Contribution à l'étude des variations de la composition du lait et leurs conséquences en technologies laitières

Le lait est une matière première aux ressources considérables mais dont la composition est variable. Le but de cette thèse est d'étudier les variations des différents composants du lait en fonction de facteurs intrinsèques (liés à l'animal : race, stade de lactation,...) et des facteurs extrinsèques (liés à l'environnement : alimentation,saison, technique de récolte et de traitement du lait) de la production laitière. Cette étude permet en parallèle d'approcher les différentes techniques utilisées par les intervenants de la filière : éleveurs, industriels laitiers, qui permettent de fabriquer, à partir d'une matière première variable, des produits laitiers aux caractéristiques constantes et répondant aux exigences des consommateurs. Seront en particulier envisagés, l'importance des recherches en matière de génétique animale pour améliorer le rendement de la lactation, et l'utilisation, en industrie laitière, des techniques de séparation par membrane pour séparer les différents constituants du lait

Strong polarization of the residual nucleus in a heavy-ion induced transfer reaction

A strong polarization of 20Ne levels has been observed in the 16O(16O, 12C)20Ne* reaction along an axis perpendicular to the reaction plane. This polarization differs from that reported in the (7Li, t) reaction, when the same nuclear levels were populated. D.W.B.A. calculations which fitted both angular distributions and polarization in the (7Li, t) reaction and which can also describe the (16O, 12C) angular distributions fail to reproduce the associated 20Ne* polarization

Low Energy States of 3181Ga50^{81}_{31} Ga_{50} : Elements on the Doubly-Magic Nature of 78^{78}Ni

Excited levels were attributed to $^{81}_{31}$Ga$_{50}$ for the first time which were fed in the $\beta$-decay of its mother nucleus $^{81}$Zn produced in the fission of $^{nat}$U using the ISOL technique. We show that the structure of this nucleus is consistent with that of the less exotic proton-deficient N=50 isotones within the assumption of strong proton Z=28 and neutron N=50 effective shell effects.Comment: 4 pages, REVTeX 4, 5 figures (eps format

Discovery of the Vanadium Isotopes

Twenty-four vanadium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.Comment: to be published in At. Data. Nucl. Data Table

Excited states of 19N and 21O

(18O, 19N) and (18O, 21O) nuclear reactions on a 18O target provide measurements of excited state energies at 1.12 and 1.59 MeV for 19N and at 1.35 and 3.00 MeV for 21O. The 19N mass is remeasured as 15.856 ± 0.050 MeV

Discovery of the Cobalt Isotopes

Twenty-six cobalt isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.Comment: to be published in Atomic Data and Nuclear Data Table

On the discovery of doubly-magic 48^{48}Ni

The paper reports on the first observation of doubly-magic Nickel-48 in an experimental at the SISSI/LISE3 facility of GANIL. Four Nickel-48 isotopes were identified. In addition, roughly 100 Nickel-49, 50 Iron-45, and 290 Chromium-42 isotopes were observed. This opens the possibility to search for two-proton emission from these nuclei.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let

Collapse of the N=28 shell closure in 42^{42}Si

The energies of the excited states in very neutron-rich $^{42}$Si and $^{41,43}$P have been measured using in-beam $\gamma$-ray spectroscopy from the fragmentation of secondary beams of $^{42,44}$S at 39 A.MeV. The low 2$^+$ energy of $^{42}$Si, 770(19) keV, together with the level schemes of $^{41,43}$P provide evidence for the disappearance of the Z=14 and N=28 spherical shell closures, which is ascribed mainly to the action of proton-neutron tensor forces. New shell model calculations indicate that $^{42}$Si is best described as a well deformed oblate rotor.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. let

Release properties of UCx_x and molten U targets

The release properties of UC$_x$ and molten U thick targets associated with a Nier- Bernas ion source have been studied. Two experimental methods are used to extract the release time. Results are presented and discussed for Kr, Cd, I and Xe