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Im Rahmen des im Metrologischen Forschungsprogramms EMRP geförderten Projekt NEWSTAR wurde experimentell die Berechenbarkeit eines berechenbaren quanteneffizienten Detektors bzgl. seines polarisations-, winkel- und bandbreitenabhängigen Verhaltens überprüft und bestätigt. Die Empfindlichkeit eines Photometers wurde schließlich gegen diesen Detektor kalibriert und das Ergebnis mit dem Wert verglichen, der sich aus der Kalibrierung entsprechend der aktuellen Rückführungskette ergibt, wobei sich eine Übereinstimmung im Rahmen der Messunsicherheit ergab.

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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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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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Reference microphone for airborne ultrasound (¼-inch measurement microphone mounted on an adapter to ½ inch) in the calibration setup at PTB’s acoustic anechoic chamber.

At PTB, a procedure has been developed for the calibration of microphones in the ultrasound range of up to 100 kHz. By means of this procedure, reference standards and working standards can be produced for laboratories in industry and research in order to ensure the traceability of airborne ultrasound. This new calibration service is now available.

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Fluorescence scatter diagram for the identification of the CD34-positive stem cells, of the white blood cells (leukocytes) and of the calibration particles that have been added to the sample.

When transplanting stem cells, the dose is a decisive factor. To improve the determination of the dose by the measurement of the required concentration of viable stem cells, PTB has developed a reference procedure. It has been applied for the first time for comparison with results of the two methods that are currently used.

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The German part of the link uses commercially rented optical fibres and facilities
of the German National Research and Education Network (DFN). The
French part of the link uses the Network for Education and Research, RENATER,
which is operated by the GIP RENATER. Approximately midway,
signals from LNE-SYRTE and PTB meet at the IT Centre of the University of
Strasbourg, so that the clocks of the two institutes can be compared there.
(Fig.: PTB)

In the past few years, optical atomic clocks have made spectacular progress. They have become 100 times more precise than the best cesium clocks. So far, their precision has been available only locally, since frequency transfer via satellite cannot provide sufficient resolution. This has now changed thanks to a novel 1,400 km optical fiber link between Braunschweig and Paris. This link allows frequencies to “travel” and optical atomic clocks to be compared across national borders. In the first comparison between PTB’s optical strontium clocks and those of the French LNE-SYRTE, an unrivaled fractional uncertainty of 5 · 10−17 was achieved.

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