A precise measurement of absolute beam intensity is essential for many areas of science. It is a key parameter to monitor any losses in a beam and to calibrate the absolute number of particles delivered to the experiments.
However, this type of measurement is very challenging with traditional beam current diagnostics when it comes to low energy, low intensity beams due to the very low signal levels. Particle accelerator experts from the University of Liverpool have now experimentally demonstrated a new type of monitor in a collaboration with CERN, the GSI Helmholtz Centre for Heavy Ion Research and Friedrich Schiller University and Helmholtz Institute Jena.
A paper just published in the IOP “Superconducting Science and Thechnology” journal, the challenges of implementation and first beam measurements are reported. These are the first-ever measurements of this type performed in a synchrotron using both coasting and short bunched beams.
The Antiproton Decelerator (AD) is a synchrotron that provides low-energy antiprotons for studies of antimatter. These studies rely on creating antimatter atoms (such as anti-hydrogen) and using them as probes for the most fundamental symmetries in nature such as the invariance of CPT, or of the gravitational acceleration on matter and antimatter.
A precise measurement of the beam intensity in the AD is essential to monitor any losses during the deceleration and cooling phases of the AD cycle, and to calibrate the absolute number of particles delivered to the experiments. However, this is very challenging with traditional beam current diagnostics due to the low intensity of the antiproton beam which is of the order of only 10 Million particles, corresponding to beam currents as low as a few hundred nano-Amperes. To cope with this, a Cryogenic Current Comparator (CCC) based on a Superconducting QUantum Interference Device (SQUID) was developed and installed in the AD, in a collaboration between accelerator experts from the University of Liverpool and CERN, the GSI Helmholtz Centre for Heavy Ion Research, Friedrich Schiller University and the Helmholtz Institute Jena.
Previous incarnations of CCC’s for accelerators suffered from issues concerning sensitivity to mechanical vibrations and electromagnetic perturbations. Furthermore, these setups were used for measuring slow beams, usually from transfer lines of accelerators, and were unable to measure short bunched beams presenting fast current variations. In order to measure the beam current and intensity throughout the cycle of a synchrotron machine such as the AD, the CCC needed to be adapted to cope with the fast signals of bunched beams.
In an open access paper just published in the IOP “Superconducting Science and Thechnology” journal, Miguel Fernandes and co-authors describe the challenges of implementation and first beam measurements. These are the first-ever CCC beam current measurements performed in a synchrotron using both coasting and short bunched beams. The paper demonstrates the exciting prospects of this new type of beam diagnostics device.
The University of Liverpool is a teaching and research university based in the city of Liverpool, England.
Founded in 1881 (as a university college), it is also one of the six original “red brick” civic universities. It comprises three faculties organised into 35 departments and schools. The university has an enviable international reputation for innovative research and academic excellence. It is a founding member of the Russell Group of large research-intensive universities, the N8 Group for research collaboration and The University Management school is AACSB accredited.
The university has produced eight Nobel Prize winners and offers more than 230 first degree courses across 103 subjects. It was the world’s first university to establish departments in Oceanography, Civic Design, Architecture, and Biochemistry at the Johnston Laboratories. In 2006 the university became the first in the UK to establish an independent university in China making it the world’s first Sino-British university. It has an annual turnover of £410 million, including £150 million for research.
Graduates of the University are styled with the post-nominal letters Lpool, to indicate the institution.
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An international group of researchers has synthesized an extremely rare mineral and used it as a catalyst precursor to improve two reactions that are of great importance to the chemical industry.
Using a technique called supercritical anti-solvent precipitation (SAS), the group produced large quantities of highly pure georgeite, a disordered copper-hydroxycarbonate that is found naturally only in Australia and in an old copper mine in Snowdonia, Wales.
The group tested georgeite’s catalytic activity against commercial catalysts that have been used for a half-century in the water-gas shift reaction, in which water reacts with carbon dioxide to produce hydrogen.
“We found that the georgeite was a superb catalyst for the water-gas shift reaction and had a much higher performance compared to the commercial catalyst currently used in industry,” said Graham Hutchings, director of the Cardiff Catalysis Institute at Cardiff University in Wales.
Hydrogen is an essential ingredient in the manufacture of methanol and ammonia, which form the basis of hundreds of chemicals, including fuels, plastics, paints, solvents and fertilizer.
The group also found that their synthesized georgeite material was highly effective in carrying out methanol synthesis, in which CO2 and hydrogen are combined to make methanol.
“Catalysts based on copper-zinc oxide minerals have been used for many decades to catalyze both of these reactions,” said Christopher J. Kiely, professor of materials science and chemical engineering at Lehigh. “Our georgeite-derived materials represent the first time something potentially better has come along.”
The group reported its findings this week in Nature magazine in an article titled “Stable amorphous georgeite as a precursor to a high-activity catalyst.” The article was authored by researchers from Cardiff, Lehigh, the UK Catalysis Hub, University College London, Diamond Light Source in the United Kingdom, the University of Liverpool, the Technical University of Denmark, and Johnson Matthey, a multinational chemicals and sustainable technologies company headquartered in Royston, UK.
A readily synthesized precursor
Georgeite belongs to a family of minerals called copper hydroxycarbonates that are widely used as catalyst precursors in the chemical industry. Scientists are familiar with other hydroxycarbonates, such as malachite, aurichalcite and rosasite, but know little about georgeite because of its extreme rarity, low purity, instability and highly disordered nature.
Chemists at the Cardiff Catalysis Institute synthesized georgeite using SAS, in which CO2 is subjected to conditions of heat and pressure that put it into a supercritical state where it displays the characteristics of both a liquid and a gas.
