Today we have published a paper in Phys. Lett. B, in which we report on the detection of individual spin quantum transitions of a single trapped antiproton in a Penning trap. The spin state determination is based on the unambiguous detection of axial frequency shifts which are induced by the spin transition in presence of a magnetic bottle. We have achieved a detection fidelity of 92.6 % and demonstrated spin state initialization with 99.9% fideltiy.

Today our article on an improved measurement of the magnetic moment of the antiproton, with a fractional precision of 0.8 parts in a million, was published in Nature Communications. This is, so far, the culmination point of 10 years of dedicated work on proton and antiproton magnetic moment measurements.

Our colleagues from the ALPHA collaboration just published an article on the Observation of the 1S/2S Transition in Trapped Antihydrogen.
We congratulate to this fantastic result!!!

See also the Nature-News and Views-Point

The construction of ELENA, the Extra Low Energy Antiproton Ring, which is dedicated to slow-down the 5.3 MeV AD antiprotons to keV energies has been finished and is entering the commissioning phase. In a recent AD users meeting the ELENA team around project coordinator Christian Carli has reported on first circulating beam, CONGRATULATIONS! For more information read the CERN courier article.

Our article "Highly sensitive superconducting circuits at ∼700 kHz with tunable quality factors for image-current detection of single trapped antiprotons" has been published in Review of Scientific Instruments. There we describe highly sensitive image-current detection systems based on superconducting toroidal coils and ultra-low noise amplifiers for non-destructive measurements of the axial frequencies (550–800 kHz) of single antiprotons stored in the BASE multi-Penning-trap system.

A crucuial device in the BASE multi-Penning trap system is a reservoir trap for antiprotons. This trap is loaded with a cloud of antiprotons provided by CERN's antiproton decelerator and methods were developed to extract single particles from this reservoir and to supply them to our high precision measurement traps. This allows BASE to continuously perform experiments with antiprotons, independent from accelerator maintenance and shutdown cycles.

A short overview-article on BASE has been released in CERN's EP-newsletter.

We developed a technique to extract arbitrary fractions of antiprotons in a reservoir trap. This method enables us to operate BASE almost independent from accelerator cycles, and especially during the winter shut-down when magnetic field noise in the antiproton decelerator hall is low. For further details read this article.  

In a paper published today in Nature we report the high-precision comparison of the antiproton-to-proton charge to mass ratio. In our measurements we compared the cyclotron frequencies of antiprotons to that of negatively charged hydrogen ions, which are used as a proxy for the proton. We achieved a fractional precision of 69 parts in a trillion, which corresponds in our magnetic field of 1.95 Tesla to an absolute energy resolution of 2mHz. Our result is consistent with CPT invariance.