| To satisfy the progressive requirements of neutron scattering measurements, a neutron standard test beam line (NSTB) based on the reactor neutron source at Chinese Mianyang Research Reactor (CMRR) had been proposed, and its conceptual design was shown in the thesis. This instrument would be employed to test the performance of components designed for spectrometer and develop the quantitative analysis of special materials.To meeting above requirement, NSTB was designed as a neutron scattering spectrometer, which was composed of monocromator, monitor, collimator, slit, sample stage and detectors. First, it was simulated by Vitess software. Then some adjustment about its physical parameter was optimized based on the simulation results. In this system, the monochoromator was designed with vertical focusing function which could provide neutrons with continuous wavelength (0.1nm～0.3nm). The monitor was designed with GEM technology, more than 95% neutron beam could come across it and its maximum counter rates could be up to 108/cm2.s. Between the monitor and the slit, the collimator was removable. For high flux mode, the neutron flux at sample stage can reach to 6.15×106n/cm2·s with the collimator out of the beam. For high resolution mode (0.2%), the neutron flux would reduce to 2.07×106n/cm2·s. The area of slit window was adjustable from O×0mm2 to 10×100mm2. A multi degree of freedom motion platform designed for the sample stage in this instrument could bear large scale and very heavy sample. The NSTB could also cooperate with additional sample environments, such as goniometer, and then it was updated to a texture spectrometer. Anymore, NSTB could realize the irradiation function of neutron, X ray and y ray at the same time.As a key component, detector system contained a new type neutron detector and its readout system. This kind of detector was designed based on 10B film, which had potential to replace 3He detector. Its readout system was based on delay line method which contained preamplifier, constant fraction discriminator (CFD), time to digital converter circuit (TDC) and data acquisition software. Because the polars of output signals from the detector were different. In this case, two kinds of preamplifiers were designed to meet aforementioned requirements. One amplified signals had the same polar, and the other had opposite polar. Both of them were designed as transimpedance amplifiers with a rise time of 50ns, a signal-to-noise ratio higher than 20dB, and an automatic gain control function. CFD used in this paper was a commercial product manufactured by Philips which could candle 5-chennels signal at the same time. TDC was designed based on an ASIC chip TDC-GPX and a commercial FPGA whose time resolution could up to 81ps.Finally, we conducted a series of experiments at CNTAS to test the performance of this detector system. The detecting efficiency was about 3.5%@0.4nm and its resolution is around 5mm. All the experimental results were in accordance to our expectations. However, this performance could not satisfy the requirements of practical application. At last, we proposed an effective method to improve the detecting efficiency and resolution. |
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