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Artificial neural network algorithm for pulse shape discrimination in 2πα and 2πβ particle surface emission rate measurements
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作者 Yuan-Qiao Li Bao-Ji Zhu +4 位作者 Yang Lv Heng Zhu Min Lin Ke-Sheng Chen Li-Jun Xu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第10期91-102,共12页
To enhance the accuracy of 2πα and 2πβ particle surface emission rate measurements and address the identification issues of nuclides in conventional methods, this study introduces two artificial neural network(ANN... To enhance the accuracy of 2πα and 2πβ particle surface emission rate measurements and address the identification issues of nuclides in conventional methods, this study introduces two artificial neural network(ANN) algorithms: back-propagation(BP) and genetic algorithm-based back-propagation(GA-BP). These algorithms classify pulse signals from distinct α and β particles. Their discrimination efficacy is assessed by simulating standard pulse signals and those produced by contaminated sources, mixing α and β particles within the detector. This study initially showcases energy spectrum measurement outcomes, subsequently tests the ANNs on the measurement and validation datasets, and contrasts the pulse shape discrimination efficacy of both algorithms. Experimental findings reveal that the proportional counter's energy resolution is not ideal, thus rendering energy analysis insufficient for distinguishing between 2πα and 2πβ particles. The BP neural network realizes approximately 99% accuracy for 2πα particles and approximately 95% for 2πβ particles, thus surpassing the GA-BP's performance. Additionally, the results suggest enhancing β particle discrimination accuracy by increasing the digital acquisition card's threshold lower limit. This study offers an advanced solution for the 2πα and 2πβ surface emission rate measurement method, presenting superior adaptability and scalability over conventional techniques. 展开更多
关键词 pulse shape discrimination Artificial neural networks Alpha and beta sources Multi-wire proportional counter Surface emission rate
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Femtosecond strong-field coherent control of nonresonant ionization with shaped pulses 被引量:1
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作者 Qiu-Nan Tong Zhen-Zhong Lian +3 位作者 Liang Zhao Hong-Xia Qi Zhou Chen Zhan Hu 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第3期153-160,共8页
The strong-field coherent control of the nonresonant ionization of nitrous oxide using shaped pulses is investigated.We study the dependence of periodic coherent oscillation of the total ionization yield on the variat... The strong-field coherent control of the nonresonant ionization of nitrous oxide using shaped pulses is investigated.We study the dependence of periodic coherent oscillation of the total ionization yield on the variation of laser phase parameters. The physical mechanism of the strong-field coherent control is investigated experimentally and theoretically by the nonresonant spectral phase interferences in the frequency domain. We show that the intense shaped pulses with broadband and off-resonance can be used as a robust strong-field coherent control method. 展开更多
关键词 COHERENT control nonresonant IONIZATION shaped pulse
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Interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser 被引量:3
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作者 王大帅 吴戈 +1 位作者 高博 田小建 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第1期263-267,共5页
We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by contro... We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the intercavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons. 展开更多
关键词 passively mode-locked fiber laser parabolic-shaped pulse pair pulses interaction
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Controlling Rydberg excitation process with shaped intense ultrashort laser pulses
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作者 Xiao-Yun Zhao Chun-Cheng Wang +3 位作者 Shi-Lin Hu Wei-Dong Li Jing Chen Xiao-Lei Hao 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第8期79-83,共5页
We perform a theoretical investigation on the control over the atomic excitation of Rydberg states with shaped intense ultrashort laser pulses. By numerically solving the time-dependent Schr?dinger equation(TDSE), w... We perform a theoretical investigation on the control over the atomic excitation of Rydberg states with shaped intense ultrashort laser pulses. By numerically solving the time-dependent Schr?dinger equation(TDSE), we systematically study the dependence of the population of the Rydberg states on the π phase step position in the frequency spectra of the laser pulse for different intensities, central wavelengths and pulse durations. Our results show that the Rydberg excitation process can be effectively modulated using shaped intense laser pulses with the laser intensity as high as 1 × 1014 W/cm2. Our work also have benefit to the future investigation to find out the dominant mechanism behind the excitation of Rydberg states in strong laser fields. 展开更多
关键词 shaped laser pulse RYDBERG STATES EXCITATION INTENSE field
