Tagged: Laser Technology Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 7:00 am on November 10, 2017 Permalink | Reply
    Tags: , Gravitatioal waves, Improve LIGO’s sensitivity with better coatings for its interferometers, Laser Technology, LIGO Scientific Collaboration Center for Coatings Research, ,   

    From Stanford: “LIGO mirror coatings get an upgrade with new Stanford-led national collaboration” 

    Stanford University Name
    Stanford University

    November 9, 2017
    Vicky Stein

    1
    Stanford is leading an effort to improve facilities that capture galaxy-shaking events like the recently revealed collision of two neutron stars. (Image credit: ikonacolor / Getty Images)

    Stanford scientists will lead a new national cooperative effort, the LIGO Scientific Collaboration Center for Coatings Research, to improve detection of gravitational waves at the twin LIGO facilities.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    LIGO, the Laser Interferometer Gravitational-wave Observatory, has a problem of scale: galaxy-shaking events like the recently revealed collision of two neutron stars happened so far away that the echoes took 130 million years to travel to our planet. A collision of black holes detected in 2015 was even farther, 1.3 billion light years away.

    By the time the effects of these massive events reach Earth, they are tiny enough that they can only be detected using the most sensitive equipment scientists could devise. Changes in distance (as detected over the sprawling four-kilometer arms of LIGO) caused by gravitational waves, said Stanford researcher Riccardo Bassiri, are “a thousand times smaller than the size of an atomic nucleus.”

    Any “noise” or molecular disarray introduced by the mirrors can completely obscure the faint signals from distant gravitational wave sources.

    “It’s quite amazing, this four-kilometer, massive piece of machinery – and the coatings on the mirrors play this key role in how many gravitational-wave events we can observe,” Bassiri said. In the end, the sensitivity of LIGO’s massive interferometers is limited by atomic-scale vibrations of molecules in the mirrors that reflect the facilities’ powerful lasers. These vibrations are known collectively as Brownian thermal noise. According to Bassiri, it will be the dominant noise source limiting LIGO’s sensitivity, and a major challenge to future generations of the facilities.

    The goal of the new center, comprising 10 US institutions and led at Stanford by Martin Fejer, professor of applied physics, will be to improve LIGO’s sensitivity with better coatings for its interferometers. Researchers hope to have new materials ready in time for the next update to the LIGO facilities in as soon as three years. If they are successful and halve the amount of thermal noise from the mirror coatings, they could expand the volume of the universe that LIGO can observe eight times over current capabilities.

    The coatings in question are comprised of multiple layers no larger than a few hundreds of nanometers in thickness each – hundreds of times thinner than a human hair. In the past, researchers have followed an iterative process, creating a new coating and then testing it, hoping to improve on previous versions.

    Through the new center, Stanford will be leading researchers and facilities across the country in what they hope will be a more targeted approach. For example, working with collaborators at the SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource, scientists can inspect newly devised mirror coatings at an atomic level.

    With this critical mass of funding and participation, “rather than following this trial-and-error Edisonian approach, we can come to a materials-by-design process,” Bassiri said. “Ultimately, the reward of developing better coatings for LIGO will be to further enable exploration of the universe through gravitational wave astronomy.”

    The Center for Coatings Research is funded by the Gordon and Betty Moore Foundation and the National Science Foundation.

    The nine other US institutions that form the CCR are: American University; California State University, Los Angeles; California State University, Fullerton; Colorado State University; Hobart and William Smith Colleges; Syracuse University; University of California, Berkeley; University of Florida; and Whitman College.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

    Advertisements
     
  • richardmitnick 9:20 am on October 18, 2017 Permalink | Reply
    Tags: , , HERCULES 300 TW laser, Laser Technology,   

    From U Michigan – Hercules Laser: “HERCULES 300 TW laser” 

    U Michigan bloc

    University of Michigan

    1
    Joseph Xu, Michigan Engineering. Science Alert.

    From Science Alert
    A $US2 million upgrade could soon see the world’s most intense laser crank it up a notch.

    The laser they call HERCULES (because of course it is) is already currently capable of emitting a terrifying 300 terawatts of power. Clearly in a case of laser envy, a few new parts could see it spit out 1,000 terawatt beams of light, enough to produce next generation particle accelerators that could fit on your dining room table.

    HERCULES is getting a little old for lasers, being built back in 2007 when 300 terawatts was something to crow about.

    That doesn’t mean you shouldn’t be impressed. Assuming 1,360 watts of sunlight hit your average square metre, 300 terawatts would be more or less like collecting the light that falls on an area the size of Nebraska. And then some.


    View video on High Field Science Research at CUOS

    From U Michigan
    HERCULES 300 TW laser

    The construction and operation of a high-field petawatt class laser, HERCULES, is a major CUOS activity. The National Science Foundation through the Physics Frontier Center FOCUS supported the development and construction of this laser. The goal of High-Field Science program at CUOS is to explore the ultra-relativistic intensity regime of laser-matter interaction. The Petawatt stage of HERCULES was activated in 2007 and reached power of 300 TW [1]. This was the first multi-100 TW-scale repetitive laser. HERCULES holds world records for the highest focused intensity, 2×1022 Wcm-2 and for Amplified Spontaneous Emission (ASE) temporal contrast of 10-11.

    The HERCULES laser design is based on chirped-pulse amplification with cleaning of amplified spontaneous emission (ASE) noise after the first amplifier (Fig. 1).The output pulse of the short pulse oscillator (12 fs-pulsewidth, Femtolasers) of the HERCULES laser is preamlified in the two-pass preamlifier to the microjoule energy level. ASE added by the two-pass amplifier is removed by the cleaner based on cross-polarized-wave generation [2] providing a record ASE contrast of 10-11 [3]. The clean microjoule energy pulse is stretched to ~0.5 ns by the stretcher based on a modified mirror-in-grating design [4]. The whole laser is designed by ray-tracing analysis to be fifth-order dispersion-limited over 104 nm bandwidth. The high-energy regenerative amplifier [5] and cryogenically cooled 4-pass amplifier bring the pulse energy to a joule energy level with nearly diffraction-limited beam quality. Two sequential 2-pass-Ti:sapphire amplifiers of 1′ and 2″ beam diameter respectively raise the output energy to a value approaching 20 J.

