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  • richardmitnick 9:07 am on April 2, 2018 Permalink | Reply
    Tags: , , Neutrons, , ,   

    From STFC: “Why would we want test the robustness of space electronics against neutrons?” 


    STFC

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    STFC ISIS Neutron and Muon Source

    In spite of their size high energy neutrons cause severe disruption to the normal operation of integrated circuits, which make up the advanced electronic devices used in space missions. 🚀 These neutrons are generated by the collision of cosmic rays with the atmosphere, spacecraft components and even the surface of planets. With space missions filled with advanced electronic devices it is of great importance to thoroughly assess their robustness before they even leave the ground.

    Researchers from Italy 🇮🇹 and the UK 🇬🇧 have utilised two neutron beamlines at ISIS Neutron and Muon Source, ChipIr and VESUVIO, to test flash memory devices of interest for space applications.

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    STFC ISIS Neutron and Muon Source

    The beamlines generate neutron spectra similar to that we would expect to see in space and planetary environments. Just one hour in the beam mimics the exposure a device would receive over hundreds of thousands of years in the real environment, allowing researchers to rapidly assess the susceptibility of their device to high-energy neutrons.

    See the full article here .

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    STFC Hartree Centre

    Helping build a globally competitive, knowledge-based UK economy

    We are a world-leading multi-disciplinary science organisation, and our goal is to deliver economic, societal, scientific and international benefits to the UK and its people – and more broadly to the world. Our strength comes from our distinct but interrelated functions:

    Universities: we support university-based research, innovation and skills development in astronomy, particle physics, nuclear physics, and space science
    Scientific Facilities: we provide access to world-leading, large-scale facilities across a range of physical and life sciences, enabling research, innovation and skills training in these areas
    National Campuses: we work with partners to build National Science and Innovation Campuses based around our National Laboratories to promote academic and industrial collaboration and translation of our research to market through direct interaction with industry
    Inspiring and Involving: we help ensure a future pipeline of skilled and enthusiastic young people by using the excitement of our sciences to encourage wider take-up of STEM subjects in school and future life (science, technology, engineering and mathematics)

    We support an academic community of around 1,700 in particle physics, nuclear physics, and astronomy including space science, who work at more than 50 universities and research institutes in the UK, Europe, Japan and the United States, including a rolling cohort of more than 900 PhD students.

    STFC-funded universities produce physics postgraduates with outstanding high-end scientific, analytic and technical skills who on graduation enjoy almost full employment. Roughly half of our PhD students continue in research, sustaining national capability and creating the bedrock of the UK’s scientific excellence. The remainder – much valued for their numerical, problem solving and project management skills – choose equally important industrial, commercial or government careers.

    Our large-scale scientific facilities in the UK and Europe are used by more than 3,500 users each year, carrying out more than 2,000 experiments and generating around 900 publications. The facilities provide a range of research techniques using neutrons, muons, lasers and x-rays, and high performance computing and complex analysis of large data sets.

    They are used by scientists across a huge variety of science disciplines ranging from the physical and heritage sciences to medicine, biosciences, the environment, energy, and more. These facilities provide a massive productivity boost for UK science, as well as unique capabilities for UK industry.

    Our two Campuses are based around our Rutherford Appleton Laboratory at Harwell in Oxfordshire, and our Daresbury Laboratory in Cheshire – each of which offers a different cluster of technological expertise that underpins and ties together diverse research fields.

    The combination of access to world-class research facilities and scientists, office and laboratory space, business support, and an environment which encourages innovation has proven a compelling combination, attracting start-ups, SMEs and large blue chips such as IBM and Unilever.

    We think our science is awesome – and we know students, teachers and parents think so too. That’s why we run an extensive Public Engagement and science communication programme, ranging from loans to schools of Moon Rocks, funding support for academics to inspire more young people, embedding public engagement in our funded grant programme, and running a series of lectures, travelling exhibitions and visits to our sites across the year.

    Ninety per cent of physics undergraduates say that they were attracted to the course by our sciences, and applications for physics courses are up – despite an overall decline in university enrolment.

