分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-04-07
摘要: 在现场快速准确地实现放射性核素活度测量在放射性医学诊断中具有重要作用。本文采用电容积分式的电路结构,设计了低噪声前置放大器电路,并与高精度信号采集与处理电路相配合,成功研制了弱电流测量电路,实现了20 fA~10 μA弱电流测量。结合前端井型电离室,搭建了电容积分式放射性活度计的原型装置。测试结果表明:本文研制的放射性活度计重复性与商用RM-905A性能基本一致,本底小于0.065 MBq,重复性不超过0.84%,不稳定性为1.94%。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-03-28
摘要: 高帧频面探测器是上海硬X射线自由电子激光装置(Shanghai HIgh repetitioN rate xfel and Extreme light facility,SHINE)上开展相干衍射成像、串行晶体学等科学实验的关键设备。面探测器所产生的海量数据的高速传输和处理对数据获取(DAQ)软件提出了极大挑战。为满足百万像素规模、10kHz帧频的面探测器数据传输要求,DAQ需实现≥20 GB·s-1的稳定数据传输能力。本研究开发了基于C++的分布式DAQ软件,旨在实现高速并行的数据读出,满足高帧频面探测器的数据获取。本研究成功实现了4个节点20 GB·s-1的高通量数据传输和事例重建能力,并对数据刻度、无损压缩等数据预处理功能以及软件整体的分布式运行进行了实现和测试。本研究可以为采用面探测器的相关实验的超高通量数据获取提供必要支持。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-03-20
摘要: 气体探测器中工作气体的平均电离能、法诺因子及漂移速度等性质对于探测器的前期模拟及参数设计乃至径迹重建有着重要影响。SeF6 作为国内无中微子双贝塔衰变实验中的目标工作气体,相关参数未知需要探究。为研究该气体相关参数设计了一套测量方案, 并采用 Ar/CH4=90/10(P10) 工作气体对该实验方案的测量精度和可靠性进行了检验。实验中通过屏栅电离室测量 𝛼 源得出 P10 平均电离能为 27.10±0.04 eV、当能量分辨率达到 0.91% 时,刻度电子学后扣除噪声得到法诺因子为 0.175±0.001。同时采用266 nm 激光和时间投影室完成漂移速度的测量,其结果与 Garifield++ 模拟结果吻合。实验结果表明该测量方案可行,测量结果可靠性高。为后续开展 SeF6 性质的研究工作做好了准备。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-03-15
摘要: 在软X射线能谱探测中,采用硅漂移探测器(Silicon Drift Detector,SDD)与复位型电荷灵敏前置放大器集成的一体化探测设备,其输出信号为包含射线能谱信息的阶梯型锯齿波。文章针对该设备产生的阶梯型锯齿波信号无法直接精确提取幅度信息的问题,提出了一种用模拟电路对该信号进行整形放大处理的方案,并通过Cadence软件仿真的方法,探究了此方案的可行性以及在该方案下影响能谱能量分辨率的因素。文章还通过对比不同噪声幅度输入时电路的输出信号,最终得到在相应的能量分辨率指标要求下前放输出信号噪声指标的最低要求。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-03-07
摘要: The High Energy Cosmic-Radiation Detection (HERD) facility is planned to launch in 2027 and scheduled to be installed on the China Space Station. It serves as a dark matter particle detector, a cosmic ray instrument, and an observatory for high-energy gamma rays. A transition radiation detector placed on one of its lateral sides serves dual purpose, (i) calibrating HERD’s electromagnetic calorimeter in the TeV energy range, and (ii) serving as an independent detector for high-energy gamma rays. In this paper, the prototype readout electronics design of the transition radiation detector is demonstrated, which aims to accurately measure the charge of the anodes using the SAMPA application specific integrated circuit chip. The electronic performance of the prototype system is evaluated in terms of noise, linearity, and resolution. Through the presented design, each electronic channel can achieve a dynamic range of 0-100 fC, the RMS noise level not exceeding 0.15 fC, and the integral nonlinearity was less than 0.2%. To further verify the readout electronic performance, a joint test with the detector was carried out, and the results show that the prototype system can satisfy the requirements of the detector’s scientific goals.