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Coherent control of fragmentation of methyl iodide by shaped femtosecond pulse train
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作者 Qiu-Nan Tong De-Hou Fei +5 位作者 Zhen-Zhong Lian Hong-Xia Qi Sheng-Peng Zhou Si-Zuo Luo Zhou Chen Zhan Hu 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第9期157-163,共7页
Coherent control of fragmentation of CH_3I using shaped femtosecond pulse train is investigated.The dissociation processes can be modulated by changing the separation of the shaped pulse train, and the yield of I^+und... Coherent control of fragmentation of CH_3I using shaped femtosecond pulse train is investigated.The dissociation processes can be modulated by changing the separation of the shaped pulse train, and the yield of I^+under the irradiation of the optimal pulse is significantly increased compared with that using the transform-limited pulse.We discuss the control mechanism of dissociation processes with coherent interference in time domain.A three-pulse control model is proposed to explain the counterintuitive experimental results. 展开更多
关键词 COHERENT CONTROL FRAGMENTATION shaped pulse
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Pulse-shaping method for real-time neutron/gamma discrimination at low sampling rates
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作者 Jia‑Xin Li Hui‑Liang Hou +2 位作者 Yue‑Feng Huang Mao‑Song Cheng Zhi‑Min Dai 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第11期51-63,共13页
The Na I:Tl scintillator is an innovative material for dual-gamma-ray and neutron detection with a low ^(6)Li concentration.To achieve real-time n/γ discrimination,a zero-crossing time comparison algorithm based on t... The Na I:Tl scintillator is an innovative material for dual-gamma-ray and neutron detection with a low ^(6)Li concentration.To achieve real-time n/γ discrimination,a zero-crossing time comparison algorithm based on trapezoidal pulse shaping was developed.The algorithm can operate efficiently at low sampling rates and was implemented on a single-probe portable digital n/γ discriminator based on a field-programmable gate array.The discriminator and Na I:Tl,^(6)Li detector were tested in a neutron-gamma mixed field produced by an ^(241)Am-Be neutron source to evaluate the performance of the algorithm.The figure of merits was measured as 2.88 at a sampling rate of 50 MHz,indicating that the discriminator with its embedded algorithm has a promising n/γ discrimination capability.Efficient discrimination at sampling rates of 40 and 25 MHz demonstrates that the capability of this method is not limited by low sampling rates. 展开更多
关键词 FPGA NaI:Tl ^(6)Li Real time Neutron/gamma discrimination pulse shaping
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Implementation of a cusp-like for real-time digital pulse shaper in nuclear spectrometry 被引量:7
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作者 Jun Liu Jian Yang +3 位作者 Guo-Qiang Zeng Kai-Qi Zhang Shi-Long Wei Liang-Quan Ge 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第7期79-84,共6页
Pulse shaping,which improves signal-to-noise ratio excellently,has been extensively used in nuclear signal processing.This paper presents a cusp-like pulse-shaping technique developed through the recursive difference ... Pulse shaping,which improves signal-to-noise ratio excellently,has been extensively used in nuclear signal processing.This paper presents a cusp-like pulse-shaping technique developed through the recursive difference equation in time domain.It can be implemented in field programmable gate array hardware system.Another flat-topped cusp-like shaper is developed to optimize the time constant of pulse shaping and reduce the influence of ballistic deficit.The methods of both baseline restoration and pile-up rejection are described.The ^(137)Cs energy spectra measured with the digital cusp-like shaper are 6.6% energy resolution,while those by traditional analog pulse shaper are 7.2% energy resolution,under the same conditions.This technique offers flexibility,too,in adjusting the pulse shaper parameters. 展开更多
关键词 脉冲整形器 现场可编程门阵列 能量分辨率 尖点 实时 谱仪 递归差分方程 整形技术
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A pulse shape discrimination of CsI(Tl) crystal with ~6He beam 被引量:1
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作者 FAISAL Jamil-Qureshi 《Nuclear Science and Techniques》 SCIE CAS CSCD 2010年第1期35-38,共4页
The performance test of a CsI(Tl) crystal (70×27×23 mm3) was performed by applying the pulse shape discrimination technique for identification of light charged particles .The crystal is coupled to a photomul... The performance test of a CsI(Tl) crystal (70×27×23 mm3) was performed by applying the pulse shape discrimination technique for identification of light charged particles .The crystal is coupled to a photomultiplier tube during an experiment with 6He beam.The pulse waveform is fully recorded by employing a high precision digital oscilloscope.The fast and slow gates are used for the pulse shape discrimination and the best values for the gate widths were determined to be 0.5 μs and 1.67 μs,respectively.The 6He,4He and 3He are successfully discriminated with this technique. 展开更多
关键词 脉冲形状甄别 次级束流 晶体 CSI TI 识别技术 光电倍增管 数字示波器
