Reliability studies of the custom-designed front-end and ADC chips used for JUNO large photomultipliers electronics

Objective The Jiangmen Underground Neutrino Observatory,which is currently being constructed in South China,will be a cutting-edge liquid scintillator detector for neutrino physics in the coming decade.The read-out electronics will be installed in close proximity to the large photomultipliers and directly inside the water pool surrounding the detector.Once installed,these electronics will not be accessible for repair or replacement;therefore,ensuring their reliability is of utmost importance.A crucial aspect of this reliability analysis involves evaluating the failure rate of custom-designed analog-to-digital converter and front-end chips used in underwater read-out electronics.Methods The Arrhenius model shall be utilized to compute the reliability failure rate value.During ageing,the ambient temperature of the setup system was set at 115℃.The high-gain and low-gain output channels were chosen as references for detecting failures in the tested sample for front-end chips of Jiangmen Underground Neutrino Observatory,while for analog-to-digital converters,effective number of bits are considered as reference parameters.Results After ageing,all chips were re-measured.The ADC and FEC tests revealed no failures.As a result,the upper limit for the failure rate of front-end chips is 0.43 failures in time,and the upper limit for analog-to-digital converters is 0.42 failures in time at 30°C.Conclusion The reliability test result shows that custom-designed chips can be used in underwater read-out electronics of Jiangmen Underground Neutrino Observatory.

A high time resolution and low-power ASIC for MRPC applications

Purpose The structure of readout circuits needs to be improved to meet the requirements of the endcap time of flight upgrade with multi-gap resistive plate chamber(MRPC)in Beijing SpectrometerⅢexperiments,posing a demand for the high time resolution and low-power electronics.Methods Considering MRPC features,an application-specific integrated circuit(ASIC)called FEEWAVE,which integrates the front-end circuit and digitization function,is proposed to meet the above requirements.The front-end circuit implements I/V conversion and signal amplification.To reduce power consumption and further improve the time resolution,the waveform sampling technique based on switch capacitor array is adopted.Results and conclusion A 30 fC to 1.2 pC input signal dynamic range is obtained,and the jitter is less than 21 ps rms.At the same time,the chip realizes 5 GSPS(gigabit samples per second)sampling rate,trigger rate capability of 50 kHz and 25 mW/channel power consumption.The 6-channel ASIC has been designed and taped out with 0.18μm complementary metal oxide semiconductor technology.The preliminary test results of FEEWAVE have been achieved.

The exploration of chiral N-cyano sulfiliminyl dicarboxamides on insecticidal activities

Due to new mechanism of action and ecofriendly characteristics,dicarboxamide insecticides have attracted more and more attentions in modern pest management.A series of 20 dual chiral N-cyano sulfilimines containing two centers（carbon and sulfur） were designed and synthesized.All title compounds were determined by ^1H NMR,high-resolution mass spectrometry（HRMS） and optical polarimeter.The preliminary results indicated that some of them exhibited favourable insecticidal activities against oriental armyworm（Pseudaletia separata Walker）.These isomers exhibited different impact on activity following the sequence as（Sc,Ss） 〉（Sc,Rs）,and the rule of title compounds＇ activity against oriental armyworm was 3-CF3≥2—CH3—4—Cl〉2,3,4-trifluro in the anilide moiety.The results indicated that these groups such as 3-CF3,2—CH3—4—Cl or 2,3,4-trifluro were inefficient to replace heptafluoroisopropyl group for high larvicidal activity,which provided some guidance for the further modifications of sulfiliminyl dicarboxamides.

Reliability study of custom designed ADC for the Jiangmen underground neutrino observatory

Objective The Jiangmen underground neutrino observatory(JUNO)is the largest and most precise liquid scintillator detector under construction in the south of China.The front-end readout electronics system will be installed very close to the photomultiplier tubes under water.Therefore,the system’s absolute reliability is mandatory.As an important piece,the failure rate of the custom designed analog-to-digital convertor(ADC)must be measured.Methods The Arrhenius High Temperature Operating Life(HTOL)model is usually used to calculate the standard reliability value failure rate(λ).A temperature acceleration test of the ADC is performed with a 115℃ambient temperature based on a custom aging system.The performance of ADC is compared before and after aging,and the most significant bit(MSB)of the digital output is monitored during the test.Results The result of a 2400-hour-long test shows that there were no failures.The upper limit of the failure rate is calculated as 5.8FIT,which can be added to the failure rate of other components to meet the overall failure rate requirements(84FIT).Conclusion With the test system,we established a method based on the HTOL model to obtain the upper limit of the ADC reliability for overall failure rate calculation in JUNO.This method can be applied to the reliability measurement for any other custom designed ADC.This experiment can be repeated with a new set of parameters to get a satisfactory failure rate according to other overall system requirements.