65 research outputs found
Complex scaling method for three- and four-body scattering above the break-up thresholds
A formalism based on the complex-scaling method is presented to solve the few
particle scattering problem in configuration space using bound state techniques
with trivial boundary conditions. Several applications to A=3,4 systems are
presented to demonstrate the efficiency of the method in computing elastic as
well as break-up reactions with Hamiltonians including both short and
long-range interaction.Comment: FB20 conference proceeding
Elastic proton scattering on tritium below the n- threshold
Elastic proton scattering on nucleus is studied inbetween p-%
and n- thresholds, in the energy region where
-particles first excited state is inbeded in the continuum. For this
aim Faddeev-Yakubovski equations are solved in configuration space, fully
considering effects due to the isospin breaking as well as rigorously treating
Coulomb interaction. Different realistic nuclear Hamiltonians are tested,
elucidating open problems in nuclear interaction description.Comment: 13 pages,3 figure
Modelling double charge exchange response function for tetraneutron system
This work is an attempt to model the response function of a recent RIKEN
experimental study of the double charge exchange He(He,Be)n
reaction in order to put in evidence an eventual enhancement mechanism of the
zero energy cross section, including a near-threshold resonance. This resonance
can indeed be reproduced only by adding to the standard nuclear Hamiltonian an
unphysically large T=3/2 attractive 3n-force which destroys the neighboring
nuclear chart. No other mechanisms like cusps or related structures were found
Time Reversal Invariance Violating and Parity Conserving effects in Proton Deuteron Scattering
Time reversal invariance violating parity conserving (TVPC) effects are
calculated for elastic proton deuteron scattering with proton energies up to
MeV. Distorted Wave Born Approximation is employed to estimate TVPC matrix
elements, based on hadronic wave functions, obtained by solving three-body
Faddeev-Merkuriev equations in configuration space with realistic potentials
Search for new physics with neutrinos at Radioactive Ion Beam facilities
We propose applications of Radioactive Ion Beam facilities to investigate
physics beyond the Standard Model. In particular, we focus on the possible
measurement of coherent neutrino-nucleus scattering and on a search for sterile
neutrinos, by means of a low energy beta-beam with a Lorentz boost factor
. In the considered setup the collected radioactive ions are
sent inside a 4 detector. For the first application we provide the number
of events associated with neutrino-nucleus coherent scattering, when the
detector is filled in with a noble liquid. For the sterile search we consider
that the spherical detector is filled in with a liquid scintillator, and that
the neutrino detection channel is inverse-beta decay. We provide the exclusion
curves for the sterile neutrino mixing parameters, based upon the 3+1
formalism, depending upon the achievable ion intensity. Our results are
obtained both from total rates, and including spectral information with binning
in energy and in distance. The proposed experiment represents a possible
alternative to clarify the current anomalies observed in neutrino experiments.Comment: 9 pages, 6 figures. v2 - added 2 figure
Etude de la diffusion de particules lourdes sur des systèmes atomiques et nucléaires
In this thesis quantum mechanical non-relativistic few-body problem is discussed. Basing on fundamentals ideas of Faddeev and Yakubovski three and four body equations are formulated and solved for fermionic atomic and nuclear systems. Former equations are modified to include long range interactions. Original results for nuclear and molecular physics were obtained : - Positively charged particle scattering on Hydrogen atoms was considered. Predictions for -H, -H and p-H scattering lengths were given. Existence of an unknown, very weakly bound H bound state was predicted. - Motivated by the possible observation of bound four neutron structure at GANIL we have studied compatibility of such an existence within the current nuclear interaction models. - 4 nucleon scattering at low energies was investigated. Obtained results for n-3H, p-3H and p-3He systems were compared with the experimental data. Validity of realistic nucleon-nucleon interaction models is questioned.Cette thèse est consacrée à l'étude numérique de systèmes quantiques non-relativistes à trois et quatre particules. Les équations de Faddeev-Yakubovski ont été modifiées pour pouvoir inclure les interactions à longue portée et ont été appliquées à l'étude des nombreux systèmes physiques. Des résultats originaux ont été obtenus pour les systèmes nucléaires et moléculaires : - Dans le cadre de la physique moléculaire, la diffusion des particules chargées sur les atomes d'hydrogène a été étudiée. Les longueurs de diffusion pour les systèmes -H, -H et p-H ont été prédites. L'existence d'un nouvel état, très faiblement lié de l'ion moléculaire H a été prédit. - Suite à l'annonce d'une possible mise en évidence expérimentale du tetraneutron (état lié à 4 neutrons) au GANIL, nous avons étudié la compatibilité d'une telle existence avec nos connaissances des forces neutron-neutron. - La diffusion des systèmes à 4 nucléons (n-3H, p-3H et p-3He) à basse énergie a été examinée. Les résultats sont comparés aux résultats expérimentaux. La validité des potentiels nucléon- nucléon a ainsi été remise en cause. MOTS-CLES: Few-body, quatre corps, diffusion, diffusion Coulombienne, états liés, états de resonance, tetraneutron, ion moléculaire d'hydrogèn
Low energy structures in nuclear reactions with 4n in the final state
We present a reaction model to describe the fast removal of the
-particle core in He nucleus with eventual emission of four
neutrons. The obtained four neutron energy distributions allows to explain the
sharp low energy peak observed by studying the missing mass spectra of four
neutrons in [Nature Vol. 606, p. 678], as a consequence of dineutron-dineutron
correlations
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