[en] The main topic of this work is the study of the low-spin and high-spin states of the transitional odd-odd nucleus ¹⁸⁴Au. This nucleus has been studied from the β⁺/CE decay of ¹⁸⁴Hg produced by the ¹⁴⁸Sm(⁴⁰Ar,4n) reaction. The reaction products were then transported by a helium jet system. This nucleus has also been studied from the ¹⁶⁵Ho(²⁴Mg,5n) and ¹⁷⁰Yb(¹⁹F,5n) reactions at the ''Chateau de Cristal'' setup at Orsay. The level schemes of both high and low spin states have been established from γ-γ-t coincidence relationships. Experimental results have been interpreted in the frame of the ''rotor plus two quasi-particles'' model. This calculations have shown that this model, which has his strongest justification in well deformed nuclei regions, reproduces correctly the experimental results for the transitional nucleus ¹⁸⁴Au. The influence of the neutron-proton residual interaction has been studied comparing the different results obtained in the ''rotor+2qp'' calculations with and without taking into account the residual interaction. (author). 60 refs., 54 figs., 10 tabs

[en] The study of nuclei far from stability is constitutive of the history of nuclear physics at its very beginning and has been making considerable great strides since then. The study of these nuclei give the opportunity to reach new information on the nuclear structure and thus to measure the solidity of our knowledge on nuclear matter and its validity when it is pushed to its limits. The reaction selected for the production of exotic nuclei in the framework of the PARRNe program is the fission of uranium 238. The nuclei produced have an intermediate mass and are very rich in neutrons. The technique to recover them in order to accelerate them is the thick target method called also the Isol technique. The installation of the ancient Lep injector at the Tandem line in Orsay (IPN) is expected to increase by a factor 100 the production rate of exotic nuclei in the PARRNe program, it is the Alto project. The work presented here concerns studies carried out at the Lohengrin spectrometer installed at the ILL in Grenoble, and at the Tandem installation in Orsay. This document is divided into 4 parts: 1) in flight techniques at Lohengrin, 2) the Isol technique, 3) magic numbers in the domain N=50, and 4) the Alto project

[en] In order to probe neutron-rich radioactive noble gases produced by photofission, a PARRNe 1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) has been carried out at CERN. The incident electron beam of 50 MeV was delivered by the LIL machine (LEP Injector Linac). The experiment allowed one to compare under the same conditions two production methods of radioactive noble gases: fission induced by fast neutrons and photofission. The obtained results show that the use of the electrons is a promising mode to obtain intense neutron-rich ion beams. Thereafter, with the success of this photofission experiment, a conceptual design for the installation at IPN Orsay of a 50-MeV electron accelerator close to the PARRNe 2 device has been worked out: the ALTO project. This work has started within a collaboration between IPNO, LAL, and CERN groups

[en] In order to probe neutron-rich radioactive noble gases produced by photofission, a PARRNe 1 experiment has been carried out at CERN. The electron beam of 50 MeV was used. The experiment allowed to compare under the same conditions two production methods of radioactive noble gases: fission induced by fast neutrons and photofission. The obtained results show that use of the electrons is a promising mode to get intense neutron-rich ion beams. Thereafter, the success of this photofission experiment, a conceptual design for the installation at IPN Orsay of a 50-MeV electron accelerator device has been worked out: ALTO Project

[en] Full text: The ALTO facility (Accelerateur Lineaire et Tandem d'Orsay) at Institut de Physique Nucleaire d'Orsay is authorized to run at full intensity. The aim of this facility is to provide neutron rich isotope beams for both nuclear physics study (away from the valley of stability) and developments dedicated to next generation facilities such as SPIRAL2. The neutron rich isotopes are produced by photofission of ²³⁸U induced by the 50 deg MeV electrons from the linear accelerator. The isotopes coming out of the fission target effuse towards an ion source to form a beam that is analyzed through the on line separator PARRNe. Additional experimental beam lines have been constructed. First experimental results will be presented. (author)

[en] The ALTO project at IPN Orsay is based on the installation in the experimental area of the Tandem, of a 50 MeV (10 μA) electron accelerator dedicated to the production of neutron rich radioactive beams. About 1011 fission fragments per second are expected to be produced by photofission of a uranium carbide target. The ISOL type device PARRNe will allow a large program of physics from beta decay measurements to mass measurements

[en] The Alto project means the installation of an electron linear accelerator inside the experimental area of the tandem accelerator of the nuclear physics institute of Orsay (IPNO, France). This linear accelerator comes from CERN where it was operating as a pre-injector for LEP. This equipment will allow IPNO'teams to perform fast kinetics studies in a domain different from that of ELYSE accelerator. The time resolution will not be as high as that of ELYSE (picosecond) but will be sufficient (microsecond) to produce free radicals in aqueous and gaseous media. The main expectations of this installation can be classified according 3 axis: 1) basic research (mainly the study of nuclear matter through photo-fission, 2) research and development of accelerators (by providing a test bench for new high frequency systems and superconducting components), and 3) applied research for industry concerning: biochemistry under irradiation, radiation sensibility, DNA breaking, food and drug sterilization and behaviour of electronic components under irradiation. This rapport details the research program that could be achieved with this equipment, describes its contributions in terms of economic development, cooperation with industry, student training, and specifies the needed investment and the operating and maintenance costs. (A.C.)

[en] The ALTO facility (Accelerateur Lineaire et Tandem d'Orsay) at Institut de Physique Nucleaire d'Orsay is under commissioning. The aim of this facility is to provide neutron rich isotope beams for both nuclear physics study (away from the valley of stability) and developments dedicated to next generation facilities such as SPIRAL2. The neutron rich isotopes are produced by photofission of ²³⁸U induced by the 50 MeV electrons from the linear accelerator. The isotopes coming out of the fission target effuse towards an ion source to form a beam that is analyzed through the on line separator PARRNe. Additional experimental beam lines are currently under construction. Experimental data will be presented and compared to simulations. (author)

[en] The PARRNe facility has been used to produce neutron-rich isotopes ^83,84Ga. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The two first excited levels in ⁸³Ge and the first excited level in ⁸⁴Ge, have been measured for the first time

[en] It is determined what extent an axial prolate rotor + 1 or 2 quasiparticle model succeeds in describing the transitional odd and odd-odd Ir and Au nuclei. The relative location of the excited states as well as the properties of the ground and isomeric states, particularly the magnetic and spectroscopic quadrupole moments, are compared to the predictions of the model