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  • richardmitnick 11:04 am on September 15, 2019 Permalink | Reply
    Tags: "This device harnesses the cold night sky to generate electricity in the dark", , Physics,   

    From Stanford University via Science News: “This device harnesses the cold night sky to generate electricity in the dark” 

    Stanford University Name
    From Stanford University

    via

    Science News

    September 12, 2019
    Maria Temming

    A prototype powered a small light-emitting diode in a trial run.

    1
    A new device that harvests energy from the cold night sky could one day light up rooms, charge phones and power devices for people off the grid. Credit Ryan Hutton/Unsplash

    A new device is an anti-solar panel, harvesting energy from the cold night sky.

    By harnessing the temperature difference between Earth and outer space, a prototype of the device produced enough electricity at night to power a small LED light. A bigger version of this nighttime generator could someday light rooms, charge phones or power other electronics in remote or low-resource areas that lack electricity at night when solar panels don’t work, researchers report online September 12 in Joule.

    The core of the new night-light is a thermoelectric generator, which produces electricity when one side of the generator is cooler than the other (SN: 6/1/18). The sky-facing side of the generator is attached to an aluminum plate sealed beneath a transparent cover and surrounded with insulation to keep heat out. This plate stays cooler than the ambient air by shedding any heat it absorbs as infrared radiation (SN: 9/28/18). That radiation can zip up through the transparent cover and the atmosphere toward the cold sink of outer space.

    Meanwhile, the bottom of the generator is attached to an exposed aluminum plate that is continually warmed by ambient air. At night, when not baking under the sun, the top plate can get a couple of degrees Celsius cooler than the bottom of the generator.

    Engineer Wei Li of Stanford University and colleagues tested a 20-centimeter prototype of the device on a clear December night in Stanford, Calif. The generator produced up to about 25 milliwatts of power per square meter of device — enough to light a small light-emitting diode, or LED bulb. The team estimates that further design improvements, like better insulation around the cool top plate, could boost production up to at least 0.5 watts per square meter.

    3
    A device that uses the night sky to generate electricity (pictured) powered a small LED bulb in one rooftop experiment. Credit Wei Li

    “It’s a very clever idea,” says Yuan Yang, a materials scientist at Columbia University not involved in the work. “The power generation is much less than solar panels,” which generally produce at least 100 watts per square meter. But this nighttime generator may be useful for emergency backup power, or energy for people living off the grid, Yang says.

    A typical lamp bulb might consume a few watts of electricity, says Shanhui Fan, an electrical engineer at Stanford University who worked on the device. So a device that took up a few square meters of roof space could light up a room with energy from the night sky.

    Aaswath Raman, a materials scientist and engineer at UCLA, also envisions using their team’s generator to help power remote weather stations or other environmental sensors. This may be especially useful in polar regions that don’t see sunlight for months at a time, Raman says. “If you have some low-power load and you need to power it through three months of darkness, this might be a way.”

    See the full article here .


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    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

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  • richardmitnick 12:28 pm on September 13, 2019 Permalink | Reply
    Tags: , , CBETA-Cornell-Brookhaven “Energy-Recovery Linac” Test Accelerator or, , , Innovative particle accelerator, , , Physics   

    From Brookhaven National Lab & Cornell University: “Innovative Accelerator Achieves Full Energy Recovery” 

    From Brookhaven National Lab

    September 10, 2019
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    Collaborative Cornell University/Brookhaven Lab project known as CBETA offers promise for future accelerator applications.

    1
    Brookhaven Lab members of the CBETA team with Laboratory Director Doon Gibbs, front row, right.

    An innovative particle accelerator designed and built by scientists from the U.S. Department of Energy’s Brookhaven National Laboratory and Cornell University has achieved a significant milestone that could greatly enhance the efficiency of future particle accelerators. After sending a particle beam for one pass through the accelerator, machine components recovered nearly all of the energy required for accelerating the particles. This recovered energy can then be used for the next stage of acceleration—to accelerate another batch of particles—thus greatly reducing the potential cost of accelerating particles to high energies.

    “No new power is required to maintain the radiofrequency (RF) fields in the RF cavities used for acceleration, because the accelerated beam deposits its energy in the RF cavities when it is decelerated,” said Brookhaven Lab accelerator physicist Dejan Trbojevic, who led the design and construction of key components for the project and serves as the Principal Investigator for Brookhaven’s contributions.

    The prototype accelerator—known as the Cornell-Brookhaven ERL Test Accelerator (CBETA), where ERL stands for “energy-recovery linac”—was built at Cornell with funding from Brookhaven Science Associates (the managing entity of Brookhaven Lab) and the New York State Energy Research and Development Authority (NYSERDA) as a research and development project in support of a possible future nuclear physics facility, the Electron-Ion Collider (EIC). The energy-recovery approach could play an essential role in generating reusable electron beams for enhancing operations at a future EIC. The electrons would reduce the spread of ion beams in the EIC, thus increasing the number of particle collisions scientists can record to make physics discoveries.

    2
    Schematic of the CBETA energy recovery linac installed at Cornell University. Electrons produced by a direct-current (DC) photo-emitter electron source are transported by a high-power superconducting radiofrequency (SRF) injector linac into the high-current main linac cryomodule, where SRF cavities accelerate them to high energy before sending them around the racetrack-shaped accelerator. Each curved arc is made of a series of fixed field, alternating gradient (FFA) permanent magnets. After passing through the second FFA arc, the electrons re-enter the main linac cryomodule, which decelerates them and returns their energy to the RF cavities so it can be used again.

    In designing and executing this project, the Brookhaven team drew on its vast experience of improving the performance of the Relativistic Heavy Ion Collider (RHIC), a DOE Office of Science user facility for nuclear physics research.

    BNL/RHIC

    The accelerator technologies being developed for the EIC would push beyond the capabilities at RHIC and open up a new frontier in nuclear physics.

    3
    The injector and main linac cryomodule.

    Tech specs

    CBETA consists of a direct-current (DC) photo-emitter electron source that creates the electron beams to be accelerated. These electrons pass through a high-power superconducting radiofrequency (SRF) injector linac that transports them into a high-current main linac cryomodule (MLC). There, six SRF cavities accelerate the electrons to high energy, sending them around the racetrack-shaped accelerator. Each curved section of the racetrack is a single arc of permanent magnets designed with fixed-field alternating-gradient (FFA) optics that allow a single vacuum tube to accommodate beams at four different energies at the same time. After passing through the second FFA arc, the electrons re-enter the MLC, which has been uniquely optimized to decelerate the particles after a single pass and return their energy to the RF cavities so it can be used again.

    When completed, CBETA will accelerate particles through four complete turns, adding energy with each pass—all of which will be recovered during deceleration after the beams have been used. This will make it the world’s first four-turn superconducting radiofrequency ERL.