分类: 物理学 >> 核物理学 分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-02-27
摘要: 正在建设中的强流重离子加速器装置 HIAF 配备了一条先进的放射性束流线 HFRS,建成后将为中国 高能放射性核束物理研究提供新的机遇。HFRS 的特点是流强极高 (初级束流强度 1 × 1011 ppp),这对用于粒 子鉴别的能损探测器提出了非常高的计数率要求。传统的能损探测器对信号处理一般依次采用电荷灵敏前放、 主放、ADC 的技术路线。该方案存在电子学响应速度较慢、灵活性较差、难以处理高计数率下信号堆积严重 等问题。我们对此提出一种新的适用于高计数率的能损探测器方案:以耐辐照的多次取样电离室为能损探测 器,优化结构和读出方式提高探测器响应速度,使用快电荷灵敏前放对能损探测器信号初步放大后、直接用 波形数字化仪采集波形再进行后续数字算法处理。并利用放射源和束流对该方案进行了验证测试。利用 3 组 分 𝛼 源测试时,对采集的波形使用数字成形算法处理,能量分辨率(FWHM)可达 1.31%。在 RIBLL2 提供 300 MeV/u 的 56Fe 束流测试中,采用时间常数 𝜏f = 2 𝜇𝑠 的快电荷灵敏前放在计数率接近 1 MHz 时仍未发生明显堆积。
分类: 核科学技术 >> 核探测技术与核电子学 分类: 物理学 >> 核物理学 提交时间: 2024-02-26
摘要: 使用宇宙射线对兰州重离子加速器冷却储存环 (HIRFL-CSR) 外靶实验终端 (ETF) 的 Veto 探测器开展了刻度工作,工作主要分为位置刻度与时间刻度两部分。位置刻度可给出粒子在探测器上的击中位置,时间刻度则能为粒子在探测器上击中时刻的探测建立统一标准。这些信息是剔除入射到中子墙探测器的带电粒子事件的依据,可为中子墙探测器物理目标的实现提供重要支持。在刻度过程中,得到了 Veto 探测器的位置分辨半高全宽 (FWHM) 为 2.53 cm,所有单元条时间归一后的时间分辨 FWHM 为 1.09 ns。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-02-25
摘要: A combination of scintillator, wavelength shifting (WLS) fiber, and silicon photomultiplier (SiPM) shows excellent performance in the `KLandμdetector (KLM)' of the Belle II experiment. We describe the RD for a similar detection technology with a new scintillator and SiPM, which can be implemented for a muon detector for the proposed CEPC experiment and the upgrade of KLM in Belle II. The RD contains the study of the performance of a new scintillator with a length of 150 cm, the NDL SiPM with a sensitive surface of 3 mm×3 mm or the Hamamatsu MPPC with a sensitive surface of 1.3 mm×1.3 mm, the construction of a detector strip, and the methods to achieve excellent light collection. The cosmic ray tests show good photon collections by NDL SiPM or MPPC, efficiencies well above 90% with a threshold of 8 p.e., and time resolutions of better than 1.7 ns for the hits at the far end of a scintillator strip. The performance shows a good option for an excellent muon detector for CEPC and the possible upgrade of Belle II KLM.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-02-23
摘要: Time-encoded imaging is useful for identifying potential special nuclear materials and other radioactive sources at a distance. In this study, a large field-of-view time-encoded imager was developed for gamma-ray and neutron source hotspot imaging based on a depth-of-interaction (DOI) detector. The imager primarily consists of a DOI detector system and a rotary dual-layer cylindrical coded mask. An EJ276 plastic scintillator coupled with two SiPMs was designed as the DOI detector to increase the field of view and improve the imager performance. The difference in signal time at both ends and the log of the signal amplitude ratio were used to calculate the interaction position resolution. The position resolution of the DOI detector was calibrated using a collimated Cs-137 source, and the full width at half maximum of the reconstruction position of the Gaussian fitting curve was approximately 4.4 cm. The DOI detector can be arbitrarily divided into several units to independently reconstruct the source distribution images. The unit length was optimized via Am-Be source-location experiments. A multidetector filtering method is proposed for image denoising. This method can effectively reduce image noise caused by poor DOI detector position resolution. The vertical field of view of the imager was (-55°, 55°) when the detector was placed in the center of the coded mask. A DT neutron source at 20 m standoff could be located within 2400 s with an angular resolution of 3.5°.
