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  • richardmitnick 3:23 pm on October 5, 2015 Permalink | Reply
    Tags: , , X-ray Lasers   

    From SLAC: “200-terawatt Laser Brings New Extremes in Heat, Pressure to X-ray Experiments” 

    SLAC Lab

    October 5, 2015

    An upgraded high-power laser is designed to synchronize with X-rays for high-temperature, high-pressure experiments in this large chamber, at left. The chamber is in the Matter in Extreme Conditions experimental station at SLAC’s Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    A view of the large crystal that is integral to a high-power laser system at SLAC’s Matter in Extreme Conditions experimental station at the Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    Eduardo Granados, a laser scientist at SLAC, inspects a large titanium-sapphire crystal, a key component in a newly upgraded high-power laser system. The laser system is designed to work in conjunction with pulses from SLAC’s Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    A newly upgraded high-power laser at the Department of Energy’s SLAC National Accelerator Laboratory will blaze new trails across many fields of science by recreating the universe’s most extreme conditions, such as those at the heart of stars and planets, in a lab.

    It is the first high-power laser system to be paired with SLAC’s X-ray laser, the Linac Coherent Light Source (LCLS).

    SLAC LCLS Inside
    Inside the LCLS

    LCLS can precisely measure extreme forms of matter created by the high-power pulses – with temperatures reaching millions of degrees and pressures approaching 2 billion tons per square inch, about 300 billion times the pressure at sea level – as it rapidly transforms at the atomic scale. The upgraded laser will be useful for studying how materials transform under stress and for understanding the physics of nuclear fusion, which could one day serve as a revolutionary source of energy.

    Scientists can also use its pulses to drive a variety of particle beams that explore forms of matter, such as star-like dense plasmas, in new ways. Plasmas, which are considered a fourth state of matter because they are not like solids, liquids or gases, consist of a gassy soup of charged particles that includes free-floating electrons and the atoms the electrons were stripped away from.

    “This will give us more insight into the processes at work, from the atomic to electronic states,” said Eduardo Granados, a laser scientist at SLAC who oversaw the upgrade.

    The upgraded laser system is designed to reach a peak of 200 terawatts of power, seven times higher than its previous peak and equivalent to about 100 times the world’s total power consumption compressed into tens of femtoseconds, or quadrillionths of a second. Its peak power before the upgrade was 30 terawatts. The laser’s pulses are now far more powerful than the total combined pulse power of the more than 150 other laser systems in operation at SLAC.

    New Ways to Probe Materials

    Even though SLAC’s upgraded laser is not the most powerful in the world – a laser completed in Japan this year now holds the record, with roughly 10 times higher power, and many other laser systems around the globe are several times more powerful – what makes it unique is its ability to synchronize with the intense, ultrafast X-ray pulses produced at LCLS, a DOE Office of Science User Facility.

    The growth in these high-power laser systems around the globe opens new avenues for discovery and has excited interest among researchers working in astrophysics, materials research, planetary sciences, geology, and nuclear and energy sciences, among other fields. On Sept. 30, an international symposium organized by the Science Council of Japan met at SLAC to discuss the latest developments in using high-power lasers and X-ray lasers to study matter at extreme conditions, and similar discussions are planned during a two-day High-Power Laser Workshop this week at SLAC and during an upcoming lab-based astrophysics conference at SLAC.

    SLAC’s high-power laser emits light pulses at invisible, near-infrared frequencies that push samples to extreme conditions; the X-ray laser then probes their properties with incredible precision. Both laser systems can produce pulses measured in femtoseconds, and the timing delay between the high-power and X-ray pulses can be adjusted to study how materials rapidly transform after they are hit by the high-power laser pulse.

    The high-power laser can also be used to simultaneously generate beams of particles such as gamma rays, protons and a specialized form of X-rays called betatron radiation all of which can be used in concert with LCLS pulses to explore exotic states of matter in new ways.

    “We will now have a much more accurate picture of what’s happening in high-energy X-ray laser experiments,” Granados said.

    Opportunity for Future Upgrades

    At the core of SLAC’s upgraded laser system, which is housed at the Matter in Extreme Conditions experimental station at LCLS, is a large, high-quality titanium-sapphire crystal, measuring more than 3 inches in diameter. The crystal stimulates and amplifies light from another laser. That amplified light is focused down to a spot just millionths of an inch across, and timing systems help to synch the arrival of each laser pulse with an LCLS X-ray laser pulse with a precision measured in femtoseconds.

    The upgraded high-power laser at LCLS will be available to scientists during the next round of experiments at LCLS, which begins in October, at half of its designed peak power, 100 terawatts. The plan is to gradually ramp up its intensity over time toward regular operation at 200 terawatts, Granados said. The laser will initially be able to fire one pulse every 3.5 minutes at 100 terawatts, with a pulse length of about 40 femtoseconds. At its peak power of 200 terawatts, it will fire one shot every seven minutes.

    Granados said the laser system can eventually be upgraded further, up to 300 terawatts and perhaps as high as 400 terawatts, with additional equipment.

