The photoelectron energy spectra （PESs） excited by narrow bandwidth attosecond x-ray pulses in the presence of a few-cycle laser are quantum-mechanically calculated. Transfer equations are used to reconstruct the de...The photoelectron energy spectra （PESs） excited by narrow bandwidth attosecond x-ray pulses in the presence of a few-cycle laser are quantum-mechanically calculated. Transfer equations are used to reconstruct the detailed temporal structure of an attosecond x-ray pulse directly from a measured PES. Theoretical analysis shows that the temporal uncertainties of the pulse reconstruction depend on the x-ray bandwidth. The procedure of pulse reconstruction is direct and simple without making any previous pulse assumption, data fitting analysis and time-resolved measurement of PESs. The temporal measurement range is half of a laser optical cycle.展开更多
Introduction The parameters of detector can play important roles in analyzing the nuclear pulses.When getting these parameters,we can establish the mathematical model of the detector output signal and then achieve amp...Introduction The parameters of detector can play important roles in analyzing the nuclear pulses.When getting these parameters,we can establish the mathematical model of the detector output signal and then achieve amplitude,time and other information of pulse simultaneously by one measurement,which can further improve the utilization of the signal.Purposes and methods In this paper,one 500 MHz digitization card was used to measure the pulses of a scintillator detector,and a bi-exponential mathematical model was used to fit the shape of the pulse,from which the decay time of the scintillator as well as the time constant of the PMT can be well obtained.Based on these parameters,the accurate energy spectrum measurement and the reconstruction of piled-up pulses are studied on.Results It was experimentally verified that this method can significantly improve the energy resolution,up to 6.31%at 661.7 keV for NaI detector(ϕ40 mm×40 mm).In addition,the piled-up pulses are well reconstructed.Conclusions For detectors with a single fluorescence decay time,a bi-exponential model can be set and used to fit the output pulse to get the parameters of the detectors.This model can be applied to obtain energy spectrum,reconstruction pulse of pile-up and so on.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10675014)
文摘The photoelectron energy spectra （PESs） excited by narrow bandwidth attosecond x-ray pulses in the presence of a few-cycle laser are quantum-mechanically calculated. Transfer equations are used to reconstruct the detailed temporal structure of an attosecond x-ray pulse directly from a measured PES. Theoretical analysis shows that the temporal uncertainties of the pulse reconstruction depend on the x-ray bandwidth. The procedure of pulse reconstruction is direct and simple without making any previous pulse assumption, data fitting analysis and time-resolved measurement of PESs. The temporal measurement range is half of a laser optical cycle.
文摘Introduction The parameters of detector can play important roles in analyzing the nuclear pulses.When getting these parameters,we can establish the mathematical model of the detector output signal and then achieve amplitude,time and other information of pulse simultaneously by one measurement,which can further improve the utilization of the signal.Purposes and methods In this paper,one 500 MHz digitization card was used to measure the pulses of a scintillator detector,and a bi-exponential mathematical model was used to fit the shape of the pulse,from which the decay time of the scintillator as well as the time constant of the PMT can be well obtained.Based on these parameters,the accurate energy spectrum measurement and the reconstruction of piled-up pulses are studied on.Results It was experimentally verified that this method can significantly improve the energy resolution,up to 6.31%at 661.7 keV for NaI detector(ϕ40 mm×40 mm).In addition,the piled-up pulses are well reconstructed.Conclusions For detectors with a single fluorescence decay time,a bi-exponential model can be set and used to fit the output pulse to get the parameters of the detectors.This model can be applied to obtain energy spectrum,reconstruction pulse of pile-up and so on.
