Archive of the homepage-news 2006

Probing of complex micro- and nanostructures
Novel micromechanical sensors have brought production control of complex micro- and nanocomponents a decisive step forward. These sensors allow the position, form, measure - and even the roughness - to be metrologically determined also on vertical walls of smallest structures. Core piece of the sensors - for which a patent has been applied for - are cantilevers as they are also known from scanning force microscopy.
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New calibration facility for brachytherapy
The possibilities available at PTB for the calibration of radiation sources for brachytherapy could be essentially improved with a new calibration facility which has now been put into operation. A collimated beam geometry with a significantly lower scattered radiation component has allowed both radiation protection and the uncertainty of the correction for scattered radiation to be significantly decreased. With the aid of an industrial robot, the secondary standards used for calibration can be precisely positioned, which leads to a further reduction in the measurement uncertainties.
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Innovative photometer bench system
With an extensively equipped photometer bench system for the characterisation of both light sources and photometers, distances up to 40 m can now be achieved for the measurement of directed photometric quantities. Thus, the facility - which is unique worldwide - also makes it possible to calibrate even extremely strong light sources with only a small associated measurement uncertainty.
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PTB is now a Notified Body for Measuring Instruments
Starting October 30, 2006, the European Measuring Instruments Directive (MID) published in 2004 has to be applied within the European Economic Area. The Federal Ministry for Economics and Technology (BMWi) has assigned PTB the task of performing the conformity assessment procedures, and PTB has started to issue corresponding certificates for manufacturers of measuring instruments.
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Gaming machines now control themselves
At the beginning of 2006, the German Gaming Ordinance was fundamentally altered - and type examination at PTB thus placed on a new basis. For the protection of players, the modified Ordinance sets limits for winnings and losses and prescribes the installation of a mandatory monitoring unit which continuously ensures - in the background - compliance with these limits.
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DCF77: Fit for the future!
The emission of the time signal by PTB with the aid of the longwave transmitter DCF77 located in Mainflingen, near Frankfurt, has been completely modernised. The control units for the generation of the DCF77 signal have been totally renewed and were put into operation after several months of testing. The time switch to daylight-saving time on October 29 was already achieved with the aid of the new devices and could be followed live on video monitors at PTB by hundreds of visitors attending the "Lange Nacht der Zeit" - the "Long Night of Time". The new devices have been prepared to transmit also safety warnings of the Federal Government and weather information from the Meteotest company.
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Berthold Leibinger received Werner-von-Siemens Ring
The most important German technology prize, the Werner-von-Siemens Ring, was awarded to the entrepreneur Berthold Leibinger on 13th December. The Werner-von-Siemens Ring Foundation presented the honorary ring to Leibinger "in appreciation of his merits for the innovative development and successful entrepreneurial implementation of technologies for flexible sheet metal forming and industrial laser technology", as Professor Ernst O. Göbel, PTB President and Chairman of the Foundation's Board of Trustees, emphasised. The awards ceremony took place within the setting of festivities in the presence of the Federal President, Horst Köhler, in the Berlin-Brandenburgische Akademie der Wissenschaften (Berlin-Brandenburg Academy of Sciences). The Werner-von-Siemens Ring is awarded every three years to "pioneers of technology".
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PTB and TU Braunschweig establish joint research center
PTB and the Technische Universität Braunschweig (Technical University of Braunschweig) will in future be working together even more closely. They have established the Joint Optical Metrology Center (JOMC), a joint center that is dedicated to the research and development of optical measuring technology. On Tuesday, the 12th of December, both presidents, Professor Dr. Ernst O. Göbel and Professor Dr. Jürgen Hesselbach, signed the contract. Optical technologies are considered to be among the key technologies of the 21st century, and thus the establishment of the JOMC represents a new dimension of the - traditionally already close - cooperation between PTB and TU Braunschweig. Furthermore, the cooperation stands exemplarily for the intensive network of the research facilities in Braunschweig, the "City of the Sciences 2007".