    2
    Fig.1: Hercules Schematics

    We designed our own frequency-doubled Nd:glass pump laser [6] for pumping of the final two amplifiers of the HERCULES laser (Fig. 2). The pump laser has two stages of amplification. The frequency-doubled output of the first stage is used for pumping of the 1″-diameter Ti:sapphire amplifier, while the unconverted infrared light is injected into the second stage of the pump laser for further amplification. The frequency-doubled output of the second stage is used for pumping of the booster (2″- diameter) amplifier of the HERCULES laser. The pump laser has a quasi-flat-top beam profile that was achieved at 0.1 Hz repetition rate by relay imaging and thermally-introduced birefringence compensation. The booster two-pass amplifier uses a 11-cm-diameter Ti:sapphire crystal. Only a portion of this crystal is used to amplify the 2″ – diameter output beam of the HERCULES laser. In order to suppress parasitic oscillations the side surface of the crystal is covered with a thin layer of index-matching thermoplastic coating (Cargille Laboratories, Inc.) doped with organic dye absorbing at 800 nm.

    3
    Fig. 2: The Petawatt amplification stage of the Hercules and the pump laser during the shot.

    4
    Fig. 3: Output beam profile of the HERCULES laser booster amplifier.

    The output beam profile (Fig. 3) is quasi-flat-top as a result of using flat-top pump beams and of the image relaying of the amplified beam through the whole laser chain. Output energy of 17 J corresponding to 300 TW power after compression has been reached so far. The pump energy for the booster Ti:sapphire amplifier (2″-diameter) is controlled by changing the pumping level of the oscillator of the pump laser.

    The output pulse is compressed in a 4-grating compressor [7] to ~30 fs (Fig. 4). The compressor is based on two 42×21 cm-size and two 22×16.5 cm-size 1200 l/mm-gold-coated holographic gratings (Jobin Yvon).

    5
    Fig.4 Hercules Petawatt Compressor

    6
    Fig. 5. Autocorrelation of 300 TW pulse showing duration of 30 fs (FWHM). The experimental autocorrelation picture (insert) demonstrates that there is no amplitude front tilt or other spatial variations of the pulse arrival time.

    Because the beam size in the compressor is rather large (6″-diameter) achromatic lenses are used in the final relays to prevent spatially varying group delay across the beam. The pulse width is measured at full energy using beam leak-through a mirror by two methods: autocorrelator with inversion [8] (Fig. 5) – to ensure that there is no spatially varying pulse delay, and a single-shot spectral interferometry for direct electric field reconstruction (SPIDER) which was not sensitive to spatial variation of delay but was able to provide phase information for intensity reconstruction. After the beam compression it is down-collimated by the all-reflective telescope to 4″-diameter and is sent to the interaction chamber where it is focused by a parabolic mirror.

    Before the parabolic mirror we use a deformable mirror (4″-diameter, 177 actuators, dielectric coated at 800 nm, made by Xinetics) to compensate the aberrations of the parabolic mirror, astigmatism of the telescope and the residual aberrations of the laser beam. The focal distribution is characterized by using the method that we developed in [9,10]. We corrected the wavefront after the f/1 parabola and reached phase aberration (r.m.s.) of lambda/20 (Fig. 6a) leading to the nearly diffraction limited spot (Fig. 6b,c).

    7
    Fig. 6: Focal spot characterization: a) Low-energy-beam wavefront corrected by the deformable mirror, phase aberrations r.m.s. =0.034*lambda, P.V.=0.24l*lambda; b) Intensity distribution in the focal spot of parabolic mirror calculated for the corrected wavefront shown in (a); c) Measured focal spot for a reference low-energy beam focused by f/1 parabolic mirror for the corrected wavefront showing spot size of 1.3 micron (FWHM).

    By upgrading HERCULES’s laser power to 300 TW we demonstrated the highest focused intensity to date of ~2×1022 W/cm2. This intensity can be raised to 5×1022 W/cm2 by using a f/0.6 parabolic mirror (as we did in [9]) opening the radiation-dominated regime of electron-light interaction for experimental studies.

    References:
    1. V. Yanovsky, V. Chvykov, G. Kalinchenko, P. Rousseau, T. Planchon, T. Matsuoka, A. Maksimchuk, J. Nees, G. Cheriaux, G. Mourou and K. Krushelnick, “Ultra-high intensity 300 TW laser at 0.1 Hz repetition rate,” Optics Express 16, 2109 (2008).

    2. A. Jullien, O. Albert, F. Burgy, G.Hamoniaux, J.P. Rousseau, J.-P. Chambaret, F. AugERochereau, G. Chériaux, J. Etchepare, N. Minkovski, S.M. Saltiel,”10-10 temporal contrast for femtosecond ultraintense lasers by cross-polarized wave generation,” Opt. Lett. 30, 920-922 (2005).

    3. V. Chvykov, P. Rousseau, S. Reed, G. Kalinchenko, and V. Yanovsky, “Generation of 1011 contrast 50 TW laser pulses,” Opt. Lett. 31, 1456-1458 (2006).

    4. P. S. Bank, M.D. Perry, V. Yanovsky, S. N. Fochs, B.C. Stuart, and J. Zweiback “Novel All-Reflective Stretcher for Chirped-Pulse Amplification of Ultrashort Pulses” IEEE J. Quant. Electr. 36, 268-274 (2000).

    5. V. Yanovsky, C. Felix , and G. Mourou, “High-energy Broadband Regenerative Amplifier for Chirped-pulse Amplification” IEEE J. Sel. Top. Quant. Electr.” 7, 539-541 (2001).

    6. V.Yanovsky, V. Chvykov, S.-W.Bahk, G. Kalintchenko, K. TaPhuoc, Y-C. Chang and G.Mourou, “Development of Petawatt scale Ti:sapphire laser at 0.05 Hz repetition rate”, CLEO’2003, paper CME6

    7. M. Aoyama, K. Yamakawa, Y. Akahane, J. Ma, N. Inoue, H. Ueda, and H. Kiriyama, “0.85-PW, 33-fs Ti:sapphire laser,” Opt. Lett. 28, 1594-1596 (2003).

    8. Z Sacks, G. Mourou, R. Danielius, “Adjusting pulse-front tilt and pulse duration by use of a single-shot autocorrelator,” Opt. Lett. 26, 462-464, (2003).

    9. S.-W. Bahk, P. Rousseau, T. Planchon, V. Chvykov, G. Kalintchenko, A. Maksimchuk, G. Mourou, V. Yanovsky, “The generation and characterization of the highest laser intensity (1022W/cm2),” Opt. Lett. 29, 2837-2839 (2004).

    10. S.-W. Bahk, P. Rousseau, T. A. Planchon, V. Chvykov, G. Kalintchenko, A. Maksimchuk, G. A. Mourou, V. Yanovsky,” Characterization of focal field formed by a large numerical aperture paraboloidal mirror and generation of ultra high intensity (1022 W/cm2),” Appl. Phys. B 80, 823-832 (2005).

