cosmic rays

Rogue Cosmic Rays From Outer Space Are Causing Havoc With Our Smartphones

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And it’s getting worse.

Under Earth’s protective magnetic field, we don’t usually need to worry too much about the health effects of cosmic radiation – although it’s something that’s known to impact astronauts in space, and even passengers travelling in airplanes.

But the same can’t be said for our technological systems – fierce solar storms can wreak havoc on Earth’s communication networks, and new research shows that even ordinary levels of cosmic radiation can have a disruptive effect on our personal devices.

“This is a really big problem, but it is mostly invisible to the public,” says electrical engineer Bharat Bhuva from Vanderbilt University.

To see just how big the problem is, Bhuva and his team took 16-nanometre computer chips – the kind used in many of today’s consumer PCs – and exposed them to a neutron beam, in an attempt to replicate what happens when cosmic radiation penetrates our atmosphere.

When cosmic rays collide with Earth’s magnetic field, they create cascades of secondary particles – including energetic neutrons, muons, and pions.

Millions of these particles strike our bodies every second, and while they aren’t thought to have any effect on our health, they can interfere with the operation of microelectronic circuitry.

In particular, when they interact with integrated circuits, they can actually alter or ‘flip’ individual bits of data stored in memory – a phenomenon that’s called a single-event upset (SEU).

Most of the time, such an event probably wouldn’t create much of a problem. An app running on your smartphone or PC might glitch somehow, making a miscalculation, but it’s probably not something you’ll notice for more than a moment.

But in some cases, SEUs could have drastic and potentially far-reaching consequences.

In 2003, a ‘bit flip’ in a Belgian electronic voting machine gave one candidate in the election an extra 4,096 votes, before the mistake was caught.

Even more worrying – the avionics system of a Qantas passenger jetmalfunctioned due to a suspected SEU in 2008, forcing the aircraft into an abrupt dive that injured about a third of the passengers on board.

Bhuva’s research was sponsored by a number of microelectronics companies, and the results are proprietary – meaning they’re unlikely to be published any time soon.

But in a presentation of key trends in the findings at a meeting of the American Association for the Advancement of Science in Boston last Friday, he explained that as technology advances and transistors get ever smaller, the likelihood of SEUs due to cosmic rays is increasing.

“[S]emiconductor manufacturers are very concerned about this problem because it is getting more serious as the size of the transistors in computer chips shrink and the power and capacity of our digital systems increase,” says Bhuva.

“In addition, microelectronic circuits are everywhere and our society is becoming increasingly dependent on them.”

Ultimately, smaller transistors are more vulnerable to energetic particles, because they require less electrical charge to represent a logical bit – which means they flip between binary states (from 0 to 1, or vice versa) more easily when they’re struck by cosmic rays.

On the other hand, today’s transistors are smaller than ever, so they’re actually less likely to be hit by flying energy particles. Contemporary transistors are also assembled in 3D designs, that help to make them less individually susceptible to SEUs.

But since today’s computer chips include significantly higher numbers of these smaller transistors overall, at the device level, the risk of an SEU occurring is greater than ever, Bhuva says.

So, what’s the solution? Unfortunately, shielding chips from energy particles isn’t an option, as it would take more than 3 metres (10 feet) of concrete to prevent transistors from being struck. 
According to Bhuva, the answer is for device manufacturers to design systems that include three processors in place of one. In rare cases where two chips tell you one thing, and the third tells you another, majority rules – as the errant third result would likely be due to an SEU.

Plugging that hole will ultimately mean our devices run smoother than ever – but in the meantime, there’s no need to lose any sleep over your smartphone being hit by a rogue particle strike.

“This is a major problem for industry and engineers,” Bhuva says, “but it isn’t something that members of the general public need to worry much about.”

THE USE OF COSMIC RAYS WILL DISCOVER THE SECRETS OF PYRAMIDS

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Scientist will use cosmic rays to unveil Egypt’s pyramids secrets and finally show how the they were built.

Scientists from all over the world started ‘Scan Pyramids’ project, to find chambers, construction techniques and discover new tombs.

The scientists from Egypt, France, Canada and Japan, using modern infra-red technology and advanced detectors. They also hope to discover the queen Nefertiti’s tomb.

Minister of Antiquities Mamduh al-Damati announced:

“This special group will study these pyramids to see whether there are still any hidden chambers or other secrets inside them. These engineers and architects will conduct the survey using non-destructive technology that will not harm the pyramids.”

Deep-Space Radiation Could Damage Astronauts’ Brains .

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Cosmic rays could leave travelers to Mars confused, forgetful and slow to react

As NASA develops plans for a manned mission to Mars, scientists said Friday that cosmic rays during an interplanetary voyage could cause subtle brain damage, leaving astronauts confused, forgetful and slow to react to the unexpected.

