History for 2001

Twentieth International Workshop on Nuclear Theory

Rila Mountains, Bulgaria
June 11-16, 2001

The Twentieth International Workshop on Nuclear Theory was held in the Rila Mountains, Bulgaria, from 11 to 16 June, 2001. It was attended by about 40 participants from 11 countries: Australia, Bulgaria, France, Germany, Greece, Poland, South Africa, Spain, Sweden, U.K., and USA. The Workshop is organized every year by the Nuclear Theory Group of the Department of Theoretical Physics in the Institute of Nuclear Research and Nuclear Energy (INRNE, Sofia) of the Bulgarian Academy of Sciences. This year it was partly sponsored by the INRNE and the Bulgarian Nuclear Society.

The main topics advertised were:
       nucleon-nucleon correlation effects on nuclear structure and reactions
       exotic nuclei
       nuclear reactions
       algebraic methods in nuclear theory
       density functional methods in nuclear theory

Prof. K. Amos reported new results of calculations of differential cross sections as well as analyzing power for nucleon scattering at energies to 300 MeV on wide range of target nuclei. The results are obtained with a microscopic model of the nucleon-nucleus optical potential using complex energy- and density-dependent effective nucleon-nucleon interactions with one-body density-matrix elements and single-particle bound states of the target generated by large space shell-model calculations.

The lecture of Prof. H. von Geramb was devoted to studies of nucleon-nucleon and nucleon-nucleus optical models for energies to 3 GeV as a first step for an in medium search for a transition region between meson-nucleon and quark-gluon degrees of freedom in the nucleon-nucleon interaction.

The DWIA description of cross sections and analyzing power distributions of the 208Pb(p,2p)207Tl reaction at an incident energy of 200 MeV was the subject of the lecture of Prof. A. Cowley.

Dr. S. Massen presented comparison of the results of three different cluster expansions within the Jastrow correlation method in calculations of charge form factors as well as density and momentum distributions in nuclei. The information entropy of nuclei in coordinate- and momentum-space according to the three approaches was also discussed.

A successful description of the empirical data on the deuteron momentum distribution, including the high-momentum region, within the light-front dynamics method (which explains simultaneously the newest data for the deuteron monopole and quadrupole charge form factors) was reported by Prof. A.N. Antonov. A development of an approach to calculate nucleon momentum distributions in (A,Z)-nuclei on the basis of the deuteron momentum distribution was presented as well.

Dr. S. Dimitrova discussed a new approach to large-scale nuclear structure calculations based on the density matrix renormalization group method and its application to a system of many identical nucleons constrained to move in a single large j-shell with pairing and quadrupole interactions.

In his contribution Dr. M. Gaidarov presented calculations of single-particle overlap functions, spectroscopic factors and cross sections of (p,d) reaction on open-shell nuclei 24Mg, 28Si and 32S and of 32S (e,ep) reaction discussing the role of the short-range correlations incorporated in the Jastrow-type approach used on the reaction characteristics.

Prof. J. Dobaczewski made a wide review on selected topics in nuclear structurefar from stability. He presented quantitative measures for the existence of halo and skin in nuclei as well as recent results of Hartree-Fock-Bogolyubov (HFB) calculations.

Dr. J. Bartel gave a lecture on the fission dynamics investigations of the emission of light particles (neutrons, protons and a-particles) in the fission process for a variety of different compound nuclei ranging from 126Ba to super-heavy nuclei.

Prof. R. Liotta reported on critical assessment of particle decay as a probe to study the continuum.

In his lecture Dr. J. Dukelsky presented a family of exactly solvable models based on the pairing interaction for fermionic and bosonic systems and discussed their recent applications to ultrasmall superconducting grains and to boson traps.

Prof. M. Stoitsov considered systematic calculations within 14 major shells forall even-even nuclei from proton drip-line to neutron drip-line (with proton numbers Z=4,6,8,...,84) using transformed harmonic oscillator single-particle basis which is well suited for solving the HFB equations for deformed drip-line nuclei.

A fully microscopic study of the available experimental data for mixed symmetry states in medium and heavy nuclei within the quasiparticle phonon model was presented by Prof. Ch. Stoyanov.

Dr. Chr. Laftchiev contributed by considering dynamical effects of pairing correlations in nuclei within collective intrinsic vortical modes.

The lecture of Prof. A. Bulgac was devoted to neutron stars, bubble nuclei and quantum billiards. The appearance of either bubbles, rods, tubes or platesembedded in a neutron gas in dependence on the average value of the neutron density was discussed. Similar phenomena are expected to occur as well in atomic clusters, condensed matter systems, dilute atomic fermi condensates and quark-gluon plasma.

Prof. I. Vergados reviewed a wide range of studies aiming a search ofsupersymmetric dark matter.

The lecture of Prof. E. Moya de Guerra was devoted to electron scattering as a method to obtain precise and reliable information on the halo structure of light neutron- and proton drip-line nuclei. Another point of the lecture was connected with the application of the relativistic mean-field approximation to producing distinctive signatures in momentum distributions that can be explored by coincidence (e,ep) and (e,eNN) experiments.

One of the sessions of the Workshop was in memory of Dr. R.P. Roussev.

Prof. D. Bonatsos considered a three-dimensional q-deformed harmonic oscillator approach in which the magic numbers of alkali clusters and also of several divalent and trivalent metal clusters are reproduced well.

Dr. P. Terziev contributed by considering the relation between the quantum rotational model and the phenomenological model of Amalsky for the description of the ground rotational bands of the deformed even-even nuclei.

Electron-nuclear spin-spin and potential contact interactions for excited and degenerate states in the density functional methods were presented by Prof. P. Raychev.

In the lecture of Prof. P. Quentin the HFB approximation and methods to bypass it in sructure calculations have been considered.

In the lecture of Dr. G. Jaroszkiewicz studies of spatial and temporal discretization of the Skyrme model have been reported. It was focussed in the lecture on simulation in real time and the problems which arise when invariants of the motion are monitored in a simulation.

Prof. V. Nikolaev presented Skyrme model calculations in the theory of nucleons and nuclei.

In her contribution Dr. R. Nikolaeva-Hubenova discussed the role of time in modeling the brain function.

The participants had a nice opportunity to get acquainted with the attractive high-mountains places in the Malyovitza region of the Rila Mountains including the greatest Bulgarian winter resort Borovetz. They visited the famous Rila Monastery which is situated in the heart of the Mountains and keeps treasures of the Bulgarian history and culture.

Nuclear Theory Group,
Department of Theoretical Physics,
Institute of Nuclear Research and Nuclear Energy,
Bulgarian Academy of Sciences,
Sofia 1784, Bulgaria

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