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U MIchigan Campus

    The University of Michigan (U-M, UM, UMich, or U of M), frequently referred to simply as Michigan, is a public research university located in Ann Arbor, Michigan, United States. Originally, founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania, 20 years before the Michigan Territory officially became a state, the University of Michigan is the state’s oldest university. The university moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet (781 acres or 3.16 km²), and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.

    Considered one of the foremost research universities in the United States,[7] the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social sciences, and STEM fields (Science, Technology, Engineering and Mathematics) as well as professional degrees in business, medicine, law, pharmacy, nursing, social work and dentistry. Michigan’s body of living alumni (as of 2012) comprises more than 500,000. Besides academic life, Michigan’s athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference.

     
  • richardmitnick 9:10 pm on October 7, 2017 Permalink | Reply
    Tags: (3-D) quantum gas atomic clock, , , JILA physicists have created an entirely new design for an atomic clock, Laser Technology, , , Quantum gas,   

    From NIST: “JILA’s 3-D Quantum Gas Atomic Clock Offers New Dimensions in Measurement” 


    NIST

    October 05, 2017

    Laura Ost
    laura.ost@nist.gov
    (303) 497-4880

    1
    JILA

    4
    CU Boulder

    1
    JILA’s three-dimensional (3-D) quantum gas atomic clock consists of a grid of light formed by three pairs of laser beams. A stack of two tables is used to configure optical components around a vacuum chamber. Shown here is the upper table, where lenses and other optics are mounted. A blue laser beam excites a cube-shaped cloud of strontium atoms located behind the round window in the middle of the table. Strontium atoms fluorescence strongly when excited with blue light. Credit: G.E. Marti/JILA

    JILA physicists have created an entirely new design for an atomic clock, in which strontium atoms are packed into a tiny three-dimensional (3-D) cube at 1,000 times the density of previous one-dimensional (1-D) clocks. In doing so, they are the first to harness the ultra-controlled behavior of a so-called “quantum gas” to make a practical measurement device.

    With so many atoms completely immobilized in place, JILA’s cubic quantum gas clock sets a record for a value called “quality factor” and the resulting measurement precision. A large quality factor translates into a high level of synchronization between the atoms and the lasers used to probe them, and makes the clock’s “ticks” pure and stable for an unusually long time, thus achieving higher precision.

    Until now, each of the thousands of “ticking” atoms in advanced clocks behave and are measured largely independently. In contrast, the new cubic quantum gas clock uses a globally interacting collection of atoms to constrain collisions and improve measurements. The new approach promises to usher in an era of dramatically improved measurements and technologies across many areas based on controlled quantum systems.

    The new clock is described in the Oct. 6 issue of Science.

    “We are entering a really exciting time when we can quantum engineer a state of matter for a particular measurement purpose,” said physicist Jun Ye of the National Institute of Standards and Technology (NIST). Ye works at JILA, which is jointly operated by NIST and the University of Colorado Boulder.

    The clock’s centerpiece is an unusual state of matter called a degenerate Fermi gas (a quantum gas for Fermi particles), first created in 1999 by Ye’s late colleague Deborah Jin. All prior atomic clocks have used thermal gases. The use of a quantum gas enables all of the atoms’ properties to be quantized, or restricted to specific values, for the first time.

    “The most important potential of the 3-D quantum gas clock is the ability to scale up the atom numbers, which will lead to a huge gain in stability,” Ye said. “Also, we could reach the ideal condition of running the clock with its full coherence time, which refers to how long a series of ticks can remain stable. The ability to scale up both the atom number and coherence time will make this new-generation clock qualitatively different from the previous generation.”

    Until now, atomic clocks have treated each atom as a separate quantum particle, and interactions among the atoms posed measurement problems. But an engineered and controlled collection, a “quantum many-body system,” arranges all its atoms in a particular pattern, or correlation, to create the lowest overall energy state. The atoms then avoid each other, regardless of how many atoms are added to the clock. The gas of atoms effectively turns itself into an insulator, which blocks interactions between constituents.

    The result is an atomic clock that can outperform all predecessors. For example, stability can be thought of as how precisely the duration of each tick matches every other tick, which is directly linked to the clock’s measurement precision. Compared with Ye’s previous 1-D clocks, the new 3-D quantum gas clock can reach the same level of precision more than 20 times faster due to the large number of atoms and longer coherence times.

    The experimental data show the 3-D quantum gas clock achieved a precision of just 3.5 parts error in 10 quintillion (1 followed by 19 zeros) in about 2 hours, making it the first atomic clock to ever reach that threshold (19 zeros). “This represents a significant improvement over any previous demonstrations,” Ye said.

    The older, 1-D version of the JILA clock was, until now, the world’s most precise clock. This clock holds strontium atoms in a linear array of pancake-shaped traps formed by laser beams, called an optical lattice. The new 3-D quantum gas clock uses additional lasers to trap atoms along three axes so that the atoms are held in a cubic arrangement. This clock can maintain stable ticks for nearly 10 seconds with 10,000 strontium atoms trapped at a density above 10 trillion atoms per cubic centimeter. In the future, the clock may be able to probe millions of atoms for more than 100 seconds at a time.

    Optical lattice clocks, despite their high levels of performance in 1-D, have to deal with a tradeoff. Clock stability could be improved further by increasing the number of atoms, but a higher density of atoms also encourages collisions, shifting the frequencies at which the atoms tick and reducing clock accuracy. Coherence times are also limited by collisions. This is where the benefits of the many-body correlation can help.

    The 3-D lattice design—imagine a large egg carton—eliminates that tradeoff by holding the atoms in place. The atoms are fermions, a class of particles that cannot be in the same quantum state and location at once. For a Fermi quantum gas under this clock’s operating conditions, quantum mechanics favors a configuration where each individual lattice site is occupied by only one atom, which prevents the frequency shifts induced by atomic interactions in the 1-D version of the clock.

    JILA researchers used an ultra-stable laser to achieve a record level of synchronization between the atoms and lasers, reaching a record-high quality factor of 5.2 quadrillion (5.2 followed by 15 zeros). Quality factor refers to how long an oscillation or waveform can persist without dissipating. The researchers found that atom collisions were reduced such that their contribution to frequency shifts in the clock was much less than in previous experiments.

    “This new strontium clock using a quantum gas is an early and astounding success in the practical application of the ‘new quantum revolution,’ sometimes called ‘quantum 2.0’,” said Thomas O’Brian, chief of the NIST Quantum Physics Division and Ye’s supervisor. “This approach holds enormous promise for NIST and JILA to harness quantum correlations for a broad range of measurements and new technologies, far beyond timing.”

