| 1. |
- Gadea, A., et al.
(författare)
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Spectroscopy of heavy N=Z nuclei with GASP and EUROBALL
- 2003
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 34:4, s. 2429-2438
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Tidskriftsartikel (refereegranskat)abstract
- The coupling of big Ge-arrays like EUROBALL or GASP with ancillary detectors for the study of the structure properties of very exotic nuclei, far from the stability valley, has given outstanding results in the last years. A large fraction of the experiments performed with both arrays has been devoted to study both proton-rich and neutron-rich nuclei populated using stable beams provided by the LNL Legnaro and MeS Strasbourg accelerators. Nuclei lying close to the N = Z line are of particular interest being a laboratory where collective excitations as well as fundamental properties of the nuclear force can be tested, like isospin symmetry and isospin breaking terms, proton neutron pairing, dripline effects and coherent neutron and proton contributions to the nuclear excitations. Some of this properties are more evident (degree of isospin mixing) or can be only observed (collective effects) in heavy N = Z nuclei. In this contribution we present the experimental results obtained by our collaboration along and in the vicinity of N = Z line.
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| 2. |
- Gudowski, Waclaw
(författare)
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Transmutation of isotopes - Ecological and energy production aspects
- 2000
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 31:1, s. 107-122
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes principles of Accelerator-Driven Transmutation of Nuclear Wastes (ATW) and gives some flavour of the most important topics which are today under investigations in many countries. Pin assessment of the potential impact of ATW on a future of nuclear energy is also given. Nuclear reactors based on self-sustained fission reactions - after spectacular development in fifties and sixties, that resulted in deployment of over 400 power reactors - are wrestling today more with public acceptance than with irresolvable technological problems. In a whole spectrum of reasons which resulted in today's opposition against nuclear power few of them are very relevant for the nuclear physics community and they arose from the fact that development of nuclear power had been handed over to the nuclear engineers and technicians with some generically unresolved problems, which should have been solved properly by nuclear scientists. In a certain degree of simplification one can say, that most of the problems originate from very specific features of a fission phenomenon: self-sustained chain reaction in fissile materials and very strong radioactivity of fission products and very long half-life of some of the fission and activation products. And just this enormous concentration of radioactive fission products in the reactor core is the main problem of managing nuclear reactors: it requires unconditional guarantee for the reactor core integrity in order to avoid radioactive contamination of the environment; it creates problems to handle decay heat in the reactor core and finally it makes handling and/or disposal of spent fuel almost a philosophical issue, due to unimaginable long time scales of radioactive decay of some isotopes. A lot can be done to improve the design of conventional nuclear reactors (like Light Water Reactors); new, better reactors can be designed but it seems today very improbable to expect any radical change in the public perception of conventional nuclear power. In this context a lot of hopes and expectations have been expressed for novel systems called Accelerator-Driven Systems, Accelerator-Driven Transmutation of Waste or just Hybrid Reactors. All these names are used for description of the same nuclear system combining a powerful particle accelerator with a subcritical reactor. A careful analysis of possible environmental impact of ATW together with limitation of this technology is presented also in this paper.
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| 3. |
- Kwiecinski, J., et al.
(författare)
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Two-photon cross-sections from the saturation model
- 2002
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Ingår i: Acta Physica Polonica B. - : Jagellonian University, Cracow. - 0587-4254 .- 1509-5770. ; B33:6, s. 1559-
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Tidskriftsartikel (refereegranskat)abstract
- A saturation model for the total \gamma \gamma and \gamma* \gamma* cross-sections and for the real photon structure function F2\gamma (x,Q2) is described. The model is based on a QCD dipole picture of high energy scattering. The two-dipole cross-section is assumed to satisfy the saturation property with the saturation radius taken from the GBW analysis of the \gamma*p interaction at HERA. The model is combined with the QPM and non-pomeron reggeon contributions and it gives a very good description of the data on the \gamma \gamma total cross-section, on the photon structure function F2\gamma (x,Q2) at low x and on the \gamma* \gamma* cross-section. Production of heavy quarks in \gamma \gamma collisions is also studied.
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| 4. |
- Lieder, R. M., et al.
(författare)
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Development of gamma-ray tracking detectors
- 2001
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 32:9, s. 2395-2401
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Tidskriftsartikel (refereegranskat)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy AGATA will consist of gamma -ray tracking detectors. They represent high-fold segmented Ge detectors and a front-end electronics, based on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions on the basis of the Compton-scattering formula.
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| 5. |
- Palacz, M., et al.