分类: 核科学技术 >> 核探测技术与核电子学 分类: 核科学技术 >> 核仪器、仪表 提交时间: 2024-02-07
摘要: 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.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-01-26
摘要: 激光等离子体X射线能谱的诊断对于表征电子动力学和辐射源应用非常重要,高重复率超强飞秒激光器和高重复频率激光等离子体实验对脉冲X射线能谱的在线诊断技术提出了需求。 在本文中,使用闪烁体和硅PIN(P型本征N型半导体)二极管构建了宽带在线滤片堆栈谱仪。 使用遗传算法优化 了X 射线传感器和滤片的布置,使响应矩阵的条件数最小化,以优化谱仪的解谱误差。通过核素照射闪烁体和PIN二极管并比较测量的射线峰值,对探测器的响应进行了标定。 通过将 X 射线探测器与前端和后端电子学的集成化设计,研制了紧凑的 15 通道在线滤片堆栈谱仪原型系统。 原型系统可以以 1 kHz 的重复率测量脉冲X 射线能谱,并在激光驱动轫致辐射源的实时能谱监测中得到成功应用。 本文提出的优化在线滤片堆栈谱仪为超短X射线脉冲的能谱诊断提供了紧凑的解决方案,在能谱测量和重复率方面具有显著优势,可广泛用于未来的高重复率高功率激光装置实验。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-01-22
摘要: 本文在UMC55nm CMOS工艺下,实现了一款10GHz高速输出、低功耗的高性能电荷泵锁相环设计,可以为粒子物理实验中数据传输系统提供高频差分时钟脉冲。设计了一种双支路通路电荷泵,通过引入运算放大器、虚拟管等措施抑制非理想因素对电路造成的影响。设计了高速、低功耗的64分频电路将锁相环输出的10 GHz差分时钟转化成156.25MHz的单端时钟。设计了采用了互补交叉耦合结构的LC压控振荡器,使其在快速起振的同时又具有较小的相位噪声。仿真结果表明,在经典工艺角下VCO在1MHz频偏处的相位噪声为-104.14dBc/Hz。PLL在500ns完成锁定,功耗22.34mW,峰峰值抖动为6.59ps。
分类: 物理学 >> 核物理学 分类: 核科学技术 >> 核科学与技术 分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-01-08
摘要: To detect radioactive substances with low activity levels, an anticoincidence detector and a high-purity germanium (HPGe) detector are typically used simultaneously to suppress Compton scattering background, thereby resulting in an extremely low detection limit and improving the measurement accuracy. However, the complex and expensive hardware required does not facilitate the application or promotion of this method. Thus, a method is proposed in this study to discriminate the digital waveform of pulse signals output using an HPGe detector, whereby Compton scattering background is suppressed and a low minimum detectable activity (MDA) is achieved without using an expensive and complex anticoincidence detector and device. The electric-field-strength and energy-deposition distributions of the detector are simulated to determine the relationship between pulse shape and energy-deposition location, as well as the characteristics of energy-deposition distributions for full- and partial-energy deposition events. This relationship is used to develop a pulse-shape-discrimination algorithm based on an artificial neural network for pulse-feature identification. To accurately determine the relationship between the deposited energy of gamma rays in the detector and the deposition location, we extract four shape parameters from the pulse signals output by the detector. Machine learning is used to input the four shape parameters into the detector. Subsequently, the pulse signals are identified and classified to discriminate between partial- and full-energy deposition events. Some partial-energy deposition events are removed to suppress Compton scattering. The proposed method effectively decreases the MDA of an HPGe -energy dispersive spectrometer. Test results show that the Compton suppression factors for energy spectra obtained from measurements on 152Eu, 137Cs, and 60Co radioactive sources are 1.13 (344 keV), 1.11 (662 keV), and 1.08 (1332 keV), respectively, and that the corresponding MDAs are 1.4%, 5.3%, and 21.6% lower, respectively
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-12-15
摘要: 多丝结构气体探测器具有耐辐射、响应快、灵敏区大、易于建造等优势而广泛应用于核物理和核技术领域。介绍了多丝结构气体探测器的电场计算理论方法,并利用有限元程序ANSYS及探测器模拟程序GARFIELD进行了多丝结构气体探测器漂移区、雪崩放大区的电场优化设计。此外,结合GEANT4程序进行了宇宙射线入射气体探测器的模拟计算,获得了探测器电流、电压以及输出波形积分电荷的统计结果。在此基础上进行了气体探测器的研制,并用于宇宙射线的测试实验,实验结果与模拟结果基本一致。论文提出的模拟计算方法及实验技术完全可用于多丝结构气体探测器的优化设计及实验评估,为类似探测器及实验提供借鉴。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-11-01
摘要: 在核工业领域,许多场所、工厂等存在表面污染情况,在出现应急工况的时候,一般需要先对异常区域进行远程探测,再结合测量结果科学地制定解决方案。针对此现状,国际上提出了基于空气荧光的粒子测量方法,其原理是空气中的氮气在辐射作用下通过激发退激过程会发射特定波长的紫外荧光,允许被紫外相机远程探测,从而可以间接检测污染。在国内对污染远程探测技术的研究报道较少,中核四0 四联合兰州大学已经率先开展了此项研究。文章主要综述了国际上基于氮气荧光的污染远程探测技术的发展状况,简述了当前团队最新的研究工作,以期为国内开展污染远程探测研究提供参考。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-09-14