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Safety-related characteristics of "Bio Super"
Due to the promotion of renewable energy sources, the demand for fuels composed of an ethanol/petrol mixture ("Bio Super") has been increasing, whereby the ethanol is produced from biomass. As these fuels are flammable liquids, an explosion protection concept is necessary for their transport, use and storage, as well as for the operation of petrol stations. The basis of such a concept are the safety-related parameters, which, in the case of "Bio Super", differ from those of petrol. PTB has determined the characteristics and is now presenting the consequences for the respective explosion protection concepts.
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Reduced brain volume in smokers
Certain areas of the brains of long-term smokers are reduced in volume compared to never smokers. This is what researchers from Charité University Medicine, Clinic for Psychiatry and Psychotherapy, and from PTB found in a recently published study in Berlin. Particularly affected is the grey matter where most neurons and brain functions reside. Three-dimensional images of the brains of 22 smokers and 23 never-smokers were acquired by magnetic-resonance imaging and their volumes compared in a computer-based analysis. The results indicate that smoking has not only the well known detrimental effects on the lungs and the cardiovascular system, but also affects the performance of the human brain.
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Radiation protection measurements at the ISS
In a project that was realized with several partners under the auspices of the Deutsches Zentrum für Luft- und Raumfahrt (DLR) (German Center for Air and Space Travel Registered Association), radiation protection measurements were conducted in the International Space Station ISS. An especially good radiation monitoring of the astronauts is necessary as the dose they are exposed to in the space station - approx. 0.5 mSv per day at a stay of several months - clearly exceeds the mean annual limit value of 20 mSv normally valid on Earth. The measurements yield an approx. 30 % lower radiation burden for the astronauts than was measured in earlier shuttle flights to the MIR station. The PTB participated in the measurements using a personal neutron dosimeter.
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Von Klitzing's doctoral adviser: Golden anniversary of the conferral of his doctorate
On the occasion of the golden anniversary of the conferral of the doctorate for the experimental physicist, Professor Dr. emeritus Gottfried Landwehr, a festive colloquium will be held in the TU Braunschweig on Tuesday, 7th November. Landwehr investigated, above all, semiconductors, particularly in high magnetic fields and at low temperatures. For years he headed, among other things, the presidential laboratory of the PTB before he transferred to the University of Würzburg. The focal point of activities was shifted to the investigation of the properties of two-dimensional electronic systems. This led finally to the discovery of the quantum Hall effect by Klaus von Klitzing who was active in the chair of Professor Landwehr for more than eleven years.
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Material analysis with mini-electron sources
In the material analysis of surfaces electron beams are often used. However, electrons can only be in motion in a vacuum, and vacuum technology causes the apparatuses to be large, hard to handle and expensive. A step in the direction of small, portable devices has now been successfully taken in the Institute of Microtechnology Mainz GmbH (IMM) Institut für Mikrotechnik Mainz GmbH: The researchers have developed an electron source which directs an electron "spotlight" through an electron-permeable membrane onto the surface to be investigated. Thereby, the electron source is brought very close to the sample surface so that the air gap between membrane and sample is only a fraction of a millimetre. Thus, complex vacuum equipment is avoided. The very thin membranes can withstand the enormous differences in pressure because they are supported by a honeycomb-shaped supporting structure made of silicon. The PTB took active part in the project by providing simulation calculations to characterize the membrane.
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Long Night of Time in the PTB
Sleep one hour longer? No, this time, rather, it means: stay awake one hour longer. Because during the night of the clock change - from 28th to 29th October - the PTB in Braunschweig is hosting a variegated cultural and scientific night about time - with much entertainment, some physics and one extra hour of time. Admission is free. The programme begins on Saturday at 7 p.m. and doesn't end until the clocks have sprung back from 3 a.m. to 2 a.m. during the night from Saturday to Sunday. And those who have stayed until this late hour can assure themselves by means of a live link to the long-wave radio transmitter DCF77 that the clock change has worked and that the night is in fact one hour longer.