    Many scientists and engineers at Brookhaven Lab contributed to the design and construction of the magnets and other components of the accelerator, as well as the electronic devices that monitor the positions of the accelerated and decelerated beams: Francois Meot, Scott Berg, Stephen Brooks, and Nicholaos Tsoupas drove the design of the ERL’s optics; Brookhaven physicists led by Brooks and George Mahler designed, built, measured, and applied corrections to the permanent magnets; and Rob Michnoff led the design and construction of the beam position monitor system.

    “After building and successfully testing prototypes of the magnets, we established a very successful collaboration with Cornell, led by Principal Investigator Georg Hoffstaetter, to build the ERL using the refined fixed-field magnet designs,” Trbojevic said.

    Cornell provided the DC electron injector—the world’s record holder for producing high intensity, low emittance electron beams—which they recommissioned for the CBETA project. A team of young scientists and graduate students, including Adam Bartnik, Colwyn Gulliford, Kirsten Deitrick, and Nilanjan Banerjee, made other essential contributions: successfully commissioning the main linac cryomodule, and preparing the “command scripts”—computer-driven instructions—for running and commissioning the ERL in collaboration with Berg and other Brookhaven physicists.

    4
    Part of one of the fixed field, alternating gradient (FFA) permanent magnet arcs.

    “We hold weekly internet-based collaboration meetings and we had several visits and meetings at Cornell to ensure that the project was reaching the key milestones and that installation was proceeding according to the schedule,” said Michnoff, the Brookhaven Lab project manager.

    In May 2019, the team sent an electron beam with an energy of 42 million electron volts (MeV) through the FFA return loop for the first time. The beam made it through all 200 permanent magnets without the need for a single correction. In early June 2019, an energy scan in the FFA loop showed that the return beamline transported particles of different energies superbly, agreeing very well with the expectations for the design.

    Next, on June 13, the beam was accelerated to 42 MeV, transported through the FFA return loop back to the MLC, where the electrons were decelerated from 42 MeV back to the injection energy of 6 MeV, with the rest of their energy transferred back into the six SRF cavities of the main linac. And on June 24, the CBETA team achieved full energy recovery for the first time—demonstrating that each cavity could accelerate electrons on their second pass through the MLC without requiring additional external power.

    “Each cavity successfully regained the energy it expended in beam acceleration, eliminating or dramatically reducing the power needed to accelerate electrons,” Trbojevic said.

    “The successful demonstration of single-turn energy recovery shows that we are on the path toward creating this first-of-its-kind facility,” Trbojevic said. “The entire team is committed and excited to complete this four-turn energy-recovery linac—one of the most interesting and innovative accelerator physics project in the world today.”

    From Cornell University

    CORNELL LABORATORY FOR ACCELERATOR-BASED SCIENCES AND EDUCATION — CLASSE

    5

    Update on Beam Commissioning

    Cornell physicists, working with Brookhaven National Lab, are constructing a new type of particle accelerator called CBETA at Cornell’s Wilson Lab. This Energy Recovery Linac (ERL) is a test accelerator built with permanent magnets as well as electro magnets.

    How it works: CBETA will recirculate multiple beams of different energies around the accelerator at one time. The electrons will make four accelerating passes around the accelerator, while building up energy as they pass through a cryomodule with superconducting RF (SRF) accelerating structures. In four more passes, they will return to the superconducting cavities that accelerated them and return their energy back to these cavities – hence it is an Energy Recovery Linac (ERL). While this method conserves energy, it also creates beams that are tightly bound and are a factor of 1,000 times brighter than other sources. For more details, please contact the Cornell PI Prof. Georg Hoffstaetter.

    Although linear accelerators (Linac) can have superior beam densities when compared to large circular accelerators, they are exceedingly wasteful due to the beam being discarded after use and can therefore only have an extremely low current compared to ring accelerators. This means that the amount of data collected in one hour in a circular accelerator may take several years to collect in a linear accelerator. In an ERL, the energy is recovered, and the beam current can therefore be as large as in a circular accelerator while its beam density remains as large as in a Linac.

    CBETA: the first multi-turn SRF ERL

    The lynchpin of CBETA’s design is to repeat the acceleration in a SRF cavities four times by recirculating multiple beams at four different energies. The beam with highest energy (150MeV) is to be used for experiments and is then decelerated in the same cavities four times to recapture the beam’s energies into the SRF cavities. Reusing the same cavity multiple times significantly reduces the construction and operational costs of the accelerator. It also means that an accelerator which would span roughly a foot ball field can fit into a single experimental Hall at Cornell’s Wilson Laboratory.

    However, beams of different energies require different amounts of bending, in the same way that it is hard for your car to navigate a sharp bend at 100 miles per hour. Traditional magnet designs are simply unable to keep different beams on the same “track”. Instead, the CBETA design relies on cutting edge Fixed-Field Alternating Gradient (FFAG) magnets to contain all of the beams in a single 3 inch beam pipe. CBETA will be the first SRF ERL with more than one turn and it is also the first project in the history of accelerator physics to implement this new magnet technology in an Energy Recovery Linac.

    The task of creating and controlling eight beams of four different energies in a single accelerating structure sounds daunting. But by leveraging the pre-existing infrastructure and experience of Cornell with the power and expertise of Brookhaven National Laboratory, it will soon become a reality.

    Cornell University has prototyped technology essential for CBETA, including a DC gun and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current CW cryomodule for 70 MeV energy gain, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams, e.g. a beamline for measuring 6-D phase-space densities, a fast wire scanner for beam profiles, and beam loss diagnostics. All these now being used in the contrition of CBETA.

    Within the next several years, CBETA will develop into a powerhouse of accelerator physics and technology, and will be one of the most advanced on the planet (earth). When this prototype ERL is complete and expanded upon, it will be a critical resource to New York State and the nation, propelling high-power accelerator science, enabling applications of many particle accelerators, from biomedical advancement to basic physics and from computer-chip lithography to material science, driving economic development.

    7

    CBETA is composed of 4 main parts:

    -The Photoinjector that creates and prepares high-current electron beams to be injected into the Main Linac Cryomodule (MLC). The photoinjector in turn consists of a laser system that illuminates a photo-emitter cathode to produce electrons within a high-current DC electron source. These electrons traverses an emittance-matching section to produce a high-brightness beam which is then sent thorough the high-power injector cryomodule (ICM) for acceleration to the ERL’s injection energy.

    -The Main Linac Cryomodule (MLC) that accelerates the beam through several passages and then decelerates the beam the same number of times to recapture its energy.

