S. De Baerdemacker

Decomposition of a Linear Reversible Computer: Digital Versus Analog

A. De Vos (Alexis), S. De Baerdemacker
International Journal of Unconventional Computing
6 (3-4), 239-263
2010
A1
Published while none of the authors were employed at the CMM

Abstract 

Linear reversible transformations in the Galois field GF(2) and linear reversible transformations in the field of real numbers show both resemblances and differences. The former constitute a finite group isomorphic to the general linear group GL(w, 2), the latter constitute an infinite, i.e. Lie, group isomorphic to the general linear group GL(w, R) (where w is the logic width of the computation, i.e. respectively the number of bits and the number of real numbers, processed by the computer). Generators of the former group consist of merely control gates; generators of the latter group consist of both control gates and scale gates.

http://www.oldcitypublishing.com/IJUC/IJUCabstracts/IJUC6.3-4abstracts/I...

Spectral properties of a tractable collective Hamiltonian

S. De Baerdemacker, K. Heyde, V. Hellemans
Physical Review C
79 (3), 034305
2009
A1
Published while none of the authors were employed at the CMM

Abstract 

The spectral properties of a tractable collective model Hamiltonian are studied. The potential energy is truncated up to quartic terms in the quadrupole deformation variables, incorporating vibrational, γ-independent rotational, and axially deformed rotational structures. These physically significant limits are analysed in detail and confronted with well-established approximation schemes. Furthermore, transitional Hamiltonians in between the limits are presented and discussed. All results are obtained within a recently presented Cartan-Weyl based framework to calculate SU(1,1)×SO(5) embedded quadrupole collective observables.

The quadrupole collective model from a Cartan–Weyl perspective

S. De Baerdemacker, K. Heyde, V. Hellemans
Journal of Physics A: Mathematical and Theoretical
41 (30), 304039
2008
A1
Published while none of the authors were employed at the CMM

Abstract 

The matrix elements of the quadrupole variables and canonic conjugate momenta emerging from collective nuclear models are calculated within an SU(1, 1) × O(5) basis. Using a harmonic oscillator implementation of the SU(1, 1) degree of freedom, one can show that the matrix elements of the quadrupole phonon creation and annihilation operators can be calculated in a pure algebraic way, making use of an intermediate state method.

Configuration mixing in the neutron-deficient 186-196Pb isotopes

V. Hellemans, S. De Baerdemacker, K. Heyde
Physical Review C
77 (6), 064324
2008
A1
Published while none of the authors were employed at the CMM

Abstract 

In this article we report the results of detailed interacting boson model calculations with configuration mixing for the neutron-deficient Pb isotopes. Calculated energy levels and B(E2) values for 188-196Pb are discussed and some care is suggested concerning the current classification on the basis of level systematics of the 41+ and 61+ states in 190-194Pb. Furthermore, quadrupole deformations are extracted for 186-196Pb and the mixing between the different families (0p-0h, 2p-2h, and 4p-4h) is discussed in detail. Finally, the experimental and the theoretical level systematics are compared.

Quadrupole collective variables in the natural Cartan–Weyl basis

S. De Baerdemacker, K. Heyde, V. Hellemans
Journal of Physics A: Mathematical and Theoretical
40 (11), 2733
2007
A1
Published while none of the authors were employed at the CMM

Abstract 

The matrix elements of the quadrupole collective variables, emerging from collective nuclear models, are calculated in the natural Cartan–Weyl basis of O(5) which is a subgroup of a covering SU(1, 1) × O(5) structure. Making use of an intermediate set method, explicit expressions of the matrix elements are obtained in a pure algebraic way, fixing the γ-rotational structure of collective quadrupole models.

Solution of the Bohr Hamiltonian for a periodic potential with minimum at γ=π/6

S. De Baerdemacker, L. Fortunato, V. Hellemans, K. Heyde
Nuclear Physics A
769, 16-34
2006
A1
Published while none of the authors were employed at the CMM

Abstract 

We present an analytic solvable γ-periodic potential of the form μ/sin2(3γ) in the Bohr–Mottelson collective model. The choice allows for a separation in both β, γ and θι if the γ-variable in the moments of inertia is approximated by its expectation value γ0=π/6. Energy spectra, E2 transition rates and subsequent collective bands with their properties are presented. We compare the approximation of γ=γ0=π/6 with a full diagonalisation of the rotational part. These results clearly point out that the approximative analytical treatment describes the full numerical results very well.

A theoretical description of energy spectra and two-neutron separation energies for neutron-rich zirconium isotopes

J.E. Garcıa-Ramos, K. Heyde, R. Fossion, V. Hellemans, S. De Baerdemacker
The European Physical Journal A - Hadrons and Nuclei
26 (2), 221-225
2005
A1
Published while none of the authors were employed at the CMM

Abstract 

Very recently the atomic masses of neutron-rich Zr isotopes, from 96Zr to 104Zr, have been measured with high precision. Using a schematic Interacting Boson Model (IBM) Hamiltonian, the evolution from spherical to deformed shapes along the chain of Zr isotopes, describing at the same time the excitation energies as well as the two-neutron separation energies, can be rather well reproduced. The interplay between phase transitions and configuration mixing of intruder excitations in this mass region is succinctly addressed.

Configuration mixing in 188Pb: Band structure and electromagnetic properties

V. Hellemans, R. Fossion, S. De Baerdemacker, K. Heyde
Physical Review C
71 (3), 034308
2004
A1
Published while none of the authors were employed at the CMM

Abstract 

In the present paper, we carry out a detailed analysis of the presence and mixing of various families of collective bands in 188Pb. Making use of the interacting boson model, we construct a particular intermediate basis that can be associated with the unperturbed bands used in more phenomenological studies. We use the E2 decay to construct a set of collective bands and discuss in detail the (BE2) values. Monopole transition ρ2 values are calculated. We also perform an analysis of these theoretical results [Q,B(E2)] to deduce an intrinsic quadrupole moment and the associated quadrupole deformation parameter, using an axially deformed rotor model.
© 2005 The American Physical Society

Pages

Subscribe to RSS - S. De Baerdemacker