switched back on.
Geneva-based CERN’s Large Hadron Collider (LHC)—an accelerator complex and its experiments—has been fine-tuned using low-intensity beams and pilot proton collisions, and now the LHC and the experiments are ready to take an abundance of data.
The goal is to improve our understanding of fundamental physics, which ultimately in decades to come can drive innovation and inventions by researchers in other fields.
Scientists from SMU’s Department of Physics are among the several thousand physicists worldwide who contribute on the LHC research.
“All of us here hope that some of the early hints will be confirmed and an unexpected physics phenomenon will show up,” said Ryszard Stroynowski, SMU professor and a principal investigator on the LHC. “If something new does appear, we will try to contribute to the understanding of what it may be.”
SMU physicists work on the LHC’s ATLAS experiment. Run 1 of the Large Hadron Collider made headlines in 2012 when scientists observed in the data a new fundamental particle, the Higgs boson. The collider was then paused for an extensive upgrade and came back much more powerful than before. As part of Run 2, physicists on the Large Hadron Collider’s experiments are analyzing new proton collision data to unravel the structure of the Higgs.
The Higgs was the last piece of the puzzle for the Standard Model—a theory that offers the best description of the known fundamental particles and the forces that govern them. In 2016 the ATLAS and CMS collaborations of the LHC will study this boson in depth.
Over the next three to four months there is a need to verify the measurements of the Higgs properties taken in 2015 at lower energies with less data, Stroynowski said.
“We also must check all hints of possible deviations from the Standard Model seen in the earlier data—whether they were real effects or just statistical fluctuations,” he said. “In the long term, over the next one to two years, we’ll pursue studies of the Higgs decays to heavy b quarks leading to the understanding of how one Higgs particle interacts with other Higgs particles.”
In addition, the connection between the Higgs Boson and the bottom quark is an important relationship that is well-described in the Standard Model but poorly understood by experiments, said Stephen Sekula, SMU associate professor. The SMU ATLAS group will continue work started last year to study the connection, Sekula said.
“We will be focused on measuring this relationship in both Standard Model and Beyond-the-Standard Model contexts,” he said.
SMU physicists also study Higgs-boson interactions with the most massive known particle, the top-quark, said Robert Kehoe, SMU associate professor.
“This interaction is also not well-understood,” Kehoe said. “Our group continues to focus on the first direct measurement of the strength of this interaction, which may reveal whether the Higgs mechanism of the Standard Model is truly fundamental.”
All those measurements are key goals in the ATLAS Run 2 and beyond physics program, Sekula said. In addition, none of the ultimate physics goals can be achieved without faultless operation of the complex ATLAS detector, its software and data acquisition system.
“The SMU group maintains work on operations, improvements and maintenance of two components of ATLAS—the Liquid Argon Calorimeter and data acquisition trigger,” Stroynowski said.
Intensity of the beam to increase, supplying six times more proton collisions
Following a short commissioning period, the LHC operators will now increase the intensity of the beams so that the machine produces a larger number of collisions.
“The LHC is running extremely well,” said CERN Director for Accelerators and Technology, Frédérick Bordry. “We now have an ambitious goal for 2016, as we plan to deliver around six times more data than in 2015.”
The LHC’s collisions produce subatomic fireballs of energy, which morph into the fundamental building blocks of matter. The four particle detectors located on the LHC’s ring allow scientists to record and study the properties of these building blocks and look for new fundamental particles and forces.
This is the second year the LHC will run at a collision energy of 13 TeV. During the first phase of Run 2 in 2015, operators mastered steering the accelerator at this new higher energy by gradually increasing the intensity of the beams.
“The restart of the LHC always brings with it great emotion”, said Fabiola Gianotti, CERN Director General. “With the 2016 data the experiments will be able to perform improved measurements of the Higgs boson and other known particles and phenomena, and look for new physics with an increased discovery potential.”
New exploration can begin at higher energy, with much more data
Beams are made of “trains” of bunches, each containing around 100 billion protons, moving at almost the speed of light around the 27-kilometre ring of the LHC. These bunch trains circulate in opposite directions and cross each other at the center of experiments. Last year, operators increased the number of proton bunches up to 2,244 per beam, spaced at intervals of 25 nanoseconds. These enabled the ATLAS and CMS collaborations to study data from about 400 million million proton–proton collisions. In 2016 operators will increase the number of particles circulating in the machine and the squeezing of the beams in the collision regions. The LHC will generate up to 1 billion collisions per second in the experiments.
“In 2015 we opened the doors to a completely new landscape with unprecedented energy. Now we can begin to explore this landscape in depth,” said CERN Director for Research and Computing Eckhard Elsen.