    -The high-power Beam Stop where the electron beam is discarded after most of its energy has been recaptured.
    4 Spreaders and 4 combiners with electro magnets that separate beams at 4 different energies after the MLC to match them into the FFAG return loop and then combine them again before re-entering the MLC.

    -FFAG Magnets residing in the return loop. These cause very strong focusing so that beams with energies that differ by up to a factor 4 can be transported simultaneously.

    Dominant funding for CBETA comes from NYSERDA (2016 to 2020). Important for this agency is that CBETA emphasizes energy savings by its use of energy recovery technology, its application of permanent magnets, and its particle acceleration by superconducting structures. Previous funding came from the NSF (2005 – 2015) for the development of the complete accelerator chain from the source to the main ERL accelerating module, from DOE supporting developments for the LCLS (2014-2015), and from the industrial company ASML (2015-2016) for applications in computer chip lithography.

    See the full article here .


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 4:41 pm on September 9, 2019 Permalink | Reply
    Tags: "Fermilab achieves world-record field strength for accelerator magnet", , , Designing for a future collider that could serve as a potential successor to the powerful 17-mile-around Large Hadron Collider operating at CERN laboratory since 2009., , , , , Physics   

    From Fermi National Accelerator Lab: “Fermilab achieves world-record field strength for accelerator magnet” 

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    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    September 9, 2019
    Leah Hesla

    To build the next generation of powerful proton accelerators, scientists need the strongest magnets possible to steer particles close to the speed of light around a ring. For a given ring size, the higher the beam’s energy, the stronger the accelerator’s magnets need to be to keep the beam on course.

    Scientists at the Department of Energy’s Fermilab have announced that they achieved the highest magnetic field strength ever recorded for an accelerator steering magnet, setting a world record of 14.1 teslas, with the magnet cooled to 4.5 kelvins or minus 450 degrees Fahrenheit. The previous record of 13.8 teslas, achieved at the same temperature, was held for 11 years by Lawrence Berkeley National Laboratory.

    That’s more than a thousand times stronger magnet than the refrigerator magnet that’s holding your grocery list to your refrigerator.

    The achievement is a remarkable milestone for the particle physics community, which is studying designs for a future collider that could serve as a potential successor to the powerful 17-mile-around Large Hadron Collider operating at CERN laboratory since 2009. Such a machine would need to accelerate protons to energies several times higher than those at the LHC.

    And that calls for steering magnets that are stronger than the LHC’s, about 15 teslas.

    “We’ve been working on breaking the 14-tesla wall for several years, so getting to this point is an important step,” said Fermilab scientist Alexander Zlobin, who leads the project at Fermilab. “We got to 14.1 teslas with our 15-tesla demonstrator magnet in its first test. Now we’re working to draw one more tesla from it.”

    The success of a future high-energy hadron collider depends crucially on viable high-field magnets, and the international high-energy physics community is encouraging research toward the 15-tesla niobium-tin magnet.

    1
    Fermilab recently achieved a magnetic field strength of 14.1 teslas at 4.5 kelvins on an accelerator steering magnet — a world record. Photo: Thomas Strauss

    At the heart of the magnet’s design is an advanced superconducting material called niobium-tin.

    Electrical current flowing through the material generates a magnetic field. Because the current encounters no resistance when the material is cooled to very low temperature, it loses no energy and generates no heat. All of the current contributes to the creation of the magnetic field. In other words, you get lots of magnetic bang for the electrical buck.

    The strength of the magnetic field depends on the strength of the current that the material can handle. Unlike the niobium-titanium used in the current LHC magnets, niobium-tin can support the amount of current needed to make 15-tesla magnetic fields. But niobium-tin is brittle and susceptible to break when subject to the enormous forces at work inside an accelerator magnet.

    So the Fermilab team developed a magnet design that would shore up the coil against every stress and strain it could encounter during operation. Several dozen round wires were twisted into cables in a certain way, enabling it to meet the requisite electrical and mechanical specifications. These cables were wound into coils and heat-treated at high temperatures for approximately two weeks, with a peak temperature of about 1,200 degrees Fahrenheit, to convert the niobium-tin wires into superconductor at operation temperatures. The team encased several coils in a strong innovative structure composed of an iron yoke with aluminum clamps and a stainless-steel skin to stabilize the coils against the huge electromagnetic forces that can deform the brittle coils, thus degrading the niobium-tin wires.

    The Fermilab group took every known design feature into consideration, and it paid off.

    “This is a tremendous achievement in a key enabling technology for circular colliders beyond the LHC,” said Soren Prestemon, a senior scientist at Berkeley Lab and director of the multilaboratory U.S. Magnet Development Program, which includes the Fermilab team. “This is an exceptional milestone for the international community that develops these magnets, and the result has been enthusiastically received by researchers who will use the beams from a future collider to push forward the frontiers of high-energy physics.”

    And the Fermilab team is geared up to make their mark in the 15-tesla territory.

    “There are so many variables to consider in designing a magnet like this: the field parameters, superconducting wire and cable, mechanical structure and its performance during assembly and operation, magnet technology, and magnet protection during operation,” Zlobin said. “All of these issues are even more important for magnets with record parameters.”

    Over the next few months, the group plans to reinforce the coil’s mechanical support and then retest the magnet this fall. They expect to achieve the 15-tesla design goal.

    And they’re setting their sights even higher for the further future.

    “Based on the success of this project and the lessons we learned, we’re planning to advance the field in niobium-tin magnets for future colliders to 17 teslas,” Zlobin said.

    It doesn’t stop there. Zlobin says they may be able to design steering magnets that reach a field of 20 teslas using special inserts made of new advanced superconducting materials.

    Call it a field goal.

    The project is supported by the Department of Energy Office of Science.

    It is a key part of the U.S. Magnet Development Program, which includes Fermilab, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory and the National High Magnetic Field Laboratory.

    See the full here.


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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 12:13 pm on September 9, 2019 Permalink | Reply
    Tags: "Trapping atoms to protect Australia’s groundwater", , Atom Trap Trace Analysis (ATTA) facility, , Physics,   

    From University of Adelaide: “Trapping atoms to protect Australia’s groundwater” 

    u-adelaide-bloc

    From University of Adelaide

    09 Sep 2019
    Thea Williams

    1
    Research technician Punjehl Crane at the CSIRO Noble Gas Mass Spectrometry Laboratory in Adelaide. ©Nick Pitsas

    A collaboration between CSIRO and the University of Adelaide, the Atom Trap Trace Analysis (ATTA) facility uses advanced laser physics to count individual atoms of the noble gases, such as Argon and Krypton, that are naturally found in groundwater and ice cores.

    Measuring the ultra-low concentrations of these radioactive noble gases allows researchers to understand the age, origin and interconnectivity of the groundwater and how it has moved underground through space and time.

