Study of Positronium in Insulating Crystals

A positron injected in insulating material form a hydrogen-like bound state with an electron called positronium.Behavior of ositronium in insulating materials has attracted interests in relation with the properties of excitions.It is also realized as a probe of the spin states of materials.The present study revealed various aspects of the positronium interactions with materials by using2D-ACAR apparatus recently developed by us，the high intensity slow positron beam line at KEK，and conventional positron annihilation techniques including1D-ACAR，positron lifetime，Doppler broadening of annihilation radiation，Positron age-momentum correlation.New results have been obtained for the following subjects：(1)Wave functions of delocalized positronium in alkali halides at low temperatures.(2)Effect of the phonon scattering on the momentum distribution of positronium in quartz and MgF Ii D22；(3)Tunneling transition of delocalized positronium to a self-localized state.(4)Positronium emission from quartz single crystalizion from quartz single crystalized positronium to a self-localized state.(4)Positronium momentum correlation.New results have been obtained for the following subjection.(1)(8)Development of positron spin polarimeter by using positronium in solids。

A positron injected in insulating material form a hydrogen-like bound state with an electron called positronium. Behavior of ositronium in insulating materials has attracted interests in relation with the properties of excitions. It is also realized as a probe of the spin states of materials.The present study revealed various aspects of the positronium interactions with materials by using 2D-ACAR apparatus recently developed by us, the high intensity slow positron beam line at KEK, and conventional positron annihilation techniques including 1D-ACAR, positron lifetime ,Doppler broadening of annihilation radiation, positron age-momentum correlation.New results have been obtained for the following subjects :(1) Wave functions of delocalized positronium in alkali halides at low temperatures.(2) Effect of the phonon scattering on the momentum distribution of positronium in quartz and MgFィイD22ィエD2.(3) Tunneling transition of delocalized positronium to a self-localized state.(4) Positronium emission from quartz single crystal and fused silica.(5) Positronium lifetime in quartz single crystal.(6) Study of spin-crossover material and related material by using positronium.(7) Positronium quadrupole interactions in anistoropic crystals.(8) Development of positron spin polarimeter by using positronium in solids.