     
  • richardmitnick 4:41 pm on June 29, 2017 Permalink | Reply
    Tags: From the lab to the ports, , Inspiration from light-emitting diodes lead to performance boost, Neutrons, , Scintillating discovery at Sandia Labs, scintillator made of organic glass - much better   

    From Sandia: “Scintillating discovery at Sandia Labs” 


    Sandia Lab

    June 29, 2017

    Bright thinking leads to breakthrough in nuclear threat detection science.

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    Sandia National Laboratories researcher Patrick Feng, left, holds a trans-stilbene scintillator and Joey Carlson holds a scintillator made of organic glass. The trans-stilbene is an order of magnitude more expensive and takes longer to produce. (Photo by Randy Wong).

    Taking inspiration from an unusual source, a Sandia National Laboratories team has dramatically improved the science of scintillators — objects that detect nuclear threats. According to the team, using organic glass scintillators could soon make it even harder to smuggle nuclear materials through America’s ports and borders.

    The Sandia Labs team developed a scintillator made of an organic glass which is more effective than the best-known nuclear threat detection material while being much easier and cheaper to produce. Organic glass is a carbon-based material that can be melted and does not become cloudy or crystallize upon cooling. Successful results of the Defense Nuclear Nonproliferation project team’s tests on organic glass scintillators are described in a paper published this week in The Journal of the American Chemical Society.

    Sandia Labs material scientist and principal investigator Patrick Feng started developing alternative classes of organic scintillators in 2010. Feng explained he and his team set out to “strengthen national security by improving the cost-to-performance ratio of radiation detectors at the front lines of all material moving into the country.” To improve that ratio, the team needed to bridge the gap between the best, brightest, most sensitive scintillator material and the lower costs of less sensitive materials.

    Inspiration from light-emitting diodes lead to performance boost

    The team designed, synthesized and assessed new scintillator molecules for this project with the goal of understanding the relationship between the molecular structures and the resulting radiation detection properties. They made progress finding scintillators able to indicate the difference between nuclear materials that could be potential threats and normal, non-threatening sources of radiation, like those used for medical treatments or the radiation naturally present in our atmosphere.

    The team first reported [Science Direct] on the benefits of using organic glass as a scintillator material in June 2016. Organic chemist Joey Carlson said further breakthroughs really became possible when he realized scintillators behave a lot like light-emitting diodes.

    With LEDs, a known source and amount of electrical energy is applied to a device to produce a desired amount of light. In contrast, scintillators produce light in response to the presence of an unknown radiation source material. Depending on the amount of light produced and the speed with which the light appears, the source can be identified.

    Despite these differences in the ways that they operate, both LEDs and scintillators harness electrical energy to produce light. Fluorene is a light-emitting molecule used in some types of LEDs. The team found it was possible to achieve the most desirable qualities — stability, transparency and brightness — by incorporating fluorene into their scintillator compounds.

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    Sandia National Laboratories researcher Joey Carlson demonstrates the ease of casting an organic glass scintillator, which takes only a few minutes as compared to growing a trans-stilbene crystal, which can take several months. (Photo by Randy Wong).

    The gold standard scintillator material for the past 40 years has been the crystalline form of a molecule called trans-stilbene, despite intense research to develop a replacement. Trans-stilbene is highly effective at differentiating between two types of radiation: gamma rays, which are ubiquitous in the environment, and neutrons, which emanate almost exclusively from controlled threat materials such as plutonium or uranium. Trans-stilbene is very sensitive to these materials, producing a bright light in response to their presence. But it takes a lot of energy and several months to produce a trans-stilbene crystal only a few inches long. The crystals are incredibly expensive, around $1,000 per cubic inch, and they’re fragile, so they aren’t commonly used in the field.

    Instead, the most commonly used scintillators at borders and ports of entry are plastics. They’re comparatively inexpensive at less than a dollar per cubic inch, and they can be molded into very large shapes, which is essential for scintillator sensitivity. As Feng explained, “The bigger your detector, the more sensitive it’s going to be, because there’s a higher chance that radiation will hit it.”

    Despite these positives, plastics aren’t able to efficiently differentiate between types of radiation — a separate helium tube is required for that. The type of helium used in these tubes is rare, non-renewable and significantly adds to the cost and complexity of a plastic scintillator system. And plastics aren’t particularly bright, at only two-thirds the intensity of trans-stilbene, which means they do not do well detecting weak sources of radiation.

