Anode Readout Research Articles

Can machine learning reduce the number of anode readouts for reconstruction of coincident single photons in CDIR resistive sea photon detectors?

This study focuses on exploring the potential of Charge Division Imaging Readout (CDIR) for micro-Channel plate (MCP) based resistive sea photon detectors. The CDIR technique spreads the MCP charge footprint capacitively between readout nodes forming anode segments. Charge measurements at each node are then used to reconstruct incident photon’s position and time. A primary objective is to investigate the minimum number of anode segmentation’s necessary, to allow successful reconstruction of multiple photons within a given time interval where pile up would be an issue for traditional approaches. Allowing for optimisation of the anode structure, investigating for a readout schematic to improve timing, rate capability, and reduce distortion effects.Algorithmic and machine learning (ML) techniques will be compared and utilised to reconstruct spatial positions of multiple photons. The comparison will aim to determine if machine learning techniques can be utilised to correct for algorithmic systematic errors to provide a more robust system, whilst removing the need for complex calibrations and allowing for efficient implementation on FPGA in future work.

A triangular-trapezoidal dual-channel shaping algorithm for resistive anode readout systems and its FPGA implementation.

This paper introduces a novel digital triangular-trapezoidal double-channel shaping algorithm to enhance the counting rate of resistive anode detectors. The algorithm is based on the trapezoidal shaping algorithm and improves it. At the extreme counting rate, the trapezoidal shaping algorithm cannot alleviate the pulse pileup, so the counting rate cannot meet the requirements of a high performance detector. The triangular-trapezoidal double-channel shaping algorithm is introduced in the resistance anode detector, which can replace the trapezoidal shaping filtering algorithm to process the output signal of the resistance anode detector and obtain the single photon position information. This improvement improves the counting rate of the resistor anode detector and reduces the resolution degradation caused by pulse pileup. The algorithm is simulated by System Generator software and implemented on FPGA (field programmable gate array). The triangular-trapezoidal double-channel shaping algorithm presented in this paper plays an important role in reducing electronic noise and pulse pileup. The algorithm is subjected to simulation testing, and it can recognize signals with a minimum pulse interval of 1 µs and counting rate up to 1000 kcps.

Performance of a triple-GEM detector with capacitive-sharing 3-coordinate (X–Y–U)-strip anode readout

The concept of capacitive-sharing readout, described in detail in a previous study, offers the possibility for the development of high-performance three-coordinates (X–Y–U)-strip readout for Micro Pattern Gaseous Detectors (MPGDs) using simple standard PCB fabrication techniques. Capacitive-sharing (X–Y–U)-strip readout allows simultaneous measurement of the Cartesian coordinates x and y of the position of the particles together with a third coordinate u along the diagonal axis in a single readout PCB. This provides a powerful tool to address multiple-hit ambiguity and enable pattern recognition capabilities in moderate particle flux environment of collider or fixed target experiments in high energy physics HEP) and nuclear physics (NP). We present in this paper the performance of a 10 cm × 10 cm triple-GEM detector with capacitive-sharing (X–Y–U)-strip anode readout. Spatial resolutions of the order of σxres = 71.6±0.8μm for X-strips, σyres = 56.2±0.9μm for Y-strips and σures =75.2±0.9μm for U-strips have been obtained at a beam test at Thomas Jefferson National Accelerator Facility (Jefferson Lab). Modifications of the readout design of future prototypes to improve the spatial resolution and challenges in scaling to large-area MPGDs are discussed.

Spatial resolution improvements with finer-pitch GEMs

Gas Electron Multipliers (GEMs) are used in many particle physics experiments, employing their `standard' configuration with amplification holes of 140 μm pitch in a hexagonal pattern. However, the collection of the charge cloud from the primary ionisation electrons from the drift region of the detector into the GEM holes affects the position information from the initial interacting particle. In this paper, the results from studies with a triple-GEM detector with an X-Y-strip readout anode are presented. It is demonstrated that GEMs with a finer hole pitch of here 90 μm improve the detector's spatial resolution. Within these studies, also the impact of the front-end electronics on the spatial resolution was investigated, which is briefly discussed in the paper.

