| | 37 | || '''13.04.2018[[BR]](11hrs, MPIA Hoersaal)''' || '''José Crespo[[BR]](MPIK, Heidelberg)'''[[BR]] || '''How to make, trap and observe microscopic star plasmas in the laboratory, and use them as clocks'''[[BR]] [[BR]] Some of us will certainly remember José Crespo's enthusiasm for the technical sophistications employed in fundamental research, which we experienced when he gave us a noteworthy lab tour during the visit of our technical departments to MPIK last October. We have invited him to the AstroTechTalk in order to tie in with this experience.[[BR]] [[BR]] __His topic:__[[BR]] Electron beam ion traps make it possible to create and trap stationary plasmas of microscopic size capable of achieving in the lab the most extreme temperature conditions prevalent in atomic matter in the universe. The composition and the production of defined types of radiation (the "excitation conditions") can be controlled very precisely. This way very precise experimental data are obtained that drive the theory. MPIK Heidelberg has developed the worldwide largest collection of such apparatus. Using a variety of spectrometers the characteristics of astrophysical plasmas can be studied in detail.[[BR]] [[BR]] Furthermore, highly charged ions have been proposed as pulse generators for the next generation of optical atomic clocks. MPIK is collaborating with the Physikalisch-Technische Bundesanstalt to create such clocks, which will perform time measurements with a precision of more than 19 decimal points.[[BR]][[BR]] __Background:__[[BR]] Some stars contain plasmas with temperatures of several hundred million degrees. At its core, our Sun has a temperature of 15.7 million degrees, and its corona is about 2 million degrees hot. In supernova explosions, X-ray binary systems and active galactic nuclei that surround black holes even higher temperatures occur. In this kind of environment atoms are very highly ionized and posses just a few bound electrons. The signals emitted by these ions range from X-rays to the visible spectral region and are essential for astrophysical diagnostics.[[BR]][[BR]] Concerning the atomic clocks with their targeted precision, they will be used to address the fundamental question whether the constants of nature are stable.[[BR]] [[BR]]Presentation: German[[BR]][https://svn.mpia.de/trac/gulli/att/raw-attachment/wiki/AlteVortraege2018S1/2018-04-13_Sternenplasma.pdf Slides: English][[BR]]Questions: German, English || |
