Search results for "Charge exchange"
showing 10 items of 31 documents
A quantum mechanics-molecular mechanics study of dissociative electron transfer : The methylchloride radical anion in aqueous solution
2002
The dissociative electron transfer reaction CH3Cl+e−→CH3•+Cl− in aqueous solution is studied by using a QM/MM method. In this work the quantum subsystem (a methylchloride molecule plus an electron) is described using density functional theory while the solvent (300 water molecules) is described using the TIP3P classical potential. By means of molecular dynamics simulations and the thermodynamic integration technique we obtained the potential of mean force (PMF) for the carbon–chlorine bond dissociation of the neutral and radical anion species. Combining these two free energy curves we found a quadratic dependence of the activation free energy on the reaction free energy in agreement with Ma…
Core polarization phenomena in pion-nucleus charge-exchange reactions above the delta resonance.
1993
Inclusive pion-nucleus double charge exchange.
1989
Inclusive double charge exchange reaction is studied by using a model which combines a microscopic many-body calculation of reaction probabilities with a Monte Carlo simulation procedure. Comparison with present experimental results requires that the (\ensuremath{\pi},2\ensuremath{\pi}) reaction be included and a proper evaluation of this latter reaction is also done. The combined results compare favorably with experiment, giving extra support to this model of the pion-nucleus interaction which was previously shown to provide a good description of all other inclusive reactions and elastic scattering.
2p-shell admixtures in pion single charge exchange on 13C
1991
Abstract The pion charge exchange process 13 C (π + , π 0 ) 13 N(gs) is calculated with an extended nuclear wave function for the A=13 system that includes configurations outside the 1p-shell. A small amount of 2p-shell admixtures leads to an improved description of the experimental excitation function. We also find a strong sensitivity of the differential cross sections as well as asymmetry to contributions from higher shells.
New Results from the NUMEN Project
2020
NUMEN aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of the cross sections of Heavy Ion (HI) induced Double Charge Exchange (DCE) reactions. First evidence about the possibility to get quantitative information about NME from experiments is found for the (18O,18Ne) and (20Ne,20O) reactions. Moreover, to infer the neutrino average masses from the possible measurement of the half-life of 0νββ decay, the knowledge of the NME is a crucial aspect. The key tools for this project are the high resolution Superconducting Cyclotron beams and the MAGNEX magnetic sp…
Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS
2019
Abstract The NUMEN project aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ). In this view measurements of Heavy Ion (HI) induced Double Charge Exchange (DCE) reaction cross sections are performed with high-accuracy. In particular, the (18O,18Ne) and (20Ne,20O) reactions are used as tools for β+β+ and β-β- decays, respectively. In the experiments, performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania, the beams are accelerated by the Superconducting Cyclotron (CS) and the reaction ejectiles are detected the MAGNEX magnetic spectrometer. The measured cross sections are challe…
Recent results on Heavy-Ion induced reactions of interest for 0νββ decay
2019
An updated overview of recent results on Heavy-Ion induced reactions of interest for neutrinoless double beta decay is reported in the framework of the NUMEN project. The NUMEN idea is to study heavy-ion induced Double Charge Exchange (DCE) reactions with the aim to get information on the nuclear matrix elements for neutrinoless double beta (0νββ) decay. Moreover, to infer the neutrino average masses from the possible measurement of the half- life of 0νββ decay, the knowledge of the nuclear matrix elements is a crucial aspect. Uma visão geral atualizada dos resultados recentes sobre reações induzidas por íons pesados de interesse para o decaimento beta duplo sem neutrinos é relatada na es…
An anomaly in inclusive pion double charge exchange on 16O at about 1GeV
1996
The new results on the inclusive double charge exchange (DCX) reaction 16O(π-,π+)X at incident kinetic energy T0=0.75 and 1.15GeV are presented. The data were taken without using Cherentov counters. The new DCX cross sections agree well with the old ones. Both the values are about an order of magnitude larger than the theoretical cross sections calculated for the standard sequential mechanism. Two other approaches wich seem to explain the discrepancy are also briefly reviewed. Vicente Vacas, Manuel Jose, Manuel.J.Vicente@ific.uv.es