ELENA – this pretty name stands for Extra Low ENergy Antiproton Deceleration Ring, a 30-m-wide deceleration ring at CERN that slows down the 5.3-MeV antiprotons from the existing CERN antiproton decelerator to a fabulous 0.1 MeV, so that they can, among other things, be captured via so-called Penning magnetic traps and combined with positrons to form antihydrogen.

VAT all-metal vacuum valve technology plays an important role in this, as it maintains full functionality under the operating conditions of high temperature and radiation. The dynamic hard on hard sealing technology combines repeatable hermetic sealing under XHV conditions with an all-metal design.  

Examining single antihydrogen atoms

The central goal of ELENA is to keep antimatter alive as long as possible. With great success: Currently, the traps following the ELENA deceleration process achieve antimatter lifetimes between 15 minutes and one year! But also attempts to trap antimatter in so-called cryotraps – i.e., transportable traps with cryostats, where pressures up to 10-18 mbar are reached – are high on ELENA’s agenda (see the PUMA experiment for more details).

In view of the extremely short lifetime of antimatter, the ELENA system must take a wide range of special valve and vacuum technology features into account. For example, all inlets and outlets in the deceleration ring must be completely metal-sealed in order to maintain the required pressures and outgassing values. This is where VAT makes valuable use of its many years of XHV know-how, for example, in the form of the proven all-metal gate valves of the VAT series 48.

Another task that the CERN researchers have on their to-do list: They want to study antihydrogen atoms spectroscopically and then compare the effects of the gravitational force on matter and antimatter. In what is called the GBAR experiment (short for Gravitational Behavior of Antimatter at Rest), the electrically neutral antihydrogen atoms that ELENA helps producing will be dropped from a height of 20 centimeters and then the course of the fall will be recorded until their demise. Thanks to ELENA's excellent ability to keep the antiatoms under investigation as "still" as possible, the GBAR researchers are positive that even the smallest differences in the behavior of matter and antimatter in relation to the comparatively weak gravitational force can thus be detected.

In October 2018, GBAR received its first antiproton beam from ELENA. Since then, the scientists have been working feverishly on research results to get a little closer to solving the great mystery surrounding the asymmetric distribution of matter and antimatter in the universe. In the process, they are also relying on VAT all-metal vacuum valve technology.