Research and education of the KIT Center Elementary Particle and Astroparticle Physics (KCETA) are funded by the State of Baden-Württemberg, the Helmholtz Association, the Federal Ministry for Education and Research (BMBF), the German Research Association (DFG) and the European Union (EU). KCETA’s activities are in the following fields of research:
The Pierre Auger Observatory on an area of 3000 square kilometres in the Argentine Pampa consists of more than 1600 autonomous tanks: In highly pure water, energetic particles produce light flashes. In addition, four stations with 27 telescopes at the edge of the detector field observe the light tracks of cosmic particle showers. Underground muon detectors and an array of radio antenna stations complete the experimental set-up.
At lower energies experimental efforts in measuring cosmic rays were performed by the experiment KASCADE-Grande on KIT’s northern campus, where still the data is being analysed and prepared for public use via the web interface KCDC. Other activities in this research field concern cosmic ray measurements from space (JEM-EUSO) and in the Siberian taiga (TUNKA-REX) as well as the air shower simulation package CORSIKA.
We search for galactic Dark Matter by looking for collisions of WIMPs (weakly interacting massive particles) in germanium crystals. In the EDELWEISS experiment, up to 40 Ge detectors of 800 g each are cooled down to extremely low temperatures (20 milli-Kelvin). If a WIMP collides with a germanium nucleus, energy is deposited which leads to a temperature rise of the crystal of a few micro-Kelvin in coincidence with a charge signal. Requiring a characteristic ratio of both signals, background from radioactivity can be suppressed by more than 5 orders of magnitude.
EDELWEISS is a European project operated in the LSM underground lab. With its cutting-edge detector technology, it is one of the leading experiments in the international quest searching for Dark Matter particles. With EURECA, this technology will be expanded to a target mass in the ton range in a world-wide cooperation with the US-Canadian SuperCDMS collaboration.
Indirect Dark Matter Searches
Dark Matter makes up more than 80% of all matter in the universe. Assuming the Dark Matter particles to be thermal relics from the Big Bang, we only know that they must be WIMPs (Weakly Interacting Massive Particles). Such particles only exist in extensions of the Standard Model of Particle Physics, like Supersymmetry. They are predicted to annihilate into equal amounts of matter and antimatter. Such annihilations are similar to electron-positron annihilation, as studied in detail at accelerators, so the signatures are known, if WIMP annihilation really exists. To search for antimatter production from WIMP annihilation, one needs to have a magnetic spectrometer with redundant particle identification in space, since antimatter particles would annihilate in the earth atmosphere before reaching a detector on earth.
Such a state-of-the art particle detector is the AMS-02 detector
on the International Space Station (ISS). It identifies cosmic rays with energies up to the TeV range. The detector was built by an international collaboration of about 60 institutes from 16 different countries under the leadership of Nobel prize laureate Samuel Ting. In Germany the RWTH Aachen and KIT were the prime contributors to the transition radiation detector of AMS-02. First results were released in 2013.
Quantum Field Theory
The fundamental building-blocks of matter, elementary particles, are described by the so-called standard model which provides information about their properties and the forces acting between them.
The research groups at KIT which work in theoretical particle physics perform complex perturbative calculations and non-perturbative considerations within the standard model or of hypothetical theories of New Physics in order to test the quantum nature of the theory and to extract fundamental constants of nature.
Experimental Collider Physics
Teams from KIT research at the world’s most powerful particle accelerators: the high luminosity electron-positron collider Super KEKb at KEK laboratory in Tsukuba, Japan, at the Tevatron Collider at Fermilab (USA) and at the Large Hadron Collider (LHC) at CERN, Switzerland. At the LHC which started operation in 2009, conditions are generated for reactions that took place about 10-12 seconds after the Big Bang. The CMS detector is one of four large detectors installed at the LHC to investigate these reactions.
Teams from KSETA member institute IEKP have contributed since 1995 to the construction of the detector and to the data analysis which culminated in 2012 in the discovery of the Higgs Boson said to be responsible for the generation of mass. With this discovery, the Standard Model of particles and forces has been completed. During the ongoing shutdown period up to 2015, the LHC and its experiments are preparing for a new data taking run at almost twice the energy. The aim of the forthcoming runs is mostly to measure accurately the properties of the Higgs Boson and its interactions with other particles and to search for signs of physics beyond the Standard Model such as Dark Matter particles which may be produced at the LHC.
