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  • richardmitnick 1:59 am on October 9, 2021 Permalink | Reply
    Tags: "FAU physicists control the flow of electron pulses through a nanostructure channel", APF: alternating phase focusing, , , DLA uses ultra-fast laser technology and advances in semi-conductor production to potentially minimise these accelerators to merely a few millimetres or centimetres in size., DLA: dielectric laser acceleration, Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE), , , ,   

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE): “FAU physicists control the flow of electron pulses through a nanostructure channel” 

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE)

    September 23, 2021

    Chair for Laser Physics
    Dr. Roy Shiloh
    Tel.: 09131/85-27211
    roy.shiloh@fau.de

    Johannes Illmer M.Sc.
    Tel.: 09131/85-27211
    johannes.i.illmer@fau.de

    Prof. Dr. Peter Hommelhoff
    Tel.: 09131/85-27090
    peter.hommelhoff@fau.de

    1
    Experimental setup in the laser laboratory. Picture: Maximilian Schlosser.

    Particle accelerators are essential tools in research areas such as biology, materials science and particle physics. Researchers are always looking for more powerful ways of accelerating particles to improve existing equipment and increase capacities for experiments. One such powerful technology is dielectric laser acceleration (DLA). In this approach, particles are accelerated in the optical near-field which is created when ultra-short laser pulses are focused on a nanophotonic structure. Using this method, researchers from the Chair of Laser Physics at FAU have succeeded in guiding electrons through a vacuum channel, an essential component of particle accelerators. The basic design of the photonic nanostructure channel was developed by cooperation partner The Technical University of Darmstadt [Technische Universität Darmstadt] (DE). They have now published their joint findings in the journal Nature.

    Staying focused

    As charged particles tend to move further away from each other as they spread, all accelerator technologies face the challenge of keeping the particles within the required spatial and time boundaries. As a result, particle accelerators can be up to ten kilometres long, and entail years of preparation and construction before they are ready for use, not to mention the major investments involved. Dielectric laser acceleration, or DLA uses ultra-fast laser technology and advances in semi-conductor production to potentially minimise these accelerators to merely a few millimetres or centimetres in size.

    A promising approach: Experiments have already demonstrated that DLA exceeds currently used technologies by at least 35 times. This means that the length of a potential accelerator could be reduced by the same factor. Until now, however, it was unclear whether these figures could be scaled up for longer and longer structures.

    A team of physicists led by Prof. Dr. Peter Hommelhoff from the Chair of Laser Physics at FAU has taken a major step forward towards adapting DLA for use in fully-functional accelerators. Their work is the first to set out a scheme which can be used to guide electron pulses over long distances.

    Technology is key

    The scheme, known as ‘alternating phase focusing’ (APF) is a method taken from the early days of accelerator theory. A fundamental law of physics means that focusing charged particles in all three dimensions at once – width, height and depth – is impossible. However, this can be avoided by alternately focusing the electrons in different dimensions. First of all, electrons are focused using a modulated laser beam, then they ‘drift’ through another short passage where no forces act on them, before they are finally accelerated, which allows them to be guided forward.

    In their experiment, the scientists from FAU and TU Darmstadt incorporated a colonnade of oval pillars with short gaps at regular intervals, resulting in repeating macro cells. Each macro cell either has a focusing or defocusing effect on the particles, depending on the delay between the incident laser, the electron, and the gap which creates the drifting section. This setup allows precise electron phase space control at the optical or femto-second ultra-timescale (a femto-second corresponds to a millionth of a billionth of a second). In the experiment, shining a laser on the structure shows an increase in the beam current through the structure. If a laser is not used, the electrons are not guided and gradually crash into the walls of the channel. ‘It’s very exciting,’ says FAU physicist Johannes Illmer, co-author of the publication. ‘By way of comparison, the large Hadron collider at CERN uses 23 of these cells in a 2450 metre long curve. Our nanostructure uses five similar-acting cells in just 80 micrometres.’

    When can we expect to see the first DLA accelerator?

    ‘The results are extremely significant, but for us it is really just an interim step,’ explains Dr. Roy Shiloh, ‘and our final goal is clear: we want to create a fully-functional accelerator – on a microchip.’

