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Multi-channel analyzer based on a novel pulse fi tting analysis method
Qingshan Wang,Xiongjie Zhang,Xiangting Meng,Bao Wang,Dongyang Wang,Pengfei Zhou,Renbo Wang,Bin Tang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6
A novel pulse fitting analysis (PFA) method is presented for the acquisition of nuclear spectra. Thecharging process of the feedback capacitor in the resistive feedback charge-sensitive preamplifier isequivalent to the impulsive pulse, and its impulse response function (IRF) can be obtained by non-linearfitting of the falling edge of the nuclear pulse. The integral of the IRF excluding the baseline representsthe energy deposition of the particles in the detector. In addition, since the non-linear fitting process inPFA method is difficult to achieve in the conventional architecture of spectroscopy system, a new multichannel analyzer (MCA) based on Zynq SoC is proposed, which transmits all the data of nuclear pulsesfrom the programmable logic (PL) to the processing system (PS) by high-speed AXI-Stream in order toimplement PFA method with precision. The linearity of new MCA has been tested. The spectrum of 137Cswas obtained using LaBr3(Ce) scintillator detector, and was compared with commercial MCA by ORTEC. The results of tests indicate that the MCA based on PFA method has the same performance as thecommercial MCA based on pulse height analysis (PHA) method and excellent linearity for g-rays withdifferent energies, which infers that PFA method is an effective and promising method for the acquisitionof spectra. Furthermore, it provides a new solution for nuclear pulse processing algorithms involvingregression and iterative processes
Yongjin Wang,Yingchao Zhang,Renbo Song,Liang Huang,Yu Pei 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
The effect of austenitizing temperature on microstructure evolution and impact toughness of a newly developed Fe–3.0C–2.8Si–2.0Mn–0.9V–0.2Cr bainite ductile iron was investigated in this research. The ductile iron specimens were heat treatedunder different continuous cooling process, involving austenitizing between 900 and 980 °C and followed tempering at200 °C. Optical microscopy, X-ray diffraction, scanning electron microscope and transmission electron microscope tests wereconducted to investigate the microstructure evolution. Impact toughness and Rockwell hardness were measured. The resultsshowed that the microstructure of the ductile iron mainly consisted of graphite, acicular bainite and retained austenite aftercontinuous cooling process. The austenitizing temperature could change the volume fraction and size of bainite and retainedaustenite. There existed a C-area, where retained austenite accumulated near the graphite, except for specimen austenitizedat 920 °C. The impact toughness of specimens increased first and then get worse with the increasing of austenitizing temperature. The impact toughness was related with the volume fraction of bainite and the morphology of retained austenite. The fracture mechanism of the bainite ductile iron belonged to cleavage fracture. Chunky graphite acted as the source ofmicrocrack during the impact process. The bulky retained austenite behaved as a prior path for the microcrack propagation,while the bainite and thin filmy retained austenite limited its propagation.