PTB News 1/2002 (116 kB) PTB News 1/2002, English edition, Issue March 2002Die PTB betreibt am Forschungsreaktor des GKSS Forschungszentrums Geesthacht (rund 200 km von Braunschweig entfernt) das Polarisationsdiffraktometer POLDI für Neutronen. Jetzt wurde für dieses komplexe Instrument eine Fernkontrolle realisiert, mit der mehr als 20 Geräte gesteuert werden. Die bereits vorhandene Steuersoftware wurde mit Eigenentwicklungen und frei erhältlichen Open-Source-Produkten so erweitert, dass sie mit Hilfe des Internet die weltweite Kontrolle des Instruments ermöglicht.
For the control of the data acquisition, a TCP/IP (Internet protocol) based protocol has been developed and implemented in various programming and script languages, so familiar and well-tried program segments can be further used. Also, simultaneous access to different programs from different operating systems is possible.
The presentation of the instrument in the Internet is based on the open source projects LINUX, APACHE and PHP which are (the server-end) part of a web interface. By a browser (the client-end part of the interface) such as Netscape or Internet Explorer, an authorized user gets access to individual devices such as stepping motors, temperature controllers, meters, current sources. He is able to program measurement sequences, monitor and change device parameters or watch from Braunschweig the experimenter in Geesthacht.
Such experiments – which are also carried out with guests of the Geesthacht Neutron Facility – relate to magnetic model systems and technical materials. The diffractometer has also been used to develop equipment for investigating internal stresses in deformed materials and for determining material properties (spin-dependent n-cross section of 3He).