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News of the Year

Scientific Divisions

Semiconductor single-electron pump (left), connected to a high-precision current/voltage transformer ULCA (center) combined with a Josephson voltage standard for measuring voltage (right). All components and devices were developed by PTB.

In the current International System of Units (SI), the electrical base unit – the ampere – is defined as the force between two current-carrying conductors. This “conventional ampere” can be realized with a measurement uncertainty of around 0.3 μA/A. In the revised SI, whose introduction is planned for 2018, the ampere is to become more precise. In the new system of units, the ampere – the unit of...

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Fig. 1. Position and identification of the individual samples investigated in the AVO28 single crystal.

In consideration of the redefinition of the SI, the goal of the Avogadro project is to re-determine the Avogadro constant with a measurement uncertainty in the range of better than 1 · 10–8. To achieve this goal, it is necessary to measure the molar mass M(Si) of silicon with a relative measurement uncertainty of < 5 · 10–9. In addition to the chemical preparation and the mass-spectrometric...

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The frequencies of strontium lattice clocks in the French metrology institute SYRTE (Paris) and PTB were compared by means of fiber connections to Strasbourg (705 km from Paris, 710 km from Braunschweig). The individual setups comprising an interrogation laser, an optical lattice, an fs frequency comb, a transfer laser and a stabilized link are shown. The difference frequency of the two transfer lasers is measured in Strasbourg.
(Figure from an original publication: C. Lisdat, G. Grosche, N. Quintin, C. Shi, S.M.F. Raupach et al.: A clock network for geodesy and fundamental science. Nature Communications, 7:12443 (2016), DOI 10.1038/NCOMMS12443)

The worldwide network of optical glass fiber connections for the transmission of data allows access to remote instruments from several places at the same time. By modifying such glass fiber links to glassfiber- based optical interferometers, optical frequencies can be compared over very long distances. This has now been implemented on a 1400 km long glass fiber link from Braunschweig to Strasbourg...

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Figure 1: Straightness measurement of an encoder system at the nanometer comparator on the basis of the additional three displacement interferometers

The increasing demands placed on the positioning accuracy of multiaxial manufacturing and measuring machines lead to the requirement that the coordinate and straightness references have to be calibrated with small uncertainties. For this purpose, the nanometer comparator has been further improved in order to determine, in addition to the position deviations of length graduations, their...

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Overview of PTB’s ion accelerator facility “PIAF”. From the two accelerators, the ion beams are guided via a beam line system with several deflection magnets to different experimental areas. The two photos show the new 2 MV tandetron accelerator during the construction phase in October 2016. In the open tank, the so-called accelerator column can be seen in which the ions are accelerated by the applied high voltage.

PTB’s Ion Accelerator Facility (PIAF) consists of an energy-variable CV28 isochron cyclotron and an electrostatic accelerator. It is operated by Department 6.4 “Neutron Radiation” and provides proton, deuteron and alpha particle beams with energies of up to approx. 26 MeV (depending on the particle type) which are used for the generation of neutron reference fields and for experiments with ion...

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French astronaut Thomas Pesquet during his mission on ISS, using a personal dosimeter developed by PTB that immediately indicates the radiation dose. The photo was taken during training (photo: NASA, James M. Blair).

Since November 2016, a new radiation measurement system that PTB was instrumental in developing has been in use on board the International Space Station (ISS). Depending on the quality of the radiation, the system calculates the impact of the radiation on living tissue and indicates the respective radiation dose for the astronaut without time delay. Previously, it was only possible to evaluate...

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PTB has succeeded in measuring the Boltzmann constant k independently. An essential condition laid down by the Consultative Committee of Thermometry (CCT) has thereby been met, thus paving the way for the new definition of the kelvin by fixing the value of the Boltzmann constant. The final measurements of k with the dielectric-constant gas thermometer were conducted with a relative uncertainty of...

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Size comparison between a microfluidic sensor and a one eurocent coin

In flow cytometry, the full blood count is measured applying optical or impedance-based cell-counting instruments. To determine the concentration of white blood cells (the abundance of which is a factor of approx. 1000 – compared to red blood cells), the destruction of red blood cells by hemolysis is required. In the case of certain diseases, e.g. leukemia, however, the hemolysis procedure may...

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The new institute “Fundamental physics for metrology” was founded at PTB in this year. It studies new developments in physics which may be important for metrology in the future. Within the institute three different research directions were established:

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Advisory Board

Members of the Kuratorium (Advisory Board) visit one of seven terminals worldwide that are set to be used within the scope of preparations for the “Atomic Clock Ensemble in Space” (ACES), an ESA mission; ACES is designed to compare atomic clocks on the Earth and in the International Space Station (ISS). Here, the terminal’s rotating antenna, which is aimed towards the sky, can be seen on the roof of PTB’s Meitner Building.

