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Saturday, 29 November 2014

YOUNG VOLCANOES ON THE MOON

Nov 24, 2014: Back in 1971, Apollo 15 astronauts orbiting the Moon photographed something very odd.  Researchers called it "Ina," and it looked like the aftermath of a volcanic eruption. 
There's nothing odd about volcanoes on the Moon, per se.  Much of the Moon's ancient surface is covered with hardened lava. The main features of the "Man in the Moon," in fact, are old basaltic flows deposited billions of years ago when the Moon was wracked by violent eruptions. The strange thing about Ina was its age.
Planetary scientists have long thought that lunar volcanism came to an end about a billion years ago, and little has changed since. Yet Ina looked remarkably fresh. For more than 30 years Ina remained a mystery, a "one-off oddity" that no one could explain.
Turns out, the mystery is bigger than anyone imagined. Using NASA's Lunar Reconnaissance Orbiter, a team of researchers led by Sarah Braden of Arizona State University has found 70 landscapes similar to Ina.  They call them "Irregular Mare Patches" or IMPs for short.
"Discovering new features on the lunar surface was thrilling!" says Braden. "We looked at hundreds of high-resolution images, and when I found a new IMP it was always the highlight of my day."
"The irregular mare patches look so different than more common lunar features like impact craters, impact melt, and highlands material," she says.  "They really jump out at you."
On the Moon, it is possible to estimate the age of a landscape by counting its craters.  The Moon is pelted by a slow drizzle of meteoroids that pepper its surface with impact scars.  The older a landscape, the more craters it contains.
Some of the IMPs they found are very lightly cratered, suggesting that they are no more than 100 million years old. A hundred million years may sound like a long time, but in geological terms it's just a blink of an eye. The volcanic craters LRO found may have been erupting during the Cretaceous period on Earth--the heyday of dinosaurs. Some of the volcanic features may be even younger, 50 million years old, a time when mammals were replacing dinosaurs as dominant lifeforms.
"This finding is the kind of science that is literally going to make geologists rewrite the textbooks about the Moon," says John Keller, LRO project scientist at the Goddard Space Flight Center.
IMPs are too small to be seen from Earth, averaging less than a third of a mile (500 meters) across in their largest dimension.  That's why, other than Ina, they haven't been found before.  Nevertheless, they appear to be widespread around the nearside of the Moon.
"Not only are the IMPs striking landscapes, but also they tell us something very important about the thermal evolution of the Moon," says Mark Robinson of Arizona State University, the principal investigator for LRO's high resolution camera. "The interior of the Moon is perhaps hotter than previously thought."
"We know so little of the Moon!" he continues. "The Moon is a large mysterious world in its own right, and its only three days away! I would love to land on an IMP and take the Moon's temperature first-hand using a heat probe."
Some people think the Moon looks dead, "but I never thought so," says Robinson, who won't rule out the possibility of future eruptions. "To me, it has always been an inviting place of magnificent beauty, a giant magnet in our sky drawing me towards it."
Young volcanoes have only turned up the heat on the Moon's allure. Says Robinson … "let's go!"
Credits:
Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit: Science@NASA

