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  • richardmitnick 7:38 am on April 13, 2018 Permalink | Reply
    Tags: ICE, Neutron diffraction helps unlock the secrets of ice, Pearl diffractometer, , UK’s ISIS Neutron and Muon Source,   

    From UCL viaSTFC: “Neutron diffraction helps unlock the secrets of ice” 

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    University College London


    STFC

    1
    A schematic drawing of the upgraded Pearl diffractometer showing the 90 degrees and low angle detectors. (Credit: STFC).

    11 April 2018

    New research undertaken by scientists using the UK’s ISIS Neutron and Muon Source is improving our understanding of the highly unusual properties of ice and this knowledge will be of importance to any future study where ice coexists with other materials in nature, for example on icy moons such as Jupiter’s Europa.

    Although water is one of the most common elements, the complex properties of water and particularly ice are not well understood. There are many forms of ice, which are completely different to the ice you would find in a freezer.

    As water freezes its’ molecules rearrange themselves, and high pressure causes the molecules to rearrange in different ways than they normally would. The many distinct phases of ice can be explained using a phase diagram, which shows the preferred physical states of matter at different temperatures and pressures.

    Researchers from University College London (UCL) and STFC’s ISIS Neutron and Muon Source have used the PEARL high pressure neutron diffractometer at ISIS to investigate the impact of ammonium fluoride impurities on water’s phase diagram.

    The scientists discovered that the addition of this impurity caused a particular phase of ice, known as ice II, to completely disappear from water’s phase diagram whereas the other phases were unaffected.

    The many different phases of ice can be grouped into one of two types – hydrogen-ordered phases and hydrogen-disordered phases. In these different phases the orientation of water molecules is either firmly defined or disordered.

    Ice II is a hydrogen-ordered phase of ice that forms under conditions of high pressure. Unlike other phases of ice, ice II remains thermodynamically stable and hydrogen-ordered up to very high temperatures and the origin of this anomalous result is not well understood.

    Dr Christoph G. Salzmann, UCL said: “Without in-situ neutron diffraction we could not have performed this study. It was paramount to demonstrate that ice II has disappeared in the region of the phase diagram where it would normally exist.”

    “Unlike the other phases the water molecules in ice II interact with each other over very long distances. In a sense, whatever happens to one water molecule in a crystal of ice II – the effect is “felt” by all other molecules. In our study, ice II experiences a disturbance by the ammonium fluoride which destabilizes all of the ice II and makes it disappear.”

    This observation allowed researchers to infer important information on the highly unusual properties of ice II and the special properties of ice II provide a new explanation as to why the phase diagram of water displays so many anomalies, including liquid water.

    The results have been published in Nature Physics.

    See the full article here .

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    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.

    UCL campus

    UCL was founded in 1826 to open up higher education in England to those who had been excluded from it – becoming the first university in England to admit women students on equal terms with men in 1878.

    Academic excellence and research that addresses real-world problems inform our ethos to this day and are central to our 20-year strategy.

     
  • richardmitnick 8:12 am on March 17, 2016 Permalink | Reply
    Tags: , , ICE   

    From Eos: “New Insights from 60 Years of Crevasse Research” 

    Eos news bloc

    Eos

    16 March 2016
    Fabio Florindo
    fabio.florindo@ingv.it

    A hydrofractured crevasse, on the scalloped lake bottom of the supraglacial lake Greenland Ice Sheet in 2009. Credit William Colgan
    A hydrofractured crevasse, on the scalloped lake bottom of the supraglacial lake Greenland Ice Sheet in 2009. Credit William Colgan

    Warming of the climate system is unequivocal. It is evident from observations of increases in global average air and ocean temperatures, loss of ice in West Antarctica and in Greenland, and rising global sea levels. The magnitude of future ice loss, and consequent sea-level rise, is a major concern, but current projections of ice loss still have major uncertainties, in part due to our incomplete understanding of ice sheet and glacier dynamics. Crevasses – deep cracks or fractures found in an ice mass – are an important and often overlooked component of the cryosphere. A recent article published in Reviews of Geophysics summarizes research on how crevasses form and how they affect glaciers.

    Crevasses have long been relegated to the periphery of glaciological research, but there is emerging evidence that they can accelerate the decay of large bodies of ice, providing a potentially significant contribution to contemporary and future sea level rise. In addition, the distribution of crevasses on a glacier varies both in space and time, making them good indicators of glacier and ice sheet dynamics. In response to increasing scientific interest in crevasse processes, and in their influence on glacier and ice sheet volumetric changes through time, William Colgan of York University in Canada and six team members have adopted a holistic view of crevasse processes and reviewed about 60 years of in situ and remote sensing studies of crevasses as well as the numerical models now employed to simulate crevasse fracture. Although there have been a number of recently published and highly cited papers expressly dealing with crevasses, this is the first synthesis to date of both the surface mass balance and ice dynamic influences of crevasses on glacier and ice sheet mass balance. Given the broad interest in potential sea level rise caused by changes in the cryosphere, Colgan and his team provide a timely synopsis of the numerous mechanisms by which crevasses can influence glacier and ice sheet mass balance.

