A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 ...A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 μm)fluorescence emissions of Ho^(3+)ions in the PbF_(2) crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd^(3+)ions and Ho~(3+)ions under different concentrations of the Nd^(3+)ions was systematically analyzed. The results show that the Nd^(3+)ions have good sensitization and deactivation effect on the Ho^(3+)ions to stimulate the mid-infrared fluorescence emissions. The experimental analysis proves that the sensitization efficiency of the Nd^(3+)ions is relatively stable at around 93.45% with varying Nd^(3+)-doping concentrations. Concentration dependence studies indicate that the concentration of the Nd^(3+)ions has significant influence on mid-infrared emissions.When the doping concentration of the Nd^(3+)ions is up to 2.0 at%, the intensity of ~2.0, ~2.9 and ~3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd^(3+)-doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho_(0.02)Nd_(0.02)Pb_(0.96)F_(2) crystal displays the best performance. All the results show that the Nd^(3+)/Ho^(3+)co-doped PbF_(2) crystals might act as a useful optical medium for mid-infrared laser applications.展开更多
Purpose This study aims to create a new tool for fast computer simulations allowing one to design advanced electromagnetic calorimeters with the required properties.The application must calculate the calorimeter effic...Purpose This study aims to create a new tool for fast computer simulations allowing one to design advanced electromagnetic calorimeters with the required properties.The application must calculate the calorimeter efficiency and measure the particles'energies,momenta and interaction time to detect the particles.This application should become the basis for a new technology of positron emission tomography.Methods To solve the problem,a new C++application based on Geant4 simulation toolkit has been developed.To monitor the response of calorimeters to different types of primary particles,we used different auxiliary Geant4 classes.In addition,we compare the simulation results for the detectors of three different setups,taking into account the detection of both electrons and gamma-quanta,and analyze their efficiency.To evaluate the capability of calorimeters to work under radiation load,we use an experimentally measured transmission function of radiation-damaged PbF_(2).Results Three calorimeter setups exploiting PbF_(2)were simulated with a new C++application based on Geant4.We showed that such type of calorimeter has an energy resolution of 4.1%√E^(e+)[GeV]and good linearity of response for GeV positrons measurements.The efficiency of such structures is found to be approximately 20%for gamma photons’detection.The multilayered structure based on gamma-quanta detection has been proven to be more efficient.It was shown that for the total ionizing dose of 30 krad the Cherenkov light yield decreases by up to two times for 14 cm long PbF_(2)crystals,while for the shorter ones(2.5 and 1.5 cm)this effect is almost negligible.Conclusions We present a new user application in Geant4 for fast simulation of complex structures designed for detection of different high-energy neutral and charged particles.Simulation of calorimeter interaction with 10^(3) of 3 GeV positrons takes 20 min on usual laptop,while for 105511 keV gamma photons it takes 1 min on average.This application allows one to evaluate the efficiency of electromagnetic calorimeters exploiting lead fluoride crystals.Our results pave the way for advanced particle energy measurements,including those used in rapidly developing medical applications such as positron emission tomography,single-photon emission computed tomography etc.展开更多
Purpose A faster time performance can be achieved by focusing on prompt emitted photons,such as Cherenkov photons.In this study,the time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators ...Purpose A faster time performance can be achieved by focusing on prompt emitted photons,such as Cherenkov photons.In this study,the time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators were first simulated,and we evaluated the detector performance and discussed ways to improve the coincidence time resolution(CTR)results for the detector with the three radiators.Finally,we compared detection efficiency of Cherenkov radiation in three radiators.Methods In this work,we recorded the step-by-step information of Cherenkov photons and the electrons that produced them in the radiator,information of photons on the photon outputting surface,and the step-by-step information tracing of the par-ent charged particles(electrons)to evaluate the factors influencing the performance time of the detector based on Geant4.Specially,we usually use a photon amplitude timing in the experimental implements,and the arrival time of an event is defined as the arrival time of the first photon of the event accordingly.Results The time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators with a 5 mm length were simulated as 28.5 ps for PbF,40.1 ps for PbWO_(4),and 24.7 ps for Al_(2)O_(3).After considering other factors such as quantum efficiency(QE)of 30%and transit time spread(TTS)of 10 ps from the process of practical electronics,the CTR of a pair of single-pixel detectors were 56.6 ps for PbF_(2),78.8 ps for PbWO_(4),and 46.3 ps for Al_(2)O_(3) with a thickness of 5 mm.The detection efficiency of PbF_(2) is 32.25%,PbWO_(4) of 31.91%and Al_(2)O_(3) of 8.14%in the case of 5 mm length.Conclusions The simulation results indicated that using the Cherenkov photons produced in PbF_(2),PbWO_(4),Al_(2)O_(3) for detec-tor timing can obtain good CTR results.In this study,it demonstrates that it is possible to achieve a pretty good CTR with an improved QE and a reduced TTS of the photodetector.展开更多
基金Project supported by the National Natural Science Foundation of China(51972149,51872307,61935010,51702124)Key-Area Research and Development Program of Guangdong Province(2020B090922006)。
文摘A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 μm)fluorescence emissions of Ho^(3+)ions in the PbF_(2) crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd^(3+)ions and Ho~(3+)ions under different concentrations of the Nd^(3+)ions was systematically analyzed. The results show that the Nd^(3+)ions have good sensitization and deactivation effect on the Ho^(3+)ions to stimulate the mid-infrared fluorescence emissions. The experimental analysis proves that the sensitization efficiency of the Nd^(3+)ions is relatively stable at around 93.45% with varying Nd^(3+)-doping concentrations. Concentration dependence studies indicate that the concentration of the Nd^(3+)ions has significant influence on mid-infrared emissions.When the doping concentration of the Nd^(3+)ions is up to 2.0 at%, the intensity of ~2.0, ~2.9 and ~3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd^(3+)-doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho_(0.02)Nd_(0.02)Pb_(0.96)F_(2) crystal displays the best performance. All the results show that the Nd^(3+)/Ho^(3+)co-doped PbF_(2) crystals might act as a useful optical medium for mid-infrared laser applications.