    This is the first Atom Trap Trace Analysis facility in the Southern Hemisphere and, combined with CSIRO’s complementary Noble Gas Facility at the Waite campus in Adelaide, gives Australia one of the most comprehensive noble gas analysis capabilities in the world.

    “Australia relies on its groundwater for 30 per cent of its water supply for human consumption, stock watering, irrigation and mining,” said Professor Andre Luiten, Director of the University’s Institute for Photonics and Advanced Sensing which houses the ATTA facility.

    “With climate change and periods of prolonged drought, surface water is becoming increasingly more unreliable and the use of groundwater is rising.

    “We need to make sure it’s sustainable.

    “Because noble gases don’t easily react chemically, they are the gold standard for environmental tracers to track groundwater movements.

    “Before this new facility, researchers wanting to measure these ultra-low concentrations of noble gases had to rely on a very small number of overseas laboratories which can’t meet demand for their services.”

    ATTA’s analytic capability would also allow researchers to look further into the past of Antarctica’s climate, building understanding of global environmental change.

    CSIRO Senior Principal Research Scientist Dr Dirk Mallants said the new ATTA facility would enable researchers to determine how old groundwater is from decades and centuries up to one million years.

    “This allows us to understand the sources of water, where it comes from and what the recharge rates are,” Dr Mallants said.

    “That then allows us to make decisions about sustainable extraction.

    “This is critical where development of any kind might use or impact groundwater systems – from urban development where groundwater systems are used to supply communities, to agricultural and mining development.

    “It will provide Australian researchers, government and industry with unique capability of collaboration on national water challenges.”

    The new ATTA facility is partially funded under the Australian Research Council’s Linkage, Infrastructure, Equipment and Facilities scheme.

    Energy, mining and resources is a key industry engagement priority for the University of Adelaide and environmental sustainability is a research focus.

    The CSIRO, Australia’s national science agency, and the University of Adelaide in 2017 announced a new agreement to work together to tackle some of the big issues facing Australia and the region.

    The two organisations agreed to build collaborations to advance research in key areas of mutual strength, with significant potential benefit to the Australian economy, society and environment.

    See the full article here .

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    Mission & Focus
    A 21st century university for Adelaide.

    At the University of Adelaide, we embrace our role and purpose as a future-maker—for our state, our nation and our world.

    We pursue meaningful change as we celebrate our proud history: applying proven values in the pursuit of contemporary educational and research excellence; meeting our local and global community’s evolving needs and challenges; and striving to prepare our graduates for their aspirations and the needs of the future workforce.

    Our focus is informed by the manifold changes confronting today’s society, including the:

    need for economic transition—to new industries and jobs
    imperative of social transformation—demanding more accessible, lifelong learning
    impact of globalisation—making global opportunities available locally
    pervasive nature of technological disruption—redefining socio-economic constructs
    pursuit of sustainability—socially, economically and environmentally.

    The University is uniquely positioned to design and drive a prosperous, entrepreneurial future for South Australia built on knowledge, innovation and collaboration.

    We’re a dynamic participant in society, leading our community in leveraging change for social and economic benefit. We listen to industry. And we connect with diverse community groups far and wide to deliver education and research of the highest value and impact.
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  • richardmitnick 10:29 am on September 9, 2019 Permalink | Reply
    Tags: "Making and controlling crystals of light", , , Microresonators, , Physics   

    From École Polytechnique Fédérale de Lausanne: “Making and controlling crystals of light” 

    EPFL bloc

    From École Polytechnique Fédérale de Lausanne

    09.09.19
    Maxim Karpov
    Nik Papageorgiou

    1
    EPFL scientists have shown how light inside optical on-chip microresonators can be crystallized in a form of periodic pulse trains that can boost the performance of optical communication links or endow ultrafast LiDAR with sub-micron precision.

    Optical microresonators convert laser light into ultrashort pulses travelling around the resonator’s circumference. These pulses, called “dissipative Kerr solitons”, can propagate in the microresonator maintaining their shape.

    When solitons exit the microresonator, the output light takes the form of a pulse train – a series of repeating pulses with fixed intervals. In this case, the repetition rate of the pulses is determined by the microresonator size. Smaller sizes enable pulse trains with high repetition rates, reaching hundreds of gigahertz in frequency. These can be used to boost the performance of optical communication links or become a core technology for ultrafast LiDAR with sub-micron precision.

    Exciting though it is, this technology suffers from what scientists call “light-bending losses” – loss of light caused by structural bends in its path. A well-known problem in fiber optics, light-bending loss also means that the size of microresonators cannot drop below a few tens of microns. This therefore limits the maximum repetition rates we can achieve for pulses.

    Publishing in Nature Physics, researchers from the lab of Tobias J. Kippenberg at EPFL have now found a way to bypass this limitation and uncouple the pulse repetition rate from the microresonator size by generating multiple solitons in a single microresonator.

    The scientists discovered a way of seeding the microresonator with the maximum possible number of dissipative Kerr solitons with precisely equal spacing between them. This new formation of light can be thought of as an optical analogue to atomic chains in crystalline solids, and so the researchers called them “perfect soliton crystals” (PSCs).

    Due to interferometric enhancement and the high number of optical pulses, PSCs coherently multiply the performance of the resulting pulse train – not just its repetition rate, but also its power.

    The researchers also investigated the dynamics of PSC formations. Despite their highly organized structure, they seem to be closely linked to optical chaos, a phenomenon caused by light instabilities in optical microresonators, which is also common for semiconductor-based and fiber laser systems.

    “Our findings allow the generation of optical pulse trains with ultra-high repetition rates with several terahertz, using regular microresonators,” says researcher Maxim Karpov. “These can be used for multiple applications in spectroscopy, distance measurements, and as a source of low-noise terahertz radiation with a chip-size footprint.” Meanwhile, the new understanding of soliton dynamics in optical microresonators and the behavior of PSCs opens up new avenues into the fundamental physics of soliton ensembles in nonlinear systems.

    See the full article here .

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    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

     
  • richardmitnick 12:51 pm on September 8, 2019 Permalink | Reply
    Tags: , “I think I can safely say that nobody really understands quantum mechanics” observed the physicist and Nobel laureate Richard Feynman., , Bohr scored a decisive victory at least in the public-relations battle., Even Physicists Don’t Understand Quantum Mechanics, Famous debates between Albert Einstein and Niels Bohr., , Physics,   

    From The New York Times- Sean Carroll: “Even Physicists Don’t Understand Quantum Mechanics…” 

    New York Times

    From The New York Times

    Sept. 7, 2019
    Sean M. Carroll, Caltech

    …Worse, they don’t seem to want to understand it.