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Criticism of electronic voting machines
Electronic voting machines have currently come under criticism: The German Chaos Computer Club has in the Netherlands in close cooperation with the Dutch initiative "We do not trust election computers" examined electronic voting machines used by the NEDAP company for weak points and is now demanding to have such machines banned. Similar machines by the NEDAP company Ð not the same ones Ð are tested in the PTB and approved by the Federal Ministry of the Interior (Bundesministerium des Inneren) for federal elections. In a statement thereto, the PTB emphasised that they welcome every initiative which contributes to the security and reliability of electronic voting machines or exposes any possible security holes. They point out, however, that the machines used in Germany are of another type than the one on which the report is based. Moreover, one cannot, on the basis of the facts shown now, draw conclusions to possible falsifications of prior elections in Germany - there are no indications to support this and further security measures argue against this possibility.
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Early detection of damage to buildings
In Europe, an essential structural change is emerging in the building industry: Through above-average growth, building reconstruction has gained the greatest share of the construction industry. Against this background, the PTB has within the framework of a Special Research Area of the Deutsche Forschungsgemeinschaft (DFG) developed a multicomponent strain sensor which is implemented directly into the building. The advantage: early damage detection and thus lower costs for the reconstruction of a building.
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Miniaturized laser Doppler anemometer for space applications
Although laser doppler anemometers have by now become standard laboratory tools for non-disturbing flow-velocity measurements, using them under the restrictions usually imposed by space based experiments have so far not been thought feasible. A new concept developed by PTB and the Center of Applied Space-Technology and Microgravity (ZARM) in Bremen could solve this problem. The system under development for measuring two velocity components has the advantage of small size, low power consumption and simple and robust realization. Together with the newly developed algorithms for autonomous frequency estimation, it is likely to open up completely new fields for precise flow velocity measurements in space as well as on earth.
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Broadband Reference Hydrophones for Ultrasound
Hydrophone measurements are fundamental for the determination and declaration of the acoustic output of medical ultrasound equipment. In order to meet the requirements of future standards, efforts are currently undertaken by several calibration laboratories to extend the hydrophone calibration frequency ranges. To be able to compare the different calibration techniques recently developed and extended at PTB with each other and internationally with methods of other metrology institutes, special broadband reference hydrophones with small receiver elements were constructed and manufactured in the Ultrasonics Working Group. Besides the application as secondary standards, hydrophones of this type can of course be used directly for advanced exposure measurements on medical devices.
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Secure wireless communication of measurement data
Although in the consumer sector the prices of WLAN components are already quite favourable, such systems have so far been available for use in the industrial sector only to a limited degree and at high prices. This is the reason why the SIMEDAKO (Secure wireless Communication of Measurement Data) has been launched. Its aim is to make available suitable WLAN components which have special properties - e.g. for auto fuel terminals where, simultaneously, data subject to mandatory verification have to be taken into account. From September 12 to 17, PTB is exhibiting this project, which is carried out together with industrial partners, at the Automechanika, the leading international trade fair for the automotive industry, in Frankfurt.
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Bridges between west and east
For more than 15 years now, the successor states of the former Soviet Union and several other Eastern European and Asian states have been cooperating closely together in the field of metrology. COOMET is the name of their metrological organisation, whose highest committee met from 4th to the 6th September in the PTB in Braunschweig. PTB is an associated member of the organisation. Subjects of the conference were the further intensification of the cooperation, the state of affairs at the signing of the CIPM-MRA, and the new member: Georgian Republic has been accepted as the 15th member state.
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Latest issue of maßstäbe: The invariables
They change, they do not change, they change... Science does not know for sure whether the fundamental constants keep their word and indeed remain constant. But the invariability issue is only one amongst many fascinating aspects that are inherent in the subject of fundamental constants and are dealt with in the freshly published issue of maßstäbe, PTB's popular-scientific magazine.
