Design of a nondestructive two-in-one instrument for measuring the polarization and energy spectrum at an X-ray FEL facility
Abstract
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.
- Publication:
-
Journal of Instrumentation
- Pub Date:
- October 2017
- DOI:
- 10.1088/1748-0221/12/10/T10003
- arXiv:
- arXiv:1702.06652
- Bibcode:
- 2017JInst..1210003Z
- Keywords:
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- Physics - Instrumentation and Detectors;
- Physics - Accelerator Physics
- E-Print:
- 16 pages, 13 figures, Design of a Nondestructive Two-in-One Instrument for Measuring the Polarization and Energy Spectrum at an X-ray FEL Facility. Accepted by JINST