The BASE team at
The “Maxwell‘s daemon cooling double trap,” which was developed by the BASE collaboration. It can be used to cool antiprotons very quickly to temperatures that are necessary for high-precision measurements. Credit: BASE-Collaboration / Stefan Ulmer
The Role of the BASE Collaboration
This is the starting point for the BASE collaboration (“Baryon Antibaryon Symmetry Experiment”). It involves the universities in Düsseldorf, Hanover, Heidelberg, Mainz and Tokyo, the Swiss Federal Institute of Technology in Zurich and the research facilities at CERN in Geneva, the GSI Helmholtz Centre in Darmstadt, the Max Planck Institute for Nuclear Physics in Heidelberg, the National Metrology Institute of Germany (PTB) in Braunschweig and RIKEN in Wako/Japan.
“The central question we are seeking to answer is: Do matter particles and their corresponding antimatter particles weigh exactly the same and do they have exactly the same magnetic moments, or are there minuscule differences?” explains Professor Stefan Ulmer, spokesperson of BASE. He is a professor at the Institute for Experimental Physics at HHU and also conducts research at CERN and RIKEN.
The trap can be used to measure antiproton spin transitions with the highest accuracy. Credit: BASE-Collaboration / Barbara Maria Latacz
Dr. Barbara Maria Latacz from CERN and lead author of the study that has now been published as an “editor’s suggestion” in Physical Review Letters, says: “We need antiprotons with a maximum temperature of 200 mK, i.e. extremely cold particles. This is the only way to differentiate between various spin quantum states. With previous techniques, it took 15 hours to cool antiprotons, which we obtained from the CERN accelerator complex, to this temperature. Our new cooling method shortens this period to eight minutes.”
The researchers achieved this by combining two so-called Penning traps into a single device, a “Maxwell’s daemon cooling double trap”. This trap makes it possible to prepare solely the coldest antiprotons on a targeted basis and use them for the subsequent spin-flip measurement; warmer particles are rejected. This eliminates the time needed to cool the warmer antiprotons.
The significantly shorter cooling time is needed to obtain the required measurement statistics in a significantly shorter period of time so that measuring uncertainties can be reduced further. Latacz: “We need at least 1,000 individual measurement cycles. With our new trap, we need a measurement time of around one month for this – compared with almost ten years using the old technique, which would be impossible to realize experimentally.”
