Antiproton physics at GSI: Studying the physics of hadronic matter

GSI/Darmstadt is planning a major upgrade of its accelerator and experimental facilities. One of the main components of the proposed GSI-upgrade is a storage ring, in which beams of antiprotons with unprecedented quality and intensity will be available with beam momenta up to 15 GeV/c. At this facility a wide physics program is planned to investigate the structure of hadrons in the charmonium mass range, with the goal to develop a better understanding of the transition from quarks and gluons to hadrons as effective degrees of freedom. An overview of the physics program and the detector system envisioned for this project are presented.Received: 30 September 2002, Published online: 22 October 2003PACS: 13.75.-n Hadron-induced low- and intermediate-energy reactions and scattering (energy GeV) - 25.43. + t Antiproton-induced reactionsJ. Ritman: For the Antiproton Research Study Group (Antiproton Research Study Group: J. Bacelar,KVI Groningen; R. Bertini,Torino University A. Avogadro; D. Bettoni,Ferrara,INFN; T. Bressani,Torino University I; K.-T. Brinkmann,Dresden University; R. Calabrese,Ferrara,INFN; M. Düren,Giessen University; C. Ekstrom,TSL Uppsala; W. Eyrich,Erlangen University; D. Frekers,Münster University; S. Ganzhur,Bochum University; P. Gianotti,Frascati; A. Gillitzer,FZ-Jülich IKP; O. Hartmann,GSI Darmstadt; V. Hejny,FZ-Jülich IKP; M. Holzscheiter,Los Alamos; B. Kamys,Kraków University; P. Kienle,Technical University Munich; J. Kisiel,University of Silesia; H. Koch,Bochum University; W. Kühn,Giessen University; U. Lynen,GSI Darmstadt; M. Macri,Genova University; A. Martin,Trieste University and INFN; J. Marton,Austrian Academy of Science (IMEP); R. Meier,Tuebingen University; V. Metag,Giessen University; P. Moskal,FZ-Jülich IKP; H. Orth,GSI Darmstadt; M. Pallavicini,Genova,INFN; S. Paul,Technical University Munich; K. Peters,Bochum University; J. Pochodzalla,Mainz University; G. Raciti,Catania University; J. Ritman,Giessen University; G. Rosner,Glasgow University; E.L. Rizzini,Brescia University and INFN II; A. Rotondi,Pavia University; M. Sapojnikov,JINR Dubna; L. Schmitt,Technical University Munich; C. Schwarz,GSI Darmstadt; K. Seth,Northwestern University; J. Smyrski,Kraków University; I. Tikhonov,BINP Novosibirsk; N. Vlassov,JINR Dubna; A. Vodopianov,JINR Dubna; U. Wiedner,Uppsala University; A. Zenoni,Brescia University and INFN I; B. Zwieglinski,SINS Warsaw.-1)     

Uncovering the features of spin dynamics in hadronic physics

We summarize the program pursued by Michael J. Moravcsik and the authors on spin amplitude analyses and interpretation. We present the recent observations that phase histograms reveal striking peaks corresponding to spin amplitudes that tend to have definite simple phase relations. An interpretation is proposed in which the spin amplitudes receive a coherent and an incoherent contribution over large ranges of energies and angles. Continuing research directions are reported.Dedicated to the memory of Michael J. Moravcsik, whose contribution to this work, our research, and spin physics is immeasurable     

Lasers as a bridge between atomic and nuclear physics

This paper reviews the application of visible and ultraviolet laser radiation to several topics in low-energy nuclear physics. We consider laser-induced nuclear anti-Stokes transitions, laser-assisted and laser-induced internal conversion, and the electron bridge and inverse electron bridge mechanisms as tools for deexcitation and excitation of low-lying nuclear isomeric states. A study of the anomalously low-lying nuclear isomeric states (in the case of the ²²⁹Th nucleus) is presented in detail.     

Nuclear physics parallels in atomic cluster physics

This paper considers some examples of physical phenomena, manifesting themselves in electron scattering on atomic clusters, which are analogous with those known from nuclear physics. It is demonstrated that the electron diffraction plays an important role in the formation of both elastic and inelastic electron scattering cross sections. The essential role of the multipole plasmon excitations in the formation of electron energy loss spectra on clusters is elucidated. The main emphasis in the paper is laid on electron scattering on fullerenes and metal clusters, however, results are applicable to some extent to other types of clusters as well.     

Chaos in atomic physics

The influence of quantum chaos on small atomic systems is reviewed. It now seems clear that chaos in the usually understood sense (e.g. exponential sensitivity to perturbations) is not found in isolated quantum systems. However, there are phenomena which appear only when the corresponding classical system is chaotic. The stability of the classical dynamics, in other words whether it is regular or chaotic, has a profound effect on the character of the corresponding quantum spectrum and wavefunctions.     