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The Neutron-Gamma Pulse Shape Discrimination Method for Neutron Flux Detection in the ITER
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作者 徐修峰 李世平 +3 位作者 曹宏睿 袁国梁 杨青巍 阴泽杰 《Plasma Science and Technology》 SCIE EI CAS CSCD 2013年第5期417-419,共3页
The neutron flux monitor (NFM), as a significant diagnostic system in the International Thermonuclear Experimental Reactor (ITER), will play an important role in the readings of a series of key parameters in the f... The neutron flux monitor (NFM), as a significant diagnostic system in the International Thermonuclear Experimental Reactor (ITER), will play an important role in the readings of a series of key parameters in the fusion reaction process. As the core of the main electronic system of the NFM, the neutron-gamma pulse shape discrimination (n-γ PSD) can distinguish the neutron pulse from the gamma pulse and other disturbing pulses according to the thresholds of the rising time and the amplitude pre-installed on the board, the double timing point CFD method is used to get the rising time of the pulse. The n-γ PSD can provide an accurate neutron count. 展开更多
关键词 neutron pulse shape rise time NFM ITER n-γ PSD
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On-chip optical pulse shaper for arbitrary waveform generation
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作者 廖莎莎 杨婷 董建绩 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第7期382-386,共5页
We propose and demonstrate a silicon-on-insulator (SOI) on-chip optical pulse shaper based on four-tap finite impulse response. Due to different width designs in phase region of each tap, the phase differences for a... We propose and demonstrate a silicon-on-insulator (SOI) on-chip optical pulse shaper based on four-tap finite impulse response. Due to different width designs in phase region of each tap, the phase differences for all taps are controlled by an external thermal source, resulting in an optical pulse shaper. We further demonstrate optical arbitrary waveform generation based on the optical pulse shaper assisted by an optical frequency comb injection. Four different optical waveforms are generated when setting the central wavelengths at 1533.78 nm and 1547.1 nm and setting the thermal source temperatures at 23 ℃ and 33 ℃, respectively. Our scheme has distinct advantages of compactness, capability for integrating with electronics since the integrated silicon waveguide is employed. 展开更多
关键词 pulse shaping optical arbitrary waveform generation silicon photonics microwave photonics
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Optical pulse shaper with integrated slab waveguide for arbitrary waveform generation using optical gradient force
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作者 廖莎莎 闵书存 董建绩 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第12期229-234,共6页
Integrated optical pulse shaper opens up possibilities for realizing the ultra high-speed and ultra wide-band linear signal processing with compact size and low power consumption. We propose a silicon monolithic integ... Integrated optical pulse shaper opens up possibilities for realizing the ultra high-speed and ultra wide-band linear signal processing with compact size and low power consumption. We propose a silicon monolithic integrated optical pulse shaper using optical gradient force, which is based on the eight-path finite impulse response. A cantilever structure is fabricated in one arm of the Mach–Zehnder interferometer(MZI) to act as an amplitude modulator. The phase shift feature of waveguide is analyzed with the optical pump power, and five typical waveforms are demonstrated with the manipulation of optical force. Unlike other pulse shaper schemes based on thermo–optic effect or electro–optic effect, our scheme is based on a new degree of freedom manipulation, i.e., optical force, so no microelectrodes are required on the silicon chip,which can reduce the complexity of fabrication. Besides, the chip structure is suitable for commercial silicon on an insulator(SOI) wafer, which has a top silicon layer of about 220 nm in thickness. 展开更多
关键词 pulse shaping arbitrary waveform generation optical grant force
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Study on welding power source used in intelligent control system for weld pool shape in pulsed GTAW
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作者 张广军 陈善本 +1 位作者 吴林 耿正 《China Welding》 EI CAS 2001年第2期33-37,共5页
This paper analyses the performance request of arc welding power source used in intelligent control of weld pool shape in pulsed GTAW, and develops a sample power source. The main circuit of the power source takes the... This paper analyses the performance request of arc welding power source used in intelligent control of weld pool shape in pulsed GTAW, and develops a sample power source. The main circuit of the power source takes the structure of single ended inverter with two switches, and takes IGBTs as power switches. The working frequency of the inverter is set at 20 kHz. The control circuit takes PWM circuit as center, and uses single chip computer to complete the manage functions such as the control of working sequence, setting and changing of the welding parameters, sensing of the welding states and communication with outside computer etc. The dynamic reacting time of the whole power is 1 ms, the range of the output current is 5~250 A, the precision of the output current reaches to 1 A. The power strikes arc by contacting workpiece under 5 A, and have convenient interface with system computer. All above shows this power source is one with high performance. 展开更多
