title: A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser.
abstract: We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (10(3)-10(11) photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 10(3)-10(9) photons/pulse of ~10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 10(7)-10(11) photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ~10(-3) with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser.
authors.affiliation: RIKEN/SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Togo
authors.initials: T
authors.lastname: Kudo
authors.forename: Kensuke
authors.initials: K
authors.lastname: Tono
authors.forename: Makina
authors.initials: M
authors.lastname: Yabashi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Togashi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sato
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inubushi
authors.forename: Motohiko
authors.initials: M
authors.lastname: Omodani
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kirihara
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Matsushita
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yamaga
authors.forename: Sadayuki
authors.initials: S
authors.lastname: Uchiyama
authors.forename: Takaki
authors.initials: T
authors.lastname: Hatsui