分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-07-04
摘要： Cosmic-ray muons are highly penetrating background-radiation particles found in natural environments. In this study, we develop and test a plastic scintillator muon detector based on machine-learning algorithms. The detector underwent muon position-resolution tests at the Institute of Modern Physics in Lanzhou using a mul tiwire drift chamber (MWDC) experimental platform. In the simulation, the same structural and performance parameters were maintained to ensure the reliability of the simulation results. The Gaussian process regression (GPR) algorithm was used as the position-reconstruction algorithm owing to its optimal performance. The re sults of the Time Difference of Arrival algorithm were incorporated as one of the features of the GPR model to reconstruct the muon hit positions. The accuracy of the position reconstruction was evaluated by comparing the experimental results with Geant4 simulation results. In the simulation, large-area plastic scintillator detectors achieved a position resolution better than 20 mm. In the experimental-platform tests, the position resolutions of the test detectors were 27.9 mm. We also analyzed factors affecting the position resolution, including the crit ical angle of the total internal reflection of the photomultiplier tubes and distribution of muons in the MWDC. Simulations were performed to image both large objects and objects with different atomic numbers. The results showed that the system could image high- and low-Z materials in the constructed model and distinguish objects with significant density differences. This study demonstrates the feasibility of the proposed system, thereby providing a new detector system for muon-imaging applications.
分类： 物理学 >> 核物理学 提交时间： 2024-06-25
摘要： In conventional isochronous mass spectrometry (IMS) performed at a storage ring, the precision of mass measurement for short-lived nuclei depends on the precise determination of the revolution times (Ts) of stored ions. However, the resolution of T inevitably deteriorates due to the magnetic rigidity spread of the ions, resulting in limited mass resolving power. In this work, we measure the betatron tune Q (the number of betatron oscillations within a single revolution) of the ions, and construct a correlation between T and Q. From this correlation, the T are transformed corresponding to a fixed Q with higher resolution. Using the transformed Ts, we re-determine the masses of 63Ge, 65As, 67Se, and 71Kr, which agree well with the mass values measured by the newly developed IMS (Bρ-IMS). We also study the systematics of Coulomb displacement energies (CDEs) and find that the anomalous staggering in CDEs is removed using the new mass values. This method of T transformation is very useful for the conventional IMS equipped with a single time-of-flight detector.
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： 2024-04-28
摘要： A charged particle array, named MATE-PA, which serves as an auxiliary detec#2;tor system to the Multi-purpose Active-target Time projection chamber for nuclear astrophysical and exotic beam Experiments (MATE) has been con#2;structed. The array is composed of twenty single-sided strip-silicon detectors, covering around 10% of the solid angle. It is dedicated for the detection of reaction-induced charged particles which penetrate the MATE active volume. The performance of MATE-PA has been experimentally studied using an alpha source, and a 36-MeV 14N beam injected into the chamber of MATE, filled with a mixture gas of 95% 4He and 5% CO2 under the pressure of 500 mbar, at the Radioactive Ion Beam Line in Lanzhou (RIBLL). The results demonstrate good separation of light charged particles with the forward double-layer silicon detectors of MATE-PA. The energy resolution of the Si detectors was deduced to be about 1% (σ) for an energy loss of about 10 MeV by the α particles. The inclusion of MATE-PA helps improve particle identification, and increases the dynamic range for the kinetic energy of charged particles, in particular that of α particles up to about 15 MeV.
