Measurement of electromagnetic moments of unstable nucleiィイD116ィエD1NィイD2g.sィエD2

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Several anomalous features have been reported for light unstable region nuclei, suggesting that nucleons at large neutron excess may form a bound system whose behavior is radically different from nuclei of the well explored region near stability. Thus, it is challenging to carry out a systematic study of nuclear structure this region of nuclei with microscopic probes such as nuclear moments.However, in case neuclei have second order lifetime as ィイD116ィエD1NィイD2g.sィエD2., the preservation of spin orientation is important for the magnetic moment measurements for unstable nuclei.In order to overcome this difficulty, we propose to use a new type of stopper material; superfluid helium. When impurity ions are introduced into superfluid helium, large fraction of them survive being charged 1+ because of the highest ionization potential of helium atom (24.6 eV), and an aggregate of helium atoms is formed surrounding the ion due to electrostriction. This micro-structure is called "snowball". The h … More ighly symmetric structure of the snowball may cause negligibly small electromagnetic fields on the ion. It is hopeful stopper material for the measurement of nuclear moments for some specific nuclei.And also, a part of implanted ions are neutralized during their stopping process in hellium. This part is also hopeful stopper material, because the electromagnetic field surrounding neutralied atoms are averaged to small by thermal diffusion of hellium.The snowballs are positionally separated from neutral atoms under electoric field, and distinguished in these decay position by position sensitive hodoscopes.Therefore, it is possible to measure various properties, such as spin relaxation time, of each part independently.It is necessary to grasp behavior of ions in liquid helium in order to employ the liquid hellium as stopper material. In order to grasp behavior of ions in liquid helium, experiments were performed at RCNP in Osaka.To observe the motions of impurities ions, the decay vertex is determined by extrapolating the β-ray hit position in the both two plane hodoscopes. We succeded to directly observe a trajectory of Snowballs for the first time by extracting Snowballs from neutrals with a static electric field. And also this method is useful for material science by the observation of nature of quantum liquid by motion of radioactive impurities. Less