Monday, 17 November 2014

WHERE’S ALL THE ANTIMATTER? by BRIAN KOBERLEIN on NOVEMBER 17, 2014

When we look around, everything we can see is made of matter. For every type of matter from electrons, protons and quarks there is a similar type of matter known as antimatter. So why aren’t there piles of antimatter rocks, cars and chocolate bars just lying around? Why does Scotty always have a little extra kicking around in his liquor cabinet? And where do I get mine?
The primary difference between matter and antimatter is that they have opposite electric charge. Which seems pretty mundane. The negatively charged electron has an antiparticle known as the positron, which has a positive electric charge.
Anti-protons have a negative charge, and are just flat out grumpy. We’ve been able to create these particles in the lab, and have even been able to create small amounts of anti-hydrogen consisting of a positron bound to an antiproton, when examined closely there’s were shown to have a goatee and a little colorful sash or dagger.
When we create particles in accelerators such as the Large Hadron Collider, we seem to get equal amounts of matter and antimatter. This suggests that when particles were formed soon after the big bang, there should have been equal amounts of matter and antimatter.
But the universe we observe is only made of matter, and… here’s the best part… we have no idea why. Why didn’t the matter and antimatter completely annihilate each other? How come we ended up with a little more matter? This delightful mystery is known as baryon asymmetry.
We do have a few ideas, and by we, I mean some giant brained crackerjacks have come up with a few plausible options. The most popular is that somehow antimatter behaves a little differently than matter. This could cause an imbalance between matter and antimatter. After particles collided in the early universe, there would still be matter left over, hence the matter we observe.
Another idea is that the observable universe just happens to be in a region dominated by matter. Other parts of the multiverse could have observable universes dominated by antimatter. Baryon asymmetry is one of the big mysteries of modern cosmology.
There is an even crazier idea. Antimatter might have anti-gravity. In other words, an atom of anti-hydrogen would fall up instead of down. If that is the case, then matter and antimatter would repel each other, and you might have matter universes and antimatter universes that are forever separate.There have been some initial experiments to test this idea, but so far there have been no conclusive results.

What do you think? Where’s all our antimatter and how do we track it down? I’d sure love to bring some home and show my friends

Friday, 14 November 2014

X-ray telescopes find black hole may be a neutrino factory 22 hours ago

(Phys.org) —The giant black hole at the center of the Milky Way may be producing mysterious particles called neutrinos. If confirmed, this would be the first time that scientists have traced neutrinos back to a black hole.
The evidence for this came from three NASA satellites that observe in X-ray light: the Chandra X-ray Observatory, the Swift gamma-ray mission, and the Nuclear Spectroscopic Telescope Array (NuSTAR).
Neutrinos are tiny particles that carry no charge and interact very weakly with electrons and protons. Unlike light or charged particlesneutrinos can emerge from deep within their cosmic sources and travel across the universe without being absorbed by intervening matter or, in the case of charged particles, deflected by magnetic fields.
The Earth is constantly bombarded with neutrinos from the sun. However, neutrinos from beyond the solar system can be millions or billions of times more energetic. Scientists have long been searching for the origin of ultra-high energy and very high-energy neutrinos.
"Figuring out where high-energy neutrinos come from is one of the biggest problems in astrophysics today," said Yang Bai of the University of Wisconsin in Madison, who co-authored a study about these results published in Physical Review D. "We now have the first evidence that an astronomical source – the Milky Way's supermassive black hole – may be producing these very energetic neutrinos."
Because neutrinos pass through material very easily, it is extremely difficult to build detectors that reveal exactly where the neutrino came from. The IceCube Neutrino Observatory, located under the South Pole, has detected 36 high-energy neutrinos since the facility became operational in 2010.
By pairing IceCube's capabilities with the data from the three X-ray telescopes, scientists were able to look for violent events in space that corresponded with the arrival of a high-energy neutrino here on Earth.
"We checked to see what happened after Chandra witnessed the biggest outburst ever detected from Sagittarius A*, the Milky Way's supermassive black hole," said co-author Andrea Peterson, also of the University of Wisconsin. "And less than three hours later, there was a neutrino detection at IceCube."
In addition, several neutrino detections appeared within a few days of flares from the supermassive black hole that were observed with Swift and NuSTAR.
"It would be a very big deal if we find out that Sagittarius A* produces neutrinos," said co-author Amy Barger of the University of Wisconsin. "It's a very promising lead for scientists to follow."
Scientists think that the highest energy neutrinos were created in the most powerful events in the Universe like galaxy mergers, material falling onto supermassive black holes, and the winds around dense rotating stars called pulsars.
The team of researchers is still trying to develop a case for how Sagittarius A* might produce neutrinos. One idea is that it could happen when particles around the black hole are accelerated by a shock wave, like a sonic boom, that produces charged particles that decay to neutrinos.
This latest result may also contribute to the understanding of another major puzzle in astrophysics: the source of high-energy cosmic rays. Since the charged particles that make up cosmic rays are deflected by magnetic fields in our Galaxy, scientists have been unable to pinpoint their origin. The charged particles accelerated by a shock wave near Sgr A* may be a significant source of very energetic cosmic rays.

