The SMI Annual Report 2012 is available.
With the passing of Paul Kienle, former Director of the Stefan Meyer Institute, we lost an eminent scientist and pioneer in subatomic physics. He left us on Tuesday, January 29, 2013, few days after finishing his last scientific...
The annual SPARC Collaboration meeting took place in Vienna from November 26 to 28.
The universal PANDA detector will be built by an international collaboration consisting of 400 physicists to attack open fundamental problems in strong interaction physics. PANDA is devoted to strong interaction precision studies in the transition energy range of perturbative QCD and the non-perturbative QCD regime which exhibits large complexity but is essential for the understanding of nature (e.g. regime of confinement, generation of hadron masses). Experiments with the PANDA detector will take place at the HESR (high energy storage ring) of the FAIR international research center in Darmstadt, Germany.
The high-energy storage ring HESR will deliver antiproton beams in the momentum range 1.5–15 GeV/c of unprecedented precision (Δp/p ~10-5) and intensity (1011 circulating antiprotons in normal operation). Using the HESR antiproton beam resonance scans of even very narrow charmonium states (formation experiment) are feasible. All states of charmonium can be formed and studied in a direct way which is a tremendous advantage compared with production experiments. The main experimental topics of PANDA will be high-precision measurements of the strong interaction in the following fields:
· Charmonium spectroscopy: precision measurement of mass, width and decay branches of all charmonium states in order to extract information on the quark-confining potential.
· Exotic states: establishment of the QCD-predicted gluonic excitations (charmed hybrids, glueballs) in the charmonium mass range (3-5 GeV/c2).
· Search for modifications of meson properties in the nuclear medium in the charm sector and their possible relationship to partial restoration of chiral symmetry.
The PANDA project showed significant progress in 2008: The technical design report for the electromagnetic calorimeter (EMC) was finalized and published. First crystals for the EMC were already ordered. Very important was also the compilation of the PANDA Physics Book which will be published 2009. The Technical Design Report for PANDA on Solenoid and Dipole Spectrometer was prepared in 2008 and is published in February 2009.
Our institute is taking part in the PANDA international collaboration with more than 50 participating institutes. Within the EU programme of FP6, SMI contributed to the following tasks: optimisation studies of the (hydrogen) cluster-jet target and design of the PANDA interaction zone (JRA7 in I3-Hadron Physics), as well as the development of imaging Cherenkov detectors (work package PANDA1 in DIRACsecondary Beams and INTAS project on novel silicon photo detectors).
In order to fulfill the computing demands of the experiments at PANDA a dedicated computing infrastructure will be required. A conceivable way of acquiring and managing the necessary computing power for simulations and data analysis is the Grid model. As an alternative to a centralized computing centre this model allows to pool independent resources from multiple institutes or organizations.
Although PANDA is not expected to acquire data before the year 2016 the PANDA collaboration is already experimenting with the PANDA Grid. At the end of 2008 the PANDA Grid consisted of 10 sites. The underlying software allows the Grid to be expanded without disturbing its continuous operation. The PANDA analysis software (PandaRoot) is installed on the different sites and so the PANDA Grid is able to perform PANDA related tasks.
SMI is actively taking part in building up, developing, testing, and running the PANDA Grid. In 2008 a new batch farm was installed at SMI and included into the PANDA Grid. In 2008 we also had two data challenges during which large quantities of data were produced via a full chain of simulation, digitization, and reconstruction. This data is analyzed and used to improve the design of the PANDA detector.
The PANDA detector will cover the physics of strong interaction and will address several fundamental questions in this field. Antiprotons stored in the accelerator HESR will hit an internal target. This target will be mainly a high-luminosity hydrogen cluster-jet target. The interactions between beam antiprotons and target protons will generate, amongst others, mesons and baryons consisting of the heavier strange and charm quarks and will produce a lot of gluons.The high mass of the charm quark (~1.5 GeV/c²) allows applying non-relativistic potential models with correct asymptotic behaviour for the description of QCD. The free parameters in these models are determined from the comparison with experimental data. Therefore the precise spectroscopy of masses and widths of mesons with “hidden charm” (charmonium) produced in these antiproton-proton annihilations will be a powerful tool for the understanding of QCD.
Simulation studies of selected charmonium states produced in antiproton-proton and antiproton-nucleus annihilations by using the cluster-jet target have been and will be carried out at SMI in cooperation with theorists. The simulation results of these important benchmark channels were directly used for the “PANDA Physics Book”, which is ready for publication now.
In the next years the institute will continue the work on the construction and commissioning of the PANDA detector