分类： 物理学 >> 核物理学 提交时间： 2024-04-28
摘要： Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage, store energy, and decrease power variation. In this study, DC-link capacitors in pulsed power supplies were investigated. By deriving an analytical method for the capacitor current on the H-bridge topology side, the root-mean-square value of the capacitor current was calculated, which helps in selecting the DC-link capacitors. The proposed method solves this problem quickly and with high accuracy. The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement, and the capacitor’s hot spot temperature and temperature rise are calculated using the FFT transform. The test results showed that the error between the calculated and measured temperature increases was within 1.5 ◦C. Finally, the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis. The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-03-07
Jieyu Zhu
Haibo Yang
Yangzhou Su
Fenhua Lu
Yan Yang
Xiwen Liu
Ping Wei
Shucai Wan
Haoqing Xie
Xianqin Li
Cong Dai
Huijun Hu
Hongbang Liu
Shuwen Tang
Chengxin Zhao
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 提交时间： 2023-09-11
Liu, Xiangman
Tang, Shuwen
Wang, Wei
Yu, Yuhong
Sun, Zhiyu
Zhang, Yongjie
Fang, Fang
Yan, Duo
Wang, ShiTao
Zhang, Xueheng
Jin, Shuya
Hu, Bitao
摘要： Gamma-ray polarimetry is a new and prospective tool for studying various extreme high-energy celestial objects and is of great significance for the development of astrophysics. With the rapid development of microsatellite technology, the advantages in space exploration are becoming increasingly apparent. Therefore, in this paper, we conducted a simulation study on a soft gamma-ray polarimeter for a microsatellite in space. Here, we proposed a unique design structure for the polarimeter based on the microsatellite design concept and the Compton scattering principle. And then, the detailed Monte Carlo simulations using mono-energetic gamma-ray linear polarization sources and the Crab-like sources in the energy range of 0.1-10 MeV with full consideration of the orbital background were performed. The simulation results show that the polarimeter can exhibit excellent polarization detection performance. The modulation factor is 0.800.01, and the polarization angles are accurate within an error of 0.2 at 200 keV for on-axis incidence. For the Crab-like sources for on-axis incidence, the polarization degrees are consistent with the set values within the error tolerance, the modulation factor is 0.760.01, and the minimum detectable polarization reaches 2.4% at 3 for an observation time of 106 seconds. In addition, the polarimeter has recoil electron tracking, imaging, and powerful background suppression at a large field of view (2 sr). The polarimeter designed can meet the requirements of a space-soft gamma-ray polarization detector very well and has a bright research prospect.
分类： 物理学 >> 核物理学 提交时间： 2023-06-24
Wang, Yongsheng
Huang, Wenxue
Tian, Yulin
Wang, Junying
Li, Cheng
Zhang, Fengshou
Zhao, Kai
Zhou, Xiaohong
Xu, Hushan
摘要： The multinucleon transfer (MNT) reaction is one promising way to produce neutron-rich heavy nuclei and even super heavynuclei and attracts more and more attentions theoretically and experimentally. A low energy nuclear structure spectrometer calledLENSHIAF specific to the MNT reactions will be designed and constructed in the ongoing big project HIAF in China. In theLENSHIAF spectrometer, the most challenge part is how to collect and stop efficiently the high-energy MNT products into the gascell. By using Monte-Carlo method, the geometry of the gas cell, the thickness of the titanium window/degrader, and the optimalgas pressure filled in the gas cell have been calculated and estimated. For neutron-rich nuclei around N=126 from 136Xe+198Ptreaction, with a titanium window/degrader with a thickness of 2.53.5 um, a cylindrical helium gas cell with a length of 0.6 m and adiameter of 1.2 m can satisfy the requirements to stop the target-like fragments. For heavier and super heavy nuclei from 238U+238Ureaction, with a 58 um thick titanium window/degrader, the cylindrical gas cell has to be as big as a length of at least 1.6 m and adiameter of 1.6 m.
分类： 核科学技术 >> 粒子加速器 提交时间： 2021-12-31
Ma, Jin-Ying
Qiu, Feng
Shi, Long-Bo
Zhu, Zheng-Long
Jiang, Tian-Cai
Xue, Zong-Heng
Jin, Ke-An
Chen, Qi
Xu, Cheng-Ye
Ding, Xing-Hao
Gao, Zheng
Sun, Lie-Peng
Huang, Gui-Rong
He, Yuan
摘要： Precise measurements of the cavity forward (Vf) and reflected signals (Vr) are essential for characterizing other key parameters such as the cavity detuning and forward power. In practice, it is challenging to measure Vf and Vr precisely because of crosstalk between the forward and reflected channels (e.g., coupling between the cavity reflected and forward signals in a directional coupler with limited directivity). For DESY, a method based on the cavity differential equation was proposed to precisely calibrate the actual Vf and Vr. In this study, we verified the validity and practicability of this approach for the Chinese ADS front-end demo superconducting linac (CAFe) facility at the Institute of Modern Physics and a compact energy recovery linac (cERL) test ma#2;chine at KEK. At the CAFe facility, we successfully calibrated the actual Vf signal using this method. The result demonstrated that the directivity of directional couplers might seriously affect the accuracy of Vf measurement. At the cERL facility, we calibrated the Lorentz force detuning (LFD) using the actual Vf. Our study confirmed that the precise calibration of Vf significantly improves the accuracy of the cavity LFD measurement.
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