Large Number Of Readout Channels Research Articles

10Boron-film-based gas detectors at ESS

The development of detectors for the European Spallation Source is an important parallel element to the effort put into the design and construction of the neutron source and instruments. The 10Boron-film-based detector developments that started over a decade ago as basic detector concepts have now reached technical maturity after intense prototyping work and numerous testing campaigns. Several of the ESS beamlines that will soon enter the commissioning phase started welcoming the detector systems built with the 10B-film converter technology. The real-size demonstrators evolved in the last 2–3 years into a diverse suite of gas proportional counters for use in diffraction, reflectometry and small-angle scattering studies in spite of the operational complexity posed by the requirements for large-area coverage, low material budget and robustness for operation in the high-flux and high-radiation environment of ESS. The detectors are now being shipped to ESS or undergoing the last performance and calibration tests before being handed over to the instrument teams for installation in the host beamlines. A common feature of these detector systems is the very large number of readout channels that they are instrumented with in order to fulfill the demanding requirements for sensitivity, spatial resolution and count-rate capability. Across all of the detector types that will operate at ESS, the integration, testing and commissioning of the read-out technologies and software tools for data reduction, calibration and analysis are the focus of the detector and integration teams. These will yield a wealth of knowledge about their operation as well as initial results on the in-situ performance, a very important asset to ensure rapid commissioning of the detectors when neutrons from the ESS source become available. In this paper we will give an overview of the 10B-film-based detector technologies included in the ESS detector suite that are currently facing the transition from the production phase to installation and integration with the other beamline components, which comes with its own specific challenges of both organizational and technical nature.

Comparison of readout systems for high-rate silicon photomultiplier applications

Recent years have shown an increased use of silicon photomultipliers (SiPM) in experiments as they are of reasonable cost, have relatively low power consumption and are easily available in a variety of form factors allowing for a large number of readout channels. At the same time, experiments are generating data at increasingly high rates requiring the use of more efficient readout systems. In this work, the dead time, efficiency, dynamic range, coincidence time resolution and energy resolution of five different readout systems at various stages of maturity are evaluated to determine the best system for acquiring data from a detector in a high rate experiment. Additional functionalities of the systems are also discussed.

One-Dimensional Position-Sensitive LGAD With a DC Coupled and Resistive Charge Division Mechanism

Low-gain avalanche detectors (LGADs) are promising candidates for four-dimensional (4D) tracking detectors in future high-energy physics (HEP) experiments, offering high position and time resolution. However, conventional pixel array LGADs suffer from large dead areas between pixels and require a large number of readout channels, resulting in a poor spatial resolution and high cost. In this paper, we present a one-dimensional position-sensitive LGAD (1D PS-LGAD) based on DC coupling and a resistive charge division mechanism. The 1D PS-LGAD features two cathodes and one anode, with two-dimensional position coordinates obtained by cross-placing two 1D PS-LGADs. With an active thickness of 50 μm and an active area of 2.7 mm × 2.7 mm, a 1D PS-LGAD demonstrated an average position measurement error (PME) of 32.2 ±35.4 μm, accounting for 1.2% of the side length of the active area with a 100% fill factor. The coincidence time resolution and position resolution were 8.8 ps and 22.5 μm, respectively, at the center of the device for incident 532 nm light with a spot diameter of approximately 25 μm and a mean photoelectron number (MPEN) of 6000 when the reverse voltage was 620 V.

