EURORIB 2010

Coulomb excitation as a probe of nuclear polarization

Not scheduled

Village de Vacances de Lamoura

Board: 19

poster Production and manipulation of RIB

Speaker

Mr Hans Toshihide Tornqvist (CERN)

Description

Project participants: Dimiter Balabanski (University of Sofia, Bulgaria), Georgi Georgiev (CSNSM, France), Michael Hass (Weizmann Institute of Science, Israel), Lars Hemmingsen (University of Copenhagen, Denmark), Alexander Herlert (ISOLDE, Switzerland), Karl Johnston (ISOLDE, Switzerland), Thomas Nilsson (Chalmers University of Technology, Sweden), Janne Pakarinen (ISOLDE, Switzerland), Monika Stachura (University of Copenhagen, Denmark), Fredrik Wenander (ISOLDE, Switzerland), Wolf-Dietrich Zeitz (HMI, Germany). The orientation of nuclear spin ensembles is an important ingredient in nuclear physics experiments. Spin polarization can provide indispensable information in e.g. nuclear transfer reactions, Coulomb excitation etc. Therefore, obtaining a beam of polarized nuclei is of very high interest both for nuclear reactions and structure studies. A test of spin polarization, using the tilted foils (TF) method, has been carried out with the Miniball experimental setup at ISOLDE. A stable beam of 21Ne, Iπ = 3/2+, was subject to Coulomb excitation after passing through a set of tilted foils. The de-excitation gamma rays were observed in the Miniball Ge detectors in coincidence with the 21Ne particles detected in position sensitive Si detectors. The asymmetry of the angular distribution of particles can serve as a probe for the degree of the nuclear spin polarization. The difficulties of the present test originate in the contradictory requirements of obtaining a reasonable degree of nuclear polarization by the TF method (very low beam energy) and the Coulomb excitation (higher beam energies for higher excitation probabilities). The preliminary results of the 21Ne test will be presented. Tilted foils polarization is a simple technique applicable to a wide range of isotopes with predictable direction of the polarization. The atomic spin polarization occurring at the boundary of the foils is transferred to the nuclei via hyperfine interactions. Any isotope with nonzero ground state nuclear spin can be polarized in flight and the foils are easily introduced into a beam line. This experiment is the first in a series aiming to establish optimal conditions for spin-polarization at REX-ISOLDE.