    Depending on measurement goals and applications, JILA researchers can optimize the clock’s parameters such as operational temperature (10 to 50 nanokelvins), atom number (10,000 to 100,000), and physical size of the cube (20 to 60 micrometers, or millionths of a meter).

    Atomic clocks have long been advancing the frontier of measurement science, not only in timekeeping and navigation but also in definitions of other measurement units and other areas of research such as in tabletop searches for the missing “dark matter” in the universe.

    The National Bureau of Standards, now NIST, invented the first atomic clock in 1948.

    3
    Dr. Harold Lyons (right), inventor of the ammonia absorption cell atomic clock, observes, while Dr. Edward U. Condon, the director of the National Bureau of Standards, examines a model of the ammonia molecule (1949).

    The work is supported by NIST, the Defense Advanced Research Projects Agency and the National Science Foundation.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NIST Campus, Gaitherberg, MD, USA

    NIST Mission, Vision, Core Competencies, and Core Values

    NIST’s mission

    To promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.
    NIST’s vision

    NIST will be the world’s leader in creating critical measurement solutions and promoting equitable standards. Our efforts stimulate innovation, foster industrial competitiveness, and improve the quality of life.
    NIST’s core competencies

    Measurement science
    Rigorous traceability
    Development and use of standards

    NIST’s core values

    NIST is an organization with strong values, reflected both in our history and our current work. NIST leadership and staff will uphold these values to ensure a high performing environment that is safe and respectful of all.

    Perseverance: We take the long view, planning the future with scientific knowledge and imagination to ensure continued impact and relevance for our stakeholders.
    Integrity: We are ethical, honest, independent, and provide an objective perspective.
    Inclusivity: We work collaboratively to harness the diversity of people and ideas, both inside and outside of NIST, to attain the best solutions to multidisciplinary challenges.
    Excellence: We apply rigor and critical thinking to achieve world-class results and continuous improvement in everything we do.

     
  • richardmitnick 7:48 pm on September 28, 2017 Permalink | Reply
    Tags: , Laser Technology, , , Stanford PULSE Institute   

    From SLAC: “A Potential New and Easy Way to Make Attosecond Laser Pulses: Focus a Laser on Ordinary Glass” 


    SLAC Lab

    September 28, 2017
    Glennda Chui

    1
    In this illustration, a near-infrared laser beam hits a piece of ordinary glass and triggers a process called high harmonic generation. It produces laser light pulses (top right) that are just billionths of a billionth of a second, or attoseconds, long, and the photons in those pulses are much higher energy than those in the original beam. The insets zoom in on how this happens. When the incoming laser light knocks electrons (e-) out of atoms in the glass, they fly away, loop back and reconnect with either their home atom (lower right) or a neighboring atom (upper left). These reconnections generate bright bursts of light, forming a “train” of attosecond pulses that leaves the glass and can be used to probe electron movements in solids. (Greg Stewart/SLAC National Accelerator Laboratory)

    This novel method could shrink the equipment needed to make laser pulses that are billionths of a billionth of a second long for studying ultra-speedy electron movements in solids, chemical reactions and future electronics.

    The discovery 30 years ago that laser light can be boosted to much higher energies and shorter pulses – just billionths of a billionth of a second, or attoseconds, long – is the basis of attosecond science, where researchers observe and try to control the movements of electrons. Electrons are key players in chemical reactions, biological processes, electronics, solar cells and other technologies, and only pulses this short can make snapshots of their incredibly swift moves.

    Now scientists from the Stanford PULSE Institute at the Department of Energy’s SLAC National Accelerator Laboratory have found a potential new way to make attosecond laser pulses using ordinary glass – in this case, the cover slip from a microscope slide.

    The discovery, reported in Nature Communications today, was a real surprise and opens new possibilities for attosecond science and technology, including the ability to probe ultra-speedy electron motions inside glasses and other solid materials. It could also dramatically shrink the size and cost of the setups needed to produce these tiny pulses, to the point where you might be able to generate pulses inside a fiber optic cable that delivers them to where they’re needed.

    “With today’s methods, you have to shine the laser beam through a special gas jet or through a crystal that has to be grown with great care at ultra-cold temperatures,” said Yong Sing You, a postdoctoral researcher at PULSE and lead author of the study. “But this is exciting because you can use everyday glass, which is cheap and easily available, at room temperature. If you were to put your eyeglasses into the experiment, it would still work, and it would not even damage the glasses.”

    2
    Postdoctoral researcher Yong Sing You, left, and staff scientist Shambhu Ghimire in the PULSE laser lab at SLAC where the experiments were carried out. (Chris Smith/SLAC National Accelerator Laboratory)

    A String of Surprises

    The process that generates attosecond laser pulses is called high harmonic generation, or HHG. Much like pressing on a guitar string produces a note that’s higher in pitch, shining laser light through certain materials changes the nature of the light, shifting it to higher energies and shorter pulses than a laser can reach on its own.

    Most of the time this is done in a gas. Incoming photons, or particles of light, from the laser hit atoms in the gas and liberate some of their electrons. The freed electrons fly away, loop back and reconnect with their home atoms. This reconnection generates attosecond bursts of light that combine to form an attosecond laser pulse.

    Starting in 2010, a series of experiments led by PULSE researchers Shambhu Ghimire and David Reis showed HHG can be produced in ways that were previously thought unlikely or even impossible: by beaming laser light into a crystal, frozen argon gas or an atomically thin semiconductor material.

    Unlike a gas, whose atoms are so far apart that you can think of them as behaving independently, atoms in a solid are so close together that scientists thought electrons freed by an incoming laser pulse would hit neighboring atoms, scatter and never return home to make that crucial reconnection. But it turned out this was not the case, Reis said: “There’s something about the orderly structure of the crystal that allows electrons to move throughout the lattice in a way that doesn’t dissipate their energy or give them a kick in some other direction. Even if they connect with a neighboring atom, they can still participate in HHG.”

    Fundamental Science with Practical Potential

    The fact that glass could generate HHG was also a surprise, said Ghimire, who helped lead the latest study. Because it’s amorphous, meaning that its silicon and oxygen atoms are arranged in no particular order, it did not seem like a good candidate.

    But glass’s random nature was just what the team needed to answer the fundamental scientific question at the heart of the study: How do the density and crystallinity of a material – the degree to which its atoms are arranged in an orderly lattice – independently affect its ability to produce HHG? A piece of glass and a quartz crystal are both made of silicon and oxygen, and they’re roughly the same density; only the arrangement of their atoms is different. So comparing the two should provide some answers.

    The scientists put the glass cover slip in their apparatus and hit it with pulses from their infrared laser beam.