(författare)
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Investigations of Neutron Deficient Nuclei Close to 100Sn with EUROBALL
- 2001
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Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254 .- 1509-5770. ; 32, s. 999-1003
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Tidskriftsartikel (refereegranskat)abstract
- Excited states of nuclei in the vicinity of Sn-100 have been studied using: the EUROBALL detector array. Gamma-ray lines from Sn-103 have been identified for the first time, and a level scheme of low-lying excited states of Sn-103 has been established. New constraints on energies of single particle orbitals with respect to the Sn-100 core are obtained.
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| 6. |
- Satula, W., et al.
(författare)
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Cranking in isospace - Towards a consistent mean-field description of N = Z nuclei
- 2001
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 32:9, s. 2441-2456
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Tidskriftsartikel (refereegranskat)abstract
- Excitation spectra DeltaE(T) of T = 0, 1, 2 states in even-even (e-e) and odd-odd (o-o) N = Z nuclei are analyzed within a mean-field based model involving isovector and isoscalar pairing interactions and the iso-cranking formalism applied to restore approximately isospin symmetry. It is shown that T = 0 states in o-o and T = 1 states in e-e nuclei correspond to two-quasiparticle, time-reversal symmetry breaking excitations since their angular momenta are I not equal 0. On the other hand the lowest T = 2 states in e-e and T = 1 states in o-o nuclei, which both are similar in structure to their even-even isobaric analogue states, are described as e-e type vacua excited (iso-cranked) in isospace. It appears that in all cases isoscalar pairing plays a crucial role in restoring the proper value of the inertia parameter in isospace i.e. DeltaE(T).
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| 7. |
- Stefanova, E. A., et al.
(författare)
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Four-quasiparticle alignments in Ge-66
- 2003
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 34:4, s. 2237-2240
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Tidskriftsartikel (refereegranskat)abstract
- Above angular momentum 10(+), we found two positive-parity sequences, connected by energetically staggered DeltaI = 1 M1 transitions. The total Routhian surface calculations predict a strong triaxial deformation for them. To our knowledge, this is the first observation of staggered M1 transitions in a deformed four-quasiparticle pi(g(9/2)(2))v(g(9/2)(2)) regime.
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| 8. |
- Tîmneanu, Niccusor, et al.
(författare)
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Diffractive Higgs Production : Soft Colour Interactions Perspective
- 2002
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Ingår i: Acta Physica Polonica B. - : Jagellonian University, Cracow. - 0587-4254 .- 1509-5770. ; B33:11, s. 3479-
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Tidskriftsartikel (refereegranskat)abstract
- We briefly present the soft colour interaction models which are successful in reproducing a multitude of diffractive hard scattering data, and give predictions for diffractive Higgs production at the Tevatron and LHC. Only a few diffractive Higgs events may be produced at the Tevatron, but we predict a substantial rate at the LHC.
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| 9. |
- Tîmneanu, Niccusor, et al.
(författare)
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Saturation model for 2-gamma physics
- 2002
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Ingår i: Acta Physica Polonica B. - : Jagellonian University, Cracow. - 0587-4254 .- 1509-5770. ; B33:10, s. 3045-3050
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a saturation model for photon-photon interactions, based on a QCD dipole picture of high energy scattering. The two-dipole cross-section is assumed to satisfy the saturation property. This pomeron-like contribution is supplemented with QPM and non-pomeron reggeon contributions. The model gives a very good description of the data on the \gamma \gamma total cross-section, on the photon structure function F2\gamma (x,Q2) at low x and on the \gamma * \gamma * cross section.
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| 10. |
- Wyss, Ramon A., et al.
(författare)
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Rotating N=Z nuclei - A probe to the t=0 and t=1 pairing correlations
- 2001
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 32:9, s. 2457-2468
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Tidskriftsartikel (refereegranskat)abstract
- A study of heavy N=Z nuclei including t=1, t(z)=+/-1 pairing only clearly reveals the shortcoming of that model in T-z=0 nuclei. We present a simple model in which we study the response of isoscalar t=0 and isovector t=1 pairing correlations to rotational motion. In particular, we address the role played by the t=1 and t=0 pair gaps with respect to the band crossing frequency. We argue that the t=1 neutron-proton pair field is of limited importance in even-even nuclei. For the t=0 pair field, we introduce two different pairing modes. One is invariant with respect to signature symmetry and one is not. The signature conserving mode results in a delay of the band crossing frequency, whereas the signature breaking part enhances the rigidity of the moment of inertia.
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