Search

In this contribution we report on quantification of theoretical uncertainties in nuclear matrix elements relevant for modeling dark matter and electro-weak interactions with nuclei. Recently we have developed a novel ab initio framework for computations of nuclear matrix elements and applied it in calculations of reaction rates for dark matter particles scattering off selected nuclear targets [1]. To evaluate the nuclear matrix elements we used nuclear wave functions computed within an ab initio many-body framework employing state-of-the-art nuclear Hamiltonians derived from chiral effective field theory. For the first time we have quantified the nuclear-physics uncertainties of the matrix elements that result from the remaining freedom in the construction of realistic nuclear interactions and their impact on physical observables. We found significant uncertainties especially for certain spin-dependent nuclear matrix elements. While our nuclear structure calculations have been performed with the no-core shell model method and applied in the context of dark matter searches, the approach can be generalized to other ab initio methods and extended to other sectors. [ABSTRACT FROM AUTHOR]

One-nucleon removal reactions at relativistic energies have been used as spectroscopic tool to obtain information about the ground state properties of several neutron-rich isotopes in the sd-shell. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after one-nucleon removal cross-sections were measured. The relative contributions of the remaining fragments in their ground and excited states have been determined from measurements of γ rays in coincidence with the longitudinal momentum distributions. The interesting case of 23O will be directly address. The interpretation of our experimental results in the framework of a simple theoretical model will favours a spin and parity assignment of 1/2+ for the 23O ground state in agreement with shell model predictions. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

One-nucleon removal reactions at relativistic energies have been used as spectroscopic tool to obtain information about the ground state properties of [sup 8]B and [sup 23]O. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after breakup and the one-nucleon removal cross-sections were measured. The relative contributions of the remaining fragments ([sup 7]Be and [sup 22]O) in their ground and excited states have been determined from measurements of γ rays in coincidence with the longitudinal momentum distributions. In the [sup 8]B case, the experimental breakup data on two different targets (C and Pb) allow a determination of the weight of the [sup 7]Be[sup *] component in the [sup 8]B ground state wave function as (13.3±2.2) %. These results are discussed in the context of a theoretical three-body model. Preliminary results on [sup 23]O indicate a spin and parity assignment of ½[sup +] in agreement with shell model predictions. [ABSTRACT FROM AUTHOR]