Positronium interactions in atomic physics

The role of positronium in the investigation of fundamental aspects of atomic physics is discussed. The recently developed technique of timed positronium beam production and the characterisation of the beam constituents in the energy range 7–41 eV are outlined. Examples of positronium atoms as probes in atomic scattering interactions are given.     

Quantum dynamics in ultracold atomic physics

We review recent developments in the theory of quantum dynamics in ultracold atomic physics, including exact techniques and methods based on phase-space mappings that are applicable when the complexity becomes exponentially large. Phase-space representations include the truncated Wigner, positive-P and general Gaussian operator representations which can treat both bosons and fermions. These phase-space methods include both traditional approaches using a phase-space of classical dimension, and more recent methods that use a non-classical phase-space of increased dimensionality. Examples used include quantum Einstein-Podolsky-Rosen (EPR) entanglement of a four-mode BEC, time-reversal tests of dephasing in single-mode traps, BEC quantum collisions with up to 106 modes and 105 interacting particles, quantum interferometry in a multi-mode trap with nonlinear absorption, and the theory of quantum entropy in phase-space. We also treat the approach of variational optimization of the sampling error, giving an elementary example of a nonlinear oscillator.     

Rules of correspondence in atomic physics

The Smirnov method of analytic continuation (B.M. Smirnov, Sov. Phys. JETP 20, 345 (1964)) has been justified and developed for atomic physics. It has been shown that the polarizability of alkali atoms α, their van der Waals interaction constant C ₆, and the oscillator strength of the transition to the first P state f ₀₁ are related to the parameter 〈r ²〉 and gap in the spectrum \(\frac{3}{2}\frac{f}{\Delta } \approx \frac{3}{2}\alpha \Delta \approx {\left( {3{C_6}\Delta } \right)^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$2$}}}} \approx \left\langle {{r^2}} \right\rangle \). The average square of the coordinate of the valence electron 〈r ²〉 in the first approximation has a hydrogen dependence \({J_1} = \frac{1}{{2{v^2}}}.\) on the filling factor ν, which is defined in terms of the first ionization potential: xxxxxxxxx     

Weak neutral currents in atomic physics

Possible ways of detecting weak neutral currents in atomic physics through parity-violating effects in heavy atoms are analysed from a theoretical point of view.     

Bose–Einstein condensation in dilute atomic gases: atomic physics meets condensed matter physics

Bose–Einstein condensed atomic gases are a new class of quantum fluids. They are produced by cooling a dilute atomic gas to nanokelvin temperatures using laser and evaporative cooling techniques. The study of these quantum gases has become an interdisciplinary field of atomic and condensed matter physics. Topics of many-body physics can now be studied with the methods of atomic physics. Many long-standing predictions of the theory of the weakly interacting Bose gas have been verified, including thermodynamic properties of the phase transition and dynamic properties such as shape oscillations and sound propagation. Stimulated light scattering was used to determine the dynamic structure factor both in the phonon and free-particle regime. Atomic Bose condensates show a variety of novel phenomena which include multi-component spinor condensates, magnetic domain formation, miscibility and immiscibility of quantum fluids, and finite-size effects.     

Exactly solvable models in atomic and molecular physics

We construct integrable generalized models in a systematic way exploring different representations of the gl(N)$\mathit{gl}(N)$ algebra. The models are then interpreted in the context of atomic and molecular physics, most of them related to different types of Bose–Einstein condensates. The spectrum of the models is given through the analytical Bethe ansatz method. We further extend these results to the case of the superalgebra gl(M|N)$\mathit{gl}(M|N)$, providing in this way models which also include fermions.     

Spherical electron-ion systems in semiclassical approximation: Atoms and atomic clusters

A semiclassical method for calculating the total energy and spatial distribution of electron density in spherically symmetric electron-ion systems is applied to atoms and both solid and hollow atomic clusters. Both exchange-correlation interaction and second-order gradient correction are taken into account. The contribution due to the fourth-order gradient correction is discussed. An expression is proposed for the oscillating correction to the averaged electron density. An expression is obtained for the equilibrium radius of a hollow cluster. The dependence of the equilibrium radius of an endohedral cluster on the valence of the central atom is analyzed.     

Early experiments with slow positrons in atomic physics

The major steps in the evolution of techniques for producing positron beams of well defined energies over the last 25 years are reviewed. Developments in the methods of using these beams for experiments in atomic physics are then traced historically