Development of a Focussing Disc DIRC for PANDA at FAIR

There are four fundamental forces in nature, of which gravity and electromagnetism are the most familiar. The former makes apples fall from trees and keeps planets in their orbits around the sun; the latter holds molecules together and operates iPods. The third force is the so-called weak force and is responsible for beta decay processes, such as the creation of positrons in Positron Emission Tomography. The fourth force is called strong force because it is 13 orders of magnitude (or ten thousand billion times) stronger than the weak force. The strong force is responsible for binding together atomic nuclei. At an even smaller scale than nuclei, it is the interaction that forms hadrons from quarks and gluons, and is therefore responsible for most of the observable mass in the universe. Quantum Chromodynamics (QCD) is widely accepted as the fundamental theory describing the strong interaction; a recent Nobel Prize (2004, Gross, Politzer, Wilczek) was awarded for the development of this theory. The Facility for Antiproton and Ion Research, FAIR, is a new international accelerator facility, to be located on the site of the GSI laboratory in Darmstadt, Germany. GSI itself is well known for the discovery of some super-heavy elements, e.g. element 110, Darmstadtium. The existing GSI accelerators will serve as injectors for the new facility. The main accelerator of FAIR will be a double-ring synchrotron that will provide ion beams of unprecedented intensities at considerably increased energy. Intense secondary beams - unstable nuclei or antiprotons - can be produced. A system of storage-cooler rings will allow the quality of these secondary beams - their energy spread and emittance - to be drastically improved. One of the flagship experiments of FAIR, PANDA, will be a QCD experiment. It will be located in the new High Energy Storage Ring (HESR), where an anti-proton beam at momenta of 1 to 15 GeV/c impinges on a target. The main research topics at PANDA will be: - Charmonium spectroscopy: Precision measurements of charmonium states (states with charm quarks) will help to understand the origin of the masses of hadrons. In addition, the mechanism of confinement of quarks in hadrons can be investigated. -Glueballs and Hybrids: The quark model picture of mesons is that they consist of a quark and an antiquark. QCD predicts that there could be different combinations that do not fit this model: quarks with gluonic excitations, or gluons only. -Proton structure: Mapping out the spatial and spin distributions of quarks in the nucleon will lead to a deeper understanding of hadron structure. The FAIR project was launched formally in November 2007, and the construction of the accelerators will commence in 2008. This is the point in time where the construction tasks for the experiments are being distributed among the collaborating institutes. In this proposal, we are applying for funding to develop one of the crucial parts of the PANDA detector, the particle identification endcap disc DIRC, which is an innovative Glasgow-Edinburgh design and will be the first detector of its kind world-wide. We are leading this project within PANDA and are also playing a leading role in the overall particle identification. The UK groups are founding members of the PANDA experiment, now an international collaboration with ca. 400 members from 17 countries. The funding of this proposal will ensure that we continue playing a leading role in the design and construction of this vital part of the experiment.