Application of an added-sinusoid, signal-multiplexing scheme to a compact, multiplexed neutron scatter camera

The development of compact and portable neutron imagers could be transformative for nuclear nonproliferation and security. Of the currently feasible neutron imaging concepts, the neutron scatter camera is the one that can be made most compact and versatile. Beneficially, this design also inherently measures the energy of incident neutrons on an event-by-event basis. Single volume and quasi-single volume neutron scatters have been proposed to fully maximize the potential of neutron scatter cameras and enable truly man-portable neutron imagers. Such imagers will likely have a very large number of readout channels to maximize the efficiency, so signal multiplexing to reduce readout channels would significantly reduce costs and size and facilitate wide-spread deployment. In this work a multiplexing method based on adding well-defined sinusoids to detector signal is applied to a quasi-single volume neutron scatter camera comprised of 6-mm × 6-mm × 60-mm EJ-299-34 plastic scintillators coupled to arrays of SensL 60035 C-series silicon photomultipliers to create a multiplexed neutron imager (MiNI). Such straightforward multiplexing enables the use of more detector elements for a given number of available signal readouts. The necessary calibrations and system characterizations are carried out to assess the multiplexing method’s performance and to understand the behavior of the prototype MiNI. Its ability to successfully image a neutron source is demonstrated with a 252Cf spontaneous fission source placed in various locations around the MiNI. Finally, neutron spectroscopy is also performed, and the feasibility and benefits of multiplexing a quasi-single volume neutron scatter camera are demonstrated.

Development of a low power and high integration readout ASIC for time projection chambers in 65 nm CMOS

The paper presents the development of a low power readout ASIC for time projection chambers (TPCs) for the CEPC (Circular Electron Positron Collider) experiments. In order to achieve high spatial and momentum resolution, large number of readout channels is demanded with waveform sampling capability in the resolution of 8-10 bit and the sampling rate of 10-40 MS/s. Power consumption became critical and has been addressed by using advanced 65 nm CMOS process and simplifying the analog circuits in our design. The prototype chip has been developed including the analog front-end and the waveform sampling SAR (Successive Approximation Register) ADC. This paper will present the detailed circuit design and test results. The development of the digital trapezoidal filter will also be described.

Compact MR-compatible DC-DC converter module

The SAFIR collaboration is developing a high rate positron emission tomography insert for a preclinical 7 T magnetic resonance imaging (MRI) device. To meet the desired performance figures, a large number of readout channels (≈15000) and integration of data digitisation into the insert are required. Consequently, the insert will consume about 1.3 kW of input power at low voltages (⩽ 3.3 V). This corresponds to large supply currents of several 100 A, requiring heavy and bulky supply cables. To overcome these problems we developed a compact and MR-compatible DC-DC stepdown converter module. Our converter is based on an air core inductor and is optimised for low electromagnetic emissions. It has an input voltage range from 6 V to 24 V and provides an adjustable output voltage from 1 V almost up to the input voltage. The maximum continuous output current is 6 A. We measured conversion efficiencies between 70% and 87% depending on output load and input voltage. For the operation conditions foreseen (16 V input voltage, 2.4 V output voltage and 3 A output current), we achieved an efficiency of 83.8%. Our tests inside the MRI demonstrated the compatibility between the MRI system and the step-down converters developed. No mutual interference was observed. The signal-to-noise ratio of the MRI remains unaltered, independent of the activity of the step-down converter under any operation condition and no effect on the operation of the DC-DC converter was observed. This successful test of an MR-compatible DC-DC converter creates new opportunities for the power supply of complex hardware inside an MRI. 49 of the DC-DC converters will be used in our SAFIR PET insert, but they can also be used in other applications with high power demand in environments with strong magnetic fields.

Twenty-four-micrometer-pitch microelectrode array with 6912-channel readout at 12 kHz via highly scalable implementation for high-spatial-resolution mapping of action potentials.

A 24-μm-pitch microelectrode array (MEA) with 6912 readout channels at 12 kHz and 23.2-μVrms random noise is presented. The aim is to reduce noise in a "highly scalable" MEA with a complementary metal-oxide-semiconductor integration circuit (CMOS-MEA), in which a large number of readout channels and a high electrode density can be expected. Despite the small dimension and the simplicity of the in-pixel circuit for the high electrode-density and the relatively large number of readout channels of the prototype CMOS-MEA chip developed in this work, the noise within the chip is successfully reduced to less than half that reported in a previous work, for a device with similar in-pixel circuit simplicity and a large number of readout channels. Further, the action potential was clearly observed on cardiomyocytes using the CMOS-MEA. These results indicate the high-scalability of the CMOS-MEA. The highly scalable CMOS-MEA provides high-spatial-resolution mapping of cell action potentials, and the mapping can aid understanding of complex activities in cells, including neuron network activities.

