Probing the 6He halo structure with elastic and inelastic proton scattering

Proton elastic scattering and inelastic scattering to the first excited state of 6He have been measured over a wide angular range using a 40.9A MeV 6He beam. The data have been analyzed with a fully microscopic model of proton-nucleus scattering using 6He wave functions generated from large space shell model calculations. The inelastic scattering data show a remarkable sensitivity to the halo structure of 6He.Comment: 9 pages, 3 figures. RevTeX. Replaced figure 3 with updated figur

Virtual coupling potential for elastic scattering of 10,11^{10,11}Be on proton and carbon targets

International audienceThe 10;11Be(p,p) and (12C, 12C) reactions were analyzed to determine the in uence of the weak binding energies of exotic nuclei on their interaction potential. The elastic cross sections were measured at GANIL in inverse kinematics using radioactive 10;11Be beams produced at energies of 39:1 A and 38:4A MeV. The elastic proton scattering data were analyzed within the framework of the microscopic Jeukenne-Lejeune-Mahaux (JLM) nucleon-nucleus potential. The angular distributions are found to be best reproduced by reducing the real part of the microscopic optical potential, as a consequence of the coupling to the continuum. These effects modify deeply the elastic potential. Including the Virtual Coupling Potential (VCP), we show the ability of the general optical potentials to reproduce the data for scattering of unstable nuclei, using realistic densities. Finally, the concepts needed to develop a more general and microscopic approach of the VCP are discussed

Coupling effects in the elastic scattering of 6^{6}He on 12^{12}C

To study the effect of the weak binding energy on the interaction potential between a light exotic nucleus and a target, elastic scattering of 6He at 38.3 MeV/nucleon on a 12C target was measured at Grand Accélérateur National d'Ions Lourds (GANIL). The 6He beam was produced by fragmentation. The detection of the scattered particles was performed by the GANIL spectrometer. The energy resolution was good enough to separate elastic from inelastic scattering contributions. The measured elastic data have been analyzed within the optical model, with the real part of the optical potential calculated in the double-folding model using a realistic density-dependent nucleon-nucleon interaction and the imaginary part taken in the conventional Woods-Saxon (WS) form. A failure of the "bare" real folded potential to reproduce the measured angular distribution over the whole angular range suggests quite a strong coupling of the higher-order breakup channels to the elastic channel. To estimate the strength of the breakup effects, a complex surface potential with a repulsive real part (designed to simulate the polarization effects caused by the projectile breakup) was added to the real folded and imaginary WS potentials. A realistic estimate of the polarization potential caused by the breakup of the weakly bound 6He was made based on a parallel study of 6He+12C and 6Li+12C optical potentials at about the same energies

XPAD: A Photons Counting Pixel Detector for Material Sciences and Small Animal imaging

A paraître dans NIMInternational audienceExperiments on high flux and high brilliance 3rd generation synchrotron X-ray sources are now limited by detector performance. Photon counting hybrid pixel detectors are being investigated as a solution to improve the dynamic range and the readout speed of the available 2D detectors. The XPAD2 is a large surface hybrid pixel detector (68 x 65 mm$^2$) with a dynamic response which ranges from 0.01 photons/pixel/s up to 10$^6$ photons/pixel/s. High resolution data have been recorded using the XPAD2. The comparison with data measured using a conventional setup shows a gain on measurement duration by a factor 20 and on dynamic range. A new generation of pixel detector (XPAD3) is presently under development. For this, a new electronic chip (the XPAD3) has been designed to improve spatial resolution by using 130 $\mu$m pixels and detector efficiency by using CdTe sensors. XPAD2 is also operated with PIXSCAN, a CT-scanner for mice

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The hybrid pixel single photon counting detector XPAD

International audienceThe XPAD detector is a 2D X-ray imager based on hybrid pixel technology, gathering 38400 pixels on a surface of 68*68 mm(2). It is a photon counting detector, with low noise, wide dynamic range and high speed read out, which make it particularly suitable for third generation synchrotron applications, such as diffraction, small angle X-ray scattering or macro-molecular crystallography, but also for small animal imaging. High resolution powder diffraction data and in situ scattering data of crystallization of liquid oxides are presented to illustrate the properties of this detector, resulting in a significant gain in data acquisition time and a capability to follow fast kinetics in real time experiments. The characteristics of the future generation of XPAD detector, which will be available in 2007, are also presented