The development of segmented electrode thin-film parallel plate avalanche counter (PPAC)

In order to improve the counting rate and position resolution of the Parallel Plate Avalanche Counter (PPAC) within the Compact Spectrometer for Heavy Ion Experiment, a new strip film-structured PPAC has been developed. The developped PPAC detector consists of three layers of film electrodes. The upper and lower layers which serve as the anodes are comprised of self-developed strip film electrodes, oriented perpendicularly to each other. The middle layer utilizes double-sided aluminized Mylar film as the cathode. There is a 3 mm gap between each layer, and the detector has an effective area of 76 mm× 76 mm. Operating in a low-pressure environment with isobutane gas as the working medium, the performance of the PPAC has been measured using a 5.486 MeV α radiation source. The measurement results indicate that the overall position resolution of the PPAC attains approximately 380 μm, and the position resolution improves to 300 μm when using slit width correction. Finally, the Monte Carlo simulation has been performed to simulate the distribution of electrons generated by the detector's ionization under the same conditions on the anode readout strip. The simulation results closely matches the observed multiplicity of hit anode readout strips in measurement.

First operation of an ACHINOS-equipped spherical proportional counter with individual anode read-out

The multi-anode sensor ACHINOS revolutionised the capabilities of the spherical proportional counter by enabling large-size, high-pressure, operation and TPC-like reconstruction capabilities through individual anode read-out. First measurements with an individually read out ACHINOS are performed, which enables improved calibration and response homogenisation. Experimental results demonstrating the improvement in energy resolution brought by the individual anode calibration are presented. These are complemented by detailed simulation studies on the effect of sensor design and manufacturing imperfections, and how they may be corrected both in hardware and analysis.

Performance study of the Multi-purpose Time Projection Chamber (MTPC) using a four-component alpha source

The Multi-purpose Time Projection Chamber (MTPC) is a gas-filled detector designed to measure cross sections of neutron-induced light-charged particle emission and fission reactions at the Back-streaming white neutron facility (Back-n) at the China Spallation Neutron Source. A prototype MTPC has been constructed with a drift volume, a resistive Micromegas charge amplification structure, and a high-density pixelated anode readout plane with 1519 hexagonal pads. Test measurements have been performed using a four-component alpha source. Alpha-particle track reconstruction is performed to obtain the deposited energy and length information of the trajectory. The performance test and characterization of the detector have served as the basis for the optimized design of the MTPC, which is currently undergoing commissioning at Back-n.

Status and perspectives of vacuum-based photon detectors

In this overview article vacuum-based photon detectors are reviewed emphasizing their applications in Cherenkov imaging devices. After the discussion of the basic detector stages such as photo cathode, electron multiplication, and (anode) readout, the status and recent progress with single- and multi-anode dynode photomultipliers (PMTs), hybrid (avalanche) photodetectors and microchannel-plate PMTs are presented. For all of these devices selected examples of their current and planned applications in neutrino, astroparticle, and high energy physics experiments are given. Possible future developments and innovations are also debated. The last part of this review is dedicated to a comparison of important performance parameters like particle detection efficiency, gain inside a magnetic field, rate capability, aging and lifetime issues, and radiation tolerance.

Novel resistive charge-multipliers for dual-phase LAr-TPCs: towards stable operation at higher gains

Cryogenic versions of Resistive WELL (RWELL) and Resistive Plate WELL (RPWELL) detectors have been developed, aimed at stable avalanche multiplication of ionization electrons in the vapor phase of LAr (dual-phase TPC). In the RWELL, a thin resistive DLC layer deposited on top of an insulator is inserted in between the electron multiplier (THGEM) and the readout anode; in the RPWELL, a resistive ferrite plate is directly coupled to the THGEM. Radiation-induced ionization electrons in the liquid are extracted into the gaseous phase. They drift into the THGEM's holes where they undergo charge multiplication. Embedding resistive materials into the multiplier proved to enhance operation stability due to the mitigation of electrical discharges — thus allowing operation at higher charge gain compared to standard THGEM (a.k.a. LEM) multipliers. We present the detector concepts and report on the main preliminary results.

