What does the world consist of at the smallest level? What are the most fundamental particles of matter? Natural scientists have been looking into these basic questions since antiquity. In the course of their search, they have encountered ever smaller building blocks – first atoms, then atomic nuclei consisting of protons and neutrons, and finally tiny particles called quarks. Today, particle physicists are investigating the fundamental mysteries of the universe: what holds the cosmos together, and how do particles acquire their mass in the first place?

When DESY was founded in 1959, the primary task of the centre was to investigate the smallest particles. Over the decades, DESY has put into place central pieces of the mosaic of particle physics. With the PETRA storage ring, researchers discovered the gluon, the “glue particle” that holds the quarks together and without which there would be no atoms. Later, they used the HERA accelerator to investigate the proton with unprecedented precision. The surprising result: the inner workings of this particle, which is so important for our world, turned out to be much more complex than expected.

In search of the smallest particles

Today, a number of DESY researchers are taking part in the experiments currently attracting so much attention at the LHC in Geneva, the most powerful accelerator in the world. Within the Belle and Belle II collaborations in Japan, DESY physicists explore why there is more matter than antimatter in the universe. Others use the ALPS detector at DESY to search for lightweights among the particles that could provide evidence for "new physics". Data analysis of the OLYMPUS experiment and the experiments at DESY's former HERA accelerator, Germany's biggest research facility so far, provides exciting insights into the proton. DESY experts are also involved in the future project of particle physics, the International Linear Collider ILC.

Exploring the far reaches of the cosmos

The DESY scientists also conduct research in astroparticle physics, an interdisciplinary field that combines methods from astrophysics, cosmology and particle physics. Using spectacular detectors and telescopes, the experts are analysing exotic particles – neutrinos and gamma rays – that come from far corners of the universe and could provide information about fascinating phenomena, such as black holes, exploding stars and inconceivably intense eruptions of radiation.

Worldwide computer network

Particle physics experiments produce immense volumes of data. A single year’s worth of LHC data would fill more than a million DVDs. To manage this data torrent, information scientists use a new computer concept: the Grid, a variety of distributed computing. In this system, dozens of computing centres around the globe interact synergistically. DESY's Grid centre plays a major role in this global network. 

Theoretical particle physics

Without theoretical foundation, the best experiment would be worthless. Only by working closely together can theorists and experimentalists pierce the mysteries of nature and work out a comprehensive theory of all particles and forces. Theorists at DESY explore the Standard Model of particle physics, which very successfully describes the fundamental building blocks of our world and the forces acting between them. Nevertheless, it leaves essential questions unanswered. Where does the mass come from? What is dark matter made of? What happened right after the big bang? Are there any extra dimensions? The DESY theorists investigate various possibilities to extend the Standard Model and embed it within a comprehensive theory that provides answers to these questions.