Electronics design and system integration of the ATLAS New Small Wheels

The upgrades of the Large Hadron Collider (LHC) at CERN and the experiments in 2019/20 and 2024/26 will allow to increase the instantaneous luminosity to L=2× 1034 cm−2s−1 and L=5−7× 1034 cm−2s−1, respectively. For the High Luminosity (HL) HL-LHC phase, the expected mean number of interactions per bunch crossing will be 55 at L=2× 1034 cm−2s−1 and 140 at L=5× 1034 cm−2s−1. This increase drastically impacts the ATLAS trigger system and trigger rates. For the ATLAS Muon Spectrometer, a replacement of the innermost endcap stations, the so-called ``Small Wheels", which are operating in a magnetic field, is therefore planned for 2019/20 to be able to maintain a low pT threshold for single muons and excellent tracking capability in the HL-LHC regime. The New Small Wheels will feature two new detector technologies: resistive Micromegas and small strip Thin Gap Chambers comprising a system of 2.4 million readout channels. Both detector technologies will provide trigger and tracking primitives fully compliant with the post-2026 HL-LHC operation. To allow for some safety margin, the design studies assume a maximum instantaneous luminosity of L=7× 1034 cm−2s−1, 200 pile-up events, trigger rates of 1 MHz at Level-0 and 400 KHz at Level-1. A radiation dose of 1700 Gy (innermost radius) is expected. The on-detector electronics will be implemented on some 8000 boards; four different custom ASICs will be used. The large number of readout channels, high speed output data rate, harsh radiation and magnetic environment, small available space, poor access and low power consumption all impose great challenges for the system design. The overall design and first results from integration of the electronics in a vertical slice test will be presented.

Evaluation of list-mode ordered subset expectation maximization image reconstruction for pixelated solid-state compton gamma camera with large number of channels

The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated solid-state technology for nuclear medicine applications. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). For Compton camera, especially with a large number of readout channels, image reconstruction presents a big challenge. In this work, results are presented for the List-Mode Ordered Subset Expectation Maximization (LM-OSEM) image reconstruction algorithm on simulated data with the VIP Compton camera design. For the simulation, all realistic contributions to the spatial resolution are taken into account, including the Doppler broadening effect. The results show that even with a straightforward implementation of LM-OSEM, good images can be obtained for the proposed Compton camera design. Results are shown for various phantoms, including extended sources and with a distance between the field of view and the first detector plane equal to 100 mm which corresponds to a realistic nuclear medicine environment.

Development of a high-density position decoder circuit for GAPD-based PET with a large number of readout channels

Channel reduction techniques are useful for reducing the number of channels being digitized and for constructing cost effective DAQ systems. The purpose of this study was to develop a channel reduction circuit which could be used to identify the interacted channel with a coincidence event from the 256 signals transferred from PET detectors. The channel reduction circuit would then output a channel address and analog pulse corresponding to the valid channel. The circuit, called a “position decoder circuit (PDC)”, consisted of a 256 channel gain adjust circuit, eight 32:1 PDCs, and one 8:1 PDC. Two PDC boards were constructed to evaluate the performance and usefulness of the developed PDC for PET applications. The proof-of-principle PET detector block composed of a 4×4 matrix of detector modules, each of which consisted of a LYSO scintillator coupled to a 4×4 array GAPD, was also constructed. A valid channel was successfully identified by the developed PDC, and the channel address and analog pulse outputs of the interacted channel were accurately measured. The variation of the gains for all detector channels was decreased by about 78% using the gain adjustment circuit implemented in the PDC. Moreover, average energy resolution was improved by approximately 8%. The discrepancy of timing resolutions acquired with and without the PDC was negligibly small. Single/coincidence count rates were 209.3/3.2cps with the PDC and 232.7/3.8cps without the PDC. Tomographic image of the hot-rod phantom was successfully acquired using the PDC. Experimental results indicate that the PDC is useful to identify a valid channel among a large number of readout channels of PET detectors. The results also indicate that the PDC is feasible to provide high-quality PET image.

