Development Of STGC Strip Readout Electronic System In ATLAS NSW Phase-? Upgrade

In order to explore new physical laws beyond the standard model,LHC will increase its energy to 12-14 TeV with a luminosity to 3-7 × 1034cm-2s-1 within the next decade.The ATLAS detector system will be upgraded synchronously to ensure efficient data acquisition in high energy and luminosity proton collision environment.The current data analysis shows that the existing trigger system cannot distinguish between high transverse momentum muon and low energy proton produced by the end cap magnet.Moreover,the performance of the tracking chamber and trigger system will be even worse when the energy and luminosity of LHC are increased.Therefore,the ATLAS muon spectrometer upgrade program plans to develop the New Small Wheel precision tracking and trigger system.After reconstructing the muon track in the radiation environment of 15 KHz/cm2,NSW measure the angle ?? between the muon track and the infinite momentum track.If the angle is within ± 7 mrad with an accuracy of 1 mrad,the muon track comes from Interaction Point(IP).In this way,the current fake rate of 90%can be reduced.Furthermore,featuring position resolution greater than 150?m,anti-irradiation and high channel density,sTGC is applied to be NSW's trigger detector.Accordingly,the strip front-end electronic system needs to quickly measure the fC charge of 282240 strip channels on NSW within the Bunch Crossing(BC)period of 25ns,and rapidly transmit the data to the trigger and DAQ system to finish muon track reconstruction and Level-1 trigger.NSW is required to offer better tracking performance in a smaller space and a higher event rate because of the position closer to the IP than BW.The TGC front-end electronics,though running successfully in Big Wheel(BW),fails to satisfy the upgrade demand.The technical challenges on strip Front-end Board(sFEB)must be solved such as high channel density,anti-irradiation,and high-speed event readout,etc.Precision tracking and trigger of NSW depend on the fast and accurate readout of the charge of a large number of sTGC strip channels.Therefore,sFEB is required to have both high-density,high-precision analog front-end and high-speed data transmission.sFEB needs to realize an accuracy less than 2%,an inherence noise less than 1fC,a conversion time less than l?s,a dynamic range between 50fC and 1pC and an appropriate gain.Besides of these,sFEB needs 512 channels to cover all strip locations.Due to the limited NSW space and the environment,sFEB's size cannot exceed 27cm × 6cm,and has the capability of stable operation in 15KHz/cm2 irradiation and 0.4T magnetic field.Other requirements are also detailed in this article.The anti-irradiation customized ASICs are applied in sFEB to realize high channel density,high-speed communication,and anti-irradiation.It mainly includes three ASICs:VMM with 64-channel charge amplification,discrimination,neighbor logic,amplitude and timing measurement,analog-to-digital conversion;128 channels 6-bit Trigger Data Serializer(TDS)with a 4.8Gbps CERN-GBT serializer;Slow Control Adapter(SCA)with the interfaces of E-link,I2C,SPI,GPIO,etc.sFEB achieves high channel density,low noise,high speed communication and anti-irradiation by the key technology of high performance front-end electronics.Because of those custom ASIC has not yet fully formed,the sFEB prototype board,final validation board,and FEB DAQ data acquisition and control platform was designed or developed,thus easily and quickly to set up a corresponding test environment and get the corresponding test results for different test scenarios.At the last,this article introduces the sFEB electronics unit test,detector integration test and NSW system test.The sFEB electronics test showed that the typical intrinsic noise level of sFEB was about 0.19fC,the measured gain was 1.02mV/fC,and the non-linearity was 1.7%under the set gain of 1mV/fC.The ASIC on sFEB has achieved the design function with good performance.The sTGC integration test was carried out simultaneously in Shandong University and Weizmann Institute of Israel,and obtained the consistent performance parameters of sTGC detector.The NSW system test and the beam test was carried out at CERN,which verified the configuration and data transmission link of NSW back-end electronics system and sFEB,and used beam to test the performance parameters of sTGC.All results show that the design reliability of sFEB.The innovations of this paper are as follows:1.The main innovations:A new kind of front-end readout electronics has been development for small-strip thin gap chamber(sTGC).The electronics board is just 27cm×6cm,integrated 512 high density front channels which have 50 fC?1 PC dynamic range,the accuracy of 2%,0.2 fC low noise,the high event rate of 0.9MHz in each channel and 4.8 Gbps high-speed digital transmission.This is the best front-end electronics used in the same type detector at home and abroad.2.The key technology innovations:In the limited space of 27cm x 6cm,the design difficulties of high density layout and wiring of high-speed digital and high precision analog electronics,high density readout for fC small signal,high density front-end protection,etc.,have been solved innovatively3.The Application innovations:sFEB was first applied to the cosmic ray test and beam test with sTGC QS2,and obtained the performance parameters of sTGC,providing an effective basis for the mass production of the detector.