The annual meeting of the Kuratorium (Advisory Board) of PTB took place this year in Braunschweig on 12-13 May. Following a tour of the laboratories after the official introductory greeting by the President, three lectures were given by junior scientists on their most recent work. Dr. Friederike Stein gave a report on “Validation of quantized single-electron current sources at sub-ppm level”, a...

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Presidential Board

Evaluation

As part of its evaluation of PTB, the Wissenschaftsrat (German Council of Science and Humanities) visited both of PTB’s sites in September 2016.

This year, PTB was evaluated for the second time by the German Council of Science and Humanities (Wissenschaftsrat). The evaluation committee also focused their attention on the continued development in the nine years since the previous evaluation took place.

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The Laboratory for Emerging Nanometrology (LENA) is a research center at the Technische Universität Braunschweig founded in close collaboration with PTB; LENA is already being operated in collaboration with the participating institutes. It is part of MIB (Metrology Initiative Braunschweig), which encompasses additional metrology activities such as joint professorial appointments and training...

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On 1 July 2016, the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) established the new Collaborative Research Center 1227, “Designed Quantum States of Matter (DQ-mat) – generation, manipulation and detection for metrological applications and tests of fundamental physics”, at Leibniz Universität Hannover.

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At the awarding ceremony for the 2016 Helmholtz Prize

On 22 June 2016, the most distinguished prize in metrology was awarded for the first time for research work in two categories.

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"MetroSommer” students and their advisors at PTB

The first PTB MetroSommer (MetroSummer) was held from 1 August to 30 September 2016 under the motto of “Your most accurate summer!” For this voluntary internship that was offered by PTB, over 30 university students from throughout Germany (who work in STEM fields) entered applications; of these applicants, 14 were ultimately selected to put their knowledge to the test in their own projects.

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After being successfully certified as a family-friendly employer in May of 2015, PTB has now opened its Family Service Office (FamilienServiceBüro) as previously announced.

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Quality Management

Once again, PTB’s technical quality management (QM) – which is geared towards its core services in the field of calibration, measurement, testing as well as metrological research and development – has gained unlimited national and international recognition. The basis for this was provided by the legal regulations valid in the higher federal authorities; the ISO/IEC 17 025 requirements; the...

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Since the beginning of 2015, the ISO/IEC 17 025 standard “General requirements for the competence of testing and calibration laboratories” has been undergoing comprehensive revision.

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Technology Transfer

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Legal Metrology

The new Measures and Verification Act has now been in force for more than two years and – from PTB‘s point of view – has been successfully implemented by all participants. The existing high level of protection of German metrology has been maintained. By setting up a Rule Determination Committee (Regelermittlungsausschuss), the circles involved have been integrated even more intensely. This...

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Technical Cooperation

ADB Vice-President Bambang Susantono before the start of the podium discussion

For the Technical Cooperation Department, 2016 was characterized by strategic partnerships, whose development was actively advanced especially in the field of sustainable energy. This effort was visibly expressed by two prominently attended events in cooperation with the Asian Development Bank (ADB) and the International Electrotechnical Commission (IEC).

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Press and Information Office

The International System of Units (SI) is about to undergo a fundamental revision. In the future, the values of certain selected fundamental constants will be set; the units will then be derived from these values. For two units, this has already taken place: the meter is defined via the speed of light and the second via a special frequency in the cesium atom. Neither of these two units will go...

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Before the new definitions of the International System of Units can actually be adopted at the CGPM in November 2018, the experiments on the determination of the fundamental constants have to be successfully completed in the metrological laboratories. Edition 2.2016 of PTB-Mitteilungen describes these experiments without going into too much scientific detail. These articles are written with university physics students and teachers in mind, as well as schoolchildren who may be curious about this field.

Before the new definitions of the International System of Units can actually be adopted at the CGPM in November 2018, the experiments on the determination of the fundamental constants have to be successfully completed in the metrological laboratories.

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A PTB lecture titled “For all times and all cultures – the new International System of Units” made the path to the new SI accessible to a broader audience. This “lecture premiere” took place within the scope of the Berlin Science Week: PTB’s president held the lecture on 2 November 2016 at PTB’s Berlin institute. This lecture will be held on other occasions in an altered form. (A recording of this lecture can be found on PTB’s website.)

A PTB lecture titled “For all times and all cultures – the new International System of Units” made the path to the new SI accessible to a broader audience.

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The definitions of the new International System of Units will become much more abstract than they currently are by referring to the values of fundamental constants. Disseminating these new relations is a didactic challenge – one that is by no means fully solved. A possible methodology for teaching this material (taken from an idea developed by the Press and Information Office) was successfully presented in a teacher workshop. The workshop was held in Braunschweig within the scope of a series of advanced training events presented by the MIT Club of Germany e.V.

The definitions of the new International System of Units will become much more abstract than they currently are by referring to the values of fundamental constants.

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