Performance of a resistive micro-well detector with capacitive-sharing strip anode readout

The present study is carried out to demonstrate a new type of high-performance readout structure with low readout channel count developed for large-area micro pattern gaseous detectors. The structure exploits capacitive coupling between a vertical stack of 5 μ m thick copper pad layers sandwiched between 50 μ m thick polyimide foils to simultaneously transfer and spread the avalanche charges from the gaseous detector’s amplification structure to several strips or pads in the anode readout plane. The unique feature of the lateral spread of the avalanche charge size on several readout strips or pads is possible owing to well-defined configuration and sizes of the pads in layers of the vertical stack. This is known as a “capacitive-sharing” readout structure and this opens the door for high spatial resolution performance with low readout channel counts for large-area Micro Pattern Gaseous Detectors. Capacitive-sharing readout structures are fabricated using standard printed circuits boards manufacturing process. The concept is highly versatile as it can easily be implemented in any type of Micro Pattern Gaseous Detector’s amplification structure (Gas Electron Multipliers, micro-mesh gaseous structures, resistive micro-well detectors) and with a wide range of readout patterns (pads, strips, zigzags etc.). The technology also has a high degree of flexibility in terms of readout segmentation (pads or strip) pitch, with minimum impact on spatial resolution performances. The present study provides a detailed description of the capacitive-sharing readout concept and discusses a small resistive micro-well detectors prototype assembled with a two-dimensional capacitive-sharing strip readout structure as a proof of concept and with strip pitch of 800 μ m in both X and Y direction. The prototype was characterized in electron beam in the Hall D Beam Test setup at Jefferson Lab and a spatial resolution of (60 ± 1) μ m was achieved for both X and Y strips with an efficiency of (98.0 ± 0.9) % at the plateau and a signal arrival time jitter between neighboring strips less (6.00 ± 0.04) ns. Finally, we explore new ideas to expand the concept of capacitive-sharing readout structures to large particle detectors for future large scale particle physics experiments.

The Q-Pix pixelated readout concept for future Liquid Argon Time Projection Chambers: status and prospects.

Future long baseline neutrino experiments such as the Deep Underground Neutrino Experiment (DUNE) pose challenges for development of readout techniques for multi-kiloton LAr Time Projection Chambers (TPCs). In contrast to wire/strip anode readout, a pixelated readout eliminates disadvantages such as disambiguation in 2D track reconstruction. The Q-Pix Consortium, established in 2019, is developing a pixelated readout technique for LAr TPCs based on charge-integrate/reset (CIR) circuits. The CIR blocks generate a sequence of reset pulses with time intervals corresponding to fixed charge integrals, allowing signal reconstruction without continuous digitization. The Q-Pix ASIC, intended for reading out pixel arrays, comprises CIR blocks along with digital components responsible for communication and reconfigurable data routing. This work is devoted to give an overview of the Q-Pix project, its status, and prospects, with emphasis on the development and prototyping of the Q-Pix readout ASICs.

Development of a hybrid single-photon imaging detector with embedded CMOS pixelated anode

The development of a single-photon detector based on a vacuum tube, transmission photocathode, microchannel plate and CMOS pixelated read-out anode is presented. This imager will be capable of detecting up to 1 billion photons per second over an area of 7 cm2, with simultaneous measurement of position and time with resolutions of about 5 microns and few tens of picosecond, respectively. The detector has embedded pulse-processing electronics with data-driven architecture, based on the Timepix4 ASIC, producing up to 160 Gb/s data that will be handled by a high-throughput FPGA-based external electronics and data acquisition system. These performances will enable significant advances in particle physics, life sciences, quantum optics or other emerging fields where the detection of single photons with excellent timing and position resolutions are simultaneously required.

Pixelated resistive Micromegas detector for high-rate environment

The R&D work reported in this paper has been devoted to the production and test of pixelated resistive micromegas detectors able to track particles in a high-rate environment, up to 10 MHz/cm2, keeping a stable gain and a good spatial resolution. To pursue our goal, we had to reduce the occupancy by increasing the detector granularity and this has been done by changing the read-out anodes from the usual strips to pads. This minor change in the electrodes layout drastically increased the difficulty of implementing a resistive structure to protect the anodes from sparking. We present the results of the tests performed on four prototypes, with different protection schemes, showing it is possible to reach the desired rate with high gain, high efficiency and good position resolution. The response to X-rays from low (55Fe source) to high (X-rays generator) rates, as well as to beams of ionizing particles is reported.

