中子三轴谱仪二维位置灵敏探测器标定

Calibration of two-dimensional position sensitive detector of triple-axis neutron spectrometer

二维位置灵敏探测器(PSD)参数是中子散射谱仪实验数据分析的必要参数,主要用于角度和谱形修正。为此提出了PSD标定方法,并对冷中子非弹性散射/三轴谱仪所使用的PSD探测器进行了标定,获得了工作偏压、像素大小、空间分辨、探测效率及效率均匀性等数据。实验结果表明,探测器的工作偏压为4.2-4.4 kV、像素大小为0.32 mm(H&V)、探测器的空间分辨为2.15 mm(H)×2.04 mm(V)、探测效率为90.47%、效率均匀性优于10%,达到了谱仪设计要求。所建立的探测器测试方法对探测器研制和实验数据分析具有参考价值。

Background： A 200 mm×200 mm two-dimensional positional sensitive detector （PSD） has been designd and constructed for the cold-neutron triple axis spectrometer （CTAS）. The parameters of the PSD are necessary for evaluation and analysis of neutron scattering pattern obtained on CTAS and other instrument using PSD, mainly for the correction of angle and spectral shape due to the unequal solid angle and inhomogeneous efficiency of the fiat PSD. Purpose： In order to obtain the working bias voltage, pixel size, spatial resolution, detection efficiency and its uniformity, a calibration method was proposed and tested for the PSD of CTAS. Methods： The calibration was carried out at the ATHOS three-axis spectrometer installed at the neutron guide No.1 of the 10-MW steady state reactor of the Budapest Neutron Centre. The focusing copper monochrometer provided well collimated （20＇ divergence） neutron beam of wavelength equal to 0.572 nm with the second order equal to 0.286 nm. A black neutron detector having 〉99% efficiency at these wavelengths coated with boron shielding was used for efficiency test and a 0.5-mm wide Cd slit was used for the determination of pixel size and spatial resolution of the PSD. Results： The experimental results show that the working bias voltage is 4.2-4.4 kV, pixel size 0.32 mm （H＆V）, the detector spatial resolution of 2.15 mm（H）x2.04 mm（V）, the detection efficiency of 90.47% and the efficiency uniformity better than 10%. Conclusion： The established method was successfully used in the PSD calibration, which can be extended to PSD R＆D and data analysis of neutron spectrometer.