Design and development of multi-channel front end electronics based on dual-polarity charge-to-digital converter for SiPM detector applications

With the development of silicon photomultiplier(SiPM)technology,front-end electronics for SiPM signal processing have been highly sought after in various fields.A compact 64-channel front-end electronics(FEE)system achieved by fieldprogrammable gate array-based charge-to-digital converter(FPGA-QDC)technology was built and developed.The FEE consists of an analog board and FPGA board.The analog board incorporates commercial amplifiers,resistors,and capacitors.The FPGA board is composed of a low-cost FPGA.The electronics performance of the FEE was evaluated in terms of noise,linearity,and uniformity.A positron emission tomography(PET)detector with three different readout configurations was designed to validate the readout capability of the FEE for SiPM-based detectors.The PET detector was made of a 15×15 lutetium–yttrium oxyorthosilicate(LYSO)crystal array directly coupled with a SiPM array detector.The experimental results show that FEE can process dual-polarity charge signals from the SiPM detectors.In addition,it shows a good energy resolution for 511-keV gamma photons under the dual-end readout for the LYSO crystal array irradiated by a Na-22 source.Overall,the FEE based on FPGA-QDC shows promise for application in SiPM-based radiation detectors.

Prototype of the readout electronics for the RICH PID detector in the STCF

The ring imaging Cherenkov(RICH) detector for particle identification(PID) is being evaluated for the future super tau-charm facility(STCF) complex. In this work, the prototype readout electronics for the RICH PID detector is designed. The prototype RICH PID detector is based on a thick gas electron multiplier combined with a micromegas detector for Cherenkov light detection. Considering that there will be a large number(~ 690,000) of detector channels in future RICH detector, the readout electronics faces many challenges to precisely measuring time and charge information, such as reducing the noise,increasing density, and improving precision. The requirements of the readout electronics are explored, the downselection of the ASICs is made and thus a prototype readout electronics is designed and implemented. Tests are also conducted to evaluate the performance of the prototype readout electronics, and the results indicate that the time resolution is better than ~ 1 ns(RMS) when the input charge is greater than ~ 12 fC based on the APV25chip, while the time resolution is better than ~ 1 ns(RMS) at an input charge of over ~ 48 fC based on the AGET and STCF ASIC chips, and the equivalent noise charge is better than ~ 0.5 fC(RMS) @ 20 pF based on the three ASICs. The test results indicate that the prototype readout electronics design meets the requirement of the future RICH PID detector and thus provides a reference for future engineering.

Measuring Topological Charges of Optical Vortices with Multi-Singularity Using a Cylindrical Lens

We present a simple method to measure the topological charges of optical vortices with multiple singularities. Using a cylindrical lens, a vortex beam can decay into a light field distribution with multiple separated dark holes, whose number just equals the topological charge of the input beam. This conclusion is then verified via experiments and numerical simulations of the propagation of vortex beams with multiple singulaxities. This method is also reliable to measure the topological charges of broadband vortex beams with different distributions of singularities, which does not resort to multiple beam interferometrie experiments.

Detonation Propagation Characteristics of Superposition Explosive Materials

In order to investigate detonation propagation characteristics of different charge patterns,the detonation velocities of superposition strip shaped charges made up of a detonating cord and explosives were measured by a detonation velocity measuring instrument under conditions of different ignition.The experimental results and theoretical analysis show that the maximum detonation propagation velocity depends on the explosive materials with the maximum velocity among all the explosive materials.Using detonating cord in a superposition charge can shorten detonation propagation time and improve the efficiency of explosive energy.The measurement method of detonation propagation velocity and experimental results are presented and investigated.

Effects of NPB anode buffer layer on charge collection in ZnO/MEH-PPV hybrid solar cells

We investigate the effects of （N,N’-diphenyl）-N,N’-bis（1-naphthyl）-1,1’-biphenyl-4,4’-diamine （NPB） buffer layers on charge collection in inverted ZnO/MEH-PPV hybrid devices. The insertion of a 3-nm NPB thin layer enhances the efficiency of charge collection by improving charge transport and reducing the interface energy barrier, resulting in better device performances. S-shaped light J–V curve appears when the thickness of the NPB layer reaches 25 nm, which is induced by the inefficient charge extraction from MEH-PPV to Ag. Capacitance–voltage measurements are performed to further investigate the influence of the NPB layer on charge collection from both simulations and experiments.

