Background Channel electron multiplier(CEM)can be used to measure extremely few charged particles,such as electrons and ions.The CEM is widely used in particle detection,so it is very important to study their performa...Background Channel electron multiplier(CEM)can be used to measure extremely few charged particles,such as electrons and ions.The CEM is widely used in particle detection,so it is very important to study their performance parameters.Purposes Test and analyze the performance parameters of the CEM,such as resistance,gain,and pulse output for a single entrance photoelectron.Methods The heated tantalum filament is used as a stable and adjustable planar electron source to test the performance of the CEM in the analog mode.The performance parameters of the CEM in the pulse counting mode are tested by using the ultraviolet LED to excite the gold photocathode to generate a single photoelectron.Results and conclusions The gain of the CEM in the analog mode can reach more than 106 and the gain in the pulse counting mode can be two orders of magnitude higher.The curved helical channel has a greater advantage than the ordinary straight channel,which is conducive to weakening the ion feedback phenomenon.展开更多
A cued search algorithm with uncertain detection performance is proposed for phased array radars. Firstly, a target search model based on the information gain criterion is presented with known detection performance, a...A cued search algorithm with uncertain detection performance is proposed for phased array radars. Firstly, a target search model based on the information gain criterion is presented with known detection performance, and the statistical characteristic of the detection probability is calculated by using the fluctuant model of the target radar cross section （RCS）. Secondly, when the detection probability is completely unknown, its probability density function is modeled with a beta distribution, and its posterior probability distribution with the radar observation is derived based on the Bayesian theory. Finally simulation results show that the cued search algorithm with a known RCS fluctuant model can achieve the best performance, and the algorithm with the detection probability modeled as a beta distribution is better than that with a random selected detection probability because the model parameters can be updated by the radar observation to approach to the real value of the detection probability.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11535014,11975017,and 11675278)the State Key Laboratory of Particle Detection and Electronics(SKLPDE-ZZ-202215).
文摘Background Channel electron multiplier(CEM)can be used to measure extremely few charged particles,such as electrons and ions.The CEM is widely used in particle detection,so it is very important to study their performance parameters.Purposes Test and analyze the performance parameters of the CEM,such as resistance,gain,and pulse output for a single entrance photoelectron.Methods The heated tantalum filament is used as a stable and adjustable planar electron source to test the performance of the CEM in the analog mode.The performance parameters of the CEM in the pulse counting mode are tested by using the ultraviolet LED to excite the gold photocathode to generate a single photoelectron.Results and conclusions The gain of the CEM in the analog mode can reach more than 106 and the gain in the pulse counting mode can be two orders of magnitude higher.The curved helical channel has a greater advantage than the ordinary straight channel,which is conducive to weakening the ion feedback phenomenon.
基金supported by the National Natural Science Foundation of China (61372165)the Postdoctoral Science Foundation of China (201150M15462012T50874)
文摘A cued search algorithm with uncertain detection performance is proposed for phased array radars. Firstly, a target search model based on the information gain criterion is presented with known detection performance, and the statistical characteristic of the detection probability is calculated by using the fluctuant model of the target radar cross section （RCS）. Secondly, when the detection probability is completely unknown, its probability density function is modeled with a beta distribution, and its posterior probability distribution with the radar observation is derived based on the Bayesian theory. Finally simulation results show that the cued search algorithm with a known RCS fluctuant model can achieve the best performance, and the algorithm with the detection probability modeled as a beta distribution is better than that with a random selected detection probability because the model parameters can be updated by the radar observation to approach to the real value of the detection probability.
