The current most powerful particle accelerator is back in Japan – at least in the category of luminosity: The accelerator at the Japanese research center Kek has achieved a world record for the so-called luminosity, i.e. the number of particle collisions per unit of time and area – and thus beats the Large Hadron Collider (LHC) of the European Organization for Nuclear Research (Cern) in Geneva in this category.
Particle accelerators have two main parameters: beam energy and the number of collisions per unit of time. While the world record for the former is undisputed at the LHC, the two accelerators compete for the highest luminosity.
At the Kek Particle Research Center, located northeast of Tokyo, a luminosity of 2.11 by 10×34 per square centimeter per second was achieved in 2009. Nine years later, the LHC narrowly trumped this figure with 2.14 by 10.34. After the Japanese experiment has been converted into a SuperKEKB collider since 2010, it has now been able to measure a luminosity of 2.22 by 10×34 per square centimeter per second – the new world record, as announced by the Austrian Academy of Sciences (ÖAW).
In the superKEKB particle accelerator, electrons and positron collide with high energy. The particle beams are compressed at the collision point in a vertical direction to a size of only 220 nanometers to achieve the highest luminosity. The collisions of the particles produce short-lived B-mesons. How they disintegrate is recorded with the Belle II detector.
Around 1,000 physicists from 26 countries are involved in this experiment, including researchers from the Institute of High Energy Physics (Hephy) of the ÖAW. The Vienna Group has developed and built the innermost detector part of Belle II.
The SuperKEKB data is used to investigate basic physical phenomena. “With the new detector, we are hoping for results beyond the previously known standard model,” said Christoph Schwanda, head of the Austrian research group at Hephy, in 2019, when the new detector went into full operation. Examples include new evidence of differences in matter and antimatter as well as dark matter.
Cern is also continuing to work on increasing luminosity. In addition, plans for the future are already being forged after the planned end of the LHC around 2040: Thepossible successor of the currently world’s largest particle accelerator could have a length of 100 kilometers and enable collisions with seven times the energy. A final decision on the possible construction of such a mega-ring accelerator is to be made in the coming years.