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The decay of 123Ba to 123Cs has been studied with mass-separated sources. Singles spectra of γ-rays, X-rays and conversion electrons as well as γ - γ - t, γ - e- - t, and X - e- - t coincidences were recorded. A level scheme of 123Cs has been constructed including 26 new excited states and 82 transitions. The existence of a Iπ = 11/2-, T1/2 = 1.7 s isomer, bandhead of the h11/2 band, is confirmed. Its excitation energy equals 156.3 keV. A new T1/2 = 114 ns isomer has been established at 232 keV using the in-beam recoil catcher technique. It is assigned to the Iπ = 9/2+ bandhead of the πg9/2 band. Collective bands based on the 1/2+ ground state and first 3/2+ excited state are proposed. The level structure is described in the frame of the interacting boson-fermion and core-quasiparticle coupling models., SCOPUS: ar.j, info:eu-repo/semantics/published

The 176Lu properties as a cosmochronometer and a cosmothermometer are studied, combining Coulomb excitation with the recoil method. The results confirm that this isotope should be dismissed as a reliable cosmochronometer. On the other hand, this nucleus synthesis takes place, in all probability, at temperatures between 2.3510 and 3.62× 108 K. The assignment of the levels reached leads to some difficulties as to their reduced transition probabilities., SCOPUS: ar.j, info:eu-repo/semantics/published

The 176Lu properties as a cosmochronometer and a cosmothermometer are studied, combining Coulomb excitation with the recoil method. The results confirm that this isotope should be dismissed as a reliable cosmochronometer. On the other hand, this nucleus synthesis takes place, in all probability, at temperatures between 2.3510 and 3.62× 108 K. The assignment of the levels reached leads to some difficulties as to their reduced transition probabilities., SCOPUS: ar.j, info:eu-repo/semantics/published

The [Formula Presented] properties as a cosmochronometer and a cosmothermometer are studied, combining Coulomb excitation with the recoil method. The results confirm that this isotope should be dismissed as a reliable cosmochronometer. On the other hand, this nucleus synthesis takes place, in all probability, at temperatures between [Formula Presented] and [Formula Presented] The assignment of the levels reached leads to some difficulties as to their reduced transition probabilities. © 2000 The American Physical Society., SCOPUS: ar.j, info:eu-repo/semantics/published

A brief introductory survey of γ-ray detector arrays and in-beam electron spectrometers developed during the last three lustra is followed by a broad discussion of the general requirements for single and multiple in-beam e-γ spectrometers. A detailed analysis is made of a few important tools for reducing the low-energy electron background (i.e. simultaneous E-Bp selection, true and random coincidence rates, EM static fields around the target region). This survey and discussion are illustrated by the results of several in-beam e-γ measurements dealing with nuclear spectroscopic investigations of a few medium and heavy nuclei. © 1999 Elsevier Science B.V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

The 191Pb isotope, produced through different A(b,xn) 191Pb reactions, where b stands for nuclei such as 16O, 20Ne, and 31P, is studied. The half-life of some excited levels being greater than 10 ns, the recoil catcher method is suitable to look into the de-excitation γ ray and conversion electron spectra of these states. The conversion coefficients are deduced and e--γ and γ-γ coincidence measurements lead to the part of the level scheme de-exciting these isomers. This level scheme is compared to theoretical predictions obtained through a microscopic calculation in a three quasi-particle approximation, using a surface delta interaction with a reduced pairing component. The conclusions are very similar to those previously obtained for 193Pb. © 1999 Elsevier Science B.V., SCOPUS: ar.j, info:eu-repo/semantics/published

A few accelerated ion beam requirements for in-beam e-γ spectroscopy are briefly reviewed as well as several features of the MP Tandem accelerator of IPN-Orsay and the accelerated ion-beam transport devices leading to the experimental area of in-beam e-γ spectroscopy. In particular, the main capabilities of the ion-sources, the ion pulsing system, the ion stripping and stabilizing devices as well as the versatility of the ion beam transport system are discussed from the point of view of the different kinds of in-beam e-γ experiments performed in that area. © 1998 Elsevier Science B.V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

