冷中子导管模拟和参数优化计算

Simulation of cold neutron guide and parameter optimization

根据冷中子源及后续中子导管的布局参数,采用蒙特卡罗方法模拟计算了冷中子导管C3出口处中子束均匀性、准直性及注量率等数据。优化表明:a)冷源与后续导管入口间距离应尽可能短;b)中子注量率及发散度均随导管超镜因子m值增大,m值由1.5增至3.0,其Y方向发散度增大24%,注量率提高61%;c)垂直于导管弯曲面方向的发散可以用高斯分布来描述,而导管偏转方向则呈条纹状发散;d)在m=1.5、冷源与堆内导管入口距离为2.29m情况下,束流垂直发散宽度为0.86°,中子注量率为2.44×107cm–2·s–1。

Beam homogeneity, collimation and flux at the exit （C3） of a cold neutron guide（NG） were simulated by MCSTAS 1.9 based on the layout of a cold neutron source （CNS） and NG. The optimization shows that a） the distance （LS-NG） between CNS and the NG entrance should be as short as possible; b） the flux and Y divergence increased by 24% and 61%, respectively, while the supermirror factor m increased from 1.5 to 3.0; c） divergence in the normal direction of NG curved pane （Y） can be described with a Gaussian function, but divergence in the direction of curved plane （X） was in strips; and d） when m=1.5 and LS-NG=2.29 m, the Y-divergence was 0.86° and the flux was 2.44×10^7 cm^-2.s^-1.