Si ball of new type

In the research on nuclear spectroscopy using heavy ion fusion reaction, the device of identifying nuclides by the kind of evaporating particles and the measurement of their particle number has been used. However recently, in order to give more angular momentum to fusion nuclei, the heavy ions with high energy are used, and the nuclides far away from β stability line become the object of research, accordingly, the measuring apparatuses with the multiplicity of charged particles of 4π are developed in many research institutes in the world. The Si ball which is a 4π Si detector array and a small charged particle multiplicity measuring apparatus with high detection efficiency was used for the first time for a long period of 40 days in March, 1990, in Nordball in Niels Bohr Laboratory in Denmark. In this Si ball, 11 transmission type Si detectors of 170 μm thickness were attached to the pentagonal dodecahedron frame. Since there were some problems in this Si ball, the new holed detectors were attached to the beam inlet and exit of the Si ball. This new Si ball was used for measuring the life of levels by Doppler shift attenuation method in September, 1990. The experimental results are reported. (K.I.)