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Friedrich-Alexander-Universität Erlangen-Nürnberg, [FAU] (DE} is a public research university in the cities of Erlangen and Nuremberg in Bavaria, Germany. The name Friedrich–Alexander comes from the university’s first founder Friedrich, Margrave of Brandenburg-Bayreuth, and its benefactor Christian Frederick Charles Alexander, Margrave of Brandenburg-Ansbach.

    FAU is the second largest state university in the state of Bavaria. It has 5 faculties, 24 departments/schools, 25 clinical departments, 21 autonomous departments, 579 professors, 3,457 members of research staff and roughly 14,300 employees.

    In winter semester 2018/19 around 38,771 students (including 5,096 foreign students) enrolled in the university in 265 fields of study, with about 2/3 studying at the Erlangen campus and the remaining 1/3 at the Nuremberg campus. These statistics put FAU in the list of top 10 largest universities in Germany. In 2018, 7,390 students graduated from the university and 840 doctorates and 55 post-doctoral theses were registered. Moreover, FAU received 201 million Euro (2018) external funding in the same year, making it one of the strongest third-party funded universities in Germany.

    FAU is also a member of DFG (Deutsche Forschungsgemeinschaft) and the Top Industrial Managers for Europe network.

     
  • richardmitnick 3:23 pm on September 17, 2021 Permalink | Reply
    Tags: "Are pulsars the source of galactic cosmic rays?", As photons-or light particles-are created during the acceleration process gamma rays can also provide clues to the nature of cosmic accelerators., Cosmic rays were discovered by the Austrian physicist Victor Franz Hess., Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE), In her work at FAU Dr. Mitchell now hopes to provide the anticipated experimental proof that protons are accelerated by pulsars and the area around them., It is still not known where cosmic rays come from and whether they originate from one or several source populations., It was only proven in 2019 that pulsar wind nebulas are capable of accelerating positrons and electrons to energy levels of 1015 electron volts., Many colleagues tend to favour supernova remnants but experiments have so far failed to provide unambiguous proof that this is the case., Several research groups-for example in France; Poland and the USA-are working on theoretical models indicating that galactic cosmic rays originate in the area around pulsars., The most promising candidates include supernova remnants; the area around rotating neutron stars; or pulsars and black holes., Theoretical investigations have not yet succeeded in providing convincing evidence that particles in supernova remnants can be accelerated to the extremely high energy levels found in cosmic rays.   

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE): “Are pulsars the source of galactic cosmic rays?” 

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE)

    September 17, 2021

    New FAU research group hopes to provide experimental evidence for cosmic rays using high energy gamma rays from the area around pulsars.

    For Dr. Alison Mitchell, who is transferring to FAU from Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich)](CH), it would be a dream come true. From October, Dr. Mitchell and her Emmy Noether junior research group at the Erlangen Centre for Astroparticle Physics (DE) are to investigate the role pulsars play in creating galactic, high-energy cosmic rays. The project is set to run for six years, and has received nearly 1.5 million euros in funding.

    The search for the origin of cosmic rays

    Galactic cosmic rays are created within our galaxy, the Milky Way. They consist predominantly of charged particles, i.e. protons, ions, positrons and electrons that are accelerated under extreme conditions and arrive at the Earth laden with high energy. As photons-or light particles-are created during the acceleration process gamma rays can also provide clues to the nature of cosmic accelerators. The first step towards understanding this phenomenon was taken in 1912, when cosmic rays were discovered by the Austrian physicist Victor Franz Hess. Charged particles are deflected on their long journey to the Earth by interstellar magnetic fields. Research into the origin of cosmic rays therefore focuses on non-charged particles such as photons or neutrinos, as they come down to Earth directly and can give us clues as to their site of origin. Alison Mitchell is one of the leading scientists in the world for research into high-energy photons from space, known as gamma rays.

    It is still not known where cosmic rays come from and whether they originate from one or several source populations. The most promising candidates include supernova remnants; the area around rotating neutron stars; or pulsars and black holes. “Many colleagues tend to favour supernova remnants but experiments have so far failed to provide unambiguous proof that this is the case,” explains Dr. Mitchell. The longer ago the stellar explosion took place, the lower the acceleration is expected to be. In addition, theoretical investigations have not yet succeeded in providing convincing evidence that particles in supernova remnants can be accelerated to the extremely high energy levels found in cosmic rays. Scientists are therefore looking for other explanations. Several research groups-for example in France; Poland and the USA-are working on theoretical models indicating that galactic cosmic rays originate in the area around pulsars.

