title: New beam-position monitor system for upgraded Photon Factory storage ring.
abstract: Accompanying the brilliance-upgrading project at the Photon Factory storage ring, the beam-position monitor (BPM) system has been renovated. The new system was designed to enable precise and fast measurements to correct the closed-orbit distortion (COD), as well as to feed back the orbit position during user runs. There are 42 BPMs newly installed, amounting to a total of 65 BPMs. All of the BPMs are calibrated on the test bench using a coaxially strung metallic wire. The measured electrical offsets are typically 200 micro m in both directions, which is 1/2-1/3 of those of the old-type BPMs. In the signal-processing system, PIN diode switches are employed in order to improve reliability. In the fastest mode, this system is capable of measuring COD within about 10 ms; this fast acquisition will allow fast suppression of the beam movement for frequencies up to 50 Hz using a global feedback system.
authors.affiliation: Photon Factory, KEK, 1-1 Oho, Tsukuba, Ibaraki 305, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Haga
authors.forename: T
authors.initials: T
authors.lastname: Honda
authors.forename: M
authors.initials: M
authors.lastname: Tadano
authors.forename: T
authors.initials: T
authors.lastname: Obina
authors.forename: T
authors.initials: T
authors.lastname: Kasuga