CAN Revolutionary laser system produce the next LHC

An international team of physicists has proposed a revolutionary laser system, inspired by the telecommunications technology, to produce the next generation of particle accelerators, such as the Large Hadron Collider (LHC) in CERN.

The International Coherent Amplification Network (ICAN) sets out a new laser system composed of massive arrays of thousands of fibre lasers, for both fundamental research at laboratories such as CERN and more applied tasks such as proton therapy and nuclear transmutation.

Lasers can provide, in a very short time measured in femto-seconds, bursts of energy of great power counted in peta-watts or a thousand times the power of all the power plants in the world.

Compact accelerators are also of great societal importance for applied tasks in medicine, such as a unique way to democratise proton therapy for cancer treatment, or the environment where it offers the prospect to reduce the lifetime of dangerous nuclear waste by, in some cases, from 100 thousand years to tens of years or even less.

Major Difficulties
However, there are two major hurdles that prevent the high-intensity laser from becoming a viable and widely used technology in the future.

• First, a high-intensity laser often only operates at a rate of one laser pulse per second, when for practical applications it would need to operate tens of thousands of times per second.

• The second is ultra-intense lasers are notorious for being very inefficient, producing output powers that are a fraction of a percent of the input power. As practical applications would require output powers in the range of tens of kilowatts to megawatts, it is economically not feasible to produce this power with such a poor efficiency.

Technological Consortium
To bridge this technology divide, the ICAN consortium, an EU-funded project initiated and coordinated by the Ecole polytechnique and composed of the University of Southampton Optical Research Centre (ORC), Jena and CERN, as well as 12 other prestigious laboratories around the world, aims to harness the efficiency, controllability, and high average power capability of fibre lasers to produce high energy, high repetition rate pulse sources.

The aim is to replace the conventional single monolithic rod amplifier that typically equips lasers with a network of fibre amplifiers and telecommunication components.

Gerard Mourou

Gerard Mourou of Ecole polytechnique who leads the consortium says: "One important application demonstrated has been the possibility to accelerate particles to high energy over very short distances measured in centimetres rather than kilometres as it is the case today with conventional technology."

"This feature is of paramount importance when we know that today high energy physics is limited by the prohibitive size of accelerators, of the size of tens of kilometres, and cost billions of euros."

"Reducing the size and cost by a large amount is of critical importance for the future of high energy physics."

Dr Bill Brocklesby

Dr Bill Brocklesby from the ORC adds: "A typical CAN laser for high-energy physics may use thousands of fibres, each carrying a small amount of laser energy."

"It offers the advantage of relying on well tested telecommunication elements, such as fibre lasers and other components."

"The fibre laser offers an excellent efficiency due to laser diode pumping. It also provides a much larger surface cooling area and therefore makes possible high repetition rate operation."

"The most stringent difficulty is to phase the lasers within a fraction of a wavelength."

"This difficulty seemed insurmountable but a major roadblock has in fact been solved: preliminary proof of concept suggests that thousands of fibres can be controlled to provide a laser output powerful enough to accelerate electrons to energies of several GeV at 10 kHz repetition rate - an improvement of at least ten thousand times over today's state of the art lasers."

Such a combined fibre-laser system should provide the necessary power and efficiency that could make economical the production of a large flux of relativistic protons over millimetre lengths as opposed to a few hundred metres.

Societal Application
One important societal application of such a source is to transmute the waste products of nuclear reactors, which at present have half-lives of hundreds of thousands of years, into materials with much shorter lives, on the scale of tens of years, thus transforming dramatically the problem of nuclear waste management.

CAN technology could also find important applications in areas of medicine, such as proton therapy, where reliability and robustness of fibre technology could be decisive features.

Fungi Can Quickly Mutate to Produce an Infectious Ability

Fungi have significant potential for "horizontal" gene transfer, a new study has shown, similar to the mechanisms that allow bacteria to evolve so quickly, become resistant to antibiotics and cause other serious problems.

This discovery, to be published March 18 in the journal Nature, suggests that fungi have the capacity to rapidly change the make-up of their genomes and become infectious to plants and possibly animals, including humans.

They are not nearly as confined to the more gradual processes of conventional evolution as had been believed, scientists say. And this raises issues not only for crop agriculture but also human health, because fungi are much closer on the "evolutionary tree" to humans than bacteria, and consequently fungal diseases are much more difficult to treat.