基金This work was supported by the Ministry of Science and Higher Education of the Russian Federation,projects№FZWG-2020-0032(2019-1569)№FSWU-2023-0075.
文摘Purpose This study aims to create a new tool for fast computer simulations allowing one to design advanced electromagnetic calorimeters with the required properties.The application must calculate the calorimeter efficiency and measure the particles'energies,momenta and interaction time to detect the particles.This application should become the basis for a new technology of positron emission tomography.Methods To solve the problem,a new C++application based on Geant4 simulation toolkit has been developed.To monitor the response of calorimeters to different types of primary particles,we used different auxiliary Geant4 classes.In addition,we compare the simulation results for the detectors of three different setups,taking into account the detection of both electrons and gamma-quanta,and analyze their efficiency.To evaluate the capability of calorimeters to work under radiation load,we use an experimentally measured transmission function of radiation-damaged PbF_(2).Results Three calorimeter setups exploiting PbF_(2)were simulated with a new C++application based on Geant4.We showed that such type of calorimeter has an energy resolution of 4.1%√E^(e+)[GeV]and good linearity of response for GeV positrons measurements.The efficiency of such structures is found to be approximately 20%for gamma photons’detection.The multilayered structure based on gamma-quanta detection has been proven to be more efficient.It was shown that for the total ionizing dose of 30 krad the Cherenkov light yield decreases by up to two times for 14 cm long PbF_(2)crystals,while for the shorter ones(2.5 and 1.5 cm)this effect is almost negligible.Conclusions We present a new user application in Geant4 for fast simulation of complex structures designed for detection of different high-energy neutral and charged particles.Simulation of calorimeter interaction with 10^(3) of 3 GeV positrons takes 20 min on usual laptop,while for 105511 keV gamma photons it takes 1 min on average.This application allows one to evaluate the efficiency of electromagnetic calorimeters exploiting lead fluoride crystals.Our results pave the way for advanced particle energy measurements,including those used in rapidly developing medical applications such as positron emission tomography,single-photon emission computed tomography etc.
基金This research was supported by National Natural Science Foundation of China(No.11675191)Science and Technology Innovation Project funded by Institute of High Energy(IHEP),Chinese Academy of Sciences(No.E05457U207).
文摘Purpose A faster time performance can be achieved by focusing on prompt emitted photons,such as Cherenkov photons.In this study,the time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators were first simulated,and we evaluated the detector performance and discussed ways to improve the coincidence time resolution(CTR)results for the detector with the three radiators.Finally,we compared detection efficiency of Cherenkov radiation in three radiators.Methods In this work,we recorded the step-by-step information of Cherenkov photons and the electrons that produced them in the radiator,information of photons on the photon outputting surface,and the step-by-step information tracing of the par-ent charged particles(electrons)to evaluate the factors influencing the performance time of the detector based on Geant4.Specially,we usually use a photon amplitude timing in the experimental implements,and the arrival time of an event is defined as the arrival time of the first photon of the event accordingly.Results The time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators with a 5 mm length were simulated as 28.5 ps for PbF,40.1 ps for PbWO_(4),and 24.7 ps for Al_(2)O_(3).After considering other factors such as quantum efficiency(QE)of 30%and transit time spread(TTS)of 10 ps from the process of practical electronics,the CTR of a pair of single-pixel detectors were 56.6 ps for PbF_(2),78.8 ps for PbWO_(4),and 46.3 ps for Al_(2)O_(3) with a thickness of 5 mm.The detection efficiency of PbF_(2) is 32.25%,PbWO_(4) of 31.91%and Al_(2)O_(3) of 8.14%in the case of 5 mm length.Conclusions The simulation results indicated that using the Cherenkov photons produced in PbF_(2),PbWO_(4),Al_(2)O_(3) for detec-tor timing can obtain good CTR results.In this study,it demonstrates that it is possible to achieve a pretty good CTR with an improved QE and a reduced TTS of the photodetector.
