分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Two different isospin splittings of nucleon effective mass in nuclear medium as the form of mn*>mp* and mn*n/p and /+, excitation functions of /+ and K0/K+.
分类: 物理学 >> 核物理学 提交时间: 2023-05-19
摘要: We provide an investigation of the spectroscopic factors of resonance states in $A =5-8$ nuclei using two distinct nuclear models, the Gamow shell model (GSM) and the no-core shell model (NCSM).Configuration mixing is treated exactly in both GSM and NCSM. GSM employs the complex-energy Berggren ensemble, which treats bound, unbound resonance, and non-resonant continuum single-particle states on an equal footing.As a result, continuum coupling is taken into account in GSM, whereas it is absent in NCSM, where the harmonic oscillator basis is used.We first calculate low-lying states of helium isotopes and isotones. The results indicate that GSM can more accurately reproduce the low-lying resonance states than NCSM.The spectroscopic factors of the resonance states are also computed.Results from the GSM and NCSM are compared and show that continuum coupling plays an important role in the calculations of spectroscopic factors of resonance states.Overlap functions related to the resonance states are also systematically calculated by the GSM and NCSM. It is then demonstratedthat wave function asymptotes can only be reproduced in GSM, where continuum coupling is taken into account.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: The study presents an investigation of irradiation resistance properties of Ti3AlC2 under 500 keV He ions irradiation with the doses ranging from 5.0 1016 to 1.0 1018 ions cm 2 at certain temperatures, like room temperature (RT), 300 and 500 °C. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) are used to study the evolution of structural damage and the behavior of deposited He ions respec- tively. XRD analysis reveals that for the highest dose irradiation ( 52 dpa at peak), no amorphization occurs. And the structural recovery of Ti3AlC2 is more significant accompanied with the gradual disap- pearance of the irradiation-induced TiC phase as the temperature rises from RT to 300 and to 500 °C with the same dose irradiation. TEM observations show that He bubbles appear in the shapes of sphere, string and platelet but no big bubbles are formed for all irradiations. Moreover, no large cracks form in the sam- ple implanted with the highest helium concentration of 6.4 105 appm.
分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-12
摘要: A microscopic method for calculating nuclear level density (NLD) based on the covariant density functional theory (CDFT) is developed. The particle-hole state density is calculated by combinatorial method using the single-particle levels schemes obtained from the CDFT, and then the level densities are obtained by taking into account collective effects such as vibration and rotation. Our results are compared with those from other NLD models, including phenomenological, microstatistical and non-relativistic HFB combinatorial models. The comparison suggests that the general trends among these models are basically the same, except for some deviations from different NLD models. In addition, the NLDs of the CDFT combinatorial method with normalization are compared with experimental data, including the observed cumulative number of levels at low excitation energy and the measured NLDs. Compared with the existing experimental data, the CDFT combinatorial method can give reasonable results.
分类: 物理学 >> 核物理学 提交时间: 2024-04-28
摘要: The high-intensity heavy-ion accelerator facility (HIAF) is a scientific research facility complex composed ofmultiple cascade accelerators of different types, which pose a scheduling problem for devices distributed overa certain range of 2 km, involving over a hundred devices. The White Rabbit (WR), a technology-enhancingGigabit Ethernet, has shown the capability of scheduling distributed timing devices but still faces the challengeof obtaining real-time synchronization calibration parameters with high precision. This study presents a calibra#2;tion system based on a time-to-digital converter implemented on an ARM-based System-on-Chip (SoC). Thesystem consists of four multi-sample delay lines, a bubble-proof encoder, an edge controller for managing datafrom different channels, and a highly effective calibration module that benefits from the SoC architecture. Theperformance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0to 24000 ps with 120000 data for every test. The design presented in this study refines the calibration precisionof the HIAF timing system. This eliminates the errors caused by manual calibration without efficiency loss andprovides data support for fault diagnosis. It can also be easily tailored or ported to other devices for specificapplications and provides more space for developing timing systems for particle accelerators, such as whiterabbits on HIAF.
