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Energy dispersive X-ray diffraction (EDXRD) is a very effective method for explosive and narcotic threat detection in baggage screening. The XRD profiles arise from the molecular interference when X-rays are coherently scattered by a substance. The accurate identification of the target material depends on the ability to detect and resolve the peaks present in the coherent scatter profiles. A high-energy resolution High Purity Germanium (HPGe) detector is therefore generally used in such type of systems. To evaluate the suitability of costeffective room-temperature semiconductor detectors for nextgeneration baggage screening systems, an assessment of the minimal requirements for the system resolution is required.In this study a hybrid Monte Carlo code has been modified to account for the molecular interference function that gives rise to the coherent scatter signature. A model for a realistic response function for Cadmium Zinc Telluride (CZT) detectors is then used to convolve the spectral output. This simulation tool is then used to assess the system design features and their influence on spectral resolution.

An ultrafast shutter has been developed for alteration of the time structure of synchrotron radiation from storage rings in the hard X-ray regime. In test applications on the wiggler beamline BW6 at DORIS, single bunches were extracted from the incident pulsed synchrotron radiation with minimum bunch-to-bunch distances of 482 ns. Even substantially shorter time windows may be de®ned in the case of tight collimation in the incident beam, e.g. on low-emittance sources. The shutter system is based on a new chopper concept involving a rotating X-ray mirror which totally re¯ects the incident radiation onto the sample through a remote slit. Rather low rotational velocities are suf®cient to reach extremely short full open times. An additional shutter consisting of a slowly rotating disk prevents frame overlap and controls the repetition rate. A coincidence timing circuit checks the synchronization with the synchrotron bunch clock and provides trigger signals, e.g. for external excitation of a sample. The chopper system may be used, for example, in nanosecond time-resolved Laue diffraction experiments.

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