BASE STEP

Our aim is to establish the offline operation of antiproton precision measurements outside of CERN’s Antimatter Factory, to enable the next generation of antiproton precision measurements without fluctuations and noise induced by the machines and experiments operation in the antiproton decelerator complex.

We have constructed the transportable Penning trap system BASE-STEP that is capable of transporting charged particles by crane and on a truck in an autonomous operation mode, i.e. without external power supply for up to 4 hours duration. 

The BASE-STEP system is designed to store antiprotons and other charged particles and transport them over long distances. Since antiprotons annihilate upon contact with normal matter, they must be kept in an ultra-high vacuum environment, specifically at pressures below 10⁻¹⁶ mbar. This vacuum prevents annihilation caused by collisions with residual gas molecules over periods of several months. To achieve this, the antiprotons are stored in a cryogenic vacuum chamber, where the walls are maintained at liquid helium temperature (4.2 K). At such low temperatures, any residual gas present within the chamber freezes onto the cold walls.

The antiprotons are confined within a Penning trap, an ion trap configuration that uses a combination of electric and magnetic fields to keep them suspended at the center of the chamber. A magnetic field generated by a superconducting electromagnet forces the antiprotons into circular motion around the field lines. An electric field, maintained by voltages applied to a stack of cylindrical electrodes, pulls the antiprotons back to the trap’s center along the direction of the magnetic field lines.