Thursday, 6 November 2014

Breaking November 05, 2014 SCIENTISTS PROGRESS TOWARD PLASMA ACCELERATION Scientists have demonstrated the particle acceleration technique is powerful and efficient enough to drive future accelerators. 

Scientists have proven that a technique for accelerating particles on waves of plasma is efficient enough to power a new generation of shorter, more economical particle accelerators.
Using the Facility for Advanced Accelerator Experimental Tests (FACET) at SLAC National Accelerator Laboratory, scientists from SLAC and the University of California, Los Angeles, boosted bunches of electrons to energies 400 to 500 times higher than they could have reached traveling the same distance in a conventional accelerator. They were able to transfer energy to the electrons with an unprecedented level of efficiency.
Their results, described in Nature, could eventually lead to an expansion in the use of plasma wakefield acceleration in areas such as medicine, national security, industry and high-energy physics research.
“Many of the practical aspects of an accelerator are determined by how quickly the particles can be accelerated,” says SLAC accelerator physicist Mike Litos, lead author of the paper. “To put these results in context, we have now shown that we could use this technique to accelerate an electron beam to the same energies achieved in the 2-mile-long SLAC linear accelerator, in less than 20 feet.”
Plasma wakefields have been of interest to accelerator physicists for 35 years as one of the more promising ways to drive the smaller, cheaper accelerators of the future. The UCLA and SLAC groups have been at the forefront of research on plasma wakefield acceleration for more than a decade.
In this experiment, researchers sent pairs of electron bunches containing 5 billion to 6 billion electrons each into a laser-generated column of plasma inside an oven of hot lithium gas. The first bunch in each pair blasted all the free electrons away from the lithium atoms, leaving the positively charged lithium nuclei behind—a configuration known as the “blowout regime.” The blasted electrons then fell back in behind the second bunch of electrons, forming a “plasma wake” that propelled the trailing bunch to higher energy.
Previous experiments had demonstrated multi-bunch acceleration, but the team at SLAC was the first to reach the high energies of the blowout regime, where maximum energy gains at maximum efficiencies can be found. Of equal importance, the accelerated electrons wound up with a relatively small energy spread.
“These results have an additional significance beyond a successful experiment,” says Mark Hogan, SLAC accelerator physicist and one of the principal investigators of the experiment. It “has enabled us to increase the acceleration efficiency to a maximum of 50 percent—high enough to really show that plasma wakefield acceleration is a viable technology for future accelerators.”
The plasma source used in the experiment was developed by a team of scientists led by Chandrashekhar Joshi, director of the Neptune Facility for Advanced Accelerator Research at UCLA.
“It is gratifying to see that the UCLA-SLAC collaboration on plasma wakefield acceleration continues to solve seemingly intractable problems one by one through systematic experimental work,” Joshi says. “It is this kind of transformative research that attracts the best and the brightest students to this field, and it is imperative that they have facilities such as FACET to carry it out.”
There are more milestones ahead. Before plasma wakefield acceleration can be put to use, Hogan says, the trailing bunches must be shaped and spaced just right so all the electrons in a bunch receive exactly the same boost in energy, while maintaining the high overall quality of the electron beam.
“We have our work cut out for us,” Hogan says. “But you don’t get many chances to conduct research that you know in advance has the potential to be immensely rewarding, both scientifically and practically.”

Computer simulations used in the experiments were developed by Warren Mori’s group at UCLA. Additional contributors included researchers from SLAC, the University of Oslo in Norway, Tsinghua University in China and Max Planck Institute for Physics in Germany. The research was funded by the DOE Office of Science.

