Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics Subjects: Nuclear Science and Technology >> Nuclear Instrument and Meter submitted time 2024-02-07
Abstract: A new measurement method for the spatial distribution of neutron beam flux in boron neutron capture therapy (BNCT) is being developed based on the two-dimensional Micromegas detector. To address the issue of long processing time in traditional offline position reconstruction methods, this paper proposes an FPGA-based online position reconstruction method, grounded in the micro time projection chamber principle. This method encapsulates key technical aspects: self-adaptive serial link technique built upon the dynamical adjustment of delay chain length, fast sorting and coordinate matching technique based on the mapping between signal timestamps and random access memory (RAM) addresses, and precise start point merging technique utilizing a circular combined RAM. The performance test of the self-adaptive serial link shows the bit error rate of the link is better than 10^-12 at a confidence level of 99%, ensuring reliable data transmission. The combined experiment of the readout electronics and the Micromegas detector shows a spatial resolution of approximately 1.4 mm, surpassing the current method's resolution level of 5 mm. The beam experiment confirms that the readout electronics system can obtain the flux spatial distribution of neutron beam online, thus validating the feasibility of the position reconstruction method. The online position reconstruction method avoids traditional methods such as bubble sorting and traversal searching, simplifying the design of logic firmware and reducing the time complexity from O(n^2) to O(n). This study contributes to the advancement in measuring neutron beam flux for BNCT.
Subjects: Nuclear Science and Technology >> Nuclear Instrument and Meter submitted time 2024-01-15
Abstract: With the development of domestic semiconductor enterprise technology, some domestic components performance indicators have been comparable to imported components, to meet the performance needs of nuclear radiation monitoring instrumentation. A fully localized 𝛾 energy spectrometer based on a 1.5-inch LaBr3 scintillator, including scintillators, photomultiplier tubes, and electronic components, has been designed by using products of domestic manufacturers.The test results show that the resolution of the spectrometer can reach 2.8%@662keV at room temperature, the working temperature range can reach -40℃ to 50℃ , and the energy resolution is better than 3.0% in the whole temperature range, and the change rate of the all-around peak channel address of 137Cs with temperature is about -0.67/℃
, and the linearity is good. The high-voltage adjustment rate is 0.02V, which meets the requirement of 0.2V /℃ for the stable spectrum. The energy nonlinearity of the spectrometer is better than 0.01%. The experimental data show that the domestic LaBr3 scintillator, photomultiplier tube and electronic components can meet the design requirements of 𝛾 energy spectrometer.
Subjects: Nuclear Science and Technology >> Nuclear Instrument and Meter submitted time 2023-11-15
Abstract: NaI(Tl) crystal is a common radiation detector material, because its interaction with the ray produces a weak light signal, so the photomultiplier tube is needed to convert the light signal into an electrical signal for the back-end circuit to process. Silicon photomultiplier tube, as a new photoelectric conversion device, has the advantages of low noise, small size, low power consumption and diamagnetism compared with traditional photomultiplier tube. Therefore, the NaI(Tl) scintillator detector designed by SiPM has the advantages of small size, high efficiency, sensitivity and strong anti-interference. By optimizing the physical structure and signal processing circuit of the detector, the efficient detection of gamma rays is realized. In this paper, a 1-inch NaI(Tl) detector using SiPM is designed and developed, which has the advantages of small size and low background noise. The influence of the detector on the energy spectrum of 137Cs source is tested, and the results show that the detector has a resolution of 8.72% for the γ-ray energy of 0.662MeV.
Subjects: Nuclear Science and Technology >> Nuclear Instrument and Meter submitted time 2023-09-06
Abstract: Background : Two x-ray diffractometers produced by HUBER company have been installed at BL02U2 of Shanghai Synchrotron Radiation Facility (SSRF). Purpose : In order to further meet the needs of users for grazing incidence diffraction experimental methods, a new grazing incidence diffractometer was installed between the two HUBER diffractometers. Methods : This paper mainly introduces the overall scheme of the grazing incidence diffractometer, and discusses in detail several important modules such as high-precision, high-load and large-stroke linear stage, three-dimensional adjustment platform for detector, sample stage system, and the control system. Results : The compatible operation of three diffractometers was realized, and the typical experimental result of the grazing incidence diffractometer with MoS2 sample was introduced as an example. Conclusions : The grazing incidence x-ray diffractometer developed has been operated more than two years, and expands the experimental platform for material surface science research at SSRF.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Instrument and Meter submitted time 2023-06-01
Abstract:核安全防护通常需要同时探测中子和伽马射线,探测器的实时中子/伽马脉冲分辨是其关键性能参数。近年来,采用Cs2LiLaBr6 (CLLB)晶体的双读出探测器引起了广泛关注,论文研究电荷比较法、幅度比较法、时间比较法和脉冲梯度法的甄别性能,以及Sallen-Key滤波器的甄别效果。实验结果表明,通过合适的滤波,四种方法的品质因数(FOM)都有所提高。其中,电荷比较法抗噪声性能最佳,最适合CLLB探测器实时甄别中子/伽马脉冲。其甄别性能取决于参数、和。在对应脉冲峰值10%的时刻,,仅需延迟640-740 ns,此刻对应3.1-3.3 MeV的电荷比较方法最优FOM大于1.46。所提出的最大分辨差模型( MDDM)计算值与最优FOM的差异小于3.9%,表明该模型可以很好地指导电荷比较法的参数选择。