Experimental Particle and Astro-Particle Physics Seminar

Stefanos Leontsinis (University of Zurich (CH))

Abstract: The main goal of the BASE collaboration is to contribute to resolving the mystery of matter-antimatter imbalance in the observed Universe, and the origin of dark matter. This is done by performing ultra-precise comparisons of the fundamental properties, like charge-to-mass ratios and magnetic moments, of single protons and antiprotons trapped in advanced Penning-trap systems.
In particular, recently BASE reported a new antiproton-to-proton charge-to-mass ratio comparison, with an unprecedented fractional accuracy of 16 p.p.t. improving the previous best measurement by a factor of 4.3. This result constitutes the most precise test of CPT invariance in the baryon sector, and tests the Standard Model with an energy resolution of approximately 2 × 10-27 GeV. This measurement resulted also in the first-ever, direct, differential test of the weak equivalence principle with antimatter, by comparing proton and antiproton cyclotron clocks.

The most unique speciality of BASE are the direct measurements of the nuclear magnetic moment of baryons. The reported results are 300 p.p.t. precision for protons, and 1.5 p.p.b. precision for antiprotons. Currently, we are commissioning a new setup to improve these results and to reach a fractional precision of at least 100 parts in a trillion! The new apparatus features advanced magnetic shielding systems for suppression of external magnetic field fluctuations as well as local superconducting magnets, for in-situ tuning of the magnetic field of the measurement trap. As demonstrated experimentally these suppress the dominant systematic shift of the previous magnetic moment measurement by more than a factor of 1000. In addition, a dedicated cyclotron cooling trap has been implemented, with this device sub-thermal particle cooling to 200 mK has been demonstrated in minutes, about 60 times faster than in previous experiments, which will provide a drastically improved data taking rate. In parallel, we are developing new experiments to adapt our experimental technologies to search for dark matter candidates, by constraining the interaction of antiprotons with axion-like particles (ALPs), or constraining the ALP to photon conversion.

In this seminar, I will introduce the BASE experiment and how these ultra-precise measurements are being done. I will report on the recent results on the charge-to-mass ratio and weak equivalence principle measurement campaigns, on the dark matter searches, but will mainly focus on our efforts to reach <100 parts per trillion precision in our  future magnetic moment measurements.

    • 2:00 PM 3:00 PM
      BASE: Tests of fundamental symmetries by high precision comparisons of the fundamental properties of protons and antiprotons 1h
      Speaker: Barbara Maria Latacz (Max-Planck-Institut für Kernphysik, Heidelberg, Germany; RIKEN, Ulmer Fundamental Symmetries Laboratory, Japan)