The genetic mechanisms fungi use to do this are different than those often used by bacteria, but the end result can be fairly similar. The evolution of virulence in fungal strains that was once believed to be slow has now been shown to occur quickly, and may force a renewed perspective on how fungi can behave, change and transfer infectious abilities.

"Prior to this we've believed that fungi were generally confined to vertical gene transfer or conventional inheritance, a slower type of genetic change based on the interplay of DNA mutation, recombination and the effects of selection," said Michael Freitag, an assistant professor of biochemistry and biophysics at Oregon State University.

"But in this study we found fungi able to transfer an infectious capability to a different strain in a single generation," he said. "We've probably underestimated this phenomenon, and it indicates that fungal strains may become pathogenic faster than we used to think possible."

Flax And Yellow Flowers Can Produce Bioethanol

Surplus biomass from the production of flax shives, and generated from Brassica carinata, a yellow-flowered plant related to those which engulf fields in spring, can be used to produce bioethanol. This has been suggested by two studies carried out by Spanish and Dutch researchers and published in the journal Renewable and Sustainable Energy Reviews.

"These studies evaluate, from an environmental point of view, the production of bioethanol from two, as yet unexploited sources of biomass: agricultural residue from flax (for the production of paper fibres for animal bedding), and Brassica carinata crops (herbaceous plant with yellow flowers, similar to those which carpet the countryside in spring)", Sara González-García, researcher of the Bioprocesses and Environmental Engineering Group of the University of Santiago de Compostela (USC), explains to SINC.

González-García, along with other researchers from USC, the Autonomous University of Barcelona and the University of Leiden (Holland), has confirmed that if bioethanol is produced from these two types of biomass "both CO2 emissions and fossil fuel consumption will be reduced, meeting two of the objectives established by the European Union to promote biofuels".

These works have analysed the environmental load associated with the different stages of the process: the harvesting of flax or Brassica; the production of ethanol (through enzymatic hydrolysis followed by fermentation and distillation); mixing it with petrol (in varying proportions); and its use in passenger automobiles.

The results of both studies, published in the journal Renewable and Sustainable Energy Reviews, show that the use of ethanol-based fuels can help to mitigate climate change (by reducing greenhouse gases).

However, these fuels also "contribute to acidification, eutrophication, the formation of photochemical oxidants and toxicity (for people and the environment)". According to the experts, these negative effects could be lessened with the use of high-yield crops, as well as through optimisation of agricultural activity and better use of fertilisers.

Which is better: flax or Brassica?
The studies developed by the researchers reveal that flax (which is richer in cellulose) can produce up to 0.3 kg of ethanol for every kg of dry biomass, compared with 0.25kg/kg of Brassica. However, when the whole production cycle is analysed, the yellow-flowered plant offers a greater production of biomass per hectare and has a lesser environmental impact.

The biofuel produced from these two plants is "second generation bioethanol", which is obtained from forest or agricultural residues, or from herbaceous crops, and does not enter into direct competition with agricultural crops intended for animal or human consumption.

The European Union and the International Monetary Fund are promoting the development of these types of biofuels. Spain is the third largest producer of bioethanol in Europe, after France and Germany, although its use still only represents 0.4% of total energy consumption.

How Far Can a Human Travel in the Universe

HOW far could an astronaut travel in a lifetime? Billions of light years, it turns out. But they ought to be careful when to apply the brakes on the return trip.

Ever since cosmologists discovered that the universe's expansion is accelerating, many have wondered just how much this will constrain what we could see with telescopes in the future. Distant regions of the universe will eventually be expanding so fast that light from any objects there can never reach us.

Likewise, dark energy - the mysterious force behind the acceleration - places a limit on human exploration of the universe, says Juliana Kwan at the University of Sydney in New South Wales, Australia, who has now refined this limit on our travels. Even with rockets that could take us to within a whisker of light speed, expansion would still eventually leave us behind.

The furthest that light emitted from our sun today could reach, as it races in vain to outdo the accelerating expansion, currently lies around 15 billion light years away. According to previous calculations by Jeremy Heyl of the University of British Columbia in Vancouver, a super-advanced rocket could get most of this way in a human lifetime.

Accelerating at around 9 metres per second per second - which would feel roughly like a comfortable 1 g - a craft could get 99 per cent of the way to the expansion "horizon". Despite the vast distance, this would take only about 50 years in the astronaut's reference frame, because time would pass slower than on Earth due to relativity (Physical Review D, DOI: 10.1103/PhysRevD.72.107302).