    “You might think, again, that this wouldn’t work, because the electrons would bounce off their neighbors and never make it back home,” said Reis, who was not involved in the current paper. “But the surprising thing is that even in glass, if you hit the glass hard enough but not so hard that you break it, it works fine, although by a slightly different process.”

    The ability to produce HHG in glass and other solids is exciting, he said, because it has the potential to shrink the equipment needed to do this from the size of a lab bench to maybe just a few nanometers – billionths of a meter – in size.

    Ghimire added that producing harmonics in glass has potential technological applications. For instance, it produces the short wavelengths of laser light needed to design masks for patterning nanometer-scale features on semiconductor chips.

    “For this, they want as much intensity as possible, and also an easy way to deliver light to their samples,” he said. “Being able to produce short-wavelength laser light in normal glass would bring us a couple of steps closer to something they could actually use. We could even generate the short-wavelength light in the glass portion of optical fibers that then deliver it to wherever they wanted it.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 9:13 am on September 14, 2017 Permalink | Reply
    Tags: , Laser Technology, , Optical information processing, , Plasmonic cavity,   

    From Sandia: “Nanotechnology experts at Sandia create first terahertz-speed polarization optical switch” 


    Sandia Lab

    A Sandia National Laboratories-led team has for the first time used optics rather than electronics to switch a nanometer-thick thin film device from completely dark to completely transparent, or light, at a speed of trillionths of a second.

    The team led by principal investigator Igal Brener published a Nature Photonics paper this spring with collaborators at North Carolina State University. The paper describes work on optical information processing, such as switching or light polarization control using light as the control beam, at terahertz speeds, a rate much faster than what is achievable today by electronic means, and a smaller overall device size than other all-optical switching technologies.

    Electrons spinning around inside devices like those used in telecommunications equipment have a speed limit due to a slow charging rate and poor heat dissipation, so if significantly faster operation is the goal, electrons might have to give way to photons.

    To use photons effectively, the technique requires a device that goes from completely light to completely dark at terahertz speeds. In the past, researchers couldn’t get the necessary contrast change from an optical switch at the speed needed in a small device. Previous attempts were more like dimming a light than turning it off, or required light to travel a long distance.

    The breakthrough shows it’s possible to do high contrast all-optical switching in a very thin device, in which light intensity or polarization is switched optically, said Yuanmu Yang, a former Sandia Labs postdoctoral employee who worked at the Center for Integrated Nanotechnologies, a Department of Energy user facility jointly operated by Sandia and Los Alamos national laboratories. The work was done at CINT.

    1
    Former Sandia National Laboratories postdoctoral researcher Yuanmu Yang, left, and Sandia researcher Igal Brener set up to do testing in an optical lab. A team led by Brener published a Nature Photonics paper describing work on optical information processing at terahertz speeds, a rate much faster than what is achievable today by electronic means. (Photo by Randy Montoya)

    “Instead of switching a current on and off, the goal would be to switch light on and off at rates much faster than what is achievable today,” Yang said.

    Faster information processing important in communications, physics research

    A very rapid and compact switching platform opens up a new way to investigate fundamental physics problems. “A lot of physical processes actually occur at a very fast speed, at a rate of a few terahertz,” Yang said. “Having this tool lets us study the dynamics of physical processes like molecular rotation and magnetic spin. It’s important for research and for moving knowledge further along.”

    It also could act as a rapid polarization switch — polarization changes the characteristics of light — that could be used in biological imaging or chemical spectroscopy, Brener said. “Sometimes you do measurements that require changing the polarization of light at a very fast rate. Our device can work like that too. It’s either an absolute switch that turns on and off or a polarization switch that just switches the polarization of light.”

    Ultrafast information processing “matters in computing, telecommunications, signal processing, image processing and in chemistry and biology experiments where you want very fast switching,” Brener said. “There are some laser-based imaging techniques that will benefit from having fast switching too.”

    The team’s discovery arose from research funded by the Energy Department’s Basic Energy Sciences, Division of Materials Sciences and Engineering, that, among other things, lets Sandia study light-matter interaction and different concepts in nanophotonics.

    “This is an example where it just grew organically from fundamental research into something that has an amazing performance,” Brener said. “Also, we were lucky that we had a collaboration with North Carolina State University. They had the material and we realized that we could use it for this purpose. It wasn’t driven by an applied project; it was the other way around.”

    The collaboration was funded by Sandia’s Laboratory Directed Research and Development program.

    Technique uses laser beams to carry information, switch device

    The technique uses two laser beams, one carrying the information and the second switching the device on and off.

    The switching beam uses photons to heat up electrons inside semiconductors to temperatures of a few thousand degrees Fahrenheit, which doesn’t cause the sample to get that hot but dramatically changes the material’s optical properties. The material also relaxes at terahertz speeds, in a few hundred femtoseconds or in less than one trillionth of a second. “So we can switch this material on and off at a rate of a few trillion times per second,” Yang said.

    Sandia researchers turn the optical switch on and off by creating something called a plasmonic cavity, which confines light within a few tens of nanometers, and significantly boosts light-matter interaction. By using a special plasmonic material, doped cadmium oxide from North Carolina State, they built a high-quality plasmonic cavity. Heating up electrons in the doped cadmium oxide drastically modifies the opto-electrical properties of the plasmonics cavity, modulating the intensity of the reflected light.

    Traditional plasmonic materials like gold or silver are barely sensitive to the optical control beam. Shining a beam onto them doesn’t change their properties from light to dark or vice versa. The optical control beam, however, alters the doped cadmium oxide cavity very rapidly, controlling its optical properties like an on-off switch.

    The next step is figuring out how to use electrical pulses rather than optical pulses to activate the switch, since an all-optical approach still requires large equipment, Brener said. He estimates the work could take three to five years.

    “For practical purposes, you need to miniaturize and do this electrically,” he said.

    The paper’s authors are Yang, Brener, Salvatore Campione, Willie Luk and Mike Sinclair at Sandia Labs and Jon-Paul Maria, Kyle Kelley and Edward Sachet at North Carolina State.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Sandia Campus
    Sandia National Laboratory

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
    i1
    i2
    i3

     
  • richardmitnick 8:05 am on September 14, 2017 Permalink | Reply
    Tags: , atom by atom, ’ physicists create a new type of molecule, , Experiments like these pave the way for developing new methods for controlling chemistry, Help scientists understand how certain complex molecules including some that could be precursors to life came to exist in space, In step toward ‘controlling chemistry, Integrated ion-trap-time-of-flight mass spectrometer, Ion traps, Laser Technology, Narrow the gap between physics and chemistry, Octet Rule - each atom in a molecule that is produced by a chemical reaction will have eight outer orbiting electrons, , , Ultra-cold atom traps   

    From UCLA: “In step toward ‘controlling chemistry,’ physicists create a new type of molecule, atom by atom” 


    UCLA Newsrooom

    September 13, 2017
    Stuart Wolpert

    1
    By working in extremely controlled conditions, Eric Hudson and his colleagues could observe properties of atoms and molecules that have previously been hidden from view. Stuart Wolpert/UCLA

    UCLA physicists have pioneered a method for creating a unique new molecule that could eventually have applications in medicine, food science and other fields. Their research, which also shows how chemical reactions can be studied on a microscopic scale using tools of physics, is reported in the journal Science.

