Collaborators: Prof. W. Sandhas and members of his group (Bonn),

Size: px

Start display at page:

Download "Collaborators: Prof. W. Sandhas and members of his group (Bonn),"

Carmel Lawson
6 years ago
Views:

1 Few Body Systems A1 Integral Equations (AGS) A2 Integro-differential equations (Hyperspherical Harmonics) A3 Time evolution methods A4 Supersymmetric Quantum Mechanics (SUSY) and Few-Body systems A5 Astrophysics A6 Few--quark systems A7 Eta-meson light nucleus scattering A8 Resonances A9 Molecular Systems A10 Numerical and computational methods Collaborators: Prof. W. Sandhas and members of his group (Bonn), Dr M. Fabre de la Ripelle (Orsay) Prof. I. Lagaris and members of his group (Ioannina) Prof. V.B. Belyaev and members of his group (Dubna), Dr S.A. Rakityansky (Dubna) Dr H. Leeb (Vienna) Prof. E.O. Alt (Mainz), Dr W. Schweizer (T\"ubingen) Prof. S.Y. Larsen (Temple), Mr I. Matamba (Venda). Prof S Oryu (Tokyo) [A.1] Integral Equations (AGS) Study of few-body reactions, such as n + 3He ---> n + 3He p + 3H ---> d + d n + 4He ---> n + 4He in order to obtain insight into the low-energy dynamics; Test the Nucleon-Nucleon force; study break up and clustering; phenomena of light nuclei; study inter-cluster interactions; study photo- and electro-processes; develop the necessary numerical methods to

2 handle reliably fusion and astrophysical reactions. Published work (during the last 4 years): S. A Sofianos, H. Fiedeldey, and W. Sandhas, "Photo-disintegration of $^4He$ in the Integro-differential Equation approach" Phys. Rev. C 48, 2285 (1993). 2. S. A Sofianos, H. Fiedeldey, and W. Sandhas, Photo-induced Reactions on 4He" Few-Body Systems 7, 193 (1994). 3. S.A. Sofianos, H. Fiedeldey, and G. Ellerkmann, "Inclusion of Final--State-Interaction Effects in the Photo-disintegration of the alpha-particle" Few-Body Systems 18, 173(1995). 4. G. Ellerkmann, W. Sandhas, and S. A. Sofianos "Integral Equation Calculations for the Photo-disintegration of 4He" Few-Body Systems Suppl. 8, 102(1995). 5. G. Ellerkmann, W. Sandhas, S. A. Sofianos, and H. Fiedeldey "Integral Equation Calculations for the Photo-disintegration process 4He(gamma,n)3He" Phys. Rev C 53, 2638 (1996). 6. S.A. Sofianos, H. Fiedeldey, G. Ellerkmann, and W. Sandhas "Photo-induced Reactions on 4He" Few-Body Systems 7, 193 (1994). 7. R.M. Adam, H. Fiedeldey, S. A. Sofianos, and H. Leeb, "Error propagation from the nucleon--nucleon data to three- and four-nucleon binding energies" Nucl. Phys., A559, 157 (1993). 8. L. L. Howell, S. A. Sofianos, H. Fiedeldey, and G. Pantis, "Nucleon-alpha Potential by Marchenko Inversion and Supersymmetry" Nucl. Phys., A556, 29 (1993) [A.2] Integro-differential equations (Hyperspherical Harmonics) Easy construction of wave functions Obtain Bound states GO BEYOND A = 4 1. M. Fabre de la Ripelle, M. Braun, and S. A. Sofianos, "Integro-differential Equation for a Large Number of Particles" Submitted: Prog. Theor Phys. [A.3] Time evolution methods

3 Study systems where the underlying Hamiltonian is time-dependent. Developing computational methods for handling the evolution of quantum mechanical systems in time, i.e., "photograph" the events of a certain process such as the electron-light nucleus scattering. 1. I. E. Lagaris, D. G. Papageorgiou, M. Braun, and S. A. Sofianos, "A Relaxation method for Nonlocal and non-hermitian Operators" J. of Comp. Phys. 125, 229 (1996) [A.4] Supersymmetric Quantum Mechanics (SUSY) and Few-Body systems To study: Deep NN potential and their SUSY partners. Effect of SUSY applied at two--body level on few--body systems. # Intercluster interactions (see SUSY) [A.5]Astrophysics To study Helium--like Atoms in Strong (Astrophysical) Magnetic fields Besides the astrophysical aspects white dwarf stars are ``high magnetic field laboratories'' For example: The spectrum of the magnetic white dwarf GD229, discovered two decades ago, is still a complete mystery. This is the same situation as for hydrogen rich white dwarfs a few years ago. By calculating transitions of helium in strong magnetic fields it might be possible to decipher these spectra (Step towards understanding white dwarfs) Calculate bound/bound transitions for helium in strong magnetic fields relevant for white dwarf stars. Nucleosynthesis; Primordial abundances of the light elements and their impact on the standard big--bang nucleosynthesis theory. As a staring point we studied: p + d + e- ---> 3He+e- 3He + 4He + e- ----> 3He + 4He + e- at thermonuclear energies. 1. S. A. Rakityansky, S. A. Sofianos, L. L. Howell, M. Braun, and V. B. Belyaev, "Nonradiative proton-deuteron fusion in stellar plasastrma" To appear: Nucl. Phys. A. [A.6] Few--quark systems