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Highest temperatures precisely fixed
With the aid of radiation thermometry based on Planck’s radiation law, PTB could determine the melting temperatures of novel eutectic metal-carbon alloys (M-C alloys) up to nearly 3000 °C for the first time with low measurement uncertainties. To improve industrial high-temperature measurements, these M-C alloys shall in future be used to determine high-temperature fixed points.
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Small world: micro-artifacts
The measurement of micro-components is a new metrological challenge in modern production technology. For the assessment of the measuring systems used, PTB has developed micro-components for which - depending on the measuring method - a calibration uncertainty of 0.5 µm has so far been achieved for spacings and radii.
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PTB assumes EUROMET chairmanship
The European Collaboration in Measurement Standards (EUROMET) has since this year's annual General Assembly received a new chairman: Professor Dr. Michael Kühne, member of the Presidential Board of PTB, who is assuming this office immediately. Also, the management of the EUROMET secretariat now lies in the hands of PTB. EUROMET's PTB chairmanship falls within a time of far-reaching restructuring processes within European metrology. Coordinating national research tasks is the requirement of the hour.
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Detector for microparticles in space
An impact energy detector has been developed at PTB in order to measure the kinetic energy of fast micro-sized space particles. A sensitive calorimeter array measures the impact-related heating of the hit absorber.
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From the quantum Hall effect to capacitance
The realization of the unit of cpacitance by means of the quantum Hall effect (QHE) has made considerable progress. Already since 1990, the QHE has served as the quantum standard for electrical resistance with direct current (DC). At PTB, a significant development has now been achieved in the measuring technique which also allows the precise measurement of the quantum Hall resistance with alternating current (AC) and provides a quantum standard for the capacitance.
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A great leap forward towards the optical clock
With a single Ytterbium ion trapped in an ion trap and a femtosecond comb generator, PTB has made a great step towards the realization of an optical atomic clock. The frequency of an optical Yb⁺ transition was compared over a period of several days with the frequency of a primary Cs fountain clock.
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Annual Report has been published
A procedure which makes magnetic memory chips just as fast as conventional digital memory components, a particularly pure silicon for the international Avogadro Project, or two new Internet chapters directed towards medium-sized businesses and other service customers of PTB - these are only some of the highlights of the year 2005, to be read about in the freshly published Annual Report of the PTB. The complete Annual Report is to be found in the Internet, excerpts thereof may be ordered as printed brochure (166 pages) from the Press and Information Office.
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Braunschweig is the "City of Science 2007"
The city of Braunschweig may in the year 2007 bear the title of "City of Science". With its application (under the motto: Braunschweig, the "Cuisine of Ideas") Braunschweig was able to prevail over the cities of Aachen and Freiburg in the finale. The jury commended in particular the originality and the intelligibility of the application, the numerous cooperation partners, and the diversity of the formats for the events. The PTB will participate in several activities from the "Cuisine of Ideas" and will also provide an hors d'oeuvre with its "Long Night of Time" (28th/29th October).
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Hitting the books again after work
After eight semesters of commuting between Braunschweig and Lubeck and a six-day week spent partly in the lab and partly in the lecture hall, 13 staff members of PTB in Braunschweig have now received their engineer's diploma. This innovative vocational training was made possible by a close cooperation between PTB and the Technical University of Lubeck. This project will benefit not only the freshly qualified engineers but also PTB as their employer.
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From atomic clocks to satellite navigation
Once again Braunschweig will become the linchpin of time: between March 27 and 29, more than 230 scientists and engineers from 30 countries will come together in the Braunschweig Stadthalle for the 20th European Frequency and Time Forum in order to exchange their latest research results. Next-generation atomic clocks and satellite navigation systems will be two of the thematic focal points. PTB, the "guardian of time" in Germany, is the organiser of this year's conference.