Modelling the behaviour of microchannel plates using CST particle tracking software

Photon counting detectors are essential for many applications, including astronomy, medical imaging, nuclear and particle physics. An extremely important characteristic of photon counting detectors is the method of electron multiplication. In vacuum tubes such as photomultiplier tubes and microchannel plates (MCPs), secondary electron emission (SEE) provides electron multiplication through an accelerating field across the dynode(s). A significant electron cascade can be observed in these structures which are routinely used in industry and research. Both devices have been thoroughly tested experimentally. Developing new MCP designs can be expensive and time consuming so the ability to simulate new structures will provide many advantages to instrument designers and manufacturers. There are, however, significant challenges in accurately simulating MCPs, with many geometrical variables to consider as well as material SEE properties. The SEE process is probabilistic, and with MCPs having a very high gain, significant computational resource is required to simulate the resulting electron output for a model. In our research we illustrate how this can be achieved by developing an MCP model using Computer Simulation Technology (CST) Studio Suite software. The model consists of a charged particle source, a small seven-pore MCP structure (including electrodes, resistive and emissive surfaces), as well as the readout anode, with appropriate potentials applied to the components of the model. We present simulation results from the modelled MCPs, demonstrate electron multiplication performance, and compare these results with those predicted by theory. Our goal is to expand this model and identify optimum MCP parameters, for various science applications, using novel materials to optimise detector performance.

Development of a single-photon imaging detector with pixelated anode and integrated digital read-out

We present the development of a single-photon detector and the connected read-out electronics. This “hybrid” detector is based on a vacuum tube, transmission photocathode, microchannel plate and a pixelated CMOS read-out anode encapsulating the analog and digital-front end electronics. This assembly will be capable of detecting up to 109 photons per second with simultaneous measurement of position and time.The pixelated read-out anode used is based on the Timepix4 ASIC (65 nm CMOS technology) designed in the framework of the Medipix4 collaboration. This ASIC is an array of 512 × 448 pixels distributed on a 55 μm square pitch, with a sensitive area of ∼7 cm2. It features 50–70 e− equivalent noise charge, a maximum rate of 2.5 Ghits/s, and allows to time-stamp the leading-edge time and to measure the Time-over-Threshold (ToT) for each pixel. The pixel-cluster position combined with its ToT information will allow to reach 5–10 μm position resolution. This information can also be used to correct for the leading-edge time-walk achieving a timing resolution of the order of 10 ps.The detector will be highly compact thanks to the encapsulated front-end electronics allowing local data processing and digitization. An FPGA-based data acquisition board, placed far from the detector, will receive the detector hits using 16 electro-optical links operated at 10.24 Gbps. The data acquisition board will decode the information and store the relevant data in a server for offline analysis.These performance will allow significant advances in particle physics, life sciences, quantum optics or other emerging fields where the detection of single photons with excellent timing and position resolutions are simultaneously required.

SU-8 processing improvement and simulating studies for a Micromegas detector fabrication

This paper reports the manufacturing methodology to produce an electron multiplier, a Micromegas device, integrated onto a micro-pixel readout anode using a Silicon wafer as a holder. It describes the improvement in the processing of the insulating grid material SU-8 and electrical tests with the device. For the latter purpose, simulations with Garfield++ are carried out to predict the detector response for different gas mixtures. The Micromegas detector sandwich proposed in this work presents a series of problems, which we have addressed and discussed within this paper. The temperature control throughout the processing of SU-8 is extremely important, to be able to develop it. When developing the final SU-8 layer, we have used an extra photoresist, which combined with the SU-8, resulted in a much-improved shape of the Micromegas SU-8 hole-grid. Electrical testes are performed in order to verify the signals produced by a 55Fe radioactive source. A gas gain about 1,3 × 102, using Ar/C2H6 (75/25) mixture, is achieved for the prototype manufactured.