    For these reasons, Sandia Labs’ team began experimenting with organic glasses, which are able to discriminate between types of radiation. In fact, Feng’s team found the glass scintillators surpass even the trans-stilbene in radiation detection tests — they are brighter and better at discriminating between types of radiation.

    Another challenge: The initial glass compounds the team made weren’t stable. If the glasses got too hot for too long, they would crystallize, which affected their performance. Feng’s team found that blending compounds containing fluorene to the organic glass molecules made them indefinitely stable. The stable glasses could then also be melted and cast into large blocks, which is an easier and less expensive process than making plastics or trans-stilbene.

    From the lab to the ports

    The work thus far shows indefinite stability in a laboratory, meaning the material does not degrade over time. Now, the next step toward commercialization is casting a very large prototype organic glass scintillator for field testing. Feng and his team want to show that organic glass scintillators can withstand the humidity and other environmental conditions found at ports.

    The National Nuclear Security Administration has funded the project for an additional two years. This gives the team time to see if they can use organic glass scintillators to meet additional national security needs.

    Going forward, Feng and his team also plan to experiment with the organic glass until it can distinguish between sources of gamma rays that are non-threatening and those that can be used to make dirty bombs.

    See the full article here .

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    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.
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  • richardmitnick 9:37 am on July 20, 2016 Permalink | Reply
    Tags: , , IceTop, Neutrons   

    From IceCube: “IceCube aims for neutron astronomy” 

    icecube
    IceCube South Pole Neutrino Observatory

    20 Jul 2016
    Sílvia Bravo

    Cosmic-ray studies with IceCube have provided the first measurement of the anisotropy in the Southern Hemisphere. We have also measured the cosmic-ray flux, searching for signatures that can tell us about the transition from galactic to extragalactic sources and the chemical composition of cosmic rays.

    And now it’s the neutron’s turn to reveal what it can tell us about galactic cosmic ray sources. The IceCube Collaboration presents results from a search for sources of high-energy neutrons using four years of data from IceTop, the surface detector array.

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    IceTop

    Researchers have not found any evidence for astrophysical neutrons, but the results have allowed the collaboration to set new limits that constrain the possible galactic neutron sources. These results have just been submitted to the Astrophysical Journal.

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    Equatorial polar skymap of flux upper limit values for each search window. Image: IceCube Collaboration.

    Neutrons cannot be accelerated by shock waves like cosmic-ray protons and other charged nuclei, but they can be produced in the interactions of cosmic rays with matter in and nearby the sources. They would then propagate in a straight line until they decay, travelling distances of about 10 pc per every PeV of energy.

    These high-energy neutrons produce a shower of particles when they reach the Earth’s atmosphere—a cascade of particles very similar to the one produced by charged cosmic rays—and could be detected by IceTop in the energy range of around a few PeV and above.

    The search for galactic astrophysical neutrons in IceTop looked for point sources in the cosmic ray anisotropy. Neutrons are not deflected by magnetic fields and will point back to their sources, which allows performing neutron astronomy at increasing distances with higher energy neutrons. However, to date, no experiment has been able to measure a source of astrophysical neutrons.

    IceCube researchers performed two different analyses. The first one searched for hot spots anywhere in the southern sky, while the second one searched for correlations with known galactic sources, assuming that many or all these high-energy photon sources also emit neutrons.

    The results show no significant clustering of proton-like air showers in IceTop, which could be an indication of a neutron contribution to the cosmic-ray anisotropy. The lack of neutron sources allows setting the first neutron flux upper limits in the Southern Hemisphere for energies between 10 PeV and 1 EeV.

    The absence of PeV neutrons in IceTop data could be an indication of galactic neutron sources farther away, or it could be a hint that sources with GeV-TeV photon emission don’t produce neutrons. What these results definitely tell is that there is still plenty to learn before we can claim neutron astronomy as a reality.

    Science paper:
    Search for Sources of High Energy Neutrons with Four Years of Data from the IceTop Detector,” The IceCube Collaboration: M.G.Aartsen et al, Submitted to the Astrophysical Journal, arxiv.org/abs/1607.05614

    See the full article here .

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
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