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Titelseite Broschüre Junge Wissenschaft

PTB is now home to a new publication, Junge Wissenschaft, an online journal (Opens external link in new windowhttps://www.jungewissenschaft.ptb.de). Young scientists (no older than 23 years old) can publish their findings in accordance with the usual rules applying to scientific publications – including a peer review process. Junge Wissenschaft is published, edited, and editorially supported by PTB’s Press and Information Office. PTB’s considerable role in the publication of this journal dates back many years, starting with a close relationship between its founding editor (Prof. Dr. Paul Dobrinski, 1927–2009) and the then President of PTB (Prof. Dr. Ernst O. Göbel). This relationship came about due to the mutual interest of the journal and PTB in supporting junior scientists in the natural sciences.

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A collaborative research centre (CRC) on diagnostic radiology called “Matrix in Vision” has been created at the Charité university hospital in Berlin (contact: Prof. Dr. Bernd Hamm). The Freie Universität Berlin, the Max Planck Institute of Colloids and Interfaces, the BAM Federal Institute for Materials Research and Testing and PTB are also involved in this CRC in addition to Charité. This collaborative research center, which is being funded by the German Research Foundation (DFG) with 11.5 million euros, has been established to find out how pathological changes to the extracellular matrix (the substance in which the body’s cells are embedded) can be visualized by means of diagnostic radiology. The scientists involved hope that their methods will contribute to the early detection of diseases. Members of staff from Division 8 of PTB are overseeing two sub-projects on quantitative and magnetic imaging.

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A new association, the German National Committee of CIE (Deutsches Nationales Komitee der Internationalen Beleuchtungskommission CIE – DNK-CIE) was founded at PTB on 5 April 2018. Dr. Armin Sperling was elected as the first chairperson of the new association.

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Weltweit einmaliges Forschungszentrum mit PTB-Beteiligung (Foto: Carpus + Partner)

The new building housing the Hannover Institute of Technology (HITec) at Leibniz University Hannover was inaugurated on 6 July. This institute is the first in Europe to unite basic and applied research and technology development on quantum physics and geodesy under one roof. The main partner organizations directly involved in HITec’s research program are: the Laser Zentrum Hannover e.V. (LZH), the German Aerospace Center (DLR), the Max Planck Institute for Gravitational Physics/Albert Einstein Institute (AEI), the Center of Applied Space Technology and Microgravity (ZARM), and PTB.

The Hannover Institute of Technology brings together three research branches from the fields of physics and geodesy: quantum technologies, optical technologies and the development and application of quantum sensors.

The unique infrastructure in the new, recently inaugurated research building will be available to more than 100 scientists. In addition to...

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Bidirectional amplifiers are necessary for the transmission of ultra-stable optical frequencies over long-distance optical fiber links in order to compensate for the optical loss of approximately 20 dB per 100 kilometers. Brillouin fiber amplifiers developed at PTB support such bidirectional operation with a gain of up to 45 dB and have been successfully installed in the international optical fiber link between Braunschweig and Paris. These amplifiers have now been outfitted with a new, more efficient optical module that optimizes the input coupling of the pump laser while minimizing signal losses within the setup. By means of an additional monitor port, the polarization between the signal and the pump laser can now be precisely adjusted and permanently monitored. (Technology Offer 466)

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Beispielhafter Strahlenverlauf: oben mit vier Reflexionen pro Spiegel, darunter in der neuen Herriott-Zelle mit dreifach erhöhter Anzahl an Reflektionen (12 Reflexionspunkte pro Spiegel)

Tiny amounts of certain gases can have considerable effects on human health, the environment and industrial processes. It is now possible to detect such gas quantities with enhanced sensitivity resolution by means of a Herriott cell developed at PTB. Plane mirrors inside the cell make it more effective, allowing the optical path length to be increased by more than one order of magnitude at an equal volume of the cell, which also improves the detection limit. For instance, with a mirror radius of 7 cm and a distance of 1 m between the mirrors, it is possible to achieve an effective optical path length of more than a kilometer (instead of 100 m until recently). (Technology Offer 397)

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Geometrische Abweichungen bei der Kegelstrahlgeometrie. Die Bilder entstehen in unterschiedlichen Tiefen in der Szintillatorschicht des Detektors. In Rot ist der Strahlengang ohne Filter und umgebendes Material zu sehen in Blau mit Filter und umgebendem Material. Der Effekt ist abhängig vom Röntgenspektrum in Kombination mit Probenmaterial und Abstand a.

Until recently, length measurements performed by means of industrial X-ray computed tomography (CT) based on cone beam geometry (without additional tactile reference measurements) exhibited relative measurement uncertainties of approx. 1 · 10-4. A procedure developed at PTB allows this uncertainty to be improved by a factor of at least 10. This new development relies on a pixel-resolved distance correction between the X-ray source and the flat-panel detector. Moreover, with this procedure, there is less need for pre-filtering of the X-ray radiation, thus increasing intensity and allowing shorter measuring times. This also reduces measurement uncertainties that may occur during the irradiation of a specimen due to drifting. (Technology Offer 455)

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Awards

 

Joachim Ullrich

PTB-Präsident Prof. Dr. J. UllrichThe president of PTB has been awarded an honorary science doctorate by Leibniz University Hannover. By awarding this honorary title, the university has recognized Professor Ullrich’s outstanding accomplishments in the field of experimental quantum physics. These accomplishments include more than 450 publications in renowned specialist journals and numerous research prizes, among them the DFG Gottfried Wilhelm Leibniz Prize, which he received in 1999.

Leiter des Fachbereichs Zeit und FrequenzEkkehard Peik

The head of the Time and Frequency department has been appointed as Distinguished Lecturer by the IEEE’s Ultrasonics, Ferroelectric, and Frequency Control Society. In this capacity, Peik will hold lectures on PTB’s activities concerning “Optical atomic clocks with single trapped ions” at universities and research institutes from June 2018 to December 2019.

 

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Schematics of the measurement setup for the calibration of the inductive voltage divider (in the figure: ”divider”) with the two JAWS voltage standard systems. The lock-in voltage amplifier together with the transformer (centre of the picture) amplifies the signal and, thus, increases the sensitivity of the measurement method.

PTB is developing a measuring system based on pulse-driven Josephson voltage standards. This system is designed to allow alternating voltages to be measured with great accuracy at frequencies of up to 100 kHz and voltages of more than 100 V. Since the output voltages of Josephson voltage standards are limited to a few volts, it is necessary to use voltage dividers. An inductive voltage divider has now been calibrated for the first time with pulse-driven Josephson voltage standards, and the results have been compared to those obtained using a conventional calibration procedure.

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Measurement setup during a measurement with the vibrometer. The vibrometer is located in the blue housing. The foil is placed in the red lens tube and lies on the water surface.

A novel measurement setup has been developed at PTB for the primary calibration of ultrasonic hydrophones. Hydrophones are sensors used to determine ultrasonic pressure wave in liquid media. They are mainly used in medical engineering in order to test ultrasonic equipment. The new facility covers a larger frequency range and simultaneously exhibits lower uncertainty.

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