SPIROC: design and performances of a dedicated very front-end electronics for an ILC Analog Hadronic CALorimeter (AHCAL) prototype with SiPM read-out

For the future e+ e- International Linear Collider (ILC) the ASIC SPIROC (Silicon Photomultiplier Integrated Read-Out Chip) was designed to read out the Analog Hadronic Calorimeter (AHCAL) equipped with Silicon Photomultiplier (SiPM). It is an evolution of the FLC_SiPM chip designed by the OMEGA group in 2005. SPIROC2 [1] was realized in AMS SiGe 0.35 μm technology [2] and developed to match the requirements of large dynamic range, low noise, low consumption, high precision and large number of read-out channels. This ASIC is a very front-end read-out chip that integrates 36 self triggered channels with variable gain to achieve charge and time measurements. The charge measurement must be performed from 1 up to 2000 photo-electrons (p.e.) corresponding to 160 fC up to 320 pC for SiPM gain 106. The time measurement is performed with a coarse 12-bit counter related to the bunch crossing clock (up to 5 MHz) and a fine time ramp based on this clock (down to 200 ns) to achieve a resolution of 1 ns. An analog memory array with a depth of 16 for each channel is used to store the time information and the charge measurement. The analog memory content (time and charge) is digitized thanks to an internal 12-bit Wilkinson ADC. The data is then stored in a 4kbytes RAM. A complex digital part is necessary to manage all these features and to transfer the data to the DAQ. SPIROC2 is the second generation of the SPIROC ASIC family designed in 2008 by the OMEGA group. A very similar version (SPIROC2c) was submitted in February 2012 to improve the noise performance and also to integrate a new TDC (Time to Digital Converter) structure. This paper describes SPIROC2 and SPIROC2c ASICs and illustrates the main characteristics thank to a series of measurements.

Applicability of independent component analysis on high-density microelectrode array recordings

Emerging complementary metal oxide semiconductor (CMOS)-based, high-density microelectrode array (HD-MEA) devices provide high spatial resolution at subcellular level and a large number of readout channels. These devices allow for simultaneous recording of extracellular activity of a large number of neurons with every neuron being detected by multiple electrodes. To analyze the recorded signals, spiking events have to be assigned to individual neurons, a process referred to as "spike sorting." For a set of observed signals, which constitute a linear mixture of a set of source signals, independent component (IC) analysis (ICA) can be used to demix blindly the data and extract the individual source signals. This technique offers great potential to alleviate the problem of spike sorting in HD-MEA recordings, as it represents an unsupervised method to separate the neuronal sources. The separated sources or ICs then constitute estimates of single-neuron signals, and threshold detection on the ICs yields the sorted spike times. However, it is unknown to what extent extracellular neuronal recordings meet the requirements of ICA. In this paper, we evaluate the applicability of ICA to spike sorting of HD-MEA recordings. The analysis of extracellular neuronal signals, recorded at high spatiotemporal resolution, reveals that the recorded data cannot be modeled as a purely linear mixture. As a consequence, ICA fails to separate completely the neuronal signals and cannot be used as a stand-alone method for spike sorting in HD-MEA recordings. We assessed the demixing performance of ICA using simulated data sets and found that the performance strongly depends on neuronal density and spike amplitude. Furthermore, we show how postprocessing techniques can be used to overcome the most severe limitations of ICA. In combination with these postprocessing techniques, ICA represents a viable method to facilitate rapid spike sorting of multidimensional neuronal recordings.