关键词 arc welding power source pulsed GTAW weld pool shape intelligent control
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Femtosecond Stimulated Raman Line Shapes:Dependence on Resonance Conditions of Pump and Probe Pulses
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作者 ChengChen Liang-dongZhu ChongFang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第4期492-502,614,615,共13页
Resonance enhancement has been increasingly employed in the emergent felntosecond stimu- lated Raman spectroscopy (FSRS) to selectively monitor molecular structure and dynamics with improved spectral and temporal re... Resonance enhancement has been increasingly employed in the emergent felntosecond stimu- lated Raman spectroscopy (FSRS) to selectively monitor molecular structure and dynamics with improved spectral and temporal resolutions and signal-to-noise ratios. Such joint eflforts by the technique- and application-oriented scientists and engineers have laid the foundation for exploiting the tunable FSRS methodology to investigate a great variety of photosensitive systems and elucidate the underlying functional mechanisms on molecular time scales. Dur- ing spectral analysis, peak line shapes remain a major concern with an intricate dependence on resonance conditions. Here, we present a comprehensive study of line shapes by tuning the Rarnan pump wavelength from red to blue side of the ground-state absorption band of the fluorescent dye rhodarnine 6G in solution. Distinct line shape patterns in Stokes and anti-Stokes FSRS as well as from the low to high-frequency modes highlight the competition between multiple third-order and higher-order nonlinear pathways, governed by difl^rent res- onance conditions achieved by Raman pump and probe pulses. In particular, the resonance condition of probe wavelength is revealed to play an important role in generating circular line shape changes through oppositely phased dispersion via hot luminescence (HL) pathways. Meanwhile, on-resonance conditions of the Rarnan pump could promote excited-state vibrational modes which are broadened and red-shifted from the coincident ground-state vibrational modes, posing challenges for spectral analysis. Certain strategies in tuning the Raman pump and probe to characteristic regions across an electronic transition band are discussed to improve the FSRS usability and versatility as a powerful structural dynamics toolset to advance chemical, physical, materials, and biological sciences. 展开更多
关键词 Ferntosecond stimulated Rarnan spectroscopy Resonance enhancement Ra- man pump and probe pulses Wavelength tunability Dispersive line shapes Stokes and anti-Stokes FSRS
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Optimal parameter choice of CR–RC^m digital filter in nuclear pulse processing 被引量:9
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作者 Huai-Qiang Zhang Zhuo-Dai Li +1 位作者 Bin Tang He-Xi Wu 《Nuclear Science and Techniques》 SCIE CAS CSCD 2019年第7期42-46,共5页
CR–RCm filters are widely used in nuclear energy spectrum measurement systems. The choice of parameters of a CR–RCm digital filter directly affects its performance in terms of energy resolution and pulse count rate ... CR–RCm filters are widely used in nuclear energy spectrum measurement systems. The choice of parameters of a CR–RCm digital filter directly affects its performance in terms of energy resolution and pulse count rate in digital nuclear spectrometer systems. A numerical recursive model of a CR differential circuit and RC integration circuit is derived, which shows that the shaping result of CR–RCm is determined by the adjustment parameter (k, it determines the shaping time of the shaper) and the integral number (m). Furthermore, the amplitude– frequency response of CR–RC^m is analyzed, which shows that it is a bandpass filter;the larger the shaping parameters (k and m), the narrower is the frequency band. CR–RC^m digital Gaussian shaping is performed on the actual sampled nuclear pulse signal under different shaping parameters. The energy spectrum of 137Cs is measured based on the LaBr3(Ce) detector under different parameters. The results show that the larger the shaping parameters (m and k), the closer the shaping result is to Gaussian shape, the wider is the shaped pulse, the higher is the energy resolution, and the lower is the pulse count rate. For the same batch of pulse signals, the energy resolution is increased from 3.8 to 3.5%, and the full energy peak area is reduced from 7815 to 6503. Thus, the optimal shaping parameters are m -3 and k -0.95. These research results can provide a design reference for the development of digital nuclear spectrometer measurement systems. 展开更多
关键词 CR-RCm digital filter NUCLEAR pulse signal GAUSSIAN SHAPING Energy resolution
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Estimation of Gaussian overlapping nuclear pulse parameters based on a deep learning LSTM model 被引量:6