    Even before the upgrade the laser system was used for a first-of-a-kind LCLS experiment that used its pulse to produce a secondary surge of X-rays in the form of betatron X-rays. Those betatron X-rays, which cover a broader energy range than the LCLS pulses and were produced by accelerating high-energy electrons with laser light, were used to reveal more details about the samples.

    “These betatron X-rays are a promising source for future experiments that we now want to test at higher energies,” Granados said.

    See the full article here .

    Please help promote STEM in your local schools.

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

  • richardmitnick 3:32 pm on February 11, 2015 Permalink | Reply
    Tags: , , X-ray Lasers,   

    From DESY: “Taking high-speed snapshots of living cells with an X-ray laser” 



    X-ray imaging method captures living cells with unprecedented speed and resolution

    An international team led by Uppsala University and including scientists from DESY and the European XFEL has for the first time successfully imaged whole living bacterial cells with an X-ray laser. The method used in this experiment can produce results that are of higher spatial and temporal resolution than even the best optical microscopy techniques, with the added possibility of creating detailed 3D models of the cells. “When you really want to understand the details of a cell’s functions, you need it alive”, says Uppsala University Professor Janos Hajdu, one of the lead researchers in the experiment and an advisor to European XFEL. The technique, as described in the journal Nature Communications, allows scientists a clearer view into the complicated world of the cell.

    Reconstructed electron density of a cyanobacterium. Credit: Gjis van der Schot/Universität Uppsala

    The method involves spraying the cells into a fine aerosol ahead of the pulses of an X-ray laser. This aerosol — literally a beam of living cells — has a thickness less than that of a human hair. The ultra-short X-ray pulses scatter from the individual cells and the resulting diffraction patterns are picked up by a detector. Computer programs, including several developed in collaboration between Uppsala and DESY, analyze the data and reconstruct the image of the cells.

    “While the X-rays destroy the cells in the process, an X-ray laser’s ultra-short flashes and high intensity allow the diffraction data to be captured quickly enough to get an accurate picture of the sample before it disintegrates. The flashes outrun the damage,” says Anton Barty, a DESY scientist at the Center for Free Electron Laser Science who is also a co-author of this paper.

    This technique, called “diffraction-before-destruction”, has been proven to work in several studies with biological and also with inorganic samples before. The cell imaging experiment took place at the LCLS X-ray laser at SLAC National Accelerator Laboratory in Menlo Park, California. Two types of cyanobacteria were used in the study called Cyanobium gracile and Synechococcus elongatus. These cells have a roughly cylindrical shape that is immediately apparent in the reconstructions from the diffraction data.

    Nomarski image of the same cyanobacterium, calculated from the recontruction. Credit: Gjis van der Schot/Universität Uppsala

    However, the leader of the experiment, Tomas Ekeberg, an assistant professor in molecular biophysics at Uppsala University, acknowledged that the pictures could have been even better but the data were more than the detectors could handle.

    “We so far can only accurately reconstruct to 76 nanometres resolution, but the data we collected indicates that we can get down to 4 nanometres, which is the size of a protein molecule”, Ekeberg says. A nanometre is a billion times smaller than a metre. The reason for the drop in resolution was what amounted to an overexposure, just like too bright of a light in a photograph. “This experiment was a proof-of-concept study”, says Ekeberg. “We will be able to obtain much higher-resolution pictures when we can use a filter to help reduce the overexposure.” adds Gijs van der Schot, a Ph.D. student with Ekeberg and the first author on the paper.

    Acquiring high-resolution micrographs from cells in conventional experiments has usually meant long exposure times and about a million times higher radiation doses than the dose that kills a living cell. As a consequence, much of what we know today about cells at high-resolution comes from dead material. The team’s new method can access the structure of living cells at practically instantaneous speeds, before radiation damage has time to set in. Each image is formed in femtoseconds. A femtosecond is a millionth of a billionth of a second. Such a revolutionary tool could help scientists better understand some of the mysteries of cellular function and behaviour. Additionally, this technique opens the door for future 3D modelling of cells and cellular activities, and provides key insights to fundamental processes in several important areas of disease research.

    X-ray diffraction pattern produced by a cyanobacterium at the LCLS. Credit: Gjis van der Schot/Universität Uppsala

    “This is a promising method for the European XFEL”, says Joachim Schulz, a scientist at European XFEL and one of the co-authors on the paper. “It could further expand the application of bio-imaging methods to users, opening possibilities to image living organisms.”

    The team plans to fine-tune the imaging method with further experiments and work on consistently developing images at higher resolution. Additionally, Ekeberg and van der Schot predict that future studies would attempt to develop the 3D cell division models or target particular structural information about the cells for bioinformatics.

    “The contrast is tremendous between images produced using this technique and those from traditional optical microscopy of living cells”, says Hajdu. “Few believed this was possible.”

    The future for imaging is getting even brighter in Hamburg, as the European X-FEL will soon start generating ultra-short, ultra-intense X-ray pulses at 300 times higher repetition rate than the best X-ray lasers today.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

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