A new experiment to search for the permanent electric dipole moment of the neutron is being developed for installation at the Spallation Neutron Source at Oak Ridge National Laboratory. This experiment will be performed in liquid helium at ? 0:4 K an
d requires a large electric field (E ~ 75 kV/cm) to be applied in liquid helium. We have constructed a new HV test apparatus to study electric breakdown in liquid helium. Initial results demonstrated that it is possible to apply fields exceeding 100 kV/cm in a 1 cm gap between two electropolished stainless steel electrodes12 cm in diameter for a wide range of pressures.
By using molecular dynamics simulation, formation mechanisms of amorphous carbon in particular sp${}^3$ rich structure was researched. The problem that reactive empirical bond order potential cannot represent amorphous carbon properly was cleared in
the transition process from graphite to diamond by high pressure and the deposition process of amorphous carbon thin films. Moreover, the new potential model which is based on electron distribution simplified as a point charge was developed by using downfolding method. As a result, the molecular dynamics simulation with the new potential could demonstrate the transition from graphite to diamond at the pressure of 15 GPa corresponding to experiment and the deposition of sp${}^3$ rich amorphous carbon.
