Star power: Small fusion start-ups aim for break-even

Nuclear fusion will cost a fortune – or will it? A new wave of upstart companies think they’ve found cheaper, quicker ways to build a second sun

Catching the sun

A VAST earth platform looms into view above the treetops of Cadarache in France’s sultry south-east. It measures 1 kilometre long by 400 metres wide, and excavators dotted around it are digging out pits to be filled with massive, earthquake-proof concrete foundations. These foundations need to be strong: 18 giant, supercooled superconducting magnets, each weighing 360 tonnes, will be part of a payload totalling 23,000 tonnes. This is the site of ITERMovie Camera, an international scientific collaboration with funding of €15 billion.

Meanwhile, in an undistinguished building 9000 kilometres away on an industrial park in Redmond, Washington state, a handful of researchers are gathered around a slender cylindrical apparatus about 16 metres long. There are no massive foundations and no expensive cryogenics. The object of the researchers’ interest is smaller than one of ITER’s magnets.

The disparity in scale is striking, especially when you consider both pieces of kit have the same goal: to harness the awe-inspiring power of nuclear fusion. Which project is more likely to realise fusion’s promise of clean, nigh-on inexhaustible energy? ITER certainly has the funding and the physics and engineering expertise. It would be most people’s bet. Yet some diminutive upstarts are now challenging that assumption.

What the newcomers lack in size, they make up in ingenuity and dynamism, their backers say. In Redmond and elsewhere, they have gathered some serious money behind their promise to produce the first commercial fusion reactors within years, not the decades ITER will require. Could an upset be on the cards?

There’s no secret to our interest in fusion: it is what powers the stars, including our sun. At the hundred-million-degree temperatures that exist in the sun’s core, the nuclei of light atoms fuse together to form heavier nuclei, liberating colossal amounts of energy – the energy that illuminates and warms our planet some 150 million kilometres distant. What we wouldn’t give to tame that power for ourselves.

It’s not that we haven’t mastered the basics. Humanity’s first successful experiment with fusion came on 1 November 1952, with the explosion of the first hydrogen bomb above the Pacific atoll of Enewetak in the Marshall Islands. That demonstrated two things. First, the energy needed to ignite a fusion reaction is huge: an H-bomb requires a Hiroshima-style atomic bomb to set it off. Second, once the reaction is under way, it is virtually uncontrollable…. Continue reading Star power: Small fusion start-ups aim for break-even

Cosmic-ray physics with IceCube

Configuration of IceCube

IceCube as a three-dimensional air-shower array covers an energy range of the cosmic-ray spectrum from below 1 PeV to approximately 1 EeV. This talk is a brief review of the function and goals of IceTop, the surface component of the IceCube neutrino telescope. An overview of different and complementary ways that IceCube is sensitive to the primary cosmic-ray composition up to the EeV range is presented. Plans to obtain composition information in the threshold region of the detector in order to overlap with direct measurements of the primary composition in the 100-300 TeV range are also described….
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Standard Big-Bang Nucleosynthesis up to CNO with an improved extended nuclear network

Primordial or Big Bang nucleosynthesis (BBN) is one of the three strong evidences for the Big- Bang model together with the expansion of the Universe and the Cosmic Microwave Background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and we enlarge the nuclear network until Sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including \approx 270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial Beryllium, Boron, Carbon, Nitrogen and Oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, 9Be and Boron nucleosynthesis. We reevaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial Beryllium abundance increase by a factor of 4 compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 \times 10-15. On the other hand, the extension of the nuclear network has not changed the 7Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value….

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Supernovae, Neutrinos, and the Chirality of the Amino Acids

Abstract: A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is described.
The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova.
The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species.
The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth’s proteinaceous amino acids (…..)

Part of the Veil Nebula (or NGC6960). The Veil Nebula is a faint remnant of a supernova that exploded some 5,000 years ago

If this model turns out to be correct, the longstanding question of how the organic molecules necessary to create and sustain life on Earth were created will have undergone a strong suggestion that the processes of the cosmos played a major role in establishing the molecules of life on Earth, either directly, or by providing the seeds that ultimately produced homochirality in the amino acids.
These molecules would appear to have been created in the molecular clouds of the galaxy, with their enantiomerism determined by supernovae, and subsequently either transported to Earth only in meteorites, swept up as the Earth passed through molecular clouds, or included in the mixture that formed Earth when the planets were created.
Any scenario in which these molecules were created exclusively on Earth in Darwin’s “warm little pond”, and supported by the experiment of Ref. [77], would find it much more difficult to explain the enantiomerism that is observed on Earth and, apparently, generally in the cosmos.
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NASA Mission Suggests Sun And Planets Constructed Differently

WASHINGTON — Analysis of samples returned by NASA’s Genesis mission indicates our sun and its inner planets may have formed differently than scientists previously thought.

