70 research outputs found
Folding model analysis of proton scattering from O nuclei
The elastic and inelastic proton scattering on O nuclei are
studied in a folding model formalism of nucleon-nucleus optical potential and
inelastic form factor. The DDM3Y effective interaction is used and the ground
state densities are obtained in continuum Skyrme-HFB approach. A
semi-microscopic approach of collective form factors is done to extract the
deformation parameters from inelastic scattering analysis while the microscopic
approach uses the continuum QRPA form factors. Implications of the values of
the deformation parameters, neutron and proton transition moments for the
nuclei are discussed. The p-analyzing powers on O nuclei are also
predicted in the same framework.Comment: 8 pages, 5 figure
Detecting bubbles in exotic nuclei
The occurrence of a bubble, due to an inversion of s state with the
state usually located above, is investigated. Proton bubbles in neutron-rich
Argon isotopes are optimal candidates. Pairing effects which can play against
the bubble formation are evaluated. They cannot prevent bubble formation in
very neutron-rich argon isotopes such as Ar. This pleads for a
measurement of the charge density of neutron-rich argon isotopes in the
forthcoming years, with the advent of electron scattering experiments in next
generation exotic beam facilities such as FAIR or RIBF.Comment: 6 pages, 5 figures, to be published in Nucl. Phys.
Charge and current-sensitive preamplifiers for pulse shape discrimination techniques with silicon detectors
New charge and current-sensitive preamplifiers coupled to silicon detectors
and devoted to studies in nuclear structure and dynamics have been developed
and tested. For the first time shapes of current pulses from light charged
particles and carbon ions are presented. Capabilities for pulse shape
discrimination techniques are demonstrated.Comment: 14 pages, 12 figures, to be published in Nucl. Inst. Meth.
Low-lying states and structure of the exotic He via direct reactions on the proton
International audienceThe structure of the light exotic nucleus 8He was investigated using direct reactions of the 8He SPIRAL beam on a proton-rich target. The (p,p') scattering to the Click to view the MathML source state, the (p,d)7He and (p,t)6He transfer reactions, were measured at the energy Elab=15.7 A.MeV. The light charged particles (p,d,t) were detected in the MUST Si-strip telescope array. The excitation spectrum of 8He was extracted from the (p,p') reaction. Above the known Click to view the MathML source excited state at 3.6 MeV, a second resonance was found around 5.4 MeV. The cross sections were analyzed within the coupled-reaction channels framework, using microscopic potentials. It is inferred that the 8He ground state has a more complex neutron-skin structure than suggested by previous α+4n models assuming a pure (1p3/2)4 configuration
The N=14 shell closure in O viewed through a neutron sensitive probe
NESTER PTHInternational audienceTo investigate the behavior of the N=14 neutron gap far from stability with a neutron-sensitive probe, proton elastic and 2+1 inelastic scattering angular distributions for the neutron-rich nucleus 22O were measured with a secondary beam intensity of only 1200 particles per second using the MUST silicon strip detector array at the GANIL facility. A phenomenological analysis yields a deformation parameter bp;p' = 0.26 +- 0.04 for the 2+1 state, much lower than in 20O, showing a surprisingly weak neutron contribution to this state. A fully microscopic analysis was performed using optical potentials obtained from matter and transition densities generated by continuum Skyrme-HFB and QRPA calculations, respectively. When the present results and those from a 22O + 197Au scattering experiment are combined, the ratio of neutron to proton contributions to the 2+1 state is found close to the N/Z ratio, demonstrating a strong N=14 shell closure in the vicinity of the neutron drip-line
Experimental evidence for subshell closure in He and indication of a resonant state in He below 1 MeV
NESTERThe spectroscopy of the unstable He and unbound He nuclei is investigated via the p(He, d) transfer reaction with a 15.7A MeV He beam from the SPIRAL facility. The emitted deuterons were detected by the telescope array MUST. The results are analyzed within the coupled-channels Born approximation framework, and a spectroscopic factor S=4.4±1.3 for neutron pickup to the He_g.s.^{8}^{7}E^*\GammaE^*$=2.9±0.1 MeV. Both are in agreement with previous separate measurements. The reproduction of the first excited state below 1 MeV would be a challenge for the most sophisticated nuclear theories
Inverse kinematics proton scattering from the exotic nucleus O
NESTER PTHInternational audienceWe have measured for the first time elastic and inelastic proton scattering from the neutron rich nucleus 22O at 46.6 AMeV using the MUST array
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
The spatial development of hadronic showers in the CALICE scintillator-steel
analogue hadron calorimeter is studied using test beam data collected at CERN
and FNAL for single positive pions and protons with initial momenta in the
range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron
showers are parametrised with two-component functions. The parametrisation is
fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics
lists from Geant4 version 9.6. The parameters extracted from data and simulated
samples are compared for the two types of hadrons. The response to pions and
the ratio of the non-electromagnetic to the electromagnetic calorimeter
response, h/e, are estimated using the extrapolation and decomposition of the
longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to
JINS
The Time Structure of Hadronic Showers in highly granular Calorimeters with Tungsten and Steel Absorbers
The intrinsic time structure of hadronic showers influences the timing
capability and the required integration time of hadronic calorimeters in
particle physics experiments, and depends on the active medium and on the
absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15
small plastic scintillator tiles read out with Silicon Photomultipliers, the
time structure of showers is measured on a statistical basis with high spatial
and temporal resolution in sampling calorimeters with tungsten and steel
absorbers. The results are compared to GEANT4 (version 9.4 patch 03)
simulations with different hadronic physics models. These comparisons
demonstrate the importance of using high precision treatment of low-energy
neutrons for tungsten absorbers, while an overall good agreement between data
and simulations for all considered models is observed for steel.Comment: 24 pages including author list, 9 figures, published in JINS
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