The PTB at the Hannover Fair '96

In 1996, the Hannover Fair will rank first ten times in the international calendar of fairs as far as the technical subjects presented are concerned. This year's fair to be held from April 22 to 27 combines key exhibitions in the fields of robotics, automation, power engineering, environmental technology, building services management systems, lighting engineering and technology-oriented research. Added to these are the specialized areas of ancillary supplies and materials as well as surface technology and industrial plant construction. Exactly 7221 exhibiting firms from a total of 65 countries will present their high-lights and know-how on the enlarged exhibition site now 318 500 sqm in size.

With its more than 400 exhibits, the Innovation Market "Research and Technology" alone will present a wide range of new technologies from a great variety of special fields, a great number of which will use the Hannover Fair as the starting point for gaining access to the market. Many products and procedures which are now used worldwide have started on this innovation market their development from peak performances of science to multifunctional use.

As before, the PTB will be an exhibitor within the framework of the innovation market. At the PTB stand, members of the PTB staff will provide information about the tasks and organization of the PTB and of the Deutscher Kalibrierdienst (DKD, German Calibration Service), answer questions about accreditations, about the mutual recognition of calibrations, tests and certifications etc., and be available for the discussion of technical problems arising in the calibration of measuring equipment. Within the scope of the action "Personnel market with a future", a member of the staff department will discuss with students and young scientists the situation and perspectives of the start in professional life and reply to questions about back-up offered to doctoral candidates and to students working on theses to be submitted for the diploma.

Publications and graphs will be available for distribution, which will provide information on the PTB's present tasks, as will the exhibits presented as examples of the results of recent research work in the following fields:

10 V Josephson voltage standard

The 10 V Josephson voltage standard is the quantum standard of the electric unit, the volt. The PTB is bound by law to hold this unit in readiness in order to assure quality in industry (ISO 9000), to ensure that fair costs are charged to the citizens, and to achieve higher precision in the field of research. It has been possible by means of the newly developed super-electronic circuits with extra-large-scale integration to increase the voltage values from 1 V to more than 10 V. The precision of the voltage made available has thus been substantially improved. It has been planned to use devices developed at the PTB instead of purchasing instruments abroad, and to place orders also with German firms so that these, too, can benefit from the PTB's know-how. The aim is to improve the availability of the 10 V Josephson voltage standard by considerably reducing the costs. At present, the PTB is conducting negotiations with three German firms and two European institutes concerning the transfer of new, favourably-priced 10 V Josephson voltage standards. In industrial metrology, the uncertainty of measurement achievable is limited only by the characteristics of the standard to be tested. In the area of science, between 10 V and 12 V, the PTB disseminates the unit of volt without any difficulty with an uncertainty of 20 nV, i.e. 20 000 millionths of a volt.

New film dosemeter for personal dose monitoring

New quantities in radiation protection, which will take into account all recent scientific knowledge, will be introduced in the European Union and thus also in Germany. The quantity most important in personal dosimetry is the personal dose equivalent, H_p(10), for high-energy penetrating radiation. In Germany, the personal dose is chiefly measured with the film dosemeter. Film dosemeters have technical properties comparable to those of competing dosemeters, however, the former are less expensive. The film dosemeter used for many years is, however, unsuitable for measuring the new quantity. In cooperation with the official center for the measurement of X- and gamma radiation reporting to the Materials Testing Office of North Rhine-Westphalia, a new film dosemeter has, therefore, been developed which is based on a novel principle, the gliding-shadow method. It has not only been optimized for the measurement of the personal dose equivalent; it also allows the quantity "photon dose equivalent" used at present to be measured so that, in personal dose monitoring, the change-over from the former quantity to the new one will be facilitated in the measurement centers.

Furthermore, it will be possible to estimate the energy of the incident photon radiation. In addition, the dosemeter comprises components which allow the angle of incidence of photon radiation to be determined and to distinguish between beta and photon radiation.

Fluxgate magnetometer for the measurement of alternating fields with frequencies up to 1 kHz.

In view of the public discussion about potential health hazards due to electromagnetic fields, calibrations of alternating current magnetic fields with frequencies f <= 1 kHz are required to an ever increasing extent. To allow such calibrations to be carried out in a simple way, a novel fluxgate magnetometer for the measurement of d.c. and a.c. magnetic fields with industrial frequencies has been developed at the PTB. Main objective of this development was the reduction of the uncertainty of measurement due to non-linearity, to frequency response errors and to the instability with time rather than the achievement of as high a sensitivy as possible. The specifications of the magnetometer prototype available are as follows: Dimensions of the active sensor area: 30 mm x 10 mm; two measurement ranges: 0,1 mT and 1 mT; frequency range: 0 Hz to 1 kHz; resolution: 10 nT; linearity error: < 0,1%; frequency response error: < 0,1%. As the dimensions of the sensor are small, the magnetometer is also suited to measure magnetic stray fields in the environment of electrical equipment.