arXiv subjects

Jinfu Zhu

Publications and source records attributed to Jinfu Zhu.

12 recordsLinked to original sources

arXiv2026

Superconductivity of Tellurium Polyhydride with Tc above 90K

We report experimental diacovery of superconductivity (SC) in tellurium (Te) polyhydride. The compound was synthesized at high pressure and high temperature conditions using a diamond anvil cell combined with a laser heating system. Subsequent in situ transport measurements at high pressures, performed as a function of temperature and applied magnetic field, revealed a superconducting transition with a critical temperature Tc about 91 K at 263 GPa. The superconducting phase is assigned to TeH4 with characterized face shared TeH12 cage forming quasi molecular H2 units based on synchrotron x-ray diffraction experiments. Analysis of the SC behavior at magnetic fields yielded a Ginzburg Landau (GL) coherence length of approximately 54 angstroms. Tellurium polyhydride thus becomes another chalcogen polyhydride superconductor in addition to the landmark discovery of the first polyhydride high Tc SC SH3.

cond-mat.supr-con↗

arXiv2025

Mains-Synchronized Timing Trigger for Stability Enhancement in FEL Pulsed Microwave Systems

Pulsed microwave stability in linear accelerators (LINACs) is critical for maintaining high-quality electron beams in synchrotron radiation and free-electron laser (FEL) facilities. This study establishes and validates a zero-crossing synchronization strategy to suppress mains-induced disturbances in the Dalian Coherent Light Source (DCLS) accelerator. Through comprehensive numerical simulations at 10 Hz, 20 Hz, and 25 Hz repetition rates, we first demonstrate the temporal evolution of microwave amplitude perturbations under mains power disturbances. Experimental validation with the digital Low-Level Radio Frequency (LLRF) system reveals a substantial similarity between simulated and measured interference patterns, confirming the susceptibility of the klystron output to mains power modulation. The developed synchronization technique integrates real-time mains zero-crossing detection with precision timing sequence generation, effectively decoupling the microwave system from power frequency fluctuations. It achieves remarkable inter-pulse stability improvements, reducing microwave amplitude fluctuation from ~0.30% RMS to 0.07% RMS. This approach not only addresses the inherent bandwidth limitations of conventional proportional-integral-derivative (PID) controllers in low-repetition-rate accelerators but also provides a solution for troubleshooting power-related instabilities in advanced light source facilities.

physics.acc-ph↗

arXiv2025

Prototype design of a digital Low-Level RF system for S3FEL S-band Transverse Deflecting Cavities

Transverse Deflecting Cavities (TDCs) are generally adopted for electron beam diagnosis. Three sets of S-band and two sets of X-band TDCs are planned at Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL) to accurately measure the temporal distribution of ultra-short electron bunches. The microwave system of one TDC consisting of a Low-Level Radio-Frequency system (LLRF), a solid-state amplifier, a klystron, and several waveguide couplers is operated in pulse mode with a maximum repetition rate of 50 Hz. Its microwave stabilities for amplitude and phase are required to be better than 0.05%/0.05° (RMS). This article will introduce the prototype design of the hardware, firmware, and software of the digital LLRF system for S-band TDCs. We use a homemade local oscillator and commercial cards based on the MicroTCA standard in hardware design. The firmware design will use an IQ demodulation and a reference-tracking algorithm to eliminate the measurement noise and drift. The software design is based on the Experimental Physics and Industrial Control System (EPICS), achieving data acquisition, slow control, and interface display functions. This technical report will also show some preliminary test results.

physics.acc-ph↗

arXiv2024

Preliminary Design of a General Electronics Platform for Accelerator Facilities

Many accelerators require considerable electronic systems for tests, verification, and operation. In Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL), to meet the early tests and verification of various systems, save development expenses, and improve the reusability of hardware, firmware, and software systems, we have considered the needs of each system and preliminarily designed a general electronics platform based on MicroTCA.4. The Advanced Mezzanine Card (AMC) will place an FPGA Mezzanine Card (FMC) that supports 500 MSPS to 2 GSPS ADC/DAC. We will design two FMC cards on the Rear Transition Module (RTM), which can be used for analog signal conditioning and waveform digitization by 10 MSPS to 250 MSPS ADC/DAC or motor control. The commercial MCH, CPU, power module, and MTCA crate are deployed. This platform can also be applied to other accelerator facilities.

physics.ins-det↗

arXiv2020

Preliminary Design of a FADC Readout System for the Alpha/Beta Discrimination in a Large Area Plastic Scintillation Detector