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作者 Xing-Ke Ma Hong-Quan Huang +5 位作者 Qian-Cheng Wang Jing Zhao Fei Yang Kai-Ming Jiang Wei-Cheng Ding Wei Zhou 《Nuclear Science and Techniques》 SCIE CAS CSCD 2019年第11期83-94,共12页
A long short-term memory(LSTM)neural network has excellent learning ability applicable to time series of nuclear pulse signals.It can accurately estimate parameters associated with amplitude,time,and so on,in digitall... A long short-term memory(LSTM)neural network has excellent learning ability applicable to time series of nuclear pulse signals.It can accurately estimate parameters associated with amplitude,time,and so on,in digitally shaped nuclear pulse signals—especially signals from overlapping pulses.By learning the mapping relationship between Gaussian overlapping pulses after digital shaping and exponential pulses before shaping,the shaping parameters of the overlapping exponential nuclear pulses can be estimated using the LSTM model.Firstly,the Gaussian overlapping nuclear pulse(ONP)parameters which need to be estimated received Gaussian digital shaping treatment,after superposition by multiple exponential nuclear pulses.Secondly,a dataset containing multiple samples was produced,each containing a sequence of sample values from Gaussian ONP,after digital shaping,and a set of shaping parameters from exponential pulses before digital shaping.Thirdly,the Training Set in the dataset was used to train the LSTM model.From these datasets,the values sampled from the Gaussian ONP were used as the input data for the LSTM model,and the pulse parameters estimated by the current LSTM model were calculated by forward propagation.Next,the loss function was used to calculate the loss value between the network-estimated pulse parameters and the actual pulse parameters.Then,a gradient-based optimization algorithm was applied,to feedback the loss value and the gradient of the loss function to the neural network,to update the weight of the LSTM model,thereby achieving the purpose of training the network.Finally,the sampled value of the Gaussian ONP for which the shaping parameters needed to be estimated was used as the input data for the LSTM model.After this,the LSTM model produced the required nuclear pulse parameter set.In summary,experimental results showed that the proposed method overcame the defect of local convergence encountered in traditional methods and could accurately extract parameters from multiple,severely overlapping Gaussian pulses,to achieve optimal estimation of nuclear pulse parameters in the global sense.These results support the conclusion that this is a good method for estimating nuclear pulse parameters. 展开更多
关键词 NUCLEAR pulseS S–K digital SHAPING DEEP learning LSTM
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Digitalization of inverting filter shaping circuit for nuclear pulse signals 被引量:7
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作者 Huai-Qiang Zhang Hong-Tao Shi +1 位作者 Zhuo-Dai Li Yu-Wen Li 《Nuclear Science and Techniques》 SCIE CAS CSCD 2020年第9期16-24,共9页
In the design of filter shaping circuits for nuclear pulse signals,inverting filter shaping circuits perform better than non-inverting filter shaping circuits.Because these circuits facilitate changing the phase of a ... In the design of filter shaping circuits for nuclear pulse signals,inverting filter shaping circuits perform better than non-inverting filter shaping circuits.Because these circuits facilitate changing the phase of a pulse signal,they are widely used in processing nuclear pulse signals.In this study,the transfer functions of four types of inverting filter shaping circuits,namely the common inverting filter shaping,improved inverting filter shaping,multiple feedback low-pass filter shaping,and third-order multiple feedback low-pass filter shaping,in the Laplacian domain,are derived.We establish the numerical recursive function models and digitalize the four circuits,obtain the transfer functions in the Z domain,and analyze the filter performance and amplitude-frequency response characteristics in the frequency domain.Based on the actual nuclear pulse signal of the Si-PIN detector,we realize four types of inverting digital shaping.The results show that under the same shaping parameters,the common inverting digital shaping has better amplitude extraction characteristics,the third-order multiple feedback low-pass digital shaping has better noise suppression performance,and the multiple feedback digital shaping takes into account both pulse amplitude extraction and noise suppression performance. 展开更多
关键词 Nuclear pulse signal Inverting filter shaping circuit Digital shaping Amplitude-frequency response
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Control of the photoionization/photodissociation processes of cyclopentanone with trains of femtosecond laser pulses 被引量:3
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作者 宋耀东 陈洲 +3 位作者 杨雪 孙长凯 张丛丛 胡湛 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第10期240-246,共7页