    Sean M. Carroll Taken at LogiCalLA 14 January 2017 Sgerbic

    1
    Alejandro Guijarro, Tristan Hoare Gallery, London

    “I think I can safely say that nobody really understands quantum mechanics,” observed the physicist and Nobel laureate Richard Feynman. That’s not surprising, as far as it goes. Science makes progress by confronting our lack of understanding, and quantum mechanics has a reputation for being especially mysterious.

    What’s surprising is that physicists seem to be O.K. with not understanding the most important theory they have.

    Quantum mechanics, assembled gradually by a group of brilliant minds over the first decades of the 20th century, is an incredibly successful theory. We need it to account for how atoms decay, why stars shine, how transistors and lasers work and, for that matter, why tables and chairs are solid rather than immediately collapsing onto the floor.

    Scientists can use quantum mechanics with perfect confidence. But it’s a black box. We can set up a physical situation, and make predictions about what will happen next that are verified to spectacular accuracy. What we don’t do is claim to understand quantum mechanics. Physicists don’t understand their own theory any better than a typical smartphone user understands what’s going on inside the device.

    There are two problems. One is that quantum mechanics, as it is enshrined in textbooks, seems to require separate rules for how quantum objects behave when we’re not looking at them, and how they behave when they are being observed. When we’re not looking, they exist in “superpositions” of different possibilities, such as being at any one of various locations in space. But when we look, they suddenly snap into just a single location, and that’s where we see them. We can’t predict exactly what that location will be; the best we can do is calculate the probability of different outcomes.

    The whole thing is preposterous. Why are observations special? What counts as an “observation,” anyway? When exactly does it happen? Does it need to be performed by a person? Is consciousness somehow involved in the basic rules of reality? Together these questions are known as the “measurement problem” of quantum theory.

    3
    Alejandro Guijarro, Tristan Hoare Gallery, London

    The other problem is that we don’t agree on what it is that quantum theory actually describes, even when we’re not performing measurements. We describe a quantum object such as an electron in terms of a “wave function,” which collects the superposition of all the possible measurement outcomes into a single mathematical object. When they’re not being observed, wave functions evolve according to a famous equation written down by Erwin Schrödinger.

    But what is the wave function? Is it a complete and comprehensive representation of the world? Or do we need additional physical quantities to fully capture reality, as Albert Einstein and others suspected? Or does the wave function have no direct connection with reality at all, merely characterizing our personal ignorance about what we will eventually measure in our experiments?

    Until physicists definitively answer these questions, they can’t really be said to understand quantum mechanics — thus Feynman’s lament. Which is bad, because quantum mechanics is the most fundamental theory we have, sitting squarely at the center of every serious attempt to formulate deep laws of nature. If nobody understands quantum mechanics, nobody understands the universe.

    You would naturally think, then, that understanding quantum mechanics would be the absolute highest priority among physicists worldwide. Investigating the foundations of quantum theory should be a glamour specialty within the field, attracting the brightest minds, highest salaries and most prestigious prizes. Physicists, you might imagine, would stop at nothing until they truly understood quantum mechanics.

    The reality is exactly backward. Few modern physics departments have researchers working to understand the foundations of quantum theory. On the contrary, students who demonstrate an interest in the topic are gently but firmly — maybe not so gently — steered away, sometimes with an admonishment to “Shut up and calculate!” Professors who become interested might see their grant money drying up, as their colleagues bemoan that they have lost interest in serious work.

    This has been the case since the 1930s, when physicists collectively decided that what mattered was not understanding quantum mechanics itself; what mattered was using a set of ad hoc quantum rules to construct models of particles and materials. The former enterprise came to be thought of as vaguely philosophical and disreputable. One is reminded of Aesop’s fox, who decided that the grapes he couldn’t reach were probably sour, and he didn’t want them anyway. Physicists brought up in the modern system will look into your eyes and explain with all sincerity that they’re not really interested in understanding how nature really works; they just want to successfully predict the outcomes of experiments.

    This attitude can be traced to the dawn of modern quantum theory. In the 1920s there was a series of famous debates between Einstein and Niels Bohr, one of the founders of quantum theory. Einstein argued that contemporary versions of quantum theory didn’t rise to the level of a complete physical theory, and that we should try to dig more deeply. But Bohr felt otherwise, insisting that everything was in fine shape. Much more academically collaborative and rhetorically persuasive than Einstein, Bohr scored a decisive victory, at least in the public-relations battle.

    Not everyone was happy that Bohr’s view prevailed, but these people typically found themselves shunned by or estranged from the field. In the 1950s the physicist David Bohm, egged on by Einstein, proposed an ingenious way of augmenting traditional quantum theory in order to solve the measurement problem. Werner Heisenberg, one of the pioneers of quantum mechanics, responded by labeling the theory “a superfluous ideological superstructure,” and Bohm’s former mentor Robert Oppenheimer huffed, “If we cannot disprove Bohm, then we must agree to ignore him.”

    Around the same time, a graduate student named Hugh Everett invented the “many-worlds” theory, another attempt to solve the measurement problem, only to be ridiculed by Bohr’s defenders. Everett didn’t even try to stay in academia, turning to defense analysis after he graduated.

    A more recent solution to the measurement problem, proposed by the physicists Giancarlo Ghirardi, Alberto Rimini and Tulio Weber, is unknown to most physicists.

    These ideas are not simply woolly-headed “interpretations” of quantum mechanics. They are legitimately distinct physical theories, with potentially new experimental consequences. But they have been neglected by most scientists. For years, the leading journal in physics had an explicit policy that papers on the foundations of quantum mechanics were to be rejected out of hand.

    Of course there are an infinite number of questions that scientists could choose to worry about, and one must prioritize somehow. Over the course of the 20th century, physicists decided that it was more important to put quantum mechanics to work than to understand how it works. And to be fair, part of their rationale was that it was hard to actually see a way forward. What were the experiments one could do that might illuminate the measurement problem?

    The situation might be changing, albeit gradually. The current generation of philosophers of physics takes quantum mechanics very seriously, and they have done crucially important work in bringing conceptual clarity to the field. Empirically minded physicists have realized that the phenomenon of measurement can be directly probed by sufficiently subtle experiments. And the advance of technology has brought questions about quantum computers and quantum information to the forefront of the field. Together, these trends might make it once again respectable to think about the foundations of quantum theory, as it briefly was in Einstein and Bohr’s day.

    Meanwhile, it turns out that how reality works might actually matter. Our best attempts to understand fundamental physics have reached something of an impasse, stymied by a paucity of surprising new experimental results. Scientists discovered the Higgs boson in 2012, but that had been predicted in 1964. Gravitational waves were triumphantly observed in 2015, but they had been predicted a hundred years before. It’s hard to make progress when the data just keep confirming the theories we have, rather than pointing toward new ones.

