Settlement of Materials and Life Science Experimental Facility at J-PARC

Abstract

A lot of even and uneven settlement is expected to occur due to the heavy weight of the buildings and shields located at the Materials and Life Science Experimental Facility (MLF) and in the proton beam line (3NBT) that runs from the 3 GeV Rapid-Cycling Synchrotron (RCS) to the neutron target at the Japan Proton Accelerator Research Complex (J-PARC). Because of this, and in order to achieve the necessary alignment of less than 1 mm in precision, the settlement that has occurred with the MLF building and the 3NBT tunnel has been periodically surveyed (level measurement) since June 2004 until now when the MLF building has been completed. The survey results were used in determining the levels at which the beam line components were installed. The survey results indicated that the values of the settlement that had taken place were almost proportional to the located weight and could be used in estimating the settlement that would take place in the future. These results were reflected in the alignment of the proton and beam line components.