The main features of nuclear targets, recoil ion catchers and reaction chambers used in nuclear spectroscopic investigations involving in-beam multi-e-γ spectrometers are discussed. The relative importance of the δ-ray background due to the accelerated ion-target and the recoil-ion-target interaction is estimated. Its impact on the prompt low-energy electron measurements is stressed. Finally a few general features of the interplay between accelerated ion beams, targets and recoil ion catchers particularly relevant for these measurements are broadly discussed and illustrated with typical examples of in-beam e-γ studies. © 1998 Elsevier Science B. V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Fysik, ExpNP

Fysik, ExpNP

Fysik, ExpNP

Fysik, ExpNP

The 193Pb and 192Pb isotopes are produced through the 182W(16O, 5n, 6n) reactions. The de-excitation γ-ray and conversion electron spectra lead to the conversion coefficients for most transitions. With the results of the γγ and e-γ coincidences, the half-lives measured for several states, the angular distribution coefficients for the odd isotope and the transition multipolarities, the data on the 192Pb level scheme has been much enhanced and the 193Pb one studied for the first time. The experimental schemes are compared to those given by microscopic calculations, in a two or three quasi-particle approximation using a surface delta interaction with a reduced pairing component. The discrepancies between theory and experiment are attributed to the increasing influence of proton configurations. © 1991., SCOPUS: ar.j, info:eu-repo/semantics/published

The γ and conversion electron de-excitation spectra of nuclei, produced through (HI, χn) reactions, are spoiled by various phenomena, most of them related to the reaction itself. When, in the isotopes studied, one or several isomers are present, the half-life of the higher energy one being about 15 ns or more, then the compound nucleus recoil method can provide much cleaner spectra. This method is extensively described and discussed here, together with others, more briefly treated, also meant to reduce the unwanted effects; these techniques may be used either separately or combined, depending on the experiments performed. Examples of the results obtained are shown to illustrate the substantial improvements reached. © 1988., SCOPUS: ar.j, info:eu-repo/semantics/published

The 198Pb and 197Pb isotopes are produced through the 186W(16O, 4n, 5n) reactions. Conversion-electron, γ- and X-ray spectra are measured using the compound-nucleus recoil method. Conversion coefficients and multipolarities are deduced for a large number of transitions. Together with angular distribution measurements and the results of γγt multidimensional coincidences they lead to decay schemes for the two isotopes. Microscopic calculations, performed in the two- or three-quasiparticle approximation with a surface delta interaction, fail to reproduce completely the observed properties, showing similar defects for the odd and even isotope. © 1985., SCOPUS: ar.j, info:eu-repo/semantics/published

The de-excitation of the 200Pb and 199Pb isotopes, produced through the 186W(18O,4n, 5n) reactions, is investigated using γ-ray and conversion electron spectroscopy. The conversion coefficients are measured and the multipolarities deduced for a great number of transitions. The e-γ- and γγ-coincidences and the half-life measurements lead to several new levels in both level schemes; the 200Pb one is extended up to nearly 7 MeV, where an isomer is found. The experimental results are compared to those of microscopic calculations, performed in a two or three quasi-particle approximation, using a surface delta interaction with a reduced pairing component. © 1988., SCOPUS: ar.j, info:eu-repo/semantics/published

A review of in-beam electron-gamma-ray coincidence measurements in nuclear spectroscopy particularly influenced by target properties is outlined. To illustrate such an influence, aspects of the recoil ion catcher method for the study of short lived nuclear isomers performed at the Orsay MP-tandem accelerator, are reported. This method is operated with a pulsed heavy-ion beam bombarding a thin self-supported target but avoiding to hit the catcher foil. The required characteristics of the targets and recoil ion stopper foils needed for these measurements are analyzed in detail for a few typical experimental arrangements. © 1989., SCOPUS: ar.j, info:eu-repo/semantics/published

A review of in-beam electron-gamma-ray coincidence measurements in nuclear spectroscopy particularly influenced by target properties is outlined. To illustrate such an influence, aspects of the recoil ion catcher method for the study of short lived nuclear isomers performed at the Orsay MP-tandem accelerator, are reported. This method is operated with a pulsed heavy-ion beam bombarding a thin self-supported target but avoiding to hit the catcher foil. The required characteristics of the targets and recoil ion stopper foils needed for these measurements are analyzed in detail for a few typical experimental arrangements. © 1989., SCOPUS: ar.j, info:eu-repo/semantics/published