Beam asymmetry and differential cross-section for the reaction gamma p -> eta p were measured from production threshold to 1500MeV photon laboratory energy. The two dominant neutral decay modes of the eta-meson, eta -> 2 gamma and eta -> 3 pi(0) , were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.

Beam asymmetries and hyperon recoil polarizations for the reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma(0) have been measured from the threshold production to 1500 MeV with the GRAAL facility located at the ESRF in Grenoble. These results complement the database for the beam asymmetry, covering for the first time the production threshold region. Recent theoretical analyses are presented for which the beam asymmetry data bring interesting new information and allow to better determine some resonance parameters. Most importantly, these results strengthen the need of a new D-13 state around 1900 MeV.

POLAREX (POLARization of EXotic nuclei) is a new facility for the study of nuclear magnetic moments and decay modes of exotic nuclei using the established On-Line Nuclear Orientation (OLNO) method. A radioactive beam of interest is implanted into a ferromagnetic host foil held at a temperature of order 10mK in a (3)He - (4)He dilution refrigerator. The foil is magnetized by an applied magnetic field and the nuclear spins become polarized through the internal hyperfine field. The angular distribution of decay products from the polarized sample is measured. Accurate values of nuclear moment are obtained by NMR. The new facility will have access to neutron-rich nuclides produced at the ALTO facility (Linear Accelerator at Orsay Tandem) by fission induced by electrons from the linear electron accelerator. Basic concepts and initial tests are outlined.

This study is a part of an experimental program to measure nuclear moments in transfer reactions. It aims to probe for a first time the nuclear -spin orientation in multi-nucleon transfer. Fist experiments were performed to measure the quadrupole moment of an isomeric state in (66)Cu (I(pi) = 6, E(x) = 1154 keV, T (1/2) = 595(20) ns) in single nucleon transfer and the population of mu s isomers in (66)Cu and (63)Ni in multi-nucleon transfer. The experimentally tested methodology allows broad applications toward more ex otic species and feasibility of these reactions to produce species away from stability.

The N =3D 52(83) Ga beta decay was studied at ALTO. The radioactive Ga-83 beam was produced through the ISOL photofission technique and collected on a movable tape for the measurement of gamma-ray emission following beta decay. While beta-delayed neutron emission has been measured to be 56-85% of the decay path, in this experiment an unexpected high-energy 5-9MeV gamma-ray yield of 16(4)% was observed, coming from states several MeVs above the neutron separation threshold. This result is compared with cutting-edge QRPA calculations, which show that when neutrons deeply bound in the core of the nucleus decay into protons via a Gamow-Teller transition, they give rise to a dipolar oscillation of nuclear matter in the nucleus. This leads to large electromagnetic transition probabilities which can compete with neutron emission, thus affecting the beta-decay path. This process is enhanced by an excess of neutrons on the nuclear surface and may thus be a common feature for very neutron-rich isotopes, challenging the present understanding of decay properties of exotic nuclei. (C) 2017 The Author(s). Published by Elsevier B.V.

The TETRA long neutron counter is operated at ALTO ISOL facility behind the PARRNe mass separator. TETRA has been proven to be a unique instrument for measurements of beta-decay properties of short-lived neutron-rich nuclei having applications for the nuclear structure and/or astrophysical r-process calculations. A proper calibration of TETRA can allow validation of the experimental procedure used for determination of beta-delayed one-neutron emission probabilities (P-1n). It requires the use of a well-known beta-neutron decaying radioactive source which can be only produced and measured on-line due to its short half-life. Thus, the present paper reports on measurements of P-1n and T(1/2 )of Rb-96,Rb-97 nuclei using TETRA. The results obtained are in a good agreement with the values available in the literature. This proves that the developed techniques can be applied to unknown P-1n and T-1/2 of neutron-rich species.

The features of the Graal experiment at ESRF are presented. The obtained results are discussed and future developments outlined. The Graal experiment started data taking in 1997. It was run for one year with the green laser line giving rise to a photon beam of maximum energy of 1100 MeV and for one year with UV multi-line and the corresponding gamma-ray beam of 1470 MeV maximum energy. Asymmetry data and cross sections have been produced for eta, pi 0 and pi + photoproduction channels providing, for these reactions, the most extended and coherent data base available until now. Future developments of the experiment will include the study of the same channels with deuteron target and the study of the photoreaction mechanism on the quasi-free neutron. The use of a polarised target of new concept will allow to access double polarisation observables for meson photoproduction on polarised proton and polarised neutron. Finally the increase in the maximum photon energy, up to 1.8 GeV will allow to study in details eta' photoproduction and to reach the threshold for scalar mesons production

High-precision mass measurements have been performed on the exotic magnesium isotopes Mg29-33 using the MISTRAL radiofrequency spectrometer, especially suited for very short-lived nuclides. This method, combined with the powerful tool of resonant laser ionization at ISOLDE, has provided a significant reduction of uncertainty for the masses of the most exotic Mg isotopes: a relative error of 7x10(-7) was achieved for the weakly produced Mg-33 that has a half-life of only 90 ms. Moreover, the mass of Mg-33 is found to change by over 250 keV. Verifying and minimizing binding energy uncertainties in this region of the nuclear chart is important for understanding the lack of binding energy that is normally associated with magic numbers.

The double polarization (beam-recoil) observables O(x) and O(z) have been measured for the reaction gamma p -> K(+) Lambda from threshold production to E gamma similar to 1500 MeV. The data were obtained with the linearly polarized beam of the GRAAL facility. Values for the target asymmetry T could also be extracted despite the use of an unpolarized target. Analyses of our results by two isobar models tend to confirm the necessity to include new or poorly known resonances in the 1900 MeV mass region.

We have measured the spectroscopic quadrupole moment of the 6(-) isomeric state in (66)Cu to be vertical bar Q(s)vertical bar = 18.6(12) efm(2). This state results from a weak coupling of the pi p(3/2) and the nu g(9/2) orbitals, which lead to sizable deformation at oblate and prolate shapes, correspondingly, in the (68)Ni region. The interplay between these two different deformation-driving orbitals is observed at N = 37 for the 6(-) state resulting in a most probable oblate shape. (C) 2010 Elsevier B.V. All rights reserved.

In the context of nuclear orientation, we propose a new method to correct the multipole mixing ratios for asymmetries in the geometry of the setup but also in the detection system. This method is also robust against temperature fluctuations, beam intensity fluctuations and uncertainties in the nuclear structure of the nuclei. Additionally, this method provides a natural way to combine data from different detectors and make good use of all available statistics. We could use this method to demonstrate the accuracy that can be reached with the PolarEx setup now installed at the ALTO facility.