The data revealed slight differences in the types of oxygen and nitrogen present on the sun and planets. The elements are among the most abundant in our solar system. Although the differences are slight, the implications could help determine how our solar system evolved.

The air on Earth contains three different kinds of oxygen atoms, which are differentiated by the number of neutrons they contain. Nearly 100 percent of oxygen atoms in the solar system are composed of O-16, but there also are tiny amounts of more exotic oxygen isotopes called O-17 and O-18. Researchers studying the oxygen of Genesis samples found that the percentage of O-16 in the sun is slightly higher than on Earth, the moon, and meteorites. The other isotopes’ percentages were slightly lower.

“The implication is that we did not form out of the same solar nebula materials that created the sun — just how and why remains to be discovered,” said Kevin McKeegan, a Genesis co-investigator from the University of California, Los Angeles and the lead author of one of two Science papers published this week…… Continue reading NASA Mission Suggests Sun And Planets Constructed Differently

A step closer to solving one of the biggest mysteries in fundamental physics?

Where did all the matter in the universe come from? This is one of the biggest mysteries in fundamental physics and exciting results released on 15 June 2011 from the international T2K neutrino experiment in Japan could be an important step towards resolving this puzzle.

The intriguing results indicate a new property of the enigmatic  known as .
There are three types of neutrinos (called flavours) – one paired by particle interactions with the familiar electron (called the electron neutrino), and two more paired with the electron’s heavier cousins, the muon and tau leptons. Previous experiments around the world have shown that these different flavours of neutrinos can spontaneously change into each other, a  called ‘neutrino oscillation’.
Two types of oscillations have already been observed but in its first full period of operation, the T2K experiment has already seen evidence for a new type of oscillation (the appearance of electron neutrinos in a muon neutrino beam). This means that we have now observed that neutrinos can oscillate in every way possible.
This level of complexity opens the possibility that the oscillations of neutrinos and their anti-particles (called anti-neutrinos) could be different. And if the oscillations of neutrinos and anti-neutrinos are different, it would be an example of what  call CP violation. This could be the key to explaining why there is more matter than  in the universe (an excess which could not happen within the known ).
The experiment ran from January 2010 until 11 March this year, when it was dramatically interrupted by the Japanese earthquake. Fortunately, the multinational T2K team were unharmed and their highly sensitive detectors were largely undamaged. Six clean electron neutrino events are observed in the data from before the earthquake, while in the absence of oscillations there should only have been 1.5. Even though such an excess could only happen by chance about one time in a hundred, that is not good enough to confirm a new physics discovery, so this is called an ‘indication’.
Prof Dave Wark of STFC and Imperial College London, who served for four years as the International Co-Spokesperson of the experiment and is head of the UK group, explains, “People sometimes think that scientific discoveries are like light switches that click from ‘off’ to ‘on’, but in reality it goes from ‘maybe’ to ‘probably’ to ‘almost certainly’ as you get more data. Right now we are somewhere between ‘probably’ and ‘almost certainly’.”

In this projected diagram of cylinder-shaped Super-Kamiokande, each coloured dot shows a photomultiplier that detected light (these photomultipliers are mounted on the inside wall of the detector). Electron neutrinos interact with water in the detector to produce electrons, which subsequently induce electromagnetic showers to eventually emit Cherenkov light that is detected in a ring-shaped structure.

Prof Christos Touramanis from Liverpool University is the Project Manager for the UK contributions to T2K: “We have examined the near detectors and turned some of them back on, and everything that we have tried works pretty well. So far it looks like our earthquake engineering was good enough, but we never wanted to see it tested so thoroughly.”
Prof Takashi Kobayashi of the KEK Laboratory in Japan and spokesperson for the T2K experiment, said “It shows the power of our experimental design that with only 2% of our design data we are already the most sensitive experiment in the world for looking for this new type of oscillation.”
About T2K
The experiment is a huge undertaking with over 500 scientists from 12 countries. The UK has invested £14.3M in the T2K project.
There are three elements to the experiment:
• A beam of muon neutrinos is produced at the Japan Proton Accelerator Research Center in Tokai, Japan. STFC engineers from the Rutherford Appleton Laboratory helped in the design, production, and testing of a number of the elements of this neutrino production system.
• The neutrinos then pass through a complex set of near detectors located 280 meters from the target in order to determine the neutrino beam’s composition and properties before the neutrinos have a chance to oscillate. 8 STFC-supported institutions (listed below) were involved in the production of a variety of components for these near detectors.
• The neutrinos then fly under the ground for 295 km across Japan to the mammoth Super Kamiokande neutrino detector (a tank of 50,000 tons of ultra-pure water surrounded by sensitive optical detectors which can see the very faint flashes of light emitted by the very rare interactions of passing neutrinos with the water). This is capable of telling muon neutrinos from electron neutrinos with high precision, and is thus ideal for looking for the appearance of a small fraction of electron neutrinos appearing in the muon neutrino beam, the key signature of this new type of oscillation.
Read also:

