Development of supermirror neutron guide tube and its applications to slow neutron physics

点击翻译按钮获取中文摘要

1. The computer controled vacuum-deposition technique is developed to make multilayer mirrors of nickel and titanium within the accuracy of a few <゜]A> . To get the critical wavelength <lambda_c> =240 <゜]A> (normal component to the mirror), 185 layers are alternately deposited on the float glass of 6cm thick. The reflectivity of the mirror is found to be 0.85 on the average to neutrons of wavelength shorter than 580 <゜]A> , <lambda_c> of a single nickel mirror.2. The super-mirror neutron guide tube is constructed at the B-4 beam hole in the KUR by connecting 13 elements with the use of a special equipment for ajusting the curve, twist and perpendicularity of mirrors, so that the neutron loss due to the abutment error is less than 1%. It is 11.7 m in length, with the cross section of 10mmx74mm.3. The total neutron flux is measured as about 5x <10^7> n/ <cm^2> sec on the average at the exit of the guide tube. It is about 20 times as large as that at the nickel mirror guide tube installed at the E-3 beam hole. To reduce the leakage dose-rate to less than 0.5 mr/hr in the reactor room, special shieldings made of heavy concretes, <B_4> C and Li-tiles are manufactured.