Tuesday, 28 October 2014

CHANDRA OBSERVATORY IDENTIFIES IMPACT OF COSMIC CHAOS ON STAR BIRTH Oct 27, 2014

(Phys.org) —The same phenomenon that causes a bumpy airplane ride, turbulence, may be the solution to a long-standing mystery about stars' birth, or the absence of it, according to a new study using data from NASA's Chandra X-ray Observatory.
Galaxy clusters are the largest objects in the universe, held together by gravity. These behemoths contain hundreds or thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees.
This hot gas, which is the heftiest component of the galaxy clusters aside from unseen dark matter, glows brightly in X-ray light detected by Chandra. Over time, the gas in the centers of these clusters should cool enough that stars form at prodigious rates. However, this is not what astronomers have observed in many galaxy clusters.
"We knew that somehow the gas in clusters is being heated to prevent it cooling and forming stars. The question was exactly how," said Irina Zhuravleva of Stanford University in Palo Alto, California, who led the study that appears in the latest online issue of the journal Nature. "We think we may have found evidence that the heat is channeled from turbulent motions, which we identify from signatures recorded in X-ray images."
Prior studies show supermassive black holes, centered in large galaxies in the middle of galaxy clusters, pump vast quantities of energy around them in powerful jets of energetic particles that create cavities in the hot gas. Chandra, and other X-ray telescopes, have detected these giant cavities before.
The latest research by Zhuravleva and her colleagues provides new insight into how energy can be transferred from these cavities to the surrounding gas. The interaction of the cavities with the gas may be generating turbulence, or chaotic motion, which then disperses to keep the gas hot for billions of years.
"Any gas motions from the turbulence will eventually decay, releasing their energy to the gas," said co-author Eugene Churazov of the Max Planck Institute for Astrophysics in Munich, Germany. "But the gas won't cool if turbulence is strong enough and generated often enough."
The evidence for turbulence comes from Chandra data on two enormous galaxy clusters named Perseus and Virgo. By analyzing extended observation data of each cluster, the team was able to measure fluctuations in the density of the gas. This information allowed them to estimate the amount of turbulence in the gas.
"Our work gives us an estimate of how much turbulence is generated in these clusters," said Alexander Schekochihin of the University of Oxford in the United Kingdom. "From what we've determined so far, there's enough turbulence to balance the cooling of the gas.
These results support the "feedback" model involving supermassive black holes in the centers of galaxy clusters. Gas cools and falls toward the black hole at an accelerating rate, causing the black hole to increase the output of its jets, which produce cavities and drive the turbulence in the gas. This turbulence eventually dissipates and heats the gas.
While a merger between two galaxy clusters may also produce turbulence, the researchers think that outbursts from supermassive black holes are the main source of this cosmic commotion in the dense centers of many clusters

Sunday, 26 October 2014

ICE FOUND ON MERCURY, THE CLOSEST PLANET TO THE SUN - Posted by Tim De Chant on Thu, 23 Oct 2014 in pbs.org

Astronomers have confirmed that ice exists on one of the least likely places in the solar system—Mercury.
The planet is among the solar system’s hottest—only Venus has higher average temperatures—thanks to the sun’s searing proximity, which raises temperatures to as high as 800˚ F. But hidden in the frigid shadows—where temperatures can sink as low as -280˚ F—are frozen patches that are the likely remains of icy comets which have blasted the rocky terrain over the last 100 million years.
Scientists have long suspected that Mercury is home to solid H2O, but recent photos taken by the MESSENGER probe confirm it. Here’s Michael Lemonick, reporting for Time:
These are the first optical images, and nobody is entirely sure how the ice got there. One idea is that it was released from water-bearing rock in Mercury’s crust. But the leading theory suggests it arrived instead in the form of impacts from icy comets, which may well be the same way Earth got its oceans. “It’s a fair amount of ice,” Chabot said, “about equivalent to the water in Lake Ontario, so if it was one comet, it was a pretty sizable one.” More likely, she said, it would have been a series of smaller comets, falling over billions of years.
Mercury’s extreme temperature fluctuations are thanks to its extremely thin atmosphere. The planet’s small mass means it has a hard time holding onto gas particles, and the sun’s intense rays do their best to blast away what little that does cling to the rocky world. If the planet had a denser atmosphere, it would more closely resemble Venus, where the thick sky keeps average temperatures above 860˚ F.
Mercury’s thin atmosphere gives scientists another unique opportunity. Next spring, MESSENGER will be able to fly just 12 miles above the surface without burning up. During that pass, it will take extraordinarily high-resolution images of the planet, giving scientists a unique window into a world of extremes.