This paper describes a FADC Readout system developed for the tap water $α/β$ dose monitoring system which is based on EJ444 phoswich scintillation detector and wavelength shifting fiber readout. The Readout system contains dual sampling channels that can supply sampling rate up to 1 GSPS, 14-Bit vertical resolution and adequate effective number of bits (9.7 Bits at 10 MHz), which is optimum for the discrimination of the minimal difference between alpha/beta signals. Moreover, the system is based on a ZYNQ SoC which provides high data throughput speed, low latency and excellent flexibility. As for the discrimination algorithms, a simple least-square classification method is used to discriminate the $α/β$ signals and shows high discrimination capability. Besides, the front-end electronics and high voltage supply modules are also briefly introduced in the paper.

physics.ins-det↗

arXiv2020

Noise Analysis of Current Sensitive Preamplifiers and Influence on Energy Resolution of NaI:Tl Detector System

Current Sensitive Preamplifiers (CSPs) are widely used in front-end electronics in data acquire system (DAQ), due to their ability to amplify signals directly. The optimization of energy resolution requires CSPs with suitable parameters such as gain, bandwidth, and low noise, etc. With the rapid improvement of CSP's bandwidth and trans-impedance gain, it is necessary to know how does the output noise of CSPs effect the energy resolution. For this purpose, we built the noise model of CSPs and analyzed the output noise voltage density of CSPs based on different commercial operation amplifiers (OP AMPs). Theoretical and experimental results shown that OP AMPs with low input noise voltage density is superior than others on energy resolution. Moreover, noise normalization factor has been defined to verify the relationship between energy resolution and noise of CSPs. The experimental results shown that the energy resolution and noise normalization factor are linearly conformable. This paper can provide reference on selecting commercial OP AMPs to design CSPs for optimization of energy resolution.

physics.ins-det↗

arXiv2020

Analysis and Verification of Relation between Digitizer's Sampling Properties and Energy Resolution of HPGe Detectors

The CDEX (China Dark matter Experiment) aims at detection of WIMPs (Weakly Interacting Massive Particles) and 0vbb (Neutrinoless double beta decay) of 76Ge. It now uses ~10 kg HPGe (High Purity Germanium) detectors in CJPL (China Jinping Underground Laboratory). The energy resolution of detectors is calculated via height spectrum of waveforms with 6-us shaping time. It is necessary to know how sampling properties of a digitizer effect the energy resolution. This paper will present preliminary energy resolution results of waveforms at different sampling properties. The preliminary results show that the ENOB (effective number of bits) with 8.25-bit or better can meet the energy resolution @122keV of CDEX HPGe detectors. Based on the ADC (Analog-to-Digital Converter) quantized error theory, this paper will also make a quantitative analysis on energy resolution in CDEX HPGe detectors. It will provide guidance for ADC design in full-chain cryogenic readout electronics for HPGe detectors.

physics.ins-det↗

arXiv2020

Pulse Shape Discrimination of Bulk and Very Bulk Events within HPGe Detectors

The CDEX (China Dark matter Experiment) now deploys ~10 kg pPCGe (p-type Point Contact Germanium) detectors in CJPL (China Jinping Underground Laboratory). It aims to detect rare events such as dark matter and 0vbb (neutrinoless double beta decay). The discrimination of bulk and very bulk events are essential for improvements of the analysis threshold of dark matter. Very bulk events are generated near the p+ point surface of pPCGe, which are usually from radioactive materials of electronic devices. Due to different locations of charge collection, bulk and very bulk events have different pulse shape. This paper will present two linear PSD (Pulse Shape Discrimination) methods: CCM (Charge Comparison Method) and Fisher's LDA (Linear Discriminant Analysis), to realize the discrimination of bulk and very bulk events. The results show that FOMs (Figure of Merit) are 1.38 $\pm$ 0.33 and 1.62 $\pm$ 0.18 by CCM and Fisher's LDA respectively.

physics.ins-det↗

arXiv2020

Performance of Linear Classification Algorithms on alpha/gamma Discrimination for LaBr3:Ce Scintillation Detectors with Various Pulse Digitizer Properties

With the development of high-speed readout electronics, the digital pulse shape discrimination (PSD) methods have attracted the attention of more researchers, especially in the field of high energy physics and neutron detection. How to choose a PSD algorithm and corresponding data acquisition system (DAQ) naturally becomes a critical problem to settle down for the detection system designers. In this paper, the relationship between the classification performance of different PSD algorithms and digitizers' sampling properties (including sampling rate and the effective number of bits) has been researched based on $\mathrm{LaBr_3}$:Ce scintillation detectors. A self-developed integrated digitizer configured with five different ADCs and a WavePro 404HD oscilloscope were deployed to digitize the waveforms from $\mathrm{LaBr_3}$:Ce scintillators. Moreover, three PSD methods, charge comparison method (CCM), least square for classification method (LS) and Fisher's linear discriminant analysis (LDA), based on linear model were applied to discriminate the alpha signals from the intrinsic isotope $^{227}$Ac. With the LS method and a 125 MSPS 14-Bit ADC, the FoM value was 1.424$\pm$0.042, which is similar to the result from LDA but 31\% better than the result of CCM. The discrimination results showed that the performances of LS and LDA are less affected by the sampling rate with respect to the CCM method, which reflects in a better PSD capability. The results of this paper can help the developers of detector systems to make a trade-off among sampling properties, desirable discrimination results and the cost of systems.