Silicon PIN array-based charge measurement detector for HERD beam test

Purpose The high-energy cosmic radiation detection(HERD)is a dedicated space cosmic ray detector,planned to be launched and installed on the China Space Station(CSS)around 2027.One of the main goals of HERD is to measure the composition and energy spectra of cosmic rays(CR)with energies as high as several PeV by using silicon charge detectors(SCD)(Altomare et al.in The silicon charge detector of the high energy cosmic radiation detection facility,2023),plastic scintillator detectors(PSD)(Kyratzis et al.in Proceedings of Sc.(ICRC2021),vol.651,2021),and 3D calorimeters(CALO)(Liu et al.in J Instrum 18(09):09002,2023).To assess HERD’s charge measurement capability during the beam test,a particle identification detector(PID)with a large dynamic range is required.Methods A Si-PIN-based PID detector is conceptualized and manufactured.It is composed of four layers,each containing 30 Si-PIN sensors.In four IDE1160 ASICs,the signals from the Si-PIN arrays are preamplified,shaped,peak-held,and serially read out by four IDE1160 ASICs.A DAQ system is created to digitize the analog signals from ASICs,organize the data package,and transfer it to the host computer.Results and conclusion Before going to the beam test,the dynamic range,linearity,pedestal,and noise level of each channel in PID were studied at home.The dynamic range is 0 to+5 pC,the linearity is better than 2%,and the RMSE(Root Mean Square Error)of the pedestal is about 1 fC.The preliminary beam test results show that PID is capable of detecting heavy ions from(Be)to(Ga),and the charge resolution is better than 0.3 charge units(c.u.).

Surface Charge Accumulation Characteristics on DC GIL Three-post Insulators Considering the Influence of Temperature Gradient

Surface charge accumulation is considered to be a critical factor in flashover failure of three-post insulators.However,surface charge accumulation characteristics on threepost insulators with complex structures and uneven electric fields are still unclear.Furthermore,the temperature gradient field makes charge accumulation more complicated.In this presentation,surface charge profiles of DC three-post insulators under electro-thermal coupling stress are studied by establishing a multi-degree-of-freedom movement measurement system.The abdominal area of the three-post insulator accumulaftes charges of identical polarity as the DC voltage,while the leg area accumulates heteropolar charges.Charge density from the bottom of the leg to the center of the abdomen presents a trimodal distribution pattern,including two homopolar charge peaks and one heteropolar charge peak.Asymmetrical surface conductance distribution arising from the temperature gradient leads to a significant increase in amplitude and distribution range of the homopolar charge peak at the legs of insulator.Increase of the temperature gradient will further magnify the homopolar charge peak at the legs.When DC voltage is 100 kV and conductive pole temperature is 70℃,surface charge density of the three-post insulator can reach 100μC/m^(2).Therefore,surface conductance regulation of the leg region is the key to charge regulation and insulation optimization design of DC three-post insulators.

An analogue front-end ASIC prototype designed for PMT signal readout

The Water Cherenkov Detector Array （WCDA） is one of the core detectors in the Large High Altitude Air Shower Observatory （LHAASO）, and it consists of 3600 photomultiplier tubes （PMTs）. Both high resolution time and charge measurement are required over a large dynamic range from 1 photoelectron （P.E.） to 4000 P.E. The prototype of an analogue front-end Application Specific Integrated Circuit （ASIC） fabricated using Global Foundry 0.35 μm CMOS technology is designed to read out the PMT signal in the WCDA. This ASIC employs leading edge discrimination and an （RC）4 shaping structure. Combined with the following Time-to-Digital Converter （TDC） and Analog-to-Digital Converter （ADC）, both the arrival time and charge of the PMT signal can be measured. Initial test results indicate that time resolution is better than 350 ps and charge resolution is better than 10% at 1 P.E. and better than 1% with large input signals （300 P.E. to 4000 P.E.）. Besides, this ASIC has a good channel-to-channel isolation of more than 84 dB and the temperature dependency of charge measurement is less than 5% in the range 0 50℃.

Evaluation of a front-end ASIC for the readout of PMTs over a large dynamic range

The Large High Altitude Air Shower Observatory （LHAASO） project has been proposed for the survey and study of cosmic rays. In the LHAASO project, the Water Cherenkov Detector Array （WCDA） is one of the major detectors for searching for gamma ray sources. A Charge-to-Time Convertor （QTC） ASIC （Application Specification Integrated Circuit）, fabricated with GlobM Foundry 0.35 μm CMOS technology, has been developed for readout of photomultiplier tubes （PMTs） in the WCDA. This ASIC provides both time and charge measurement of PMT signals. The input charge is converted to a pulse width based on the Time-Over-Threshold （TOT） technique and linear discharge method; as for time measurement, leading edge discrimination is employed. This paper focuses on the evaluation of this front-end readout ASIC performance. Test results indicate that the time resolution is better than 400 ps and the charge resolution is better than 1% with large input signals and remains better than 15% @1 photoelectron （P.E.）, both beyond the application requirement. Moreover, this ASIC has a weak ambient temperature dependence, low input rate dependence and high channel-to-channel isolation.

Analog front-end prototype electronics for the LHAASO WCDA

In the readout electronics of the Water Cerenkov Detector Array （WCDA） in the Large High Altitude Air Shower Observatory （LHAASO） experiment, both high-resolution charge and time measurement are required over a dynamic range from 1 photoelectron （P.E.） to 4000 P.E. The Analog Front-end （AFE） circuit is one of the crucial parts in the readout electronics. We designed and optimized a prototype of the AFE through parameter calculation and circuit simulation~ and conducted initial electronics tests on this prototype to evaluate its performance. Test results indicate that the charge resolution is better than 1%@4000 P.E. and remains better than 10%@1 P.E., and the time resolution is better than 0.5 ns RMS, which is better than the application requirements.