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All about sound
Anyone strolling about the lecture halls and seminar rooms of Braunschweig Technical University (TU) between March 20 and 23 will learn all about audible sound and ultrasound, music and noise, noise measurements and sound simulations. During that time, TU will become a mecca for all acousticians in Germany. This year, PTB and TU are the organisers of the Annual Conference on Acoustics (DAGA 2006) - expecting more than 850 participants.
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Worldwide unique accelerator facility for dosimetry
PTB in Braunschweig is establishing an electron accelerator facility for dosimetry in radiation therapy. The project, whose scope is unique in the world, extends PTB's measuring possibilities for photon and electron radiation considerably. On a useful area of approx. 1000 sq m, three accelerators will cover all experimental requirements - from basic research to clinical applications. Commissioning of the facility, which costs 14 million euros, is planned for the end of 2007. The foundation stone will be laid on the 16th of March.
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Fluorescence measurements are now comparable worldwide
In a cooperation between PTB, the Bundesanstalt für Materialforschung und -prüfung (BAM) (Federal Ministry of Materials Research and Testing) as well as two partners from industry, spectral fluorescence standards were developed, characterized and certified. These allow device-specific effects on the fluorescence signal to be eliminated. Thus, also fluorescence measurements carried out on different devices can now be compared and a simple and quick radiometric traceability of fluorescence measurements becomes possible.
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No trace of "Hitler's bomb" in soil samples
In connection with speculations regarding a possible atomic explosion in Ohrdruf (Thuringia) at the end of World War II, the PTB has carried out extensive radionuclide analyses on soil samples from the local area. The measurement results indeed show contaminations which are due to, among other things, the reactor accident in Chernobyl, but as for an atomic explosion, there are "no findings".
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PTB Braunschweig is a "Place of Ideas"
On 6th February, the PTB Braunschweig will be awarded a badge and an honorary certificate as a "Place of Ideas" around the subject "Precise time measurement". What that means will be presented by PTB on the night of the conversion to Middle European Winter Time - 28th to 29th October - with an extensive "Long Night of Time". PTB is one of the winners of a nation-wide competition with the aim of presenting Germany as an open-minded country, rich in ideas - exemplified by special places - to the guests of the Football World Championship 2006.
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Following the path of a tablet in the body
A new technique developed in PTB Berlin enables following the path of a pharmaceutical through the body. Instead of marking the active substance radioactively (which has been the case up to now), magnetic marking and highly accurate magnetic field measurements are used. The effectiveness of this technique is to be investigated now by Socratec R u. D GmbH, Oberursel, in a standard clinical test procedure. It is an example for successful technology transfer from PTB into practice.
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A change in the vice-presidency at PTB
At PTB, a change in staff is about to take place at the executive level: The previous vice-president, Prof. Dr. Manfred Kochsiek, is retiring and will hand over his office to Prof. Dr. Manfred Peters. This staff decision is evidence of continuity: Kochsiek and Peters are both renowned experts of German and international metrology. The transfer of office will take place on 7th February at 4 p.m. in the PTB auditorium.
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Avogadro project: First isotope-pure silicon single-crystal
Within the scope of the international Avogadro project, the objective of which is to re-determine the Avogdro constant, a perfect isotopically and chemically pure silicon single-crystal has been successfully manifactured for the first time. A sample crystal of over 400 g in mass and more than 99,99 % isotopic purity was delivered to PTB for test measurements. - more (German)

The micro-ion beam is speeding up
A new device at PTB's micro-ion beam facility allows irradiating several hundred cells individually per second. The procedure is thus about ten times faster than previously. It can now be efficiently used to investigate radiation damage mechanisms in individual cells. Understanding the damage mechanisms is important for dosimetry in the low-dose range.
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New portable standard for ultrasonic measuring devices
Ultrasonic physiotherapy is a widely used medical application. Measuring devices which are used to supervize the ultrasonic physiotherapy equipment are subject to quality management. In order to improve the traceability, a portable ultrasonic power standard has been developed in an international cooperation. The power standard is now being held available on loan to interested parties. more...
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