In a NASA-funded study of radiation-exposed mice published Friday in Science Advances, researchers at the University of California, Irvine and the University of Nevada warned that prolonged bombardment by charged particles in deep space could affect the brain cells involved in decision-making and memory, with implications for possible manned forays into deep space.

“These sorts of cognitive changes could manifest during the mission and could be a real problem,” said Cary Zeitlin at the Southwest Research Institute in San Antonio, who wasn’t involved in the study. In 2013, Dr. Zeitlin reported radiation levels between Earth and Mars detected by the Mars Science Laboratory craft during its cruise to the red planet, and found that the exposure was the equivalent of getting “a whole-body CT scan once every 5 or 6 days.”

Deep-space radiation is a unique mix of gamma rays, high-energy protons and cosmic rays from newborn black holes, and radiation from exploding stars. Earth’s bulk, atmosphere and magnetic field blocks or deflects most deep-space cosmic rays. Shielding on spacecraft also helps.

In 54 years of human spaceflight, astronauts have rarely experienced a full dose. Apollo crews, who ventured furthest from Earth’s protective shield on their journeys to the Moon, reported seeing flashes of light when they closed their eyes, caused by galactic cosmic rays speeding through their retinas.

Researchers at the National Aeronautics and Space Administration have studied the potential health hazards of space radiation for decades, including the elevated risk of cancer. But it has been hard to simulate the behavioral effects of prolonged exposure to low levels of radiation that would be encountered by interplanetary travelers.

Although NASA funded the new experiment, the agency declined requests for interviews with its own radiation experts.

A NASA representative instead issued a written statement: “NASA recognizes the importance of understanding the effects of space radiation on humans during long-duration missions beyond Earth orbit, and these studies and future studies will continue to inform our understanding as we prepare for the journey to Mars.”

To test the neural effects of deep-space travel, a dozen researchers led by UC Irvine radiation oncologist Charles Limoli briefly exposed mice to charged particles in a radiation beam at the U.S. Department of Energy’s Brookhaven National Laboratory in Upton, N.Y. Six weeks later, they tested the irradiated mice and found the lab animals lacked normal curiosity, were less active, and became more easily confused, compared with a control group, the researchers said.

“Their curiosity is way down,” said Dr. Limoli. “They don’t want to explore novelties.”

The researchers found the mice had damaged neurons and synapses in areas associated with memory and decision-making, such as the hippocampus and prefrontal cortex.

“I don’t think our findings preclude future space missions,” Dr. Limoli said. “But they suggest we need to come up with some engineering solutions.”

Where do the highest-energy cosmic rays come from? Not from gamma-ray bursts, says IceCube study.

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The IceCube neutrino telescope encompasses a cubic kilometer of clear Antarctic ice under the South Pole, a volume seeded with an array of 5,160 sensitive digital optical modules (DOMs) that precisely track the direction and energy of speeding muons, massive cousins of the electron, which are created when neutrinos collide with atoms in the ice. The IceCube Collaboration recently announced the results of an exhaustive search for high-energy neutrinos that would likely be produced if the violent extragalactic explosions known as gamma-ray bursts (GRBs) are the source of ultra-high-energy cosmic rays.

“According to a leading model, we would have expected to see 8.4 events corresponding to GRB production of neutrinos in the IceCube data used for this search,” says Spencer Klein of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), who is a long-time member of the IceCube Collaboration. “We didn’t see any, which indicates that GRBs are not the source of ultra-high-energy cosmic rays.”

“This result represents a coming-of-age of neutrino astronomy,” says Nathan Whitehorn from the University of Wisconsin-Madison, who led the recent GRB research with Peter Redl of the University of Maryland. “IceCube, while still under construction, was able to rule out 15 years of predictions and has begun to challenge one of only two major possibilities for the origin of the highest-energy cosmic rays, namely gamma-ray bursts and active galactic nuclei.”

Redl says, “While not finding a neutrino signal originating from GRBs was disappointing, this is the first neutrino astronomy result that is able to strongly constrain extra-galactic astrophysics models, and therefore marks the beginning of an exciting new era of neutrino astronomy.”

The IceCube Collaboration’s report on the search appears in the April 19, 2012, issue of the journal Nature.

Blazing fireballs and nature’s accelerators

Cosmic rays are energetic particles from deep in outer space – predominately protons, the bare nuclei of hydrogen atoms, plus some heavier atomic nuclei. Most probably acquire their energy when naturally accelerated by exploding stars. A few rare cosmic rays pack an astonishing wallop, however, with energies prodigiously greater than the highest ever attained by human-made accelerators like CERN’s Large Hadron Collider. Their sources are a mystery.

“Nature is capable of accelerating elementary particles to macroscopic energies,” says Francis Halzen, IceCube’s principal investigator and a professor of physics at the University of Wisconsin-Madison. “There are basically only two ideas on how she does this: in gravitationally driven particle flows near the supermassive black holes at the centers of active galaxies, and in the collapse of stars to a black hole, seen by astronomers as gamma ray bursts.”

