Time-resolved detection of x-ray generated pulses on coplanar stripline sensors

Abstract

X-ray detectors have been developed to measure the time profile of synchrotron x-ray pulses by sampling electrical pulses traveling along coplanar striplines. Electro-optic techniques originally developed for characterizing sub-picosecond laser pulses have been adapted for ∼100 ps synchrotron pulses. The first approach samples a small part of the current across a photoconducting gap excited by a sub-ps laser pulse, while the second detects the transient electric field in the gap on a birefringent lithium tantalate substrate by measuring the field-induced rotation of optical polarization. Both have measured x-ray pulses with ∼50 ps time resolution, but the optical polarization approach demonstrated much better signal-to-noise. Materials explored include semi-insulating GaAs, ion-implanted GaAs, low-temperature GaAs, and an InGaAs photodiode device. Important differences between the response to laser and x-ray pulses have been discovered, in the search for improved time resolution.