Development of a Low- $Q$ Cavity-Type Beam Position Monitoring System

A beam position monitor (BPM) with the nanometer-scale position resolution and the decay time of approximately 20 ns is developed as an interaction point BPM, to verify the nanometer stabilization of the International Linear Collider beam trains at the Accelerator Test Facility (ATF), High Energy Accelerator Research Organization (KEK). The developed low-Q cavity BPM consists of a one-cell sensor cavity and a one-cell reference cavity. An electronic system is developed, based on the beam test results, to process the signals from the BPM. The beam position resolution of the low-Q cavity BPM with the electronics system is measured at the ATF2 beam line of KEK, and the results of the beam tests conducted on the developed low-Q cavity-type BPM are described.