    For the past 200 years, scientists have developed rules to describe chemical reactions that they’ve observed, including reactions in food, vitamins, medications and living organisms. One of the most ubiquitous is the “octet rule,” which states that each atom in a molecule that is produced by a chemical reaction will have eight outer orbiting electrons. (Scientists have found exceptions to the rule, but those exceptions are rare.)

    But the molecule created by UCLA professor Eric Hudson and colleagues violates that rule. Barium-oxygen-calcium, or BaOCa+, is the first molecule ever observed by scientists that is composed of an oxygen atom bonded to two different metal atoms.

    Normally, one metal atom (either barium or calcium) can react with an oxygen atom to produce a stable molecule. However, when the UCLA scientists added a second metal atom to the mix, a new molecule, BaOCa+, which no longer satisfied the octet rule, had been formed.

    2
    Michael Mills, Prateek Puri, Eric Hudson and Christian Schneider. Stuart Wolpert/UCLA

    Other molecules that violate the octet rule have been observed before, but the UCLA study is among the first to observe such a molecule using tools from physics — namely lasers, ion traps and ultra-cold atom traps.

    Hudson’s laboratory used laser light to cool tiny amounts of the reactant atoms and molecules to an extremely low temperature — one one-thousandth of a degree above absolute zero — and then levitate them in a space smaller than the width of a human hair, inside of a vacuum chamber. Under these highly controlled conditions, the scientists could observe properties of the atoms and molecules that are otherwise hidden from view, and the “physics tools” they used enabled them to hold a sample of atoms and observe chemical reactions one molecule at a time.

    The ultra-cold temperatures used in the experiment can also be used to simulate the reaction as it would occur in outer space. That could help scientists understand how certain complex molecules, including some that could be precursors to life, came to exist in space, Hudson said.

    The researchers found that when they brought together calcium and barium methoxide inside of their system under normal conditions, they would not react because the atoms could not find a way to rearrange themselves to form a stable molecule. However, when the scientists used a laser to change the distribution of the electrons in the calcium atom, the reaction quickly proceeded, producing a new molecule, CaOBa+.

    The approach is part of a new physics-inspired subfield of chemistry that uses the tools of ultra-cold physics, such as lasers and electromagnetism, to observe and control how and when single-particle reactions occur.

    UCLA graduate student Prateek Puri, the project’s lead researcher, said the experiment demonstrates not only how these techniques can be used to create exotic molecules, but also how they can be used to engineer important reactions. The discovery could ultimately be used to create new methods for preserving food (by preventing unwanted chemical reactions between food and the environment) or developing safer medications (by eliminating the chemical reactions that cause negative side effects).

    “Experiments like these pave the way for developing new methods for controlling chemistry,” Puri said. “We’re essentially creating ‘on buttons’ for reactions.”

    Hudson said he hopes the work will encourage other scientists to further narrow the gap between physics and chemistry, and to demonstrate that increasingly complex molecules can be studied and controlled. He added that one key to the success of the new study was the involvement of experts from various fields: experimental physicists, theoretical physicists and a physical chemist.

    A key player in the research is already making a name for itself in Hollywood. A device called the integrated ion-trap-time-of-flight mass spectrometer, which was invented by Hudson’s lab and which was used to discover the reaction — was featured on a recent episode of the sitcom “The Big Bang Theory.”

    “The device enables us to detect and identify the products of reactions on the single-particle level, and for us, it has really been a bridge between chemistry and physics,” said Michael Mills, a UCLA graduate student who worked on the project. “We were delighted to see it picked up by the show.”

    Co-authors of the study are Christian Schneider, a UCLA research scientist; Ionel Simbotin, a University of Connecticut physics postdoctoral scholar; John Montgomery Jr., a University of Connecticut research professor of physics; Robin Côté, a University of Connecticut professor of physics; and Arthur Suits, a University of Missouri professor of chemistry.

    The research was funded by the National Science Foundation and Army Research Office.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    UC LA Campus

    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 7:35 am on September 1, 2017 Permalink | Reply
    Tags: , , , Laser Technology, MEC- Matter in Extreme Conditions, , , ,   

    From SLAC: “Newly Upgraded Laser Allows Scientists to Peer Further Into the Extreme Universe at SLAC’s LCLS” 


    SLAC Lab

    August 15, 2017
    Miyuki Dougherty

    1
    Highly reflective mirrors and telescope lenses in the Matter in Extreme Conditions (MEC) optical laser system are carefully positioned to propagate the instrument’s high-quality laser beams. The laser beams create extreme pressure and temperature conditions in materials that are instantaneously probed using hard X-rays from SLAC’s Linac Coherent Light Source (LCLS). (Dawn Harmer/SLAC National Accelerator Laboratory)

    Tripling the energy and refining the shape of optical laser pulses at the Matter in Extreme Conditions instrument allows researchers to create higher-pressure conditions and explore unsolved fusion energy, plasma physics and materials science questions.

    Scientists at the Department of Energy’s SLAC National Accelerator Laboratory recently upgraded a powerful optical laser system used to create shockwaves that generate high-pressure conditions like those found within planetary interiors. The laser system now delivers three times more energy for experiments with SLAC’s ultrabright X-ray laser, providing a more powerful tool for probing extreme states of matter in our universe.

    Together, the optical and X-ray lasers form the Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS).

    SLAC/LCLS

    The high-power optical laser system creates extreme temperature and pressure conditions in materials, and the X-ray laser beam captures the material’s response.

    With this technology, researchers have already examined how meteor impacts shock minerals in the Earth’s crust and simulated conditions in Jupiter’s interior by turning aluminum foil into a warm, dense plasma.

    Higher Intensity and More Controlled Pulse Shapes

    The MEC instrument team received funding from the Office of Fusion Energy Sciences (FES) within the DOE’s Office of Science to double the amount of energy the optical beam can deliver in 10 nanoseconds, from 20 to 40 joules.

    But they went even further.