    The problem is that, despite the success of our current theories at fitting the data, they can’t be the final answer, because they are internally inconsistent. Gravity, in particular, doesn’t fit into the framework of quantum mechanics like our other theories do. It’s possible — maybe even perfectly reasonable — to imagine that our inability to understand quantum mechanics itself is standing in the way.

    After almost a century of pretending that understanding quantum mechanics isn’t a crucial task for physicists, we need to take this challenge seriously.

    See the full article here .

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  • richardmitnick 11:43 am on September 7, 2019 Permalink | Reply
    Tags: A resulting gravito-magnetic field analogous to the magnetic field surrounding the two poles of a magnet would explain the alignment of the jets with the source’s north-south axis of rotation., Albert Einstein’s equations of gravity and James Clerk Maxwell’s equations of electromagnetism., Astronomers expect that a new satellite (LARES 2) to be launched at the end of 2019 will with data from LAGEOS give an accuracy of 0.2%., Astrophysicists have already taken gravito-magnetism on board., , But how far can such mathematical analogies be pushed? Is “gravito-magnetic induction” real? If it is it should show up as a tiny wobble in the orbit of satellites., , For frame-dragging the best agreement with GR has been within 0.2%, Gravito-electromagnetism, In some ways mathematics is like literature. It has its own definitions and grammatical rules – although unfortunately these are the bane of too many students’ lives., It suggests a mechanism to explain the mysterious jets of gas that have been observed spewing out of quasars and active galactic nuclei., Making physical analogies is fundamental in the process of physics because it helps physicists to imagine new physical phenomena., , Physics, Rotating supermassive black holes at the heart of these cosmic powerhouses would produce enormous frame-dragging and geodetic effects., Simpler versions that work with an accuracy of 5%., The intriguing mathematical analogy between the equations of Newtonian gravity and Coulomb’s law of electrostatics., The prediction of a new force: “gravito-magnetism”, The same is true of mathematical analogies applied to physical reality – and especially of the interplay between mathematical and physical analogies., Today this so-called “gravito-electromagnetism” or GEM for short is generally treated mathematically via the “weak field” approximation to the full GR equations – simpler versions that work   

    From COSMOS Magazine: “Introducing the amazing concept of gravito-electromagnetism” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    05 September 2019
    Robyn Arianrhod

    1
    Mathematician and poet James Clerk Maxwell. Credit SIR GODFREY KNELLER / GETTY IMAGES / (BACKGROUND) SOLA

    In some ways, mathematics is like literature. It has its own definitions and grammatical rules – although unfortunately these are the bane of too many students’ lives. Which is a great pity, because when used elegantly and clearly, mathematical language can help readers to see things in entirely new ways. Take analogies, for example. They’re obviously powerful in literature – who doesn’t thrill to a creative, well-aimed metaphor? But they can be even more powerful in mathematical physics.

    Making physical analogies is fundamental in the process of physics, because it helps physicists to imagine new physical phenomena. We still speak of the “flow” of an electric “current”, using liquid metaphors that physicists coined before they knew that electrons existed. On the other hand, the old concept of “ether” – a hypothetical light-carrying medium analogous to water or air – has long passed its use-by date. Physical analogies can be creative and useful, but sometimes they can lead one astray.

    The same is true of mathematical analogies applied to physical reality – and especially of the interplay between mathematical and physical analogies. An analogy that has tantalised mathematicians and physicists for a century, and which is still a hot if much-debated topic, is that between Albert Einstein’s equations of gravity and James Clerk Maxwell’s equations of electromagnetism. It’s led to an exciting new field of research called “gravito-electromagnetism” – and to the prediction of a new force, “gravito-magnetism”.

    5
    Diagram regarding the confirmation of Gravitomagnetism by Gravity Probe B. Gravity Probe B Team, Stanford, NASA

    The surprising idea of comparing gravity and electromagnetism – two entirely different kinds of phenomena – began with the intriguing mathematical analogy between the equations of Newtonian gravity and Coulomb’s law of electrostatics. Both sets of equations have exactly the same inverse-square form.

    In 1913, Einstein began exploring the much more complex idea of a relativistic gravitational analogue of electromagnetic induction – an idea that was developed by Josef Lense and Hans Thirring in 1918. They used Einstein’s final theory of general relativity (GR), which was published in 1916.

    Today this so-called “gravito-electromagnetism”, or GEM for short, is generally treated mathematically via the “weak field” approximation to the full GR equations – simpler versions that work well in weak fields such as that of the earth.

    It turns out that the mathematics of weak fields includes quantities satisfying equations that look remarkably similar to Maxwell’s. The “gravito-electric” part can be readily identified with the everyday Newtonian downward force that keeps us anchored to the earth. The “gravito-magnetic” part, however, is something entirely unfamiliar – a new force apparently due to the rotation of the earth (or any large mass).

    It’s analogous to the way a spinning electron produces a magnetic field via electromagnetic induction, except that mathematically, a massive spinning object mathematically “induces” a “dragging” of space-time itself – as if space-time were like a viscous fluid that’s dragged around a rotating ball. (Einstein first identified “frame-dragging”, a consequence of general relativity elaborated by Lense and Thirring.)

    But how far can such mathematical analogies be pushed? Is “gravito-magnetic induction” real? If it is, it should show up as a tiny wobble in the orbit of satellites, and – thanks also to the “geodetic” effect, the curving of space-time by matter – as a change in the direction of the axis of an orbiting gyroscope. (The latter is analogous to the way a magnetic field generated by an electric current changes the orientation of a magnetic dipole.)

    Finally, after a century of speculation, answers are unfolding. Independent results from several satellite missions – notably Gravity Probe B, LAGEOS, LARES, and GRACE – have confirmed the earth’s geodetic and frame-dragging effects to varying degrees of precision.


    NASA/Gravity Probe B

    2
    LAGEOS satellite, courtesy of NASA

    3
    The LARES Satellite. Italian Space Agency

    NASA/ German Research Centre for Geosciences (GFZ) Grace-FO satellites

    For frame-dragging, the best agreement with GR has been within 0.2%, with an accuracy of 5%, but astronomers expect that a new satellite (LARES 2), to be launched at the end of 2019, will, with data from LAGEOS, give an accuracy of 0.2%.

    More accurate results will provide more stringent tests of GR, but astrophysicists have already taken gravito-magnetism on board. For instance, it suggests a mechanism to explain the mysterious jets of gas that have been observed spewing out of quasars and active galactic nuclei. Rotating supermassive black holes at the heart of these cosmic powerhouses would produce enormous frame-dragging and geodetic effects. A resulting gravito-magnetic field analogous to the magnetic field surrounding the two poles of a magnet would explain the alignment of the jets with the source’s north-south axis of rotation.