    It was only proven in 2019 that pulsar wind nebulas are capable of accelerating positrons and electrons to energy levels of 1015 electron volts. It follows that the main components of galactic cosmic rays, in other words protons and ions, may also originate from the area around a pulsar. In her work at FAU Dr. Mitchell now hopes to provide the anticipated experimental proof that protons are accelerated by pulsars and the area around them. ‘As far as I am aware, the extensive research programme we are planning is the only one of its kind in the world,’ she explains.

    On the lookout with gigantic telescopes

    As high-energy particles are hard to find using satellites, researchers are using the Earth’s atmosphere as a detector. Čerenkov telescopes intercept the faint glow that is emitted when a photon from the gamma rays collides with the Earth’s atmosphere. The five telescopes at the HESS observatory in Namibia accurately plot the direction of the gamma rays.

    Alison Mitchell and other researchers from FAU are also involved in the major international project to build a ground-based observatory for gamma ray astronomy known as the Čerenkov Telescope Array (CTA).

    Algorithms are to be used to improve the resolution of the telescopes. Currently, researchers are also working on new methods aimed at detecting gamma ray sources spread over a wider area. Mitchell believes that thanks to its leading position in the field of theoretical astrophysics and neutrino, X-ray and gamma ray astronomy, FAU offers a very broad range of possible avenues for her project. “It is extremely likely both supernovas and pulsars are responsible for galactic cosmic rays, but I believe that pulsars can accelerate particles to energies thousands of times higher than those attained by supernova remnants.”

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Friedrich-Alexander-Universität Erlangen-Nürnberg, [FAU] (DE} is a public research university in the cities of Erlangen and Nuremberg in Bavaria, Germany. The name Friedrich–Alexander comes from the university’s first founder Friedrich, Margrave of Brandenburg-Bayreuth, and its benefactor Christian Frederick Charles Alexander, Margrave of Brandenburg-Ansbach.

    FAU is the second largest state university in the state of Bavaria. It has 5 faculties, 24 departments/schools, 25 clinical departments, 21 autonomous departments, 579 professors, 3,457 members of research staff and roughly 14,300 employees.

    In winter semester 2018/19 around 38,771 students (including 5,096 foreign students) enrolled in the university in 265 fields of study, with about 2/3 studying at the Erlangen campus and the remaining 1/3 at the Nuremberg campus. These statistics put FAU in the list of top 10 largest universities in Germany. In 2018, 7,390 students graduated from the university and 840 doctorates and 55 post-doctoral theses were registered. Moreover, FAU received 201 million Euro (2018) external funding in the same year, making it one of the strongest third-party funded universities in Germany.

    FAU is also a member of DFG (Deutsche Forschungsgemeinschaft) and the Top Industrial Managers for Europe network.

     
  • richardmitnick 1:08 pm on April 20, 2021 Permalink | Reply
    Tags: "FAU research team investigate new star-forming region", , A triangular structure in the largest satellite galaxy surrounding the Milky Way has left astrophysicists around the world puzzled due to its unusually energetic X-ray emissions., , , , Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE), Large Magellanic Cloud (LMC), The study shows that the plasma in the X-ray spur indeed has a higher temperature than typically expected for the LMC.,   

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE): “FAU research team investigate new star-forming region” 

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE)

    April 19, 2021

    Jonathan Knies
    jonathan.knies@fau.de

    Prof. Dr. Manami Sasaki
    manami.sasaki@fau.de

    1
    In the image, the two colliding atomic hydrogen components (cold gas) are shown in green and red, while the X-ray emission observed with XMM-Newton (hot plasma) is shown in blue Credit: Jonathan Kniess).

    A triangular structure in the largest satellite galaxy surrounding the Milky Way has left astrophysicists around the world puzzled due to its unusually energetic X-ray emissions. FAU researchers have now investigated this phenomenon using the ESA XMM-Newton X-ray observatory and can reveal that it is caused by the collision of two gas clouds, which will most likely cause a new star-forming region.

    The Large Magellanic Cloud (LMC) is the largest of the satellite galaxies surrounding the Milky Way and is host to many fascinating celestial objects.

