To study nuclear-matter property, such as incompressibility and symmetry energy,and electron capture rate in iron-group and heavier nuclei,a gaseous active target operated with deuterium gas is being developed in Center for Nuclear Study, the University of Tokyo.
The incompressibility and symmetry energy are the function of density and asymmetry of the numbers of protons and neutrons (isospin). So far, the incompressibility is determined by measuring the energies of Giant Monopole Resonance (GMR) in stable nuclei, which are excited via the inelastic scattering. However, extension of measurements to unstable nuclei is needed for the study of isospin dependence and extraction of symmetry energy.
To deduce the GMR strength, above the particle-decay threshold, we have to perform multipole decomposition analysis, where the forward angle scattering is very important. In the study of electron capture rate via the measurement of Gamow-Teller resonance, the forward-angle scattering is also important.
Gaseous active target enables us to measure such a forward angle measurement in missing mass spectroscopy of unstable nuclei. I will present the design and the basic performance of our active target system and the test experiment with stable nuclei, 56Fe.