4 Study the few quark system within the non-relativistic few--body theory 1. E.J.O Gavin, H.Fiedeldey, H. Leeb, and S. A. Sofianos, "Supersymmetric quantum mechanics applied to non-relativistic quark models" Int. J. Mod. Phys. A, 8, 1437 (1993). 2. E. J. O. Gavin, H. Fiedeldey, and S. A. Sofianos, "Three-body forces from n-body inversion" Intern. Journal of Modern Phys. E 4, 431(1995) 3. E. J. O. Gavin, R. M. Adam, H. Fiedeldey, and S. A. Sofianos, "Relationship between the proton charge form factor and the quark--quark interaction" Few-Body Systems 19, 59(1995) [A.7] Eta-meson light nucleus scattering To study the question of isotopic invariance breaking, the meson--nucleus scattering mechanism and various other particle and nuclear physics questions S. Rakityansky, S. A. Sofianos and B. V. Belyaev, "Near Threshold eta-meson interaction with light nuclei in "Effective Interactions in Quantal Systems" ed. S. A. Sofianos, Unisa, Dec S. Rakityansky, S. A. Sofianos, V. B. Belyaev, and W. Sandhas in "On the possibility of an eta-meson light nucleus bound state formation'' Few-Body Systems Suppl. 9, 227(1995). 3. S. Rakityansky, S. A. Sofianos, W. Sandhas, and V. B. Belyaev "Threshold scattering of the eta-meson off light nuclei" Physics Letter B 359, 33(1995). 4. V. B. Belyaev, S. A. Rakityansky, S. A. Sofianos, M Braun, and W. Sandhas in "Low-- energy interaction of eta-meson with light nuclei'' Chinese Journal of Physics 34,998 (1996). 5. S. A. Rakityansky, S. A. Sofianos, M Braun, V. B. Belyaev, and W. Sandhas in "Quasi-- bound states of eta-nucleus systems" Phys. Rev. C 53, R2043 (1996). [A.8] Resonances Investigate via an exact method the presence of potential resonances (two-body) and their manifestation and effects in few-body systems. Extremely important in molecular physics.

5 1. S. Rakityansky, S. A. Sofianos, and K. Amos "A method of calculating the Jost function for analytic potentials" Il Nuovo Cimento, 111 B, 353 (1996). 2. S. A. Sofianos and S. A. Rakityansky, "Exact method for locating potential resonances and Regge trajectories" Accepted: J. of Phys. G [A.9] Molecular systems Investigate Molecular systems: bound states and ultra-low energy scattering. The 4He trimer is of interest in various areas of Physics Chemistry, and Molecular physics such as the condensed-matter, nuclear, and the rare-gas atoms behaviour under First step towards understanding liquid 4He drops, superfluidity in 4He films. Work using Variational and Monte-Carlo. Exact microscopic calculations can, in principle, performed using Faddeev equations. However, the underlying van der Waal forces are of a hard-core nature which make investigations via these equations cumbersome and tedious. Use of Boundary Condition Model. 1. M. Braun, S. A. Sofianos, D. G. Papageorgiou, I. E. Lagaris, "Ground State Calculations for 4He-molecules" Submitted: Nuovo Cimento 2. E. A. Kolganova, A. K. Motovilov, and S. A. Sofianos "Ultra-low energy scattering of a He atom off a He dimer" Submitted: PRA (Rapid Comm.) 3. E. A. Kolganova, A. K. Motovilov, and S. A. Sofianos "Three--Body Configuration Space Calculations with Hard Core Potentials" Submitted: PRA [A.10] Numerical and computational methods Study various numerical analysis questions! 1. M. Braun, S. A. Sofianos, D. G. Papageorgiou, I. E. Lagaris, "An Efficient Chebyshev-- Lanzcos Method for obtaining Eigensolutions of the Schr\"odinger Equation on a Grid" J. Comput. Phys. 125, 215 (1996).

Emission of Helium Nuclei in Relativistic Proton Interactions Leading to Total Break up of Ag and Br Nuclei. Z.Physik A 279, 407 (1976).

Emission of Helium Nuclei in Relativistic Proton Interactions Leading to Total Break up of Ag and Br Nuclei. Z.Physik A 279, 407 (1976). Inelastic Interactions of 69.0 GeV/c Protons with Emulsion Nuclei.