分类: 物理学 >> 核物理学 提交时间: 2023-10-13
摘要: The Electron Cyclotron Resonance (ECR) ion source is a critical device for producing highly charged ion beams in various applications. Analyzing the charge-state distribution of the ion beams is essential, but the manual analysis is labor-intensive and prone to inaccuracies due to impurity ions. An automatic spectrum recognition system based on intelligent algorithms was proposed for rapid and accurate chargestate analysis of ECR ion sources. The system employs an adaptive window-length Savitzky-Golay (SG) filtering algorithm, an improved automatic multiscale peak detection (AMPD) algorithm, and a greedy matching algorithm based on the relative distance to accurately match different peaks in the spectra with the corresponding charge-state ion species. Additionally, a user-friendly operator interface was developed for ease of use. Extensive testing on the online ECR ion source platform demonstrates that the system achieves high accuracy, with an average root mean square error of less than 0.1 A for identifying charge-state spectra of ECR ion sources. Moreover, the system minimizes the standard deviation of the first-order derivative of the smoothed signal to 81.1846 A. These results indicate the capability of the designed system to identify ion beam spectra with mass numbers less than Xe, including Xe itself. The proposed automatic spectrum recognition system represents a significant advancement in ECR ion source analysis, offering a rapid and accurate approach for charge-state analysis while enhancing supply efficiency. The exceptional performance and successful implementation of the proposed system on multiple ECR ion source platforms at IMPCAS highlight its potential for widespread adoption in ECR ion source research and applications.
分类: 物理学 >> 核物理学 提交时间: 2023-06-25
摘要: The ion motions in a Penning trap have been studied in detail in the presence of azimuthal dipolar and quadrupolar radio-frequency excitations and buffer gas cooling. The numerical solutions by using the Runge-Kutta method and thus the pictures of the ion trajectories in the trap have been obtained for different cases and summarized in graphical form. For the recentering of the ion of interest and to perform the purification of the ion species, one has to set a reasonable buffer gas pressure in the trap and apply azimuthal quadrupolar excitation at frequency rf = c.
分类: 物理学 >> 核物理学 提交时间: 2023-06-24
摘要: A new method including two sub-procedures, global search and local refine, has been developed and presented to design a multiple-reflection time-of-flight (MRTOF) mass analyzer. By using this method, a different type of MRTOF mass analyzer, in which each mirror consists of five cylindrical electrodes, has been designed for isobaric separation for Lanzhou Penning Trap (LPT). The optimal potential parameters of the electrodes have been obtained and the maximal resolving power has been achieved to be 1.3x105 with a total time-of-flight of 6.5 ms for an ion species of 40Ar1+. The simulation shows the inaccuracy of the potentials applied to the mirror electrodes must be less than 50 ppm or preferably 20 ppm.
分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The operation of the HIRFL accelerator has shown that the beam transmission efficiency of the sector focusing cyclotron (SFC) injector line is rather poor. Beam simulations have been performed to investigate the possible causes for this low transmission. It is predicted that the property of transversal coupling of the ion beam from electron cyclotron resonance (ECR) ion source can be an important factor to degrade the beam quality by increasing the beam emittance, resulting in a serious particle loss. An improved operation scheme for the SECRAL associated line has been proposed, and the corresponding experiment was carried out. This paper presents the test results.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A Neutron Time-Of-Flight (NTOF) spectrometer, based at the Heavy Ion Research Facility in Lanzhou (HIRFL) was developed for studies of neutron production of proton induced spallation reactions related to the ADS project. After the presentation of comparisons between calculated spallation neutron production double-differential cross sections and the available experimental data, a detailed description of the NTOF spectrometer is given. Test beam results show that the spectrometer works well and data analysis procedures are established. The comparisons of the test beam neutron spectra with those of GEANT4 simulations are presented.
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: Single event effects (SEEs) induced by radiations become a significant reliability challenge for modern electronic systems. To evaluate SEEs susceptibility for microelectronic devices and integrated circuits (ICs), an SEE testing system with flexibility and robustness was developed at Heavy Ion Research Facility in Lanzhou (HIRFL). The system is compatible with various types of microelectronic devices and ICs, and supports plenty of complex and high-speed test schemes and plans for the irradiated devices under test (DUTs). Thanks to the combination of meticulous circuit design and the hardened logic design, the system has additional performances to avoid an overheated situation and irradiations by stray radiations. The system has been tested and verified by experiments for irradiating devices at HIRFL.