“Supercritical CO2 expands like a gas to fill up a volume while retaining the viscosity of a liquid,” said Kiely. “It’s an unusual state of matter and has the ability when bubbled through a solution to make solids precipitate out very quickly. Supercritical CO2 is also used for processes such as decaffeinating coffee.”
Chemists at the Cardiff Catalysis Institute synthesized georgeite by dissolving a copper-zinc-oxide precursor in an organic solvent and then passing supercritical CO2 through the solvent to rapidly precipitate out the georgeite.
“[We have shown] that stable georgeite can be readily synthesized using supercritical carbon dioxide as an anti-solvent in a precipitation process,” the researchers wrote in Nature. “The synthetic georgeite materials are precursors to highly active methanol synthesis and superior water gas shift catalysts as compared to those currently prepared from crystalline malachite.
“This new route to georgeite will open up new opportunities for the use of this important material in a number of applications.”
A crucial role for crystals
Researchers at Lehigh and the Technical University of Denmark used advanced electron microscopy techniques to structurally characterize the georgeite and determine why it produces such high performing catalysts.
“We looked at the georgeite with an aberration-corrected STEM [scanning transmission electron microscope],” said Kiely. “Georgeite had been thought to be completely amorphous, that is, more like glass than a crystalline mineral. We found that georgeite is in fact about 90 percent amorphous but has 2-nanometer crystals of copper oxide embedded within it.
“The actual catalyst is not a pure georgeite material,” said Kiely. “The georgeite, when deliberately doped with some zinc, is really a precursor to the active catalyst. It needs to be calcined, or heated in air, and then reduced in hydrogen gas before it can be used as a catalyst.”
To learn what happened during calcination and reduction, the group turned to colleagues at the Technical University of Denmark, which has an environmental transmission electron microscope (ETEM).
“The ETEM is a very specialized instrument,” said Kiely. “The beauty of it is that you can take a zincian georgeite precursor, heat it up in the microscope under a gaseous environment and then watch how it changes during the process. This allowed us to dynamically view the precursor material as it transformed into the active catalyst.
“What we saw with the ETEM is that when calcined zincian georgeite is reduced in hydrogen, it forms very tiny copper particles intimately supported on nanoscopic zinc oxide grains. This special nanostructure is responsible for the good catalytic properties.
“We compared this with the conventional catalyst materials derived from a crystalline malachite, and found that our zincian georgeite results in a much finer microstructure, with smaller copper and zinc oxide particles, which ultimately contributes to the superior catalytic performance.”
The synthetic zincian georgeite catalyst, said Kiely, has the additional advantage that its composition can be easily tuned, or altered, by adjusting the ratio of copper atoms to zinc atoms in the starting solution. It can also be made in large quantities.
It is usually possible to make well-controlled interfaces when two materials have similar crystal structures, yet the ability to combine materials with different crystal structures has lacked the accurate design rules that increasingly exists in other areas of materials chemistry.
The design and formation of an atomic-scale bridge between different materials will lead to new and improved physical properties, opening the path to new information technology and energy science applications amongst a myriad of science and engineering possibilities – for example, atoms could move faster at the interface between the materials, enabling better batteries and fuel cells.
Many devices, for example a transistor or blue LED, rely on the creation of very clean, well-ordered interfaces between different materials to work.
Liverpool Materials Chemist, Professor Matthew Rosseinsky, said: “When we try to fit materials together at the atomic scale, we are used to using the sizes of the atoms to decide which combinations of materials will “work” i.e. will produce a continuous well-ordered interface.
Learn more: Scientists bridge different materials by design
“The findings will help us feed a growing global population by speeding up the development of new varieties of wheat able to cope with the challenges faced by farmers worldwide.”
UK, German and US scientists decipher complex genetic code to create new tools for breeders and researchers across the world.
Scientists, including Professor Keith Edwards and Dr Gary Barker from the University of Bristol, have unlocked key components of the genetic code of one of the world’s most important crops. The first analysis of the complex and exceptionally large bread wheat genome, published today in Nature, is a major breakthrough in breeding wheat varieties that are more productive and better able to cope with disease, drought and other stresses that cause crop losses.
The identification of around 96,000 wheat genes, and insights into the links between them, lays strong foundations for accelerating wheat improvement through advanced molecular breeding and genetic engineering. The research contributes to directly improving food security by facilitating new approaches to wheat crop improvement that will accelerate the production of new wheat varieties and stimulate new research. The analysis comes just two years after UK researchers finished generating the sequence.
The project was led by Neil Hall, Mike Bevan, Keith Edwards, Klaus Mayer, from the University of Liverpool, the John Innes Centre, the University of Bristol, and the Institute of Bioinformatics and Systems Biology, Helmholtz-Zentrum, Munich, respectively, and Anthony Hall at the University of Liverpool. W. Richard McCombie at Cold Spring Harbor Laboratory, and Jan Dvorak at the Univerisity of California, Davis, led the US contribution to the project.
The team sifted through vast amounts of DNA sequence data, effectively translating the sequence into something that scientists and plant breeders can use effectively. All of their data and analyses were freely available to users world-wide.
Professor Keith Edwards said: “Since 1980, the rate of increase in wheat yields has declined. Analysis of the wheat genome sequence data provides a new and very powerful foundation for breeding future generations of wheat more quickly and more precisely, to help address this problem.”
The analysis is already being used in research funded by the Biotechnology and Biological Sciences Research Council (BBSRC) to introduce a wider range of genetic variation into commercial cultivars and make use of wild wheat’s untapped genetic reservoirs that could help improve tolerance to diseases and the effects of climate change. The wheat breeding community and seed suppliers have welcomed the research.