Theoretical Collider Physics
Information about the forces acting between elementary particles is obtained by experiments, in which particles are scattered at very high energies. Highest energies and, hence, smallest distances are reached at modern colliders, such as the LHC at Geneva. Theoretical collider physics makes predictions for these experiments and helps interpreting the data.
Matter comes in flavours providing a rich spectrum of phenomena to be studied. Doing this with highest precision for processes, that the standard theory of particle physics suppresses or forbids, allows to find hints for physics beyond the known and for mass scales beyond any direct reach. Especially the subtle breaking of symmetries and processes with quantum loops are promising. But only if theoretical wit and experimental finesse are optimally combined to assemble the splintered and scattered hints to a full mosaic of the fundamental picture.
The Belle II experiment will take data with an integrated luminosity 1000 times that of its closest competitor LHCb.
Neutrinos play a key role for our understanding of the Universe at the largest scales, as truly enormous numbers of neutrinos have been produced in the Big Bang. Their investigation touches and unifies fundamental questions of particle physics and cosmology.
To understand the role of these weakly interacting particles one has to measure the uncharted mass scale and mass hierarchy of neutrinos. The Karlsruhe Tritium Neutrino Experiment KATRIN will be the first worldwide to measure directly and model independent the mass of neutrinos with a sufficient sensitivity to determine their role as cosmic architects. But also in particle physics measured neutrino properties like KATRINs mass scale measurement provide unique access to (novel) extensions of the standard model.
Computational Physics (GridKa)
The research fields of particle and astroparticle physics are not feasible without the use of high-performance computers and distributed high throughput computing infrastructures, like the Worldwide LHC Computing Grid (WLCG).
GridKa at SCC, one of 11 Tier-1 centres of WLCG, is a major hub for computing and data distribution of all four of the LHC experiments as well as other HEP experiments and Auger. In addition to huge amounts of storage capacity and compute power, GridKa provides highly available Grid services used by the various experiment collaborations.
To optimize the use of computing resources, KIT develops effective algorithms and optimized software to solve physical problems in particle and astroparticle physics.
Already at the startup of the largest particle accelerator of the world, the LHC at CERN, Geneva, scientists of KCETA are working on the development of novel detectors for the next accelerator generation. It is aimed at increasing the resistance of the detector against radiation damage and at increasing the solid angle acceptance by using new cooling techniques.
For the KATRIN experiment unprecedented high vacuum systems and large superconducting magnet systems are designed and brought into operation. Locating the KATRIN experiment at KIT allows to make use of the unique expertise of the on-site Tritium Laboratory Karlsruhe (TLK), which is the only scientific laboratory equipped with a closed tritium cycle and licensed to handle the required amount of tritium."
Detection of radio signals from air showers (LOPES) opens up new promising options in the investigation of cosmic radiation. The method is optimized in prototype experiments.
Accelerator Physics and Research
The accelerator team comprises a variety of expertise, represented by their members and distributed over LAS, IPS, and the ANKA accelerator complex consisting of the storage ring and its injector chain: electron gun, microtron and booster synchrotron. Student education in accelerator physics within LAS, as part of the Faculty of Physics, in addition to research projects located at the university and, within the department of Accelerator Research at IPS, at the research center of the Helmholtz Association, contributes to an accelerator development program covering a wide variety of topics.
The accelerator team also operates, maintains, and develops the ANKA accelerator complex and, currently, constructs a new linear accelerator FLUTE (Ferninfrarot Linac- Und Test Experiment) for ultrashort bunches to generate intense, short pulse, terahertz radiation.
The topics to investigate range from single and multi-particle beam dynamics and optics, design and study of new lattices for storage rings, accelerator devices such as undulators and wigglers, new modes of operation such as a low alpha mode for the production of short bunches and, subsequently, intense coherent synchrotron radiation (CSR) in the far-infrared and terahertz region, bunch compression, new types of diagnostics for ultrashort electron bunches, ultrashort light pulses and terahertz radiation.
The scientific topics are continuously developed. The driving forces in this dynamical process are the scientific curiosity as well as the program cycles of the funding programs mentioned above. Presently, we discuss as possible new activities the multi-messenger astroparticle physics with cosmic rays, the extended and intensified search for Dark Matter in direct collision experiments and at accelerators, the constitution of the theoretical astroparticle physics , the close interconnection of theoretical and experimental studies by the evaluation of LHC data and the application of GRID computing.