 

Klein, the deputy director of Berkeley Lab’s Nuclear Science Division (NSD, explains that in active galactic nuclei (AGNs) “the black holes suck in matter and eject enormous particle jets, perpendicular to the galactic disk, which could act as strong linear accelerators.” Of gamma-ray bursts he says, “Some GRBs are thought to be collapses of supermassive stars – hypernova – while others are thought to be collisions of black holes with other black holes or neutron stars. Both types produce brief but intense blasts of radiation.”

The massive fireballs move away from the explosion at nearly the speed of light, releasing most of their energy as gamma rays. The fireballs that give rise to this radiation might also accelerate particles to very high energies through a jet mechanism similar to that in AGNs, although compressed into a much smaller volume.

Accelerated protons in a GRB’s jets should interact with the intense gamma-ray background and strong magnetic fields to produce neutrinos with energies about five percent of the proton energy, together with much higher-energy neutrinos near the end of the acceleration process.

 

Neutrinos come in three different types that change and mix as they travel to Earth; the total flux can be estimated from the muon neutrinos that IceCube concentrates on. The muons these neutrinos create can travel up to 10 kilometers through the Antarctic ice. Thus many neutrino interactions occur outside the actual dimensions of the IceCube array but are nevertheless visible to IceCube’s detectors, effectively enlarging the telescope’s aperture.

“The way we search for GRB neutrinos is that we build a huge detector and then we just watch and wait,” says Klein. “When it comes to detecting neutrinos, size really does matter.”

IceCube watches with its over 5,000 DOMs, digital optical modules conceived, designed, and proven by Berkeley Lab physicists and engineers, which detect the faint light from each passing muon. Scientists can rely on their remarkable dependability to wait as long as necessary. Almost no failures occurred after the DOMs were installed; 98 percent are working perfectly and another one percent are usable. Now frozen in the ice, they will never be seen again.

IceCube records a million times more muon tracks moving downward through the ice than upward, mainly debris from direct cosmic-ray hits on the surface or secondary products of cosmic-ray collisions with Earth’s atmosphere. Muons moving upward, however, signal neutrinos that have passed all the way through Earth. When the telescope is searching for bright neutrino sources in the northern sky, the planet makes a marvelous filter.

Zeroing in on gamma-ray bursts

A network of satellites circles the globe and reports almost 700 GRBs each year, which readily stand out from the cosmic background. They’re timed, their positions are triangulated, and the data are distributed by an international group of researchers. Some blaze for less than two seconds and others for a few minutes. Neutrinos they produce should arrive at IceCube during the burst or close to it.

“IceCube’s precision timing and charge resolution, plus its large size, allow it to precisely determine where a neutrino comes from – often to within one degree,” says Lisa Gerhardt of Berkeley Lab, whose research has focused on detecting ultra-high-energy neutrino interactions. Indeed, a GRB neutrino should send a muon track through the ice with an angular resolution of about one degree with respect to the GRB’s position in the sky.

IceCube researchers sifted through data on 307 GRBs from two periods in 2008 and 2009 when IceCube was still under construction, looking for records of muon trails coincident in time and space with GRBs. (Forty strings, with 60 DOMs each, had been installed by 2008, and 59 strings by 2009. The finished IceCube has 86 strings.) The fireball model predicted that when the expected flux from all the samples had been summed, at least 8.4 related muon events would be found within 10 degrees of a GRB during the seconds or minutes when it was blazing brightly.

“Different calculations of the neutrino flux from GRBs are based on slightly different assumptions about how the neutrinos are produced and on uncertainties such as how fast the fireball is moving toward us,” says Klein. “Among the published predictions, the lowest estimate of neutrino production is about a quarter of what the fireball model predicts. That’s barely consistent with our zero observations.”

Says Halzen, “After observing gamma-ray bursts for two years, we have not detected the telltale neutrinos for cosmic ray acceleration.”

If it’s likely that GRBs aren’t up to the task of accelerating cosmic rays to ultra-high-energies, what are the options? Klein points to a salient fact about natural accelerators: a small, rapidly spinning object must accelerate particles very rapidly; this requires an extremely energy-dense environment, and there are many ways the particles could lose energy during the acceleration process.

“But remember the other popular model of ultra-high-energy cosmic rays, active galactic nuclei,” says Klein. “GRBs are small, but AGNs are big – great big accelerators that may be able to accelerate particles to very high energies without significant loss.”

Are AGNs the real source of the highest-energy cosmic rays? IceCube has looked for neutrinos from active galactic nuclei, but as yet the data sets are not sensitive enough to set significant limits. For now, IceCube has nothing to say on the subject – beyond the fact that the fireball model of GRBs can’t meet the specs.

Source:  Lawrence Berkeley National