    “The team exceeded our expectations, an exciting accomplishment for the DOE High Energy Density program and future MEC instrument users,” says Kramer Akli, program manager for High Energy Density Laboratory Plasma at FES.

    The team tripled the amount of energy the laser can deliver in 10 nanoseconds to a spot on a target no bigger than the width of a few human hairs. When focused down to that small area, the laser provides users with intensities up to 75 terawatts per square centimeter.

    “In other terms, the upgraded laser has the same power as 17 Teslas discharging their 100 kilowatt-hour batteries in one second,” says Eric Galtier, a MEC instrument scientist.

    A portion of the energy upgrade can be attributed to the optical laser’s new, homemade diode pumped front-end, designed with the help of Marc Welch, a MEC laser engineer. The scientists also built and automated a system for shaping the laser pulses with extraordinary precision, allowing users substantially greater flexibility and control over the pulse shapes used in their experiments.

    A more powerful and reliable laser means that researchers can study higher pressure regimes and reach conditions relevant to fusion energy studies.

    Simulating the Core of Planets

    The MEC upgrade is promising for many researchers, including Shaughnessy Brennan Brown, a doctoral student in Mechanical Engineering, whose research focuses on high energy density science, which spans chemistry, materials science, and physics. Brennan Brown uses the MEC experimental hutch to drive shock waves through silicon and generate high-pressure conditions that occur in the Earth’s interior.

    “The MEC upgrade at LCLS enables researchers like me to generate exciting, previously-unexplored regimes of exotic matter – such as those found on Mars, our next planetary stepping stone – with crucial reliability and repeatability,” Brennan Brown says.

    Brennan Brown’s research examines the processes by which silicon in Earth’s core rearranges atomically under high temperature and pressure conditions. The thermodynamic properties of these high-pressure states affect our magnetic field, which protects us from the solar wind and allows us to survive on Earth. The laser upgrade will permit Brennan Brown to reach higher pressure and temperature conditions inside her samples, a long-standing goal.

    2
    Inside the MEC vacuum target chamber where researchers create transient states of matter using high-power optical lasers, which are then examined with SLAC’s Linac Coherent Light Source (LCLS) X-rays. (Matt Beardsley/SLAC National Accelerator Laboratory)

    Intensity Plus Precision

    The optical laser amplifies a low-power beam in stages and reaches increasingly high energies. However, the quality of the laser beam and ability to control it diminish during amplification. A low-quality pulse may start and end with a significantly different shape, which is not useful for researchers trying to recreate specific conditions.

    “The initial low energy pulse must have a pristine spatial mode and the properly configured temporal shape – that is, a precise sculpting of the pulse’s power as a function of time – before amplification to produce the laser pulse characteristics needed to enable each users’ experiment,” says Michael Greenberg, the MEC Laser Area Manager.

    Each target is unique and requires a specific energy and pulse shape, making manual tests and adjustments time-consuming. Prior to the upgrade, the team optimized the pulse shape by hand, taking anywhere from a few hours to a few days to properly calibrate it.

    To resolve this issue, Eric Cunningham, a laser scientist at MEC, developed an automated control system to shape the low-powered beam before amplification.

    3
    To demonstrate the MEC laser system’s enhanced ability to tailor the shape of laser pulses, scientists generated pulse shapes that spell out “M-E-C” in a plot of laser intensity vs. time. (Eric Cunningham and Michael Greenberg/SLAC National Accelerator Laboratory)

    “The new system allows for precise tailoring of the pulse shape using a computerized feedback loop system that analyzes the pulses and automatically re-calibrates the laser,” Cunningham said. The new optimizer is a promising system for generating many high-quality pulses in the most accurate and timely manner possible.

    In addition to the improved pulse shapes, the upgraded system deposits energy on samples more consistently from shot to shot, which allows researchers to very closely reproduce extreme states of matter in their samples. As a result, both the data quality and operational efficiency are improved.

    Brennan Brown says it’s the people and technology that make the instrument so successful: “The capability and competency of the laser scientists and engineers at the MEC experimental station offer researchers the technological resources they need to explore unanswered questions of the universe and bring their theories to life.”

    LCLS is a DOE Office of Science User Facility.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 8:36 pm on July 14, 2017 Permalink | Reply
    Tags: A high Mach number shock wave, High-energy plasma, Laser Technology, , , The first high-energy shock waves in a laboratory setting, U Rochester OMEGA EP Laser System   

    From PPPL: “Scientists create first laboratory generation of high-energy shock waves that accelerate astrophysical particles” 


    PPPL

    July 14, 2017
    John Greenwald

    1
    Physicist Derek Schaeffer. (Photo by Elle Starkman/Office of Communications).

    Throughout the universe, supersonic shock waves propel cosmic rays and supernova particles to velocities near the speed of light. The most high-energy of these astrophysical shocks occur too far outside the solar system to be studied in detail and have long puzzled astrophysicists. Shocks closer to Earth can be detected by spacecraft, but they fly by too quickly to probe a wave’s formation.

    2
    No image credit or caption.

    Opening the door to new understanding

    Now a team of scientists has generated the first high-energy shock waves in a laboratory setting, opening the door to new understanding of these mysterious processes. “We have for the first time developed a platform for studying highly energetic shocks with greater flexibility and control than is possible with spacecraft,” said Derek Schaeffer, a physicist at Princeton University and the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), and lead author of a July paper in Physical Review Letters that outlines the experiments.

    Schaeffer and colleagues conducted their research on the Omega EP laser facility at the University of Rochester Laboratory for Laser Energetics.

    3
    U Rochester OMEGA EP Laser System

    U Rochester Omega Laser

    Collaborating on the project was PPPL physicist Will Fox, who designed the experiment, and researchers from Rochester and the universities of Michigan and New Hampshire. “This lets you understand the evolution of the physical processes going on inside shock waves,” Fox said of the platform.

    To produce the wave, scientists used a laser to create a high-energy plasma — a form of matter composed of atoms and charged atomic particles — that expanded into a pre-existing magnetized plasma. The interaction created, within a few billionths of a second, a magnetized shock wave that expanded at a rate of more than 1 million miles per hour, congruent with shocks beyond the solar system. The rapid velocity represented a high “magnetosonic Mach number” and the wave was “collisionless,” emulating shocks that occur in outer space where particles are too far apart to frequently collide.

    Discovery by accident

    Discovery of this method of generating shock waves actually came about by accident. The physicists had been studying magnetic reconnection, the process in which the magnetic field lines in plasma converge, separate and energetically reconnect. To investigate the flow of plasma in the experiment, researchers installed a new diagnostic on the Rochester laser facility. To their surprise, the diagnostic revealed a sharp steepening of the density of the plasma, which signaled the formation of a high Mach number shock wave.