Saturday, 25 October 2014

DECADES-OLD SCIENTIFIC PAPER MAY HOLD CLUES TO DARK MATTER - By Adrian Cho  24 October 2014 3:00 am

Here’s one reason libraries hang on to old science journals: A paper from an experiment conducted 32 years ago may shed light on the nature ofdark matter, the mysterious stuff whose gravity appears to keep the galaxies from flying apart. The old data put a crimp in the newfangled concept of a "dark photon" and suggest that a simple bargain-basement experiment could put the idea to the test.
No one really knows what dark matter is. Since the 1980s, theorists' best hunch has been that it consists of so-called weakly interacting massive particles, or WIMPs. If they exist, WIMPs would have a mass between one and 1000 times that of a proton. They would interact only through the feeble weak nuclear force—one of two forces of nature that ordinarily flex their muscle only within the atomic nucleus—and could disappear only by colliding and annihilating one another. So if the infant universe cooked up lots of WIMPs, enough of them would naturally survive to produce the right amount of dark matter today. But physicists have yet to spot WIMPs, which every now and then should ping off atomic nuclei in sensitive detectors and send them flying.
More recently, theorists have explored other ideas, such as self-interacting dark matter. This would consist of a particle, known as a χ (pronounced chi), with a mass between 1/1000 and one times that of the proton. Those particles would interact with one another through a force like the electromagnetic force, which produces light. That force would be conveyed by a massive particle called a dark photon—a dark matter version of a particle of light—that might "mix" slightly with the ordinary ones. So with some small probability, a dark photon might interact with ordinary charged particles such as electrons and atomic nuclei—just as ordinary photons do.
Self-interacting dark matter has attractive properties. In particular, a dark photon could also explain a particle physics puzzle. A particle called the muon appears to be very slightly more magnetic than theory predicts, and that discrepancy could be resolved if the muon interacts with dark photons lurking in the vacuum. However, χs and dark photons would be hard to detect with WIMP detectors; with their low masses, they couldn't whack a nucleus hard enough to create a signal.
But archival data already rule out dark photons with certain combinations of properties, argues Rouven Essig, a theoretical physicist at Stony Brook University in New York, and his colleagues. The data come from E137, a "beam dump" experiment that ran from 1980 to 1982 at SLAC National Accelerator Laboratory in Menlo Park, California. In the experiment, physicists slammed a beam of high-energy electrons, left over from other experiments, into an aluminum target to see what would come out. Researchers placed a detector 383 meters behind the target, on the other side of a sandstone hill 179 meters thick that blocked any ordinary particles. They then looked for hypothetical particles called axions, which would have pierced the earth and reached the detector—and saw none.
But electrons hitting the target should also have produced a beam of high-energy χs. A χ could have traversed the hill and interacted with an electron in the detector through a dark photon, blasting it into motion. The fact that E137 saw no recoiling electrons enabled Essig and his colleagues to nix some possible combinations of the dark photon's mass and the strength of its mixing with ordinary photons, as they report this week in Physical Review Letters. The results do not prove that the dark photon cannot exist at all, but they do put limits on its possible properties.
Other physicists have used archival data to test new dark matter theories. Last year, Philip Schuster, a theorist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, and a colleague used the result from another beam dump experiment at SLAC that ran in 1994 and 1995 to probe self-interacting dark matter. But the millicharge, or mQ, experiment was sensitive to χs sending atomic nuclei flying and set somewhat looser limits. "The electron-recoil limit looks a little better," Schuster says.
With certain assumptions, the analysis disfavors a dark photon with the properties needed to explain the muon's magnetism. But those assumptions could be loosened and the idea more thoroughly tested with a new experiment, Schuster says. He and roughly 80 other physicists hope to build a new beam dump experiment called BDX, which would look at 100 times as many events as E137 did. They have submitted a letter of intent to the Thomas Jefferson National Accelerator Facility in Newport News, Virginia, although the experiment could be staged elsewhere.
Compared with some particle physics experiments, BDX would be small and cheap, says Marco Battaglieri of Italy's National Institute for Nuclear Physics in Genoa and co-spokesman for the BDX team. "We are not talking about thousands of tons of detector," he says. "We are talking about a 1-ton detector." BDX would cost a few million dollars, Battaglieri says.
The study also suggests it's not so easy to dream up models of dark matter that don't run afoul of data already taken, Schuster says: "All of this has to be done in a very tight straitjacket."

