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PTB News

Three times a year, PTB News provides topical information from the varied spectrum of activities of the Physikalisch-Technische Bundesanstalt (PTB) consisting of fundamental research, legal metrology and PTB's various activities in the service of the economy.

PTB-News 3.2021 - SCIENTIFIC NEWS

Our brains process information via slow and fast brain currents. Up to now, it has been necessary to introduce electrodes into the brain to examine the latter. Within a cooperation between PTB and the Charité, these fast brain signals have been made visible from the outside for the first time – and a surprising variability has been observed. The measurements of these extremely small magnetic...

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Principle of magneto-Seebeck microscopy: An AFM tip is moved across the surface and couples IR radiation into the CuMnAs layer. There, a hot spot and a measurable voltage occur at the connections. This voltage is recorded as a function of the place. It is characteristic of the individual domain orientation at hand.

Internally, antiferromagnetic materials are magnetic, but the order of their microscopic moments changes directions between individual elementary magnets. This is why there is no net magnetic moment. The magnetic state of an antiferromagnet has now become measurable using magneto-Seebeck microscopy. This magnetic state can be used in applications such as spintronics.

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Gauge block made of single-crystal silicon. Dimensions: 197 mm × 35 mm × 9 mm

At PTB, absolute length measurements on a single-crystal silicon gauge block have been performed using imaging interferometry. These measurements have a smaller measurement uncertainty than all previous measurements. They provide more accurate values for the CODATA reference data and are valuable for a new secondary realization of the meter.

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Einblick in den Prototypen mit angedeTop view of the prototype – the optical path is indicated by the red arrows with the laser diode (LD), the beam splitter (BS) and the photodetectors (PD).utetem Strahlengang mit Laserdiode (LD), Strahlteiler (BS) und Photodetektoren (PD)

In collaboration with an industrial partner, PTB has developed and assessed a very compact wavelength standard. This standard is based on a diode laser whose frequency is stabilized to transitions of the iodine molecule. In the future, this type of lasers could replace power-intensive and bulky helium-neon lasers as a wavelength standard for interferometric length measurement.

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Simulated developments of possible random-walk progressions of the error signal x across the number <em>t</em> of repetitions of the circuit operation, taking the counting statistics of the error signal that as measured experimentally into account. The orange curve emphasizes the example of one of these possible progressions. The linewidths of the blue curves correspond to the statistical frequencies of each of the assumed states.

Manipulating individual electrons with the goal of employing quantum effects promises qualitatively new applications in electronics. However, these single-electron circuits, which are governed by the laws of quantum mechanics, exhibit statistical deviations from error-free operation. This results in a fundamental uncertainty that is essential to understand and to quantify for further developments....

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Example of measurement setup with a spectrometer and a dosemeter at PTB’s USP laser machine. The material used for this measurement was a tungsten rod.

Ultrashort pulse lasers in which an individual pulse only lasts a few picoseconds are increasingly being used in materials processing. Since these devices may generate undesired X-rays, the German Radiation Protection Act has made them subject to prior authorization since 20 May 2021. PTB has contributed to this legal amendment by performing exhaustive radiation protection measurements on its new...

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At present, lithium-sulfur batteries cannot reach their theoretical maximum capacity and lifetime. According to time-resolved, species sensitive and traceable measurements performed for sulfur at the BESSY II synchrotron radiation source, the accumulation of polysulfides at the anode could be the main reason for these shortcomings.

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PTB-News 3.2021 - TECHNOLOGY TRANSFER

a) Front view of the mirrorholder b) rear view of the mirrorholder

In some optical assemblies, it is necessary to independently adjust two beams which are separated by a few millimeters. Such situations make it desirable to perform the adjustment of both beams with a single mirror holder to reduce the beam spacing and the total mechanical footprint while the mechanical stability is improved. PTB’s concept of a double mirror holder offers a simple solution to this...

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Function principle of the measurement procedure for detecting the electrostatic charging of powder flows

For the explosion protection of industrial plants, it is extremely important to know the electrostatic charging behavior of particles (e.g., powders) during transport in flows. The new technology is based on two different measurements which use particle image velocimetry (PIV). A test channel is located between two defined measurement sections. An electrostatic field is applied to this test...

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Schematic representation of a sorption artefact consisting of three disks.

When calibrating mass standards, it is important to determine the mass of substances that may have accumulated on the surface of the standard. The mass of these substances can be determined by means of sorption artefacts that consist of several individual disks. The values gaines in this way are taken into account in the form of a correction to increase the measurement accuracy. A new concept from...

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PTB-News 3.2021 - MISCELLANEOUS

 Cornelia Denz

Prof. Dr. Cornelia Denz, a physicist from the University of Münster, will become the new President of PTB on 1 May 2022. The current President, Prof. Dr. Dr. h.c. Joachim Ullrich, who has held the presidency since 2012, will leave at that time when he retires. Cornelia Denz will be the first woman to lead PTB in the institute’s 135-year history. She was appointed to this top...

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The German Federal Ministry of Education and Research (BMBF) is providing the MIQRO joint project with 15.8 million euros in funding. In this project, a quantum computer is to be developed which is based on high-frequency-controlled ions. In addition to PTB, Leibniz University Hannover, the University of Siegen, Heinrich Heine University Düsseldorf, and the QUARTIQ and eleQtron companies are also...

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The hydrogen innovation laboratory called “Nachhaltige Verbrennungskonzepte” (sustainable combustion concepts) has been launched. The project is entering its threeyear implementation phase with funding provided by Lower Saxony’s Ministry of Science and Culture totaling 1.2 million euros. PTB is participating alongside Leibniz University Hannover, TU Braunschweig, TU Clausthal and Jade University...

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UDO, PTB’s underground laboratory, has now been in existence for 30 years. As it has one of the lowest radiation levels in the world, it offers optimum conditions for environmental radioactivity monitoring and, thus, also indirectly has optimum conditions for the observation of climate change and its parameters by means of the radon tracer method. Originally, the laboratory was set up in the Asse...

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