Between 2010 and 2013 the LHC produced proton-proton collisions with 8 Tera-electronvolts of energy. In the spring of 2015, after a two-year shutdown, LHC operators ramped up the collision energy to 13 TeV. This increase in energy enables scientists to explore a new realm of physics that was previously inaccessible. Run II collisions also produce Higgs bosons—the groundbreaking particle discovered in LHC Run I—25 percent faster than Run I collisions and increase the chances of finding new massive particles by more than 40 percent.
But there are still several questions that remain unanswered by the Standard Model, such as why nature prefers matter to antimatter, and what dark matter consists of, despite it potentially making up one quarter of our universe.
The huge amounts of data from the 2016 LHC run will enable physicists to challenge these and many other questions, to probe the Standard Model further and to possibly find clues about the physics that lies beyond it.
The physics run with protons will last six months. The machine will then be set up for a four-week run colliding protons with lead ions.
“We’re proud to support more than a thousand U.S. scientists and engineers who play integral parts in operating the detectors, analyzing the data, and developing tools and technologies to upgrade the LHC’s performance in this international endeavor,” said Jim Siegrist, Associate Director of Science for High Energy Physics in the U.S. Department of Energy’s Office of Science. “The LHC is the only place in the world where this kind of research can be performed, and we are a fully committed partner on the LHC experiments and the future development of the collider itself.”
The four largest LHC experimental collaborations, ALICE, ATLAS, CMS and LHCb, now start to collect and analyze the 2016 data. Their broad physics program will be complemented by the measurements of three smaller experiments—TOTEM, LHCf and MoEDAL—which focus with enhanced sensitivity on specific features of proton collisions.
“Professionals” coming out today in an article about the peeling crust into the Asthenosphere causing earthquakes in the Southeast United States… while telling people on the East coast and Southeast that they do NOT NEED an earthquake plan or to prepare.
Telling people they don’t need to have a plan for an earthquake in an area where earthquakes are picking up?
This is asinine.
Meanwhile, I had to remove my East coast earthquake warning last night (now below my youtube video instead of here on facebook).
Chunks of Earth’s Mantle Are ‘Peeling Off’
Scientists suspect that chunks from the bottom of the North American tectonic plate, which is the upper portion of the mantle, are peeling off and sinking. Replacing the resulting void is gooey material from the asthenosp
An odd phenomenon may explain why the Southeastern United States has experienced recent earthquakes, even though the region sits snugly in the middle of a tectonic plate and not at the edges, where all the ground-shaking action usually happens.
This seismicity — or relatively frequent earthquakes — may be the result of areas along the bottom of the North American tectonic plate peeling off, the researchers said. And this peeling motion is likely to continue, leading to more earthquakes in the future, like the 2011 magnitude-5.8 temblor that shook the nation’s capital. [Image Gallery: This Millennium’s Destructive Earthquakes]
To figure out the cause of these earthquakes, Berk Biryol, a seismologist at UNC Chapel Hill, and colleagues created 3D images of the uppermost part of Earth’s mantle, which is just below the crust and comprises the bottom of a tectonic plate. These tectonic plates scoot around atop a layer of warm, viscous fluid called the asthenosphere.
The resulting X-ray images revealed that the plate’s thickness in the southeast United States was uneven, with thick regions of dense, old rock combined with thinner areas composed of younger rocks that were also less dense.
Here’s what the researchers think caused the wonkiness: Over time, as new material was added to the plate and parts of the plate were pulled apart, areas of higher density formed. Gravity would have pulled down the denser areas into the mantle, and at some point chunks would have broken off to sink into the gooey asthenosphere below, the researchers speculated.
At the same time, to fill the void left by the chunks peeling off from the bottom of the plate, the lighter material in the asthenosphere would have moved up to fill in the space. That buoyant material then would have cooled to become the thinner, younger section of the plate.
Where parts of the plate broke off or peeled, it became thinner and more prone to slip along fault lines, thus causing seismic activity. Biryol estimates that this activity has occurred for the past 65 million years or so.
“These events, usually, when they occur, they occur over long periods of time. The geological time scale is millions of years,” Biryol said.
While the research looks only at what has occurred in the past, and not what seismic activity there may be in the future, Biryol said people living in the Southeast don’t need earthquake preparedness kits just yet.
“I don’t think things will be changing in the future, at least not in our lifetimes or our grandchildren’s grandchildren’s life,” Biryol told Live Science. “Geological processes take place over long periods of time and nothing will change dramatically overnight.”