    Making analogies is a tricky business, however, and there are some interpretive anomalies still to unravel. To take just one example, questions remain about the meaning of analogical terms such as gravitational “energy density” and “energy current density”. Things are perhaps even more problematic – or interesting – from the mathematical point of view.

    For example, there is another, purely mathematical analogy between Einstein’s and Maxwell’s equations, which gives rise to a very different analogy from the GEM equations. To put it briefly, it’s a comparison between the so-called Bianchi identities in each theory.

    The existence of two (and in fact several) such different mathematical analogies between the equations of these two physical phenomena is incredibly suggestive of a deeper connection. At present, though, there are some apparent physical inconsistencies between the “electric” and “magnetic” parts in each mathematical approach.

    Still, the formal analogies are useful in helping mathematicians find intuitively familiar ways to think about the formidable equations of GR. And there’s always the tantalising possibility that this approach will prove as physically profound as the prediction of gravito-magnetism.

    See the full article here .


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  • richardmitnick 3:31 pm on September 5, 2019 Permalink | Reply
    Tags: , , , , , , Physics,   

    From Techniche Universitat Munchen: “Closing in on elusive particles” 

    Techniche Universitat Munchen

    From Techniche Universitat Munchen

    1
    Working on the germanium detector array in the clean room of Gran Sasso underground laboratory.
    Image: J. Suvorov / GERDA

    05.09.2019
    Prof. Dr. Stefan Schönert
    Technical University of Munich
    Experimental Astroparticlephysics (E15)
    Tel.: +49 89 289 12511
    E-Mail: schoenert@ph.tum.de

    Major steps forward in understanding neutrino properties.

    In the quest to prove that matter can be produced without antimatter, the GERDA experiment at the Gran Sasso Underground Laboratory is looking for signs of neutrinoless double beta decay. The experiment has the greatest sensitivity worldwide for detecting the decay in question. To further improve the chances of success, a follow-up project, LEGEND, uses an even more refined decay experiment.

    MPG GERmanium Detector Array (GERDA) at Gran Sasso, Italy

    LEGEND Collaboration

    LEGEND experiment at Gran Sasso looking for signs of neutrinoless double beta decay

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

    While the Standard Model of Particle Physics has remained mostly unchanged since its initial conception, experimental observations for neutrinos have forced the neutrino part of the theory to be reconsidered in its entirety.

    Standard Model of Particle Physics

    Neutrino oscillation was the first observation inconsistent with the predictions and proves that neutrinos have non-zero masses, a property that contradicts the Standard Model. In 2015, this discovery was rewarded with the Nobel Prize.

    Are neutrinos their own antiparticles?

    Additionally, there is the longstanding conjecture that neutrinos are so-called Majorana particles: Unlike all other constituents of matter, neutrinos might be their own antiparticles. This would also help explain why there is so much more matter than antimatter in the Universe.

    The GERDA experiment is designed to scrutinize the Majorana hypothesis by searching for the neutrinoless double beta decay of the germanium isotope 76Ge: Two neutrons inside a 76Ge nucleus simultaneously transform into two protons with the emission of two electrons. This decay is forbidden in the Standard Model because the two antineutrinos – the balancing antimatter – are missing.

    The Technical University of Munich (TUM) has been a key partner of the GERDA project (GERmanium Detector Array) for many years. Prof. Stefan Schönert, who heads the TUM research group, is the speaker of the new LEGEND project.

    The GERDA experiment achieves extreme levels of sensitivity

    GERDA is the first experiment to reach exceptionally low levels of background noise and has now surpassed the half-life sensitivity for decay of 1026 years. In other words: GERDA proves that the process has a half-life of at least 1026 years, or 10,000,000,000,000,000 times the age of the Universe.

    Physicists know that neutrinos are at least 100,000 times lighter than electrons, the next heaviest particles. What mass they have exactly, however, is still unknown and another important research topic.

    In the standard interpretation, the half-life of the neutrinoless double beta decay is related to a special variant of the neutrino mass called the Majorana mass. Based the new GERDA limit and those from other experiments, this mass must be at least a million times smaller than that of an electron, or in the terms of physicists, less than 0.07 to 0.16 eV/c2 [1] SCIENCE.

    Consistent with other experiments

    Also other experiments limit the neutrino mass: the Planck mission provides a limit on another variant of the neutrino mass: The sum of the masses of all known neutrino types is less than 0.12 to 0.66 eV/c2.

    The tritium decay experiment KATRIN at the Karlsruhe Institute of Technology (KIT) is set-up to measure the neutrino mass with a sensitivity of about 0.2 eV/c2 in the coming years. These masses are not directly comparable, but they provide a cross check on the paradigm that neutrinos are Majorana particles. So far, no discrepancy has been observed.

    From GERDA to LEGEND

    During the reported data collection period, GERDA operated detectors with a total mass of 35.6 kg of 76Ge. Now, a newly formed international collaboration, LEGEND, will increase this mass to 200 kg of 76Ge until 2021 and further reduce the background noise. The aim is to achieve a sensitivity of 1027 years within the next five years.

    More information:

    GERDA is an international European collaboration of more than 100 physicists from Belgium, Germany, Italy, Russia, Poland and Switzerland. In Germany, GERDA is supported by the Technical Universities of Munich and Dresden, the University of Tübingen and the Max Planck Institutes for Physics and for Nuclear Physics. German funding is provided by the German Federal Ministry of Education and Research (BMBF), the German Research Foundation (DFG) via the Excellence Cluster Universe and SFB1258, as well as the Max Planck Society.

    Prof. Schönert received an ERC Advanced Grant for preparatory work on the LEGEND project in 2018. A few days ago, Prof. Susanne Mertens received an ERC grant for her work on the KATRIN experiment. In the context of that experiment, she will search for so-called sterile neutrinos.

    KATRIN Experiment schematic

    +

    KIT Katrin experiment

    [1] In particle physics masses are specified not in kilograms, but rather in accordance with Einstein’s equation E=mc2: electron volts [eV] divided by the speed of light squared. Electron volts are a measure of energy. This convention is used to circumvent unfathomably small units of mass: 1 eV/c2 corresponds to 1.8 × 10-36 kilograms.

    See the full article here .

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    Techniche Universitat Munchin Campus

    Techniche Universitat Munchin is one of Europe’s top universities. It is committed to excellence in research and teaching, interdisciplinary education and the active promotion of promising young scientists. The university also forges strong links with companies and scientific institutions across the world. TUM was one of the first universities in Germany to be named a University of Excellence. Moreover, TUM regularly ranks among the best European universities in international rankings.