    To simulate the findings, the researchers ran a computer code called “PSC” on the Titan supercomputer, the most powerful U.S. computer, housed at the DOE’s Oak Ridge Leadership Computing Facility.

    ORNL Cray XK7 Titan Supercomputer

    The simulation utilized data derived from the experiments and results of the model agreed well with diagnostic images of the shock formation.

    Going forward, the laboratory platform will enable new studies of the relationship between collisionless shocks and the acceleration of astrophysical particles. The platform “complements present remote sensing and spacecraft observations,” the authors wrote, and “opens the way for controlled laboratory investigations of high-Mach number shocks.”

    Support for this research came from the DOE Office of Science, the DOE INCITE Leadership Computing program, and the National Nuclear Security Administration, a semi-autonomous agency within the DOE.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 9:24 am on July 13, 2017 Permalink | Reply
    Tags: , extraterrestrial ice can form in just billionths of a second, Laser Technology, , , Stanford scientists discover how dense, ,   

    From Stanford: “Stanford scientists discover how dense, extraterrestrial ice can form in just billionths of a second” 

    Stanford University Name
    Stanford University

    July 12, 2017
    Adam Hadhazy

    1
    At the Linac Coherent Light Source, Stanford scientists used the world’s most powerful X-ray laser to create an extraterrestrial form of ice. (Image credit: Brad Plummer).

    Stanford researchers have for the first time captured the freezing of water, molecule-by-molecule, into a strange, dense form called ice VII (“ice seven”), found naturally in otherworldly environments, such as when icy planetary bodies collide.

    In addition to helping scientists better understand those remote worlds, the findings – published online July 11 in Physical Review Letters – could reveal how water and other substances undergo transitions from liquids to solids. Learning to manipulate those transitions might open the way someday to engineering materials with exotic new properties.

    “These experiments with water are the first of their kind, allowing us to witness a fundamental disorder-to-order transition in one of the most abundant molecules in the universe,” said study lead author Arianna Gleason, a postdoctoral fellow at Los Alamos National Laboratory and a visiting scientist in the Extreme Environments Laboratory of Stanford’s School of Earth, Energy & Environmental Sciences.

    Scientists have long studied how materials undergo phase changes between gas, liquid and solid states. Phase changes can happen rapidly, however, and on the tiny scale of mere atoms. Previous research has struggled to capture the moment-to-moment action of phase transitions, and instead worked backward from stable solids in piecing together the molecular steps taken by predecessor liquids.

    “There have been a tremendous number of studies on ice because everyone wants to understand its behavior,” said study senior author Wendy Mao, an associate professor of geological sciences and a Stanford Institute for Materials and Energy Sciences (SIMES) principal investigator. “What our new study demonstrates, and which hasn’t been done before, is the ability to see the ice structure form in real time.”

    Catching ice in the act

    Those timescales became achievable thanks to the Linac Coherent Light Source, the world’s most powerful X-ray laser located at the nearby SLAC National Accelerator Laboratory. There, the science team beamed an intense, green-colored laser at a small target containing a sample of liquid water. The laser instantly vaporized layers of diamond on one side of the target, generating a rocket-like force that compressed the water to pressures exceeding 50,000 times that of Earth’s atmosphere at sea level.

    As the water compacted, a separate beam from an instrument called the X-ray Free Electron Laser arrived in a series of bright pulses only a femtosecond, or a quadrillionth of a second, long. Akin to camera flashes, this strobing X-ray laser snapped a set of images revealing the progression of molecular changes, flip book–style, while the pressurized water crystallized into ice VII. The phase change took just 6 billionths of a second, or nanoseconds. Surprisingly, during this process, the water molecules bonded into rod shapes, and not spheres as theory predicted.

    The platform developed for this study – combining high pressure with snapshot images – could help researchers probe the myriad ways water freezes, depending on pressure and temperature. Under the conditions on our planet’s surface, water crystallizes in only one way, dubbed ice Ih (“ice one-H”) or simply “hexagonal ice,” whether in glaciers or ice cube trays in the freezer.

    Delving into extraterrestrial ice types, including ice VII, will help scientists model such remote environments as comet impacts, the internal structures of potentially life-supporting, water-filled moons like Jupiter’s Europa, and the dynamics of jumbo, rocky, oceanic exoplanets called super-Earths.

    “Any icy satellite or planetary interior is intimately connected to the object’s surface,” Gleason said. “Learning about these icy interiors will help us understand how the worlds in our solar system formed and how at least one of them, so far as we know, came to have all the necessary characteristics for life.”

    Other co-authors on the study include Cindy Bolme of Los Alamos National Laboratory; Eric Galtier, Hae Ja Lee and Eduardo Granados of the SLAC National Accelerator Laboratory; Dan Dolan, Chris Seagle and Tom Ao of Sandia National Laboratories; and Suzanne Ali, Amy Lazicki, Damian Swift and Peter Celliers of Lawrence Livermore National Laboratory.

    Funding was provided by the National Science Foundation, the Los Alamos National Laboratory, the U.S. Department of Energy Office of Science, Fusion Energy Science and the SLAC National Accelerator Laboratory.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

     
  • richardmitnick 7:30 pm on July 11, 2017 Permalink | Reply
    Tags: , Laser Technology, ,   

    From Northwestern: “New laser design offers more inexpensive multi-color output” 

    Northwestern U bloc
    Northwestern University

    July 11, 2017
    Kristin Samuelson

    1
    Photo courtesy of John Krzesinski, 2011, Flickr

    From checkout counters at supermarkets to light shows at concerts, lasers are everywhere, and they’re a much more efficient light source than incandescent bulbs. But they’re not cheap to produce.

    A new Northwestern University study has engineered a more cost-effective laser design that outputs multi-color lasing and offers a step forward in chip-based lasers and miniaturization. The findings could allow encrypted, encoded, redundant and faster information flow in optical fibers, as well as multi-color medical imaging of diseased tissue in real time.

    The study was published July 10 in Nature Nanotechnology.

    “In our work, we demonstrated that multi-modal lasing with control over the different colors can be achieved in a single device,” said senior author Teri W. Odom, a Charles E. and Emma H. Morrison Professor of Chemistry in the Weinberg College of Arts and Sciences at Northwestern. “Compared to traditional lasers, our work is unprecedented for its stable multi-modal nanoscale lasing and our ability to achieve detailed and fine control over the lasing beams.”

    This work offers new insights into the design and mechanism of multi-modal nanoscale lasing based on structural engineering and manipulating the optical band structures of nanoparticle superlattices. Using this technology, the researchers can control the color and intensity of the light by simply varying its cavity architecture.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: