Fiber-Optic Taper Coupled with a Large Format Charge-coupled Device X-ray Detector: Fast Readout and High Duty-Cycle Ratio

Abstract

A novel fiber‐optic taper (FOT) coupled with a charge‐coupled device (CCD) X‐ray detector was developed as a basic module of the simultaneous small‐ and wide‐angle X‐ray scattering measurement apparatus at SPring‐8 BL45XU. The detector consists of two identical units, each comprising a phosphor (CsI:Tl, 80 μm thickness), a 2:1 demagnifying FOT, and an interline transfer‐type CCD as an image sensor. The CCD has a 4000 × 2624 pixel format with a 9 μm pitch, resulting in an effective pixel size of 18 μm at the large end of the FOT. The active area size is 72.0 mm × 47.2 mm in each unit. The image stored in the CCD can be readout through the dual readout channels with 12 bits ADC within 220 ms without binning and 65 ms with 8 × 8 binning, respectively. Moreover, this detector is not necessary to stop the incoming X‐rays during the CCD readout and can simultaneously execute both exposure and readout on the CCD with a small dead time of ∼1 μs so that a duty‐cycle ratio of almost 100% is achieved. Therefore, it allows the continuous rotation method, where data is collected without stopping the rotation of a sample crystal in macromolecular crystallography. The continuous rotation method was performed with a total data collection time of 12 s for a range of 180° with 1.5° per frame (120 frames). In this paper, the design, performance characteristics, and verification experiment of the detector will be described.