     
  • richardmitnick 2:49 pm on September 4, 2019 Permalink | Reply
    Tags: , Another major component of the Phase-1 upgrade for ATLAS is the improvement of the trigger selection for the operation at the future HL-LHC., ATLAS teams are also preparing for the following long shutdown (LS3 starting in 2024), “The installation of new electronics for the liquid-argon calorimeter is proceeding smoothly and we are advancing through the different stages of production for the TDAQ deliverables., , During LS3 an all-silicon inner tracker will replace the current one using state-of-the-art silicon technologies to keep pace with the HL-LHC rate of collisions., , In parallel, Located at the centre of the ATLAS detector the role of the inner tracker is to measure the direction; momentum; and charge of electrically charged particles produced in each proton–proton collision, New electronics to achieve a higher resolution of the electromagnetic calorimeter’s trigger., , , Physics, the consolidation of the detector system is progressing according to schedule., The first phase of our HL-LHC upgrade programme has started., The new muon small wheels-developed to trigger and measure muons precisely despite the increased rate of collisions expected at the High-Luminosity LHC (HL-LHC), the scintillators located between the central barrel and the extended barrels of the tile calorimeter are currently being installed., We have replaced cooling connectors connecting the modules of the tile calorimeter to the overall cooling infrastructure in almost all 256 modules of the calorimeter.   

    From CERN ATLAS: “LS2 Report: ATLAS upgrades are in full swing” 

    CERN/ATLAS detector

    CERN ATLAS Higgs Event

    CERN ATLAS another view Image Claudia Marcelloni ATLAS CERN


    CERN ATLAS New II Credit CERN SCIENCE PHOTO LIBRARY


    From CERN ATLAS

    3 September, 2019
    Anaïs Schaeffer

    The assembly of the new muon small wheels and the upgrades on the electronics and trigger systems are progressing well.

    1
    One of the new small wheels of ATLAS, which you can see at Building 191 during the CERN Open Days (Image: CERN)

    A few months ago, the ATLAS Collaboration presented its schedule for the second long shutdown 2 (LS2) concerning the detector’s repair, consolidation and upgrade activities. Since then, the experiment’s LS2 programme has been refined to best meet needs and constraints.

    Although ATLAS was originally supposed to install two new muon detectors in the forward regions (new small wheels) – measuring 9.3 metres in diameter and developed to trigger and measure muons precisely despite the increased rate of collisions expected at the High-Luminosity LHC (HL-LHC) – only one will be installed during LS2. “While considerable progress has been made on the assembly, the second wheel will not be ready before the end of LS2. So we decided to aim for installing that one in the next year-end technical stop (YETS, at the end of 2021),” says Ludovico Pontecorvo, ATLAS Technical Coordinator. A replacement of the first small wheel (on side A of the detector) is foreseen for August 2020.

    Another major component of the Phase-1 upgrade for ATLAS is the improvement of the trigger selection for the operation at the future HL-LHC, which requires new electronics to achieve a higher resolution of the electromagnetic calorimeter’s trigger. It also involves upgrading the level-1 trigger processors, and installing new electronic cards for the trigger and data-acquisition (TDAQ) system. “The installation of new electronics for the liquid-argon calorimeter is proceeding smoothly and we are advancing through the different stages of production for the TDAQ deliverables. The upgrade of the infrastructure and the necessary maintenance work is almost completed. The first phase of our HL-LHC upgrade programme has started,” says Ludovico Pontecorvo.

    In parallel, the consolidation of the detector system is progressing according to schedule. “We have replaced cooling connectors connecting the modules of the tile calorimeter to the overall cooling infrastructure in almost all 256 modules of the calorimeter and the standard maintenance of the read-out electronics is ongoing. In addition, the scintillators located between the central barrel and the extended barrels of the tile calorimeter are currently being installed,” adds Ludovico Pontecorvo.

    ATLAS teams are also preparing for the following long shutdown (LS3, starting in 2024), which will see the installation of an all-new inner tracker. Located at the centre of the ATLAS detector, the role of the inner tracker is to measure the direction, momentum and charge of electrically charged particles produced in each proton–proton collision. During LS3, an all-silicon inner tracker will replace the current one, using state-of-the-art silicon technologies to keep pace with the HL-LHC rate of collisions. The manoeuvre to lower and insert this new element (2 m in diameter, 7 m long) looks arduous, so, in March, the team in charge of its installation took advantage of the shutdown to practice the procedure in the cavern with a mock-up of the tracker. The two lowering options tested required a great meticulousness, given that, at the worst moment, the margin was only a few centimetres.

    See the full article here .


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    Please help promote STEM in your local schools.

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    CERN Courier

    Quantum Diaries
    QuantumDiaries

    CERN map


    CERN LHC Grand Tunnel
    CERN LHC particles

     
  • richardmitnick 9:21 am on September 3, 2019 Permalink | Reply
    Tags: , Physics, , Scientists have calculated that a hydrogen-rich compound could conduct electricity without resistance at temperatures up to about 200° Celsius., , The newly predicted superconductor — a compound of hydrogen; magnesium; and lithium — comes with its own complications however., The proposed superconductor must be squeezed to extremely high pressure nearly 2.5 million times the pressure of Earth’s atmosphere.   

    From Science News: “A predicted superconductor might work at a record-breaking 200° Celsius” 

    From Science News

    August 30, 2019
    Emily Conover

    1
    A theoretical type of superconductor, made of atoms of lithium (illustrated in green), magnesium (blue) and hydrogen (red), could function even at temperatures above the boiling point of water, scientists say. H. Liu

    The hydrogen-rich material would still need to be squeezed to extremely high pressures.

    Scientists have calculated that a hydrogen-rich compound could conduct electricity without resistance [Physical Review Letters] at temperatures up to about 200° Celsius — well above the 100° C boiling point of water. If that prediction is confirmed experimentally, the material would stand in stark contrast to all other known superconductors, which must be cooled below room temperature to work (SN: 12/15/15).

    The newly predicted superconductor — a compound of hydrogen, magnesium and lithium — comes with its own complications, however. It must be squeezed to extremely high pressure, nearly 2.5 million times the pressure of Earth’s atmosphere, physicist Hanyu Liu and colleagues, of Jilin University in Changchun, China, report in the Aug. 30 Physical Review Letters [link above].

    Scientists previously have used similar techniques to predict that a pressurized compound of lanthanum and hydrogen would be superconducting at higher temperatures than any yet known. That prediction seems likely to be correct: In 2018, physicist Russell Hemley and colleagues reported signs that the compound is superconducting up to a record-breaking −13° C (SN: 9/10/18).

    If the new calculation is confirmed, the purported superconductor would smash Hemley and colleagues’ temperature record. “This is an important prediction using a level of theory that has proven quite accurate,” says Hemley, of the University of Illinois at Chicago, who was not involved in the research.

    See the full article here .


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