The Design and Optimization of a Neutron Time-of-Flight Spectrometer with Double Scintillators for Neutron Diagnostics on EAST

Neutron energy spectrometry diagnosis plays an important role in magnetic con-finement fusion.A new neutron time-of-flight (TOF) spectrometer with double scintillators is designed and optimized for the EAST tokamak.A set of optimal parameters is obtained by Monte Carlo simulation,based on the GEANT4 and ROOT codes.The electronic setup of the measurement system is designed.The count rate capability is increased by introducing a flash ADC.The designed spectrometer with high resolution and efficiency is capable of being applied to fusion neutron diagnostics.Applications in mixed-energy and continuous energy neutron fields can also be considered.     

回收料掺量对温拌再生沥青混合料性能的影响

通过室内试验研究了回收沥青混合料(RAP)掺量(质量分数)对Evotherm温拌再生沥青混合料高温稳定性、低温性能、水稳定性及疲劳性能的影响.结果表明:采用Evotherm温拌技术可将RAP掺量提高到50%;温拌再生沥青混合料的高温稳定性、水稳定性及低温性能均随RAP掺量的增加先升后降,且在RAP掺量为30%~40%时出现峰值;疲劳性能随RAP掺量的增加逐渐降低,且应变水平越高降低幅度越大;温拌再生沥青混合料的高温稳定性、水稳定性较热拌再生沥青混合料差,疲劳性能优于热拌再生沥青混合料;在相同RAP掺量下,温拌再生沥青混合料与热拌再生沥青混合料的低温性能相当.     

基于数字化技术的芪晶体探测器脉冲形状甄别方法研究

建立了一套基于芪晶体探测器和示波器的数字化中子谱仪,数据获取和处理由基于Lab-VIEWTM发展的软件完成。用电荷积分法、过零时间法、上升时间法和脉冲梯度法实现了对镅铍中子源测量的n/γ甄别。实验比较发现,电荷积分法效果最好且易于实现,具有较好抗噪能力的过零时间法也显示了较好的n/γ甄别能力。     

Calibration and Unfolding of the Pulse Height Spectra of Liquid Scintillator-Based Neutron Detectors Using Photon Sources

An accurate energy calibration of a 5’’ ×2’’ BC501A liquid scintillator-based neutron detector by means of photon sources and the unfolding of pulse height spectra are described. The photon responses were measured with 22Na, 137Cs and 54Mn photon sources and simulated using the GRESP code, which was developed at the Physikalisch Technische Bundesanstalt in Germany. Pulse height spectra produced by three different photon sources were employed to investigate the effects of the unfolding techniques. It was found that the four unfolding codes of the HEPRO and UMG3.3 packages, including GRAVEL, UNFANA, MIEKE and MAXED, performed well with the test spectra and produced generally consistent results. They could therefore be used to obtain neutron energy spectra in tokamak experiments.