[en] The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)

[en] The author proposes a synthesis of research activities performed since 1995 in the field of experimental nuclear physics, and more particularly in the investigation of two nucleus extreme states: deformation on the one hand, heavy and very heavy nuclei on the other hand. After a presentation of the context of investigations on deformation, rotation, and heavy nuclei, he gives an overview of developments regarding instruments (gamma spectrometers, detection of fission fragments, and detection at the focal plane of spectrometers or separators) and analysis techniques. Experiments and results are then reported and discussed, concerning super-deformed states with a high angular moment, spectroscopy of neutron-rich nuclei, very heavy nuclei close to nucleus map borders. He finally draws perspectives for middle and long term studies on the heaviest nuclei

[en] A new method for optimizing the processing of events from a highly efficient large array γ-ray detector is described in this article. The spherical gates technique, developed to project high-fold events, consists of optimizing n-dimensional gate shape as a function of peak width and shape of each detector. Formulas in closed form are proposed for determining the projected statistics from coincidence fold and peak shape and for estimating the increased quality of projected spectra. This procedure has been tested on high-fold, high statistics data sets including superdeformed cascades. Compared to the classical 'square-gate' technique, better peak-to-background ratios as well as a reduction in fluctuations are observed. A quality parameter is defined to characterize the optimal parameter set. This method leads roughly to a gain in spectral quality equivalent of one fold. It is also shown that the efficiency of the method increases with coincidence fold. This should be particularly suited for future higher-fold data sets. The consequences of a γ-peak profile with a left tailing due to neutron damage is also studied and a method for processing correctly this kind of data is proposed. (author)

[en] Spectroscopy of the proton-odd transfermium isotopes ²⁴⁷Es, ²⁵¹Md and ²⁵⁵Lr has been performed using decay and in-beam techniques. Single particle states have been studied at GANIL and the University of Jyvaeskylae using spectroscopy after α decay of ²⁵⁵Lr. Prompt gamma-ray spectroscopy of ²⁵¹Md and ²⁵⁵Lr was performed at Jyvaeskylae using the Jurogam array coupled to the RITU separator. These experimental results are compared to new Hartree-Fock-Bogoliubov calculations. Future prospects for the study of the heaviest elements at GANIL with the existing facility and the future SPIRAL2 and LINAG beams are presented. (author)

[en] A rotational band has been unambiguously observed in an odd-proton transfermium nucleus for the first time. An in-beam γ-ray spectroscopic study of ₁₀₁²⁵¹Md has been performed using the γ-ray array JUROGAM combined with the gas-filled separator RITU and the focal plane device GREAT. The experimental results, compared to Hartree-Fock-Bogolyubov calculations, lead to the interpretation that the rotational band is built on the [521]1/2^- Nilsson state. (authors)

[en] The goal of the meeting was to discuss the status of experiments using Exogam and its ancillary detectors. Presentations include details of experiments already run and those in preparation. This document gathers most of the slides presented at the meeting. The results of 7 experiments are described. There are 9 contributions as it follows: 1) presentation of the Vamos spectrometer p.1-15, 2) the Clara (detector) and Prisma (spectrometer) setup: status and perspectives p.16-33, 3) experiment E344aS: shape coexistence near the N=Z line and collective properties of Kr isotopes investigated by low-energy Coulomb excitation p.34-56, 4) experiment E389: study of effective charges at Sm¹⁰⁰ via the nuclear lifetime measurements in Pd⁹⁶ and Cd⁹⁸ p.57-68, 5) experiment E375: spectroscopy of trans-fermium nuclei p.69-91, 6) experiment E408S: He⁸ on Pb²⁰⁸ and Bi²⁰⁹ p.92-102, 7) experiment E462: very neutron rich calcium isotopes at N=32, structure of magic Ca⁵⁴ studied by gamma-spectroscopy with deep inelastic reactions p.103-115, 8) experiment E451: searching for T=D pairing and a new coupling scheme in Pd⁹² and Ru⁸⁸ p.116-141, and 9) experiment E404aS: identification of gamma rays in nuclei around the drip-line nucleus Sm¹³⁰, probing the maximally deformed light rare earth region

[en] A new generation of high resolution γ-ray spectrometers capable of recording high-fold coincidence events with a large efficiency will soon be available. Algorithms are developed to analyze high-fold γ-ray coincidences. As a contribution to the software development associated with the EUROGAM spectrometer, the performances of computer codes designed to select multi-dimensional gates from 3-, 4- and 5-fold coincidence databases were tested. The tests were performed on events generated with a Monte Carlo simulation and also on real experimental triple data recorded with the 8π spectrometer and with a preliminary version of the EUROGAM array. (R.P.) 14 refs.; 3 figs.; 3 tabs

[en] This paper describes the results of two complementary experiments which studied the properties of the well-deformed nucleus ¹⁷¹Hf. The first experiment, with a thin self-supporting target, extended the rotational bands built upon the [633]7/2, [512]5/2 and [521]1/2 configurations up to spins of 73/2-85/2ℎ. The configurations of these bands and observed band crossings are discussed within the framework of the cranked-shell model. The second experiment employed a backed target in order to measure the lifetimes, by the Doppler Shift Attenuation method, and thereby establish deformations for some of the states in the collective rotational bands. The extracted deformations are found to be consistent with those predicted from theoretical Total Routhian Surface calculations. These deformations provide strong evidence that the high-spin states in ¹⁷¹Hf, and perhaps more importantly, in the region where the high-K (K^π=19/2⁺ and K^π=23/2^-) isomeric states decay, retain their well-deformed axial symmetry

[en] This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements

[en] The quantum-mechanic nature of nuclear matter is at the origin of the vision of a region of enhanced stability at the upper right end of the chart of nuclei, the so-called ‘island of stability’. Since the 1960s in the early second half of the last century, various models predict closed shells for proton numbers 114–126 and neutron numbers such as 172 or 184. Being stabilized by quantum-mechanic effects only, those extremely heavy man-made nuclear species are an ideal laboratory to study the origin of the strong nuclear interaction which is the driving force for matter properties in many fields ranging from microscopic scales like hadronic systems to cosmic scales in stellar environments like neutron stars. Since the 1950s, experiments on the synthesis of new elements and isotopes have also revealed various exciting nuclear structure features. The contribution of Bohr, Mottelson and Rainwater with, in particular, the development of the unified model played an essential role in this context. Although not anticipated in the region of the heaviest nuclei, many phenomena were subsequently discovered like the interplay of collective features manifesting themselves e.g. in nuclear deformation, ranging from spherical to prolate and oblate shapes with the possible occurrence of triaxial symmetries, and single particle states and their excitation into quasiparticle configurations. The continuous development of modern experimental techniques employing advanced detection set-ups was essential to reveal these exciting nuclear structure aspects in the actinide and transactinide regions since the production cross-section becomes extremely small with increasing mass and charge. Further technological progress, in particular, high intensity stable ion beam accelerator facilities presently under construction, as well as potentially in the farther future radioactive neutron rich ion beams provide a high discovery potential for the basic understanding of nuclear matter. (invited comment)