This study presents a low-noise,high-rate front-end readout application-specific integrated circuit(ASIC)designed for the electromagnetic calorimeter(ECAL)of the Super Tau-Charm Facility(STCF).To address the high back...This study presents a low-noise,high-rate front-end readout application-specific integrated circuit(ASIC)designed for the electromagnetic calorimeter(ECAL)of the Super Tau-Charm Facility(STCF).To address the high background-count rate in the STCF ECAL,the temporal features of signals are analyzed node-by-node along the chain of the analog front-end circuit.Then,the system is optimized to mitigate the pile-up effects and elevate the count rate to megahertz levels.First,a charge-sensitive amplifier(CSA)with a fast reset path is developed,enabling quick resetting when the output reaches the maximum amplitude.This prevents the CSA from entering a pulse-dead zone owing to amplifier saturation caused by the pile-up.Second,a high-order shaper with baseline holder circuits is improved to enhance the anti-pile-up capability while maintaining an effective noise-filtering performance.Third,a high-speed peak-detection and hold circuit with an asynchronous first-input-first-output buffer function is proposed to hold and read the piled-up signals of the shaper.The ASIC is designed and manufactured using a standard commercial 1P6M 0.18μm mixed-signal CMOS process with a chip area of 2.4 mm×1.6 mm.The measurement results demonstrate a dynamic range of 4–500 fC with a nonlinearity error below 1.5%.For periodically distributed input signals,a count rate of 1.5 MHz/Ch is achieved with a peak time of 360 ns,resulting in an equivalent noise charge(ENC)of 2500 e^(-)-.The maximum count rate is 4 MHz/Ch at a peak time of 120 ns.At a peak time of 1.68μs with a 270 pF external capacitance,the minimum ENC is 1966 e^(-)-,and the noise slope is 3.08 e^(-)-∕pF.The timing resolution is better than 125 ps at an input charge of 200 fC.The power consumption is 35 mW/Ch.展开更多
The real time and in situ investigation of the crystallization process and structure transitions of asymmetric crystalline-crystalline diblock copolymers from the melt was performed with synchrotron simultaneous SAXS/...The real time and in situ investigation of the crystallization process and structure transitions of asymmetric crystalline-crystalline diblock copolymers from the melt was performed with synchrotron simultaneous SAXS/WAXS. The asymmetric poly（ethylene oxide）-b-poly（ε-caprolactone） diblock copolymers were chosen for the present study. It was shown that the short blocks crystallized later than the long blocks and final lamellar structure was formed in all of the asymmetric diblock copolymers. The final lamellar structure was confirmed by AFM observation. The SAXS data were analyzed with different methods for the early stage of the crystallization. The Guinier plots indicated that there were no isolated domains formed before the formation of lamellae in the asymmetric diblock copolymers during the crystallization process. Debye- Bueche plots implied the formation of correlated domains during crystallization.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12375191,12275218,12341502,12105224,12205307)National Key Research and Development Program of China(No.2023YFE0206300,2023YFF0719600)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012141)China Postdoctoral Science Foundation(No.2023M742850)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX2021025)。
文摘This study presents a low-noise,high-rate front-end readout application-specific integrated circuit(ASIC)designed for the electromagnetic calorimeter(ECAL)of the Super Tau-Charm Facility(STCF).To address the high background-count rate in the STCF ECAL,the temporal features of signals are analyzed node-by-node along the chain of the analog front-end circuit.Then,the system is optimized to mitigate the pile-up effects and elevate the count rate to megahertz levels.First,a charge-sensitive amplifier(CSA)with a fast reset path is developed,enabling quick resetting when the output reaches the maximum amplitude.This prevents the CSA from entering a pulse-dead zone owing to amplifier saturation caused by the pile-up.Second,a high-order shaper with baseline holder circuits is improved to enhance the anti-pile-up capability while maintaining an effective noise-filtering performance.Third,a high-speed peak-detection and hold circuit with an asynchronous first-input-first-output buffer function is proposed to hold and read the piled-up signals of the shaper.The ASIC is designed and manufactured using a standard commercial 1P6M 0.18μm mixed-signal CMOS process with a chip area of 2.4 mm×1.6 mm.The measurement results demonstrate a dynamic range of 4–500 fC with a nonlinearity error below 1.5%.For periodically distributed input signals,a count rate of 1.5 MHz/Ch is achieved with a peak time of 360 ns,resulting in an equivalent noise charge(ENC)of 2500 e^(-)-.The maximum count rate is 4 MHz/Ch at a peak time of 120 ns.At a peak time of 1.68μs with a 270 pF external capacitance,the minimum ENC is 1966 e^(-)-,and the noise slope is 3.08 e^(-)-∕pF.The timing resolution is better than 125 ps at an input charge of 200 fC.The power consumption is 35 mW/Ch.
基金supported by the National Natural Science Foundation of China (Nos. 20974077, 51173130)Synchrotron experiments at Beam line A2 were supported by HASYLAB project (I-20110306, II20090111)
文摘The real time and in situ investigation of the crystallization process and structure transitions of asymmetric crystalline-crystalline diblock copolymers from the melt was performed with synchrotron simultaneous SAXS/WAXS. The asymmetric poly（ethylene oxide）-b-poly（ε-caprolactone） diblock copolymers were chosen for the present study. It was shown that the short blocks crystallized later than the long blocks and final lamellar structure was formed in all of the asymmetric diblock copolymers. The final lamellar structure was confirmed by AFM observation. The SAXS data were analyzed with different methods for the early stage of the crystallization. The Guinier plots indicated that there were no isolated domains formed before the formation of lamellae in the asymmetric diblock copolymers during the crystallization process. Debye- Bueche plots implied the formation of correlated domains during crystallization.