physics.ins-det↗

arXiv2019

Prototype of Pulse Digitizer and Readout Electronics for CDEX-10 in CJPL

The CDEX (China Dark matter Experiment) is currently in the stage to upgrade to approximately 10 kg HPGe (High Purity Germanium) detectors (CDEX-10) in CJPL (China Jinping Underground Laboratory) and aims to detect the WIMP (Weakly Interacting Massive Particles). Six analog signals and one inhibited signal are outputted from preamplifier by one HPGe detector (~1 kg) of CDEX-10. The analog signals are conditioned with two 6-us and one 12-us shaping amplifiers, and three timing amplifiers respectively. The inhibited signal is used for trigger. The analog signals from shaping and timing amplifiers are digitized to obtain energy spectrum and rise-time distribution. The rise-time distribution is used to discriminate surface, bulk, and very bulk events, which can help to supress the background level in dark matter detection. Composed of commercial modules, the previous DAQ (Data Acquisition Systems) is insufficient in discriminating between bulk and very bulk events due to the limited sampling rate (100 MSPS). Besides, as number of channel increases, the system will be simplified by integrating the trigger logic in FPGA (Field Programmable Gate Array). In this paper, a prototype named RAIN4HPGe is designed with pulse digitizer and readout electronics, integrating 14-Bit 100 MSPS ADCs (Analog-to-Digital Converters), 12-Bit 1 GSPS ADCs, FPGA etc.. The RAIN1000Z1 readout module based on ZYNQ SoC (System on Chip) is used for readout over Gigabit Ethernet. Better energy resolution, e.g. improving from 558 eV to 474 eV @122 keV, can be achieved by RAIN4HPGe compared to previous DAQ (Data Acquisition Systems) with commercial solution. Moreover, the discrimination performance of bulk, and very bulk events has been improved by RAIN4HPGe with 1 GSPS ADC.

physics.ins-det↗

arXiv2019

Optimization of Energy Resolution and Pulse Shape Discrimination for a CLYC Detector with Integrated Digitizers

Sufficient current pulse information of nuclear radiation detectors can be retained by direct waveform digitization owing to the improvement of digitizer's performance. In many circumstances, reasonable cost and power consumption are on demand while the energy resolution and PSD performance should be ensured simultaneously for detectors. This paper will quantitatively analyse the influence of vertical resolution and sampling rate of digitizers on the energy resolution and PSD performance. The energy resolution and PSD performance can be generally optimized by improving the sampling rate and ENOB (effective number of bits) of digitizers. Several integrated digitizers, with sampling rates varying from 100 MSPS to 500 MSPS and vertical resolution ranging from 12-Bit to 16-Bit, were designed and integrated with a CLYC detector for verifications. Experimental results show good accordance with theoretical calculations. The conclusion can give guidance to designs of digitizes for similar applications in need of optimizing the energy resolution and PSD performance, and help to choose proper digitizers for different requirements.

physics.ins-det↗

arXiv2018

Preliminary Design of Integrated Digitizer Base for Photomultiplier Tube

In many physical experiments and applications with photomultiplier tubes (PMTs), high-speed pulse digitalization is used extensively. The current pulse from a PMT has a rising time of several to a hundred nanoseconds. The current pulse shape can be used to obtain the pulse energy and discriminate between different particles. The conventional readout system with a PMT uses the discrete or integrated pulse-shaping circuits and analogue-to-digital converter boards which are based on the NIM or VME system to implement the data acquisition function. In many applications, such as security instruments, there are only several PMTs used in the whole system, or in some distributed applications, long-distance analogue cable with high-voltage power cable is not applicable due to the tremendous number of channels and enormous distributed space. In this paper, an integrated digitizer base is designed and interfaced with a Cs2LiYCl6 (CLYC) scintillator with a PMT. The CLYC scintillator has the ability to realize the pulse shape discrimination (PSD) between the neutron and gamma-rays. There is only one Gigabit of unscreened twisted-pair cable needed for over 700 Mbps TCP data throughput and more than 10 W power. The boards of high voltage supply, current sensitive preamplifier, 500 MSPS/12-Bit ADC (Analog-to-Digital Converter), readout module based on ZYNQ SoC (System on Chip), power over Ethernet, and user interface circuits are stacked with board-to-board connectors. The system can achieve 4.6% gamma-ray energy resolution at 662 keV with a 20-μs pulse integral and PSD figure-of-merit of ~3.0 for the whole energy of neutrons and gamma-rays. This integrated digitizer base can also be interfaced with other detectors with a PMT.

physics.ins-det↗