    The brightest and most interesting structure in the LMC is the emission nebula 30 Doradus, also known as the Tarantula nebula, which is one of the most active star-forming regions. Emission nebulae are formed from clouds of interstellar gas that emit light in different colours.

    X-ray observations have revealed an intriguingly large, triangular structure just south of 30 Doradus, called the ‘X-ray spur’ which has left astrophysicists puzzled as its X-ray emissions appear to be more energetic than usually expected from similar structures.

    Higher temperature than expected

    Researchers at the Dr. Karl Remeis Observatory at FAU have now studied the X-ray spur using ESA’s XMM-Newton X-ray observatory in an international collaboration. ‘The high-energy radiation of the structure was first discovered in the 1990s with the German ROSAT X-ray telescope and has been a puzzle ever since.


    Thanks to XMM-Newton, we are now able to study interstellar structures of this size for the first time,’ explains FAU astrophysicist Prof. Dr. Manami Sasaki.

    The study shows that the plasma in the X-ray spur indeed has a higher temperature than typically expected for the LMC. In fact, it is comparable to the temperature in the emission nebula 30 Doradus, which has been heated by a large number of young, massive stars.

    A new star-forming region is likely

    ‘Our multiwavelength analysis shows that there are no indications for the past and present existence of massive stars, which might have explained the heating of the plasma in the X-ray spur,’ explains Jonathan Knies, who led the study.

    ‘Instead, the X-ray spur is located between two giant clouds of atomic hydrogen, which are in the process of colliding with each other and seem to cause the heating of the environment. This collision most likely started further north, at around the position where 30 Doradus is located now and is continuing to the south. We expect that the X-ray spur will eventually evolve into an active star-forming region like 30 Doradus and its surroundings.’

    The study which connects the origin of the X-ray spur with that of 30 Doradus for the first time was recently published in the journal Astronomy & Astrophysics.

    The image in the ESA press release (see image above) shows the complex structure of the interstellar gas and clouds in the LMC, with the XMM-Newton data being the last piece that was missing in the puzzle.

    In the image, the two colliding atomic hydrogen components (cold gas) are shown in green and red, while the X-ray emission observed with XMM-Newton (hot plasma) is shown in blue. The image also shows H-alpha emission from the gas which was ionised by the massive stars, shown as magenta contours and the emission from molecular clouds (high-density regions harbouring new star-forming regions) shown as cyan contours.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Friedrich-Alexander-Universität Erlangen-Nürnberg, [FAU] (DE} is a public research university in the cities of Erlangen and Nuremberg in Bavaria, Germany. The name Friedrich–Alexander comes from the university’s first founder Friedrich, Margrave of Brandenburg-Bayreuth, and its benefactor Christian Frederick Charles Alexander, Margrave of Brandenburg-Ansbach.

    FAU is the second largest state university in the state of Bavaria. It has 5 faculties, 24 departments/schools, 25 clinical departments, 21 autonomous departments, 579 professors, 3,457 members of research staff and roughly 14,300 employees.

    In winter semester 2018/19 around 38,771 students (including 5,096 foreign students) enrolled in the university in 265 fields of study, with about 2/3 studying at the Erlangen campus and the remaining 1/3 at the Nuremberg campus. These statistics put FAU in the list of top 10 largest universities in Germany. In 2018, 7,390 students graduated from the university and 840 doctorates and 55 post-doctoral theses were registered. Moreover, FAU received 201 million Euro (2018) external funding in the same year, making it one of the strongest third-party funded universities in Germany.

    FAU is also a member of DFG (Deutsche Forschungsgemeinschaft) and the Top Industrial Managers for Europe network.

     
  • richardmitnick 1:56 pm on December 11, 2020 Permalink | Reply
    Tags: "Record resolution in X-ray microscopy", , , Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE),   

    From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE): “Record resolution in X-ray microscopy” 

    From From Friedrich-Alexander-Universität Erlangen-Nürnberg [FAU] (DE)

    December 4, 2020

    Prof. Dr. Rainer Fink
    Chair of Physical Chemistry II
    Phone: +49 9131 85-27322
    rainer.fink@fau.de

    Chemists at FAU achieve new dimension in direct imaging.