摘要: A fully digital data acquisition system based on a field-programmable gate array (FPGA) was developed for a CsI(Tl) array at the External Target Facility (ETF)in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by -rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard and sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution and digital charge comparison was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33 MeV rays and excellent - identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: As photoelectrically detected 252Cf-source-driven neutron signals always contain noise, a denoising algorithm is proposed based on compressive sensing for the noised neutron signal. In the algorithm, Empirical Mode Decomposition (EMD) is applied to decompose the noised neutron signal and then find out the noised Intrinsic Mode Function (IMF) automatically. Thus, we only need to use the basis pursuit denoising (BPDN) algorithm to denoise these IMFs. For this reason, the proposed algorithm can be called EMDCSDN (Empirical Mode Decomposition Compressive Sensing Denoising). In addition, five indicators are employed to evaluate the denoising effect. The results show that the EMDCSDN algorithm is more effective than the other denoising algorithms including BPDN. This study provides a new approach for signal denoising at the front-end.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A spherical tissue equivalent proportional counter (TEPC) for neutron monitoring has been developed. It was properly designed to produce a uniform electric field intensity around the anode wire. An internal 241Am alpha source was adopted for lineal energy calibration. The TEPC was characterized in terms of dose equivalent response in a standard 252Cf neutron field, and was tested with 2.45 MeV neutrons. Microdosimetric spectra, frequency mean lineal energy and dose-average mean lineal energy of 2.45 MeV neutrons were obtained and compared with FLUKA Monte Carlo simulation results. The measurement and simulation results agreed well. The mean quality factor and dose equivalent values evaluated from the 2.45 MeV neutron measurement were in good agreement with the recommended effective quality factor and ambient dose equivalent H*(10)(10), respectively. Preliminary results have proved the availability of the developed TEPC for neutron monitoring.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A compact X-ray detector based on the lutetium yttrium oxyorthosilicate scintillator (LYSO) and silicon photomultiplier (SiPM) has been designed and fabricated for the hard X-ray diagnosis on the HL_2A and HL_2M Tokamak devices. The LYSO scintillator and SiPM in small dimensions were combined in a heat shrink tube package, making the detector compact and integrative. The Monte Carlo particle transport simulation tool, Geant4, was utilized for the design of the detector for the hard X-ray from 10 keV to 200 keV and the best structure scheme was presented. Finally, the detector was used to measure the photon spectrum of a 137Cs gamma source with a pre-amplifier and a multichannel amplitude analyzer. The measured spectrum is consistent with the theoretic spectrum, it has shown that the energy resolution of the detector is less than 14.8% at an energy of 662 keV.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Hefei Light Source (HLS)-II is a vacuum ultraviole (VUV) synchrotron light source. A major upgrade of the light source was finished at the end of 2014. The timing system was rebuilt using compact peripheral component interconnect (cPCI) event-driven hardware to meet synchronization requirements of the machine. In the new system, the cPCI event-driven products manufactured by the micro-research finland (MRF) Oy are employed to achieve about 100 output signals with different interfaces. Device supports and drivers developed for common Experimental Physics and Industrial Control System (EPICS) records are used to access the registers on the timing modules. Five cPCI-bus input/output controllers (IOCs) distributed in different areas of the light source host timing modules for various subsystems. The delay resolution of this system is 9.8 ns for most channels and 9 ps for the channels used for triggering the electron gun and the injection kickers. The measured rms jitter of the output signal is less than 27 ps. Using the bucket chooser, this system enables the HLS-II to fill the storage ring with any designated bunch pattern. Benefitting from this upgrade, brightness and performance of the light source are significantly improved.