    Colgan, W., H. Rajaram, W. Abdalati, C. McCutchan, R. Mottram, M. S. Moussavi, and S. Grigsby (2016), Glacier crevasses: Observations, models, and mass balance implications, Rev. Geophys., 54, doi:10.1002/2015RG000504.

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 4:48 pm on July 12, 2015 Permalink | Reply
    Tags: , , , ICE, Northern Arizona University,   

    From Space.com: “Ice Lab Plays It Cool for Pluto Flyby” 

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    SPACE.com

    July 11, 2015
    Sarah Lewin

    Researchers in an Arizona ice lab spend long hours making crystal-clear ice from mixes of methane, nitrogen and even carbon monoxide — and now, with data from the New Horizons mission to Pluto arriving soon, the lab’s time has come.

    The surface of Pluto is likely covered in a coarse mixture of ices that don’t resemble anything found naturally on Earth. The bitter cold on icy dwarf planets like Pluto and Eris, discovered in 2005, crystallizes blends of substances that on Earth occur more commonly as gases: mainly nitrogen, with a heaping dose of methane and a smattering of other molecules mixing things up.

    To understand the composition of a planet like Pluto from a distance, researchers measure the wavelengths of light that bounce off of the planet’s surface, by telescope or (when possible) much closer up, by spacecraft. Those distinctive wavelengths create a sort of fingerprint for different substances, and by comparing the fingerprints to a database of ice measurements back home, researchers hope to figure out the molecular compositions, temperatures and phases of matter covering Pluto’s surface.

    Temp 0
    Northern Arizona University’s ice lab researchers Matt Bovyn (left), Stephen Tegler (center) and Will Grundy (right) modify the machinery they use to generate exotic ices like those found on Pluto. Credit: Stephen Tegler

    The ice lab at Northern Arizona University has been focusing on creating and measuring ices with different proportions of methane and nitrogen in preparation for the incoming Pluto data. They’ve also begun to incorporate some of the other molecules observed on Pluto to create ices of even greater complexity, Will Grundy, an investigator at the lab, astronomer at the Lowell Observatory and co-investigator on the New Horizons mission, told Space.com.

    Any new ice observations from Pluto’s surface that can’t be found in the database that Grundy and his colleagues have created will mean another trip to the lab to try and match those measurements.

    “We’re going to be getting observations from Pluto with New Horizons that are going to light a fire under our butts,” Grundy said.

    “Our role here in the ice lab has been sort of a support role to try and understand how ice spectra behave under different circumstances,” Stephen Tegler, the chair of Northern Arizona University’s physics and astronomy department and researcher in the ice lab, explained to Space.com. “Then, armed with that broad view, you can take all that information, knowledge and experience, and say, ‘OK, we have this particular fingerprint pattern. How does it relate to what we see in the ice lab?'”

    Temp 1
    A methane ice sample ready for investigation by Northern Arizona University’s ice lab. The methane is visible in the lower half of the cell. Credit: Stephen Tegler

    To measure the “fingerprinting” of a given ice sample, the researchers fire infrared light through the ices they create as they cool down. They track how the changes in temperature and phase of the ice affect which wavelengths of light are absorbed. Many people think “phase” refers to solid, liquid or gas — but it’s much more complicated where these nonwater ices are concerned. They go through several different solid transitions: At certain temperatures, the already-solid ices will suddenly rearrange into a new crystalline setup. (Nitrogen, for instance, suddenly changes from a hexagonal to cubic crystal as it cools past 35.6 degrees Kelvin.)

    Add combinations of different elements into the mix, which change at different temperatures, and it gets complicated fast. “Every combination, it’s almost like we’ve got to come up with a new recipe to grow that very clear ice,” Tegler said. Adding carbon monoxide, another gas present on Pluto, makes the recipes even more devilishly difficult — but also more useful to pinpointing the conditions on different parts of Pluto’s surface, which might have the molecules in different proportions and temperatures.

    “From the point of view of doing remote sensing, anything that changes is something that you could hope to detect from a telescope or from a spacecraft, so that’s a valuable thing to know about,” Grundy said.

    Any unexpected, strange or inexplicable measurements will require new ices and new analysis to interpret. The lab has only scratched the surface on the gases the probe might encounter, say the team members.

    “There are some things I haven’t worked up the courage to try,” Grundy said. “Another species that’s on Pluto is hydrogen cyanide, which is even more toxic [than carbon monoxide] — and worse, it can be explosive as well,” Grundy said.

    See the full article here.

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