The Physikalisch-Technische Bundesanstalt (PTB) is based in Braunschweig (Brunswick) and Berlin. It is the national institute for natural and engineering sciences and the highest technical authority for metrology and physical safety engineering in Germany. Part of its brief is the accurate measurement of time. It is responsible for four German caesium atomic clocks, CS1, CS2, CSF1 and CSF2, and the longwave time signal DCF77. In addition, the PTB operates time servers for the distribution of time on the internet. They are also responsible for the certification of voting machines for the German federal and European elections. The PTB was originally founded in 1887 as the Physikalisch-Technische Reichsanstalt (PTR) (the Physical and Technical Institute of the German Reich). The goal of the organization was supervising and directing calibration and establishing metrological standards. Research areas included spectroscopy, photometry, electrical engineering, and cryogenics. Werner von Siemens was instrumental in its establishment. Until 1934 the PTR was part of the Reichsinnenministerium (the Reich's Ministry of Interior Affairs).

Address
Bundesallee 100, Braunschweig, Germany
Website
http://www.ptb.de/index_en.html
Wikipedia
http://en.wikipedia.org/wiki/Physikalisch-Technische_Bundesanstalt

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Redefining the limits of measurement accuracy

For centuries, humans have been expanding their understanding of the world through more and more precise measurement of light and matter. Today, quantum sensors achieve extremely accurate results. An example of this is the ...

Testing the symmetry of space-time by means of atomic clocks

In his Special Theory of Relativity, Einstein formulated the hypothesis according to which the speed of light is always the same, no matter what the conditions are. It may, however, be possible that—according to theoretical ...

En route to the optical nuclear clock

The nucleus of thorium-229 possesses a property that is unique among all known nuclides: It should be possible to excite it with ultraviolet light. To date, little has been known about the low-energy state of the Th-229 nucleus ...

Researchers develop transportable optical atomic clock

Atomic clocks are no longer based on a microwave transition in cesium, instead operating with other atoms that are excited using optical frequencies. Some of these new clocks are portable. At its QUEST Institute, PTB is currently ...

New scales for the new kilogram

The Planck scale works according to the principle of electromagnetic force compensation: A weight force on one side of the scale is balanced by an electromagnetic force on the other side. This means that weights (so-called ...

Laser-cooled ions contribute to better understanding of friction

In physics, it is useful to know as precisely as possible how friction phenomena arise—and not only on the macroscopic scale, as in mechanical engineering, but also on the microscopic scale, in areas such as biology and ...

Paving the way for the redefinition of the unit of temperature

At present, the kelvin is literally based on no more than water—on the triple point of water, to be more precise. The base unit of temperature is therefore dependent on a material whose properties may vary. But this is ...

Team paves the way for the redefinition of the ampere

By 2018, scientists want all physical base units to be based on solid, unchangeable fundamental constants. The units "meter" and "second" are well ahead of schedule; the kelvin, the kilogram, the mole and the ampere are next ...

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