    Researchers at FAU, the Paul Scherrer Institute in Switzerland and other institutions in Paris, Hamburg and Basel, have succeeded in setting a new record in X-ray microscopy. With improved diffractive lenses and more precise sample positioning, they were able to achieve spatial resolution in the single-digit nanometre scale. This new dimension in direct imaging could provide significant impulses for research into nanostructures and further advance the development of solar cells and new types of magnetic data storage. The findings have now been published in the renowned journal Optica with the title Soft X-ray microscopy with 7 nm resolution.

    2
    Fresnel zone plates are most commonly used as diffractive focusing elements in X-ray microscopy. In the Erlangen-STXM at the Paul Scherrer Institute, the beam is focused onto the specimen, which is raster-scanned at the highest precision. The transmitted beam is sensitive to local X-ray absorption, which probes elemental, electronic, magnetic, or chemical variations. Credit: Dr. Benedikt Rösner, Paul Scherrer Institute.

    Soft X-ray microscopy, which uses low-energy X-rays is used to investigate the properties of materials in the nanoscale. This technology can be used to determine the structure of organic films that play an important role in the development of solar cells and batteries. It also enables chemical processes or catalytic reactions of particles to be observed. The method allows the investigation of so-called spin dynamics. Electrons can not only transport electric charge, but also have an internal direction of rotation, which could be used for new types of magnetic data storage.

    To improve research into these processes in the future, researchers need to be able to ‘zoom’ in to the single-digit nanometre scale. This is theoretically possible with soft X-rays, but up to now it has only been possible to achieve spatial resolution of below 10 nanometres using indirect imaging methods that require subsequent reconstruction. ‘For dynamic processes such as chemical reactions or magnetic particle interaction, we need to be able to view the structures directly,’ explains Prof. Dr. Rainer Fink from the Chair of Physical Chemistry II at FAU. ‘X-ray microscopy is especially suitable for this as it can be used more flexibly in magnetic environments than electron microscopy, for example.’

    Improved focusing and calibration

    Working with the Paul Scherrer Institute and other institutions in Paris, Hamburg, and Basel, the researchers have now broken a new record in X-ray microscopy as they have succeeded in achieving a record resolution of 7 nanometres in several different experiments. This success is not based primarily on more powerful sources of X-rays, but on improving the focus of the rays using diffractive lenses and more precise calibration of the test samples. ‘We optimised the structure size of the Fresnel zone plates which are used to focus X-rays,’ explains Rainer Fink. ‘In addition, we were able to position the samples in the device at a much higher accuracy and reproduce this accuracy.’ It is precisely this limited positioning and the stability of the system as a whole that have prevented improvements in resolution in direct imaging up to now.

    Remarkably, this record resolution was not only achieved with specially-designed test structures, but also in practical applications. For example, the researchers studied the magnetic field orientation of iron particles measuring 5 to 20 nanometres with their new optics. Prof. Fink explains: ‘We assume that our results will push forward research into energy materials and nanomagnetism in particular. The relevant structure sizes in this fields are often below current resolution limits.’

    The project has received funding from the Federal Ministry of Education and Research (BMBF), the German Research Foundation (DFG) and the EU H 2020 Research and Innovation Programme.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Friedrich-Alexander-Universität Erlangen-Nürnberg, [FAU] (DE} is a public research university in the cities of Erlangen and Nuremberg in Bavaria, Germany. The name Friedrich–Alexander comes from the university’s first founder Friedrich, Margrave of Brandenburg-Bayreuth, and its benefactor Christian Frederick Charles Alexander, Margrave of Brandenburg-Ansbach.

    FAU is the second largest state university in the state of Bavaria. It has 5 faculties, 24 departments/schools, 25 clinical departments, 21 autonomous departments, 579 professors, 3,457 members of research staff and roughly 14,300 employees.

    In winter semester 2018/19 around 38,771 students (including 5,096 foreign students) enrolled in the university in 265 fields of study, with about 2/3 studying at the Erlangen campus and the remaining 1/3 at the Nuremberg campus. These statistics put FAU in the list of top 10 largest universities in Germany. In 2018, 7,390 students graduated from the university and 840 doctorates and 55 post-doctoral theses were registered. Moreover, FAU received 201 million Euro (2018) external funding in the same year, making it one of the strongest third-party funded universities in Germany.

    FAU is also a member of DFG (Deutsche Forschungsgemeinschaft) and the Top Industrial Managers for Europe network.

     
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