Projects / Programmes
Structure of hadronic systems
January 1, 2004
- December 31, 2008
| Code |
Science |
Field |
Subfield |
| 1.02.00 |
Natural sciences and mathematics |
Physics |
|
| Code |
Science |
Field |
| P220 |
Natural sciences and mathematics |
Nuclear physics |
electromagnetic and spin structure of hadronic systems, electron coincidence experiments with polarized beams and targets, programmable logical m odules, RICH detectors, nuclear reactions, structure of nuclei in vicinity of Sn-100, high-resolution gamma-ray detection systems
Researchers (12)
Organisations (2)
Abstract
Research on the structure and dynamical processes in nucleons (quark structure of nucleons, quark confinement, structure of nuclei); deuteron (fundamental nuclear interaction, effective neutron target); 3He nucleus (neutron target, comparison with theoretical results); heavy nuclei (spectroscopy, development of detector systems, development of ab-initio models); detector simulations (calibrations).
Significance for science
The experimental centers in which the program has been pursued, have no competition in the field of intermediate energy hadronic physics. The two leading laboratories, Jefferson Lab (USA) and MAMI (Germany) are upgrading their electron accelerators to higher energies within the duration of the program. Jefferson Lab belongs to the central mid-term basic-science priorities in the US. The FAIR facility at GSI (Germany) is presently by far the largest national investment in hadronic physics. The research has had a large discovery potential. The measurements of electromagnetic form factors at high momentum transfers, where strong two-photon corrections and polarization effects are important, and at low transfers, where effects of meson cloud dominate, have shown some surprising features. With our measurements we have been extending the coverage into previously unexplored kinematic regions, stepping onto the uncharted path of the transition between perturbative QCD and hadronic physics in the region of quark confinement. The measurement of the axial and pseudoscalar form factor is of key importance to understand the axial (or spin) structure of the nucleon at low Q2. The axial form factor, although a fundamental quantity, is extremely poorly known, while the pseudoscalar form factor is believed to be dominated by the pion pole (also unchecked). There are also large deviations between individual determinations. The measurement in the A1 Collaboration exploits a specially designed short-orbit spectrometer to minimize systematic errors related to pion decay and muon contamination. We have so far been able to determine much more precisely the axial form factor. The measurements of single and double spin asymmetries with the polarized He3 target used as an effective polarized neutron target, are of exceptional importance for hadronic physics, especially for studies of the neutron itself. Free neutrons do not exist and measurements of neutron observables are much harder than the corresponding proton ones. The technology of preparation of polarized He3 targets has advanced to a level such that the statistical errors of the measured data have become comparable to the systematic errors originating in the imperfect understanding of the models of He3 structure. These models are used to interpret He3 data in terms of neutron observables. Our experiments have significantly enriched the quantitative understanding of the spin structure of the He3 nucleus, as manifesting itself in single polarization observables sensitive to the transverse quark polarization, as well as double polarization observables sensitive to the small components in the ground-state wave-function of He3. The main orientation of the measurements with the new KAOS spectrometer, being constructed with our collaboration at MAMI, is the production of strange mesons and hyper nuclear spectroscopy, yielding information on the hyperon-nucleon and hyperon-hyperon interaction. The region of single or double hypernuclei in the nuclear landscape is virtually a terra incognita, with only an extremely limited set of data. With the measurements with the KAOS spectrometer, for which our group is presently constructing the Cherenkov detector, we enter this ladscape in great strides. The A1 Collaboration at MAMI has great discovery capabilities here, and a chance of a breakthrough: an extremely well tuned and matched high-resolution spectrometer system for the electron vertex, and a specially designed KAOS spectrometer to detect kaons at very small angles in high count rates.
Significance for the country
In the program we have strongly enhanced our collaboration with industrial partners, which is directly relevant for individual companies. This segment of our research is led by the part of our group involved in design and implemenation of algorithms and electronics modlues for data acquisition and analysis within the FreeDac Collaboration (FAIR) and in cooperation with the E6 Department at the Jozef Stefan Institute. Our work is therefore important for the development of professional and engineering practices.
Most important scientific results
Final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Final report,
complete report on dLib.si