A train of three equally spaced femtosecond laser pulses is employed to control the photoionization/photodissociation processes of cyclopentanone. With the increase of pulse separation, a strong modulation of product ... A train of three equally spaced femtosecond laser pulses is employed to control the photoionization/photodissociation processes of cyclopentanone. With the increase of pulse separation, a strong modulation of product ion yield is observed. More than ten-fold changes of ion yield ratio between different products can be realized. The experimental observations further explain the compositions and formation pathways of peaks in the mass spectra. The controlling mechanisms are also discussed. 展开更多
关键词 shaped femtosecond pulse coherent control time-of-flight mass spectra photoionization and photodissociation
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The study of numerical character for femtosecond pulse shaping 被引量:2
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作者 邹华 朱卫华 王国栋 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第11期3429-3433,共5页
This paper describes the generation of shaped femtosecond multiple pulses by using the phase-only Dammann filters in 4f femtosecond shaper and gives the experimental result of femtosecond pulse characterization by the... This paper describes the generation of shaped femtosecond multiple pulses by using the phase-only Dammann filters in 4f femtosecond shaper and gives the experimental result of femtosecond pulse characterization by the frequency- resolved optical gating (FROG) technique. With the theoretical simulation, it concludes that the quality of the generated output array is relevant to the number of pixels and the spacing between the components. 展开更多
关键词 space-time conversion femtosecond pulse shaping Dammann frequency-resolved optical gating
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Selective triggering of phase change in dielectrics by femtosecond pulse trains based on electron dynamics control 被引量:2
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作者 徐传彩 姜澜 +1 位作者 冷妮 刘鹏军 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第4期334-337,共4页
In this study we experimentally reveal that the phase change mechanism can be selectively triggered by shaping femtosecond pulse trains based on electron dynamics control (EDC), including manipulation of excitations... In this study we experimentally reveal that the phase change mechanism can be selectively triggered by shaping femtosecond pulse trains based on electron dynamics control (EDC), including manipulation of excitations, ionizations, densities, and temperatures of electrons. By designing the pulse energy distribution to adjust the absorptions, excitations, ionizations, and recombinations of electrons, the dominant phase change mechanism experiences transition from nonthermal to thermal process. This phenomenon is observed in quadruple, triple, and double pulses per train ablation of fused silica separately. This opens up possibilities for controlling phase change mechanisms by EDC, which is of great significance in laser processing of dielectrics and fabrication of integrated nano- and micro-optical devices. 展开更多
关键词 phase change electron dynamics pulse shaping
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Anti-noise performance of the pulse coupled neural network applied in discrimination of neutron and gamma-ray 被引量:3
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作者 Hao-Ran Liu Zhuo Zuo +3 位作者 Peng Li Bing-Qi Liu Lan Chang Yu-Cheng Yan 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第6期89-101,共13页
In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,r... In this study,the anti-noise performance of a pulse-coupled neural network(PCNN)was investigated in the neutron and gamma-ray(n-γ)discrimination field.The experiments were conducted in two groups.In the first group,radiation pulse signals were pre-processed using a Fourier filter to reduce the original noise in the signals,whereas in the second group,the original noise was left untouched to simulate an extremely high-noise scenario.For each part,artificial Gaussian noise with different intensity levels was added to the signals prior to the discrimination process.In the aforementioned conditions,the performance of the PCNN was evaluated and compared with five other commonly used methods of n-γdiscrimination:(1)zero crossing,(2)charge comparison,(3)vector projection,(4)falling edge percentage slope,and(5)frequency gradient analysis.The experimental results showed that the PCNN method significantly outperforms other methods with outstanding FoM-value at all noise levels.Furthermore,the fluctuations in FoM-value of PCNN were significantly better than those obtained via other methods at most noise levels and only slightly worse than those obtained via the charge comparison and zerocrossing methods under extreme noise conditions.Additionally,the changing patterns and fluctuations of the FoMvalue were evaluated under different noise conditions.Hence,based on the results,the parameter selection strategy of the PCNN was presented.In conclusion,the PCNN method is suitable for use in high-noise application scenarios for n-γdiscrimination because of its stability and remarkable discrimination performance.It does not rely on strict parameter settings and can realize satisfactory performance over a wide parameter range. 展开更多
关键词 pulse coupled neural network Zero crossing Frequency gradient analysis Vector projection Charge comparison Neutron and gamma-ray discrimination pulse shape discrimination
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