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A new proposal for the measurement of blackbody radiation shift in a cesium fountain (the Politecnico di Torino method)
No full text
A New Proposal for the Measurement of blackbody Radiation Shift in a Cesium Fountain (The Politecnico di Torino Method)
No full textThe AC Stark frequency shift induced by blackbody radiation (BBR) is presently a limiting factor toward the accuracy evaluation of Cs fountain frequency standards [1] [2]. In fact, at laboratory temperature, the AC Stark relative frequency shift is of the order of 10-14 and therefore the black-body coefficient must be evaluated to the percent level if an accuracy below 10-15 is desired. The BIPM recommended coefficient is -1.69(4) · 10-14 for Cs atoms while recent BBR shift measurements performed at IEN (now INRIM) [3] [4] yield a value which differs by 18% from the accepted value. The Politecnico di Torino is now developing a new method for the measurement for the BBR shift, with the aim of resolving the discrepancy on the coefficient. In this paper the Politecnico di Torino method is analyzed with a full description of the new apparatus. The method is based on rapidly varying thermal cycles
Simple pendulum experiment for the determination of the gravitational constant G: progress report
No full textThe principle of operation, the realization, and some preliminary results of a simple pendulum experiment aimed at the determination of G are briefly describe
Precise Active Frequency Stabilization of a Microwave Cavity
No full textIn this paper, a system for precise frequency stabilization of a microwave cavity is presented. A cavity mode is probed in transmission, and a phase comparison scheme is used to measure its frequency fluctuations. In this way, shifts are corrected not only if temperature induced, but also if induced by mechanical stress, inasmuch as the latter effect is similar for the target mode and for the mode used to implement the stabilization system. A servo loop is then realized, which locks the cavity resonance to an external reference set to the nominal value by thermal actuators driven by a proportional-integral compensato
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