A: The free electron laser (FEL), as a next-generation light source, is an attractive tool in scientific frontier research because of its advantages of full coherence, ultra-short pulse duration, and controllable polarization. Owing to the demand of real-time bunch diagnosis during FEL experiments, precise nondestructive measurements of the polarization and X-ray energy spectrum using one instrument are preferred. In this paper, such an instrument based on the electron time-of-flight technique is proposed. By considering the complexity and nonlinearity, a numerical model in the framework of Geant4 has been developed for optimization. Taking the Shanghai Soft X-ray FEL user facility as an example, its measurement performances' dependence on the critical parameters was studied systematically, and, finally, an optimal design was obtained, achieving resolutions of 0.5% for the polarization degree and 0.3 eV for the X-ray energy spectrum. K: X-ray FEL, e-TOF, Polarization, Energy spectrum A X P : 1702.066521Corresponding author. 2Corresponding author.

Owing to its ultrafast scintillation, quite high light yield, strong radiation resistance, and non-deliquescence, ZnO(Ga) is a highly promising choice for an ultrafast X-ray detector. Because of its high deposition rate, good production repeatability and strong adhesive force, reactive magnetron sputtering was used to produce a ZnO(Ga) crystal on a quartz glass substrate, after the production conditions were optimized. The fluorescence lifetime of the sample was 173 ps. An ultrafast X-ray scintillating detector, equipped with a fast microchannel plate (MCP) photomultiplier tube (PMT), was developed and the X-ray tests show a signal full width at half maximum (FWHM) of only 385.5 ps. Moreover, derivation from the previous measurement shows the ZnO(Ga) has an ultrafast time response (FWHM = 355.1 ps) and a high light yield (14740 photons/MeV).

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The vitellogenin (VTG) in fish has been used as an important biomarker for monitoring endocrine disrupting compounds (EDCs). This paper reports the development of a new monoclonal antibody (McAb) against the VTG of crucian carp (Carassius carassius). The McAb has a molecular weight of 149.4 kDa (heavy chain: 53.1 kDa; light chain: 21.6 kDa), and double diffusion indicated that it belongs to the IgG1 subclass. The titer is 10 5 -10 6 and the affinity constant (K aff ) is 7.0 Â 10 8 L/mol, showing the high specificity and sensitivity of the antibody. The established sandwich ELISA was sensitive with a detection limit of VTG 0.98 ng/mL. The cross-reactivity of antibody was detected in cyprinids such as rare minnow, zebrafish, and carp. This ELISA was used to detect the variation of VTG in crucian carp exposed to secondary effluent and reclaimed water from the Gaobeidian sewage treatment plant (SRP). The VTG induction in secondary effluent was higher than that in reclaimed effluent and the VTG levels in juvenile crucian carp increased with increasing exposure time. The VTG concentration in male fish from downstream of the Gaobeidian STP was 88.627827.73 mg/mL, while that from a control site was undetectable. r

The cavity-based X-ray free-electron laser (XFEL) has promise in producing fully coherent pulses with a bandwidth of a few meV and very stable intensity, whereas the currently existing self-amplified spontaneous emission (SASE) XFEL is capable of generating ultra-short pulses with chaotic spectra. In general, a cavity-based XFEL can provide a spectral brightness three orders of magnitude higher than that of the SASE mode, thereby opening a new door for cutting-edge scientific research. With the development of superconducting MHz repetition-rate XFEL facilities such as FLASH, European-XFEL, LCLS-II, and SHINE, practical cavity-based XFEL operations are becoming increasingly achievable. In this study, megahertz cavity enhanced X-ray generation (MING) is proposed based on China’s first hard XFEL facility - SHINE, which we refer to as MING@SHINE.