Multiple Use SiPM Integrated Circuit (MUSIC) for Large Area and High Performance Sensors

The 8-channel Multiple Use Silicon Photo-multiplier (SiPM) Integrated Circuit (MUSIC) Application specific integrated circuit (ASIC) for SiPM anode readout has been designed for applications where large photo-detection areas are required. MUSIC offers three main features: (1) Sum of the eight input channels using a differential output driver, (2) eight individual single ended (SE) analog outputs, and (3) eight individual SE binary outputs using a time over threshold technique. Each functionality, summation and individual readout includes a selectable dual-gain configuration. Moreover, the signal sum implements a dual-gain output providing a 15-bit dynamic range. The circuit contains a tunable pole zero cancellation of the SiPM recovery time constant to deal with most of the available SiPM devices in the market. Experimental tests show how MUSIC can linearly sum signals from different SiPMs and distinguish even a few photons. Additionally, it provides a single photon output pulse width at half maximum (FWHM) between 5–10 ns for the analog output and a single-photon time resolution (SPTR) around 118 ps sigma using a Hamamatsu SiPM S13360-3075CS for the binary output. Lastly, the summation mode has a power consumption of ≈200 mW, whereas the individual readout consumes ≈30 mW/ch.

Study of hygroscopic expansion of anode readout boards of gaseous detectors based on FR4

The problem of hygroscopic expansion of FR4 based large-size PCBs is discussed using the example of Micromegas detector. The readout electrodes of the detector located on the anode printed circuit board assumed to have precise dimensions. During the production and delivery process, the readout PCB is exposed to different temperature and humidity conditions. As a result, the PCB size differs from the nominal one at the moment of assembly of the detector. The problem appears to be relevant for any other large-size gaseous detectors with the readout structure based on FR4. The swelling of two test PCB samples during water absorption is studied. The size of the samples is 650× 500× 0.5 mm3. Both samples have copper strips on one side. The second side is naked on sample 1 and fully covered with a copper layer on sample 2. The elongation of the samples from dry conditions to 50% RH is measured. The influence of the copper layers on the absorption rate and the value of equilibrium elongation is discussed. It is shown that elongation of sample 1 follows the Fick's law while the absorption process in sample 2 is more complicated. The coefficient of linear hygroscopic expansion of sample 1 is measured and discussed.

Photon Counting Imaging with Low Noise and a Wide Dynamic Range for Aurora Observations.

The radiation intensity of observed auroras in the far-ultraviolet (FUV) band varies dramatically with location for aerospace applications, requiring a photon counting imaging apparatus with a wide dynamic range. However, combining high spatial resolution imaging with high event rates is technically challenging. We developed an FUV photon counting imaging system for aurora observation. Our system mainly consists of a microchannel plate (MCP) stack readout using a wedge strip anode (WSA) with charge induction and high-speed electronics, such as a charge sensitive amplifier (CSA) and pulse shaper. Moreover, we constructed an anode readout model and a time response model for readout circuits to investigate the counting error in high counting rate applications. This system supports global rates of 500 kilo counts, 0.610 dark counts s−1 cm−2 at an ambient temperature of 300 K and 111 µm spatial resolution at 400 kilo counts s−1 (kcps). We demonstrate an obvious photon count loss at incident intensities close to the counting capacity of the system. To preserve image quality, the response time should be improved and some noise performance may be sacrificed. Finally, we also describe the correlation between counting rate and imaging resolution, which further guides the design of space observation instruments.

3DI: A novel ion composition and three-dimensional velocity analyzer for the topside ionosphere

A new ion composition and three-dimensional velocity analyzer, 3-Dimensional ion velocity and mass Imager (3DI), measures 3D velocity distribution functions (VDFs) for each major ion species in Earth’s topside ionosphere. The 3DI instrument is composed of a miniaturized electrostatic analyzer (ESA) and a deflector, backed by a static, magnet-based, mass spectrometer. We have developed a micro-pixel read-out anode technique that significantly saves power in the particle detection system, and integrated it into an imaging microchannel plate (MCP). We tested the ESA and deflector, magnet-based mass spectrometer, and anode in the laboratory to demonstrate the 3DI prototype’s performance. We have applied numerical calculations to evaluate and discuss 3DI’s performance and dynamic range. Due to complexities associated with imaging 3D distribution functions during fast spacecraft motion, we also discuss the operation strategy for 3DI to capture and resolve the VDF within the field of view. Once applied to flight investigations, the 3DI observations will be extremely useful in identifying ionosphere composition, mass-dependent ion transport such as upflows, and mass-dependent ion heating. Furthermore, the precise measurement of non-thermal plasma VDFs provides information to improve ionospheric environment modeling and ground-based radar observations.