1. Evidence mounts for previously unseen neutrino oscillation
2. Neutrinos caught ‘shape shifting’ in new way
3. Neutrino Oscillations Caught in the Act

Chemistry and the Universe

Chemistry, the study of the intricate dances and bondings of low-energy electrons to form the molecules that make up the world we live in, may seem far removed from the thermonuclear heat in the interiors of stars and the awesome power of supernovas. Yet, there is a fundamental connection between them.
To illustrate this connection, the familiar periodic table of elements—found in virtually every chemistry class—has been adapted to show how astronomers see the chemical Universe. What leaps out of this table is that the simplest elements, hydrogen and helium, are far and away the most abundant.

The Universe started out with baryonic matter in its simplest form, hydrogen. In just the first 20 minutes or so after the Big Bang, about 25% of the hydrogen was converted to helium. In essence, the chemical history of the Universe can be divided into two mainphases: one lasting 20 minutes, and the rest lasting for 13.7 billion years and counting.
After that initial one third of an hour, the expanding Universe cooled below the point where nuclear fusion could operate. This meant that no evolution of matter could occur again until stars were formed a few million years later. Then the buildup of elements heavier than helium could begin.
Stars evolve through a sequence of stages in which nuclear fusion reactions in their central regions build up helium and other elements (see illustration, above).The energy supplied by fusion reactions creates the pressure needed to hold the star up against gravity. Winds of gas escaping from stars distribute some of this processed matter into space in a relatively gentle manner and supernovas do it violently.

The chemical composition of the Universe has been constantly changing throughout its 13.7 billion year history.

As the enrichment of the interstellar and intergalactic gas has proceeded over vast stretches of space and time, the chemistry of the cosmos has become richer, too. Subsequent generations of stars have formed from interstellar gas enriched in heavy elements. Our Sun, Solar System, and indeed the existence of life on Earth are direct results of this long chain of stellar birth, death, and rebirth. In this way, the evolution of matter, stars and galaxies are all inextricably tied together and so too are astronomy and chemistry.
One of the principal scientific accomplishments of the Chandra X-ray Observatory has been to help unravel how the chemical enrichment by stellar winds and supernovas works on a galactic and intergalactic scale.
Chandra Images

Chandra images and spectra of individual supernova remnants reveal clouds of gas rich in elements such as oxygen, silicon, sulfur, calcium and iron, and track the speed at which these elements have been ejected in the explosion. The Chandra image of the Cas A supernova remnant shows iron rich ejecta outside silicon-rich ejecta, thus indicating that turbulent mixing and an aspherical explosion turned much of the original star inside out. Observations of Doppler-shifted emission lines for Cas A and other supernova remnants are providing three-dimensional information on the distribution and velocity of the supernova ejecta which will help to constrain models for the explosion.

On a larger scale, observations of galaxies undergoing bursts of star formation show that vast regions of these galaxies have been enriched by the combined action of thousands of supernovas. The Antennae galaxy system was produced by the collision of two galaxies. This collision created bursts of star formation and, few million years later, thousands of supernovas which heated and enriched clouds of gas thousands of light years in extent.

An unexpected agent for distributing heavy elements throughout a galaxy is a supermassive black hole in the center of a galaxy (for example, Sagittarius A*). Gas spiraling toward black holes can that become overheated and produce a wind of gas that flows away from the black hole, or it can create an intense electromagnetic field that drives enriched material into the outer reaches of the galaxy and beyond.

On a still larger scale, oxygen has been detected in intergalactic filaments millions of light years in length. This oxygen was likely produced more than ten billion years ago, in some of the first supernovas to occur in the history of the Universe. If the rate of supernovas gets so high that the combined effects of many supernova shock waves drives a galactic-scale wind that blows the gas out of the galaxy. A prime example is the galaxy M82.

Galactic winds such as the one in M82 are rare today, but they were common billions of years ago when galaxies were very young and stars were forming rapidly because of frequent collisions between galaxies. Chandra showed that the Sculptor Wall, a collection of gas and galaxies that stretches across tens of millions of light years, contains a vast reservoir of gas enriched in oxygen from galactic winds. The Sculptor Wall is thought to be part of an enormous web of hot, diffuse gas containing as much as half of all the ordinary matter in the Universe.

Periodic Table
In this version of the periodic table, the average relative abundance by mass of the various elements in the Universe is indicated by the number in the square, which gives the abundance in parts per 10,000. The sum of the abundances of all the elements without numbers is less than one part per 10,000. The abundances give important clues to the nuclear reactions and cosmic settings required to produce the various elements.

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