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC （VA140） from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.

A prototype scalable readout system for micro-pattern gas detectors

A scalable readout system （SRS） is designed to provide a general solution for different micro-pattern gas detectors in various applications. The system mainly consists of three kinds of modules： the ASIC card, the adapter card and the front-end card （FEC）. The ASIC cards, mounted with particular ASIC chips, are designed for receiving detector signals. The adapter card is in charge of digitizing the output signals from several ASIC cards. The FEC, edged-mounted with the adapter, has field-programmable gate array （FPGA）-based reconfigurable logic and I/O interfaces, allowing users to choose different ASIC cards and adapters for different experiments, which expands the system to various applications. The FEC transfers data through Gigabit Ethernet protocol realized by a TCP processor （SiTCP） IP core in FPGA. By assembling a flexible number of FECs in parallel through Gigabit Ethernet, the readout system can be tailored to specific sizes to adapt to the experiment scales and readout requirements. In this paper, two kinds of multi-channel ASIC chip, VA140 and AGET, are applied to verify the scalability of this SRS architecture. Based on this VA140 or AGET SRS, one FEC covers 8 ASIC （VA140） cards handling 512 detector channels, or 4 ASIC （AGET） cards handling 256 detector channels, respectively. More FECs can be assembled in crates to handle thousands of detector channels.

A study of time over threshold (TOT) technique for plastic scintillator counter

A new charge measurement method, time over threshold （TOT）, has been used in some gas detectors lately. HereTOT is studied for TOF system, made of plastic scintillator counter, which can simplify the electronics of the system. The signal characteristics are measured and analyzed with a high quality oscilloscope, including noise, pedestal, signal amplitude, total charge, rise time and the correlation between them. The TOT and charge are related and can be fitted by some empirical formula. The charge measurement resolution by TOT is given and this will help the design of TOF electronics.

Feasibility study of cosmic-ray componentsmeasurement by using a scintillating fiber tracker in space

Purpose The application of traditional silicon strip detectors in space experiments often suffers from heat and power consumption limitations when a large area has to be instrumented.Recently,a scintillating fiber detector with SiPM readout was proposed and adopted by ground high-energy experiments.Its excellent performance in track measurement and mechanical flexibility makes it a prospective candidate for large-area tracking detectors in the next-generation space experiments.This paper mainly focuses on its performance in cosmic-ray charge measurement.Methods A fast Geant4 simulation for a single tracker module was developed and compared with the beam test results.The non-uniformity of the detector response was studied.Moreover,a full tracker simulation using a variety of typical cosmic ray nuclei was implemented.The performance of a fiber tracker with multiple layers was evaluated.Results and conclusion The comparison between the simulation results and the beam test data of protons and helium nuclei shows a good agreement.The non-uniformity study reveals the strong dependence of the detector signal on the position and inclination angle of the incident particles.Then,a corresponding correction algorithm was developed and applied in the following data analysis.The preliminary result shows that the charge measurement capability of the fiber tracker composed of 9 XY superlayers is comparable to that of the AMS-02 inner tracker,which consists of 7 layers of double-sided silicon micro-strip ladders.This paper discusses the feasibility of using fiber trackers to measure cosmic ray charges and provide a guide for the optimization of detector design.

Measuring the topological charge of optical vortices with a single plate

Measuring the topological charge(TC) of optical vortex beams by the edge-diffraction pattern of a single plate is proposed and demonstrated. The diffraction fringes can keep well discernible in a wide three-dimensional range in this method. The redundant fringes of the diffracted fork-shaped pattern in the near-field can determine the TC value, and the orientation of the fork tells the handedness of the vortex. The plate can be opaque or translucent, and the requirement of the translucent plate for TC measurement is analyzed. Measurement of TCs up to ±40 is experimentally demonstrated by subtracting the upper and lower fringe numbers with respect to the center of the light. The plate is easy to get, and this feasible measurement can bring great convenience and efficiency for researchers.

Design of the front-end electronics for parallel plate ion chamber

Background A set of nozzle systems for proton therapy is now being developed at China Institute of Atomic Energy.To real-ize the measurement of beam dose,a set of charge measurement electronics is designed,which is used to measure the output charge signal of the ionization chamber integration plane.Also,the charge measurement device can be used to measure the position information of ion chamber strips just by changing certain parameters.Methods The device realizes the integration and amplification of charge by IVC102,a precise low-noise integrator,and the DSP controls the ADC to collect and process the data.Modbus communication protocol is used to realize communication with the host computer which makes it possible to read data and set the parameter.Results A fixed charge generator is designed to generate 20 pC to 2 nC charge,which is used to test the measuring accuracy of electronics.The results have shown that the accuracy is within 0.62%in the above charge range.Conclusion After experimental tests,the front-end electronics meet the design goal and play a certain pre-test and verification role in the dose and beam position monitoring in the proton therapy system.