In this contribution, we will present our first preliminary measurement of the differential cross section for the reaction gamma eta -> eta n. Comparison of the reactions gamma p -> eta p for free and bound proton (D(2) target) will also be discussed.

The GRAAL facility produces a highly polarized gamma-ray beam by Compton scattering of laser photons on the electrons of the European Synchrotron Radiation Facility (ESRF) at Grenoble. Preliminary results have been obtained with the LAGRANGE detector showing its excellent performances

Precision measurements of particle electric dipole moments (EDMs) provide extremely sensitive means to search for non-standard mechanisms of T (or CP) violation. For the neutron EDM, the upper limit has been reduced by eight orders of magnitude in 50 years thereby excluding several CP violation scenarios. We report here on a new effort aiming at improving the neutron EDM limit by two orders of magnitude, down to a level of 3 x 10(-28) e center dot cm. The two central elements of the approach are the use of the higher densities which will be available at the new dedicated spallation UCN source at the Paul Scherrer Institute, and the optimization of the in-vacuum Ramsey resonance technique, with storage chambers at room temperature, to reach new limits of sensitivity.

In the framework of investigation of meson photo-production on proton and neutron in a deuterium target at the GRAAL experiment, we present a method to identify the vertex of interaction when in reaction products there are at least two charged particles, by the information provided by the cylindrical multiwire proportional chambers. By this device, we are able to obtain the direction of charged particles that leave the target after a photo-production reaction. For each charged particle, the device provides the coordinates of two points in the laboratory reference system, and the z-axis represents the beam direction. We calculate the trajectory of each charged particle and its cross point, representing the vertex of the reaction.

The Sigma beam asymmetry in the photoproduction of neutral pions from quasi-free nucleons in a deuteron target was measured for the first time between 0.60 and 1.50 GeV, with the GRAAL polarized and tagged photon beam. The asymmetry values from the quasi-free proton were found equal to the ones extracted from a pure proton target. The asymmetries from quasi-free proton and quasi-free neutron were found equal up to 0.82 GeV and substantially different at higher energies. The results are compared with recent partial-wave analyses.

The static polarization of HD samples has been achieved using "brute force", for HD samples purified by double distillation. Proton polarization in excess of 60% and deuteron vector polarization higher than 14% have been reached. It has been demonstrated that the ageing technique allows to get relaxation times at 1.5 K and 1 T larger than a week. It is advocated that the conventional dynamic polarization of HD should be feasible for the proton and the deuteron contained in the HD molecule. This would simplify considerably the machinery presently necessary to perform nuclear physics experiments with HD targets polarized by the static method

The gamma p -> eta'p reaction was studied near the threshold, in the 1.44 GeV > E(gamma) < 1.55GeV energy range with the tagged photons of the former GRAAL experiment. The two neutral decays gamma gamma(Gamma(i)/Gamma = 2.10 +/- 0.12%) and pi(0)pi(0)eta(Gamma(i)/Gamma = 20.7 +/- 1.2%) were analized and preliminary results of the beam asymmetry were extracted together with the invariant masses.

The existence of a mirror world holding a copy of our ordinary particle spectrum could lead to oscillations between the neutron (n) and its mirror partner (n'). Such oscillations could manifest themselves in storage experiments with ultracold neutrons whose storage lifetime would depend on the applied magnetic field. Here, extended details and measurements from the first dedicated experimental search for nn' oscillations published in [G. Ban, K. Bodek, M. Daum, R. Henneck, S. Heule, M. Kasprzak, N. Khomutov, K. Kirch, S. Kistryn, A. Knecht, P. Knowles, M. Kuzniak, T. Lefort, A. Mtchedlishvili, O. Naviliat-Cuncic, C. Plonka, G. Quemener, M. Rebetez, D. Rebreyend, S. Roccia, G. Rogel, M. Tur, A. Weis, J. Zejma, G. Zsigmond, Direct experimental limit on neutron mirror-neutron oscillations, Phys. Rev. Lett. 99 (2007) 1616031 will be presented, focussing on a possible dependence of the UCN counts on the magnetic field and its direction. However, at present no significant change in the averaged UCN counts with respect to the applied magnetic field has been found. (C) 2009 Elsevier B.V. All rights reserved

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.

Compton backscattering gamma ray beams are characterized by a high degree of linear and circular polarization with low unpolarized backgrounds and have proven to provide very precise measurements of polarization observables. Latest results from LEGS and GRAAL experiments on proton and deuteron targets are presented. The Sigma beam asymmetry for omega photoproduction has been measured by the GRAAL collaboration for both the omega -> pi(0)gamma and the omega -> pi(+)pi(+)pi(0) decay channels on the proton target; single and double polarization asymmetries have been provided also for the K photoproduction channel. E and G double polarization asymmetries for single pion photoproduction on the proton and deuteron have been measured at LEGS using a frozen spin HD target.

The preliminary results obtained by the GRAAL collaboration for the pi(0)pi(+) photoproduction on the free and quasi-free proton (deuteron) at E(gamma) = 0.7-1.5 GeV are presented. The total cross section of the gamma p -> pi(0)pi(+)n reaction and invariant mass spectra for the pi(+)pi(0), pi(+)n and pi(0)n systems are presented in the photon energy range from 0.7 to 1.5 GeV. These results are in good agreement with the 2 pi-MAID calculations.

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.

The effort towards a new measurement of the neutron electric dipole moment (nEDM) at the Paul Scherrer Institut's (PSI) new high intensity source of ultracold neutrons (UCN) is described. The experimental technique relies on Ramsey's method of separated oscillatory fields, using UCN in vacuum with the apparatus at ambient temperature. In the first phase, R&D towards the upgrade of the RAL/Sussex/ILL apparatus is being performed at the Institut Laue-Langevin (ILL). In the second phase the apparatus, moved from ILL to PSI, will allow an improvement in experimental sensitivity by a factor of 5. In the third phase, a new spectrometer should gain another order of magnitude in sensitivity. The improvements will be mainly due to (1) much higher UCN intensity, (2) improved magnetometry and magnetic field control, and (3) a double chamber configuration with opposite electric field directions. (C) 2009 Elsevier B.V. All rights reserved.

We report on a comparison of spin relaxation rates in a Hg-199 magnetometer using different wall coatings. A compact mercury magnetometer was built for this purpose. Glass cells coated with fluorinated materials show longer spin coherence times than if coated with their hydrogenated homologues. The longest spin relaxation time of the mercury vapor was measured with a fluorinated paraffin wall coating.