Abstract:In this paper we report a fiber-type widely tunable CW mid-IR DFG/QPM laser source based on periodically poled MgO-doped LiNbO 3 (PPMgLN), which uses a ytterbium-dope fiber laser (YDFL) as the pump source and a tunable erbium-dope fiber laser (EDFL) cascaded with an erbium-doped fiber amplifier (EDFA) as the signal source. Our experimental results show that, with the PCs to adjust the pump and signal polarization orientations being parallel to the crystal principle optical axis the conversion efficiency may be optimized. The pump and signal beam spots and their longitudinal evolution behaviors determine the RCE and the crystal longitudinal position tolerance, which are measured to be 0.717 (mW) −2 and 44 mm for the mid-IR laser source, respectively. The idler output of the mid-IR DFG/QPM laser source may be continuously tuned from 3.1 to 3.6 μm with almost the same RCE.Idler output

A: Located at the center of the end of the CSR External-target Experiment (CEE), the Zero Degree Calorimeter (ZDC) is designed to rebuild the centrality and reaction plane of the nuclear-nuclear collision. To meet the target of ZDC to detect the energy distribution of colliding particles, a high-performance readout system prototype, which implements a Gaussian shaping algorithm, has been designed. The system consists of 4 channels; each channel mainly includes an I-V conversion circuit, a slow forming circuit, a threshold trigger circuit, and a digital signal processing unit based on a field-programmable gate array (FPGA).Performance studies indicate that the noise of each channel is less than 0.8 mV and the nonlinearity is better than 0.6%. Tests with a LED driver source indicate that the Gaussian shaping algorithm can improve the photon energy resolution from 7.481% to 6.196%. Tests with cosmic rays also produced expected results.

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