Posted in Physics Dark Matter

Thursday, 23 October 2014

AUSTRALIA’S FIRST DARK MATTER EXPERIMENT A proposed dark matter experiment would use two underground detectors, one in each hemisphere - Glenn Roberts Jr.

Physicists are hoping to hit pay dirt with a proposed experiment—the first of its kind in the Southern Hemisphere—that would search for traces of dark matter more than a half mile below ground in Victoria, Australia.
The current plan, now being explored by an international team, is for two new, identical dark matter experiments to be installed and operated in parallel—one at an underground site at Grand Sasso National Laboratory in Italy, and the other at the Stawell Gold Mine in Australia.
“An experiment of this significance could ultimately lead to the discovery of dark matter,” says Elisabetta Barberio of the ARC Centre of Excellence for Particle Physics at the Terascale (CoEPP) and the University of Melbourne, who is Australian project leader for the proposed experiment.
The experiment proposal was discussed during a two-day workshop on dark matter in September. Work could begin on the project as soon as 2015 if it gathers enough support. “We’re looking at logistics and funding sources,” Barberio says.
The experiments would be modeled after the DAMA experiment at Gran Sasso, now called DAMA/LIBRA, which in 1998 found a possible sign of dark matter.
DAMA/LIBRA looks for seasonal modulation, an ebb and flow in the amount of potential dark matter signals it sees depending on the time of year.
If the Milky Way is surrounded by a halo of dark matter particles, then the sun is constantly moving through it, as is the Earth. The Earth’s rotation around the sun causes the two to spend half of the year moving in the same direction and the other half moving in opposite directions. During the six months in which the Earth and sun are cooperating, a dark matter detector on the Earth will move faster through the dark matter particles, giving it more opportunities to catch them.
This seasonal difference appears in the data from DAMA/LIBRA, but no other experiment has been able to confirm this as a sign of dark matter.
For one thing, the changes in the signal could be caused on other factors that change by the season.
“There are environmental effects—different characteristics of the atmosphere—in winter and summer that are clearly reversed if you go from the Northern to the Southern hemisphere,” says Antonio Masiero, vice president for the Italian National Institute of Nuclear Physics (INFN) and a member of the Italian delegation collaborating on the proposal, which also includes Gran Sasso Director Stefano Ragazzi. If the results matched up at both sites at the same time of year, that would help to rule out such effects.
The Australian mine hosting the proposed experiment could also house scientific experiments from different fields.
“It wouldn’t be limited to particle physics and could include experiments involving biology, geosciences and engineering,” Barberio says. “These could include neutrino detection, nuclear astrophysics, geothermal energy extraction and carbon sequestration, and subsurface imaging and sensing.”
Preliminary testing has begun at the mine site down to depths of about 880 meters, about 200 meters above the proposed experimental site. Regular mining operations are scheduled to cease at Stawell in the next few years.

The ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), the local government in the Victoria area, and the mine operators have joined forces with COEPP and INFN to support the proposal.