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: Dielectric wall accelerator (DWA), towards high gradient acceleration field (30 MeV/m100 MeV/m), is under development at Institute of Modern Physics. A prototype was designed and constructed to prove the principle. This needs a short pulse high current electron source to match the acceleration field generated by the Blumlein-type pulse forming lines (PFLs). In this paper, we report the design and test of a new type short pulse high current electron gun based on principle of vacuum arc discharge. Electron beams of 100 mA with pulse width of 10 ns were obtained.
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: Field Programmable Gate Array (FPGA), combined with ARM (Advanced RISC Machines) is increasingly employed in the portable data acquisition (DAQ) system for nuclear experiments to reduce the system volume and achieve powerful and multifunctional capacity. High-speed data transmission between FPGA and ARM is one of the most challenging issues for system implementation. In this paper, we propose a method to realize the high-speed data transmission by using the FPGA to acquire massive data from FEE (Front-end electronics) and send it to the ARM whilst the ARM to transmit the data to the remote computer through the TCP/IP protocol for later process. This paper mainly introduces the interface design of the high-speed transmission method between the FPGA and the ARM, the transmission logic of the FPGA, and the program design of the ARM. The theoretical research shows that the maximal transmission speed between the FPGA and the ARM through this way can reach 50 MB/s. In a realistic nuclear physics experiment, this portable DAQ system achieved 2.2 MB/s data acquisition speed.
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 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: To study cytotoxic effect of heavy ion irradiation in the plateau region, and investigate whether autophagy induced by heavy ion irradiation is cytoprotective, HeLa cells were irradiated with 350 MeV/u carbon ions beams, and the clonogenic survival was analyzed. The results showed that cell survival decreased with increasing doses. It was also found that G2/M-phase cells increased, and the autophagy-related activity was significantly higher than the control. When autophagy was blocked by 3-methyladenine in carbon-ion irradiated cells, G2/M phase arrest and the percentage of apoptosis cells were further elevated, and cell survival decreased significantly, indicating the induction of cytoprotective autophagy by carbon-ion irradiation. Our results demonstrated that autophagy induced by carbon ion irradiation provided a self-protective mechanism in HeLa cells, short-time inhibition of autophagy before carbon-ion irradiation could enhance radiation cytotoxicity in HeLa cells.
分类: 物理学 >> 核物理学 提交时间: 2023-06-09 合作期刊: 《Nuclear Science and Techniques》
摘要: In the Chinese ADS front-end demo superconducting radiofrequency linac (CAFe) at the Institute of Modern Physics, a burst-noise signal-triggered cavity fault frequently appears during beam commissioning. These events are characterized by a rapid burst noise in the cavity pick-up, which may lead to an unexpected low-level radiofrequency (LLRF) response that eventually causes a cavity fault. To eliminate the undesirable reaction of the LLRF control loop, we propose a method that uses a burst-noise detection and processing algorithm integrated into the LLRF feedback controller. This algorithm can prevent undesired regulations in LLRF systems. Data analysis revealed that some burst-noise events did not exhibit measurable energy loss. In contrast, the other events were accompanied by a rapid loss of cavity stored energy and exhibited similarities to the “E-quench” phenomena reported in other laboratories. A particle-in-cell simulation indicated that the suspected E-quench phenomenon may be related to a plasma formation process inside the cavity. Fortunately, the LLRF algorithm is robust to the two different types of burst-noise events and can significantly mitigate the corresponding cavity faults in CAFe beam commissioning.
分类: 核科学技术 >> 粒子加速器 提交时间: 2021-12-31
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.
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: Gamma Ray Array Detector (GRAD) is one of external target facility subsystems in the Cooling Storage Ring on the Heavy Ion Research Facility at Lanzhou (HIRFL-CSR). The trigger subsystem of GRAD is required to make a fast L1 trigger decision with a fixed latency for the data acquisition. Because the hit signals from the detector are asynchronous with the local clock of the trigger system, a nondeterministic latency (the value changes between zero and one clock period) is generated when the synchronous receivers of the conventional trigger system process the hit signals. In this paper, an improved trigger logic based on a field-programmable gate array is developed, and comprised of zero-delay broadening circuits as receivers and an improved adding circuit designed for the new receivers. Software simulation and experimental measurement have been conducted. Comparison with the conventional trigger logic, the improved trigger logic has the advantage of eliminating the nondeterministic latency and reducing the total processing latency.