散裂中子源靶站和中子散射谱仪的概念设计

Conceptual design of target station and neutron scattering spectrometers for the Chinese spallation neutron source

本文介绍了可应用于多学科应用的散裂中子源(CSNS)靶站和中子散射谱仪概念设计的进展。CSNS靶站将由重水冷却多片钨靶,铍/铁反射体和铁/重混凝土生物屏蔽体组成。采用三个WING型慢化器:水(室温),液体甲烷(100K)和液体氢(20K),设有18个水平中子孔道。MonteCarlo模拟显示优化的靶截面高宽比为1:2.5左右。额定的100kW核功率的质子束轰击后,慢化器处钨靶溢出的脉冲中子通量约为2.4×1016cm?2·s?1。有限元方法计算表明,钨靶体内的总发热量是47kJ/s。即使使用截面较小的钨靶,在通常的水冷速率下,靶体温度也仅略高于90°C。靶体的热应力形变最大不超过0.2mm。根据经济实用原则选择建造粉末衍射仪、小角散射仪、反射仪及直接几何非弹性散射仪等四类有代表性的中子散射谱仪,就能覆盖>80%的中子散射研究领域。

We report the recent progress on the conceptual design of the target station and neutron scattering spectrometers for the Chinese Spallation Neutron Source （CSNS）, The CSNS target station will be constructed with three parts： tungsten targets cooled by heavy water, Be/Fe reflectors and Fe/high-density-iron-aggregate-concrete shields, There will be 3 WING moderators： water （300 K）, liquid methane （100 K） and liquid hydrogen （20 K）, and 18 horizontal neutron channels for neutron scattering spectrometers. The Monte Carlo simulation shows that the optimized ratio of height to width of the target cross-section is-1：2.5. With a nuclear power of 100kW, the pulsed neutron flux is 2.4×10^16cm^-2·s^-1 for a 40 mm×100mm×10mm×40 target stack, The emitted heat is about 47kJ/s,the target temperature is somewhat higher than 90℃ with a normal cooling efficiency, and the strain should be lower than 0.2mm. Initially 5 typical spectrometers are chosen to be constructed, including a high intensity powder diffractometer, a high resolution powder diffractometer, a small angle scattering spectrometer, a reflectometer and a direct geometry inelastic neutron scattering spectrometer. These spectrometers can cover more than 80% of the neutron scattering applications.