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UHV instrumentation for combined X-ray fluorescence and photoelectron spectroscopy on surfaces of silicon spheres

In order to become independent of the international prototype of the kilogram kept in Paris, the definition of the SI unit of mass, the kilogram, has to be revised. For this purpose, the number of silicon atoms in a monocrystalline silicon sphere has been determined at PTB within the scope of the Avogadro proj´ect. It is therefore necessary to measure the surface properties with the highest possible metrological accuracy. To this end, PTB has set up ultra-high vacuum (UHV) instrumentation with combined X-ray fluorescence spectroscopy and photoelectron spectroscopy.

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Scientists of the Institute of Photonic Sciences (Barcelona) have monitored the locations of all the atoms of an molecule while one of its bonds breaks and a single proton escapes. The “reaction microscope” used for the experiment was developed at the Max Planck Institute for Nuclear Physics in Heidelberg. The research participants included Prof. Dr. Joachim Ullrich, former Director of the Max Planck Institute for Nuclear Physics in Heidelberg and now President of the Physikalisch-Technische Bundesanstalt. Together with his research group, Dr. Ullrich helped construct the reaction microscope for this experiment in order to completely detect all fragments, and provided his assistance and advice during the complex evaluation of the data.

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Each edition of PTB News now includes a film, which will be shown online. These films will provide you with background information and a direct look at the work done in our laboratories. We began with “World record for two optical clocks” (2.2016). For this edition (3.2016), we have prepared a film for you on the topic of “How much current does a solar cell provide?” Each film can be found in the same location as the accompanying edition of PTB News: Opens internal link in current windowwww.ptb.de > Opens internal link in current windowPublications > Opens internal link in current windowPTB News.

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Opens internal link in current windowThe latest edition of maßstäße, PTB’s popular-science magazine, witch is available in German only, takes the reader on a journey through everyday life. No matter what we are doing or where we are, measurements are always there – and quite a few of them at that! Our reading journey begins by looking at our homes and our bodies, stops along the way to explore food & drink, and continues well beyond – down all kinds of transportation routes, into the air, into space, and into networks and grids of every kind. “maßstäße” can be read online at: Opens internal link in current windowwww.ptb. de > Opens internal link in current windowPress & What’s New > Opens internal link in current windowJournals & magazines > Opens internal link in current windowmaßstäbe

To order for free (including as a subscription or as a set for classroom use), please contact: Cornelia Land (+49 (0)531 592-9313, Opens window for sending emailcornelia.land(at)ptb.de)

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Logo zum Tag der offenen Tür 2016

Am 20. August wird es spannend – wenn in der Physikalisch-Technischen Bundesanstalt (PTB) Blitze durch die Hochspannungshalle und den Hörsaal fliegen, wenn Fluoreszenz Objekte im Dunkeln zum Leuchten bringt oder wenn Wissenschaftler einzelne Atome fangen. Um Spannung geht es auch beim Thema Mobilität. Denn elektrische Energie ist der Kraftstoff der Zukunft – und die Forscher der Energiemesstechnik der PTB sorgen dafür, dass dieser Kraftstoff richtig gemessen und abgerechnet wird. Beim Tag der offenen Tür erfahren die Besucher aus erster Hand – von PTB-Wissenschaftlern und ihren Partnern aus der „ForschungRegion“ –, was sich aktuell im Bereich der Elektromobilität tut. Abgerundet wird das wissenschaftliche Programm durch ein vielfältiges Rahmenprogramm mit Musik und Unterhaltung. Für reichlich Essen von Kuchen bis Bratwurst sowie Getränke von Wasser bis Cocktails ist ebenfalls gesorgt.

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Were Galileo, Newton and Einstein mistaken? At least just a little? Thanks to them, today we know that heavy mass and inertial mass are different approaches to describe the same physical effect: mass. Thus in vacuum, all objects fall to the ground with equal acceleration, no matter how heavy they are. This 400-year-old discovery has thus far withstood every test. Scientists confirm the so-called equivalence principle with an accuracy of 10-13, thus accurate to one ten billionth. However, modern physical theories, such as the string theory, assume that far behind the decimal point the proof could be waiting that heavy mass and inertial mass differ from one another. French scientists now want to put the principle to the test again – with the active support of the "Wissenschaftlicher Gerätebau" (Scientific Instrumentation Department) of the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig. It was there that two pairs of hollow...

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In principle, helium doesn’t like combining with its ilk at all. Yet, occasionally, it does exactly this, albeit with extremely slight binding energies. Scientists at Goethe University Frankfurt have successfully measured these energies for the first time. For this metrological sensation, they are to be honored with this year’s Helmholtz Prize together with their fellow researchers in Cambridge. The Cambridge researchers have enhanced the single-molecule measurement technique, which is already established in DNA analysis, in a revolutionary way using nanopores, thereby creating the conditions to, in theory, be able to detect any number of different protein molecules within the same measurement. The Helmholtz Prize’s categories of “fundamentals” and “applications” are each endowed with 20,000 euros; the prize is considered to be one of the world’s most prominent distinctions in the field of metrology, the science of precise measurement.

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