Development of an Eight-Channel Time-Based Readout ASIC for PET Applications.

An eight-channel readout ASIC has been developed for reading output signals from solid-state photomultipliers for positron emission tomography applications. This ASIC converts both the signal charge and occurring time to digital timing pulses so that only a time-to-digital converter is required for further signal processing. This provides the advantages of simplified circuit design, reduced power consumption, and suitability for applications that have a large number of readout channels. The ASIC uses a fully current mode preamplifier to achieve high bandwidth (> 100 MHz), high time resolution (better than ~1 ns FWHM), and low power consumption (a few mW/ch). The linear dynamic range of charge measurement is adjustable and can be extended up to 103 pC. The chip has been fabricated with 0.35 μm 2P4M CMOS technology. A test prototype board has been developed and used for ASIC functionality and performance evaluation. Our preliminary studies show that the targets have been successfully achieved.

Design and Characteristics of an Integrated Multichannel Ramp ADC Using Digital DLL Techniques for Small Animal PET Imaging

This paper presents a novel design of an integrated 12-bit multi-channel single-slope ramp analog-to-digital converter (ADC) for a small animal positron emission tomography(PET) imaging system. The proposed ADC is a part of a monolithic front-end readout application-specific integrated circuit(ASIC) which is dedicated to the detector modules consisting of LYSO scintillation crystals read out on both sides by the multi-channel plate (MCP) photodetectors. The function of the ADC is to digitize the voltage signals from a large number of readout channels. Digital delay-locked loop (DLL) techniques are proposed to realize time interpolations in order to reduce the conversion time and to enhance the resolution. Both high precision and low power are obtained. An eight-channel prototype chip is implemented in AMS 0.35 μm CMOS technology. The available resolution of the ADC is 9 ~ 12 bits. The maximum DNL and INL of the fine conversion in the ADC is ±0.75 LSB and ±0.5 LSB, respectively. The static power consumption of the ADC is 3 mW + 0.2 mW/Channel. This ADC architecture provides a possibility to integrate low-noise front-end readout circuits, time-to-digital converters and ADC together into a monolithic ASIC and to output both the energy quantity and the time information with digital representations for PET imaging systems.

SPIROC (SiPM Integrated Read-Out Chip): dedicated very front-end electronics for an ILC prototype hadronic calorimeter with SiPM read-out

The SPIROC chip is a dedicated very front-end electronics for an ILC (International Linear Collider) prototype of hadronic calorimeter using Silicon photomultiplier (SiPM) or Multi-Pixel Photon Counters (MPPC) readout. This ASIC is due to equip a 10,000-channel demonstrator in 2010. SPIROC is an evolution of FLC-SiPM used for the ILC Analogue HCAL physics prototype. The first prototype of SPIROC was submitted in June 2007. It embeds cutting edge features that fulfil ILC final detector requirements. It has been realized in 0.35 μm SiGe technology. It has been developed to match the requirements of large dynamic range, low noise, low consumption, high precision and large number of readout channels needed. SPIROC is an auto-triggered, dual gain, 36-channel ASIC which allows to measure on each channel the charge from one photoelectron to 2,000 photoelectron and the time with a 100 ps accurate Time-to-digital Converter (TDC). An analogue memory array with a depth of 16 for each channel is used to store the time information and the charge measurement. A 12-bit Wilkinson Analogue-to-digital Converter (ADC) has been embedded to digitize the analogue memory content (time and charge on 2 gains). The data are then stored in a 4 Kbytes RAM. A very complex digital part has been integrated to manage all these features and to transfer the data to the DAQ which is described in Dulucq et al. After an exhaustive description, the extensive measurement results of this new front-end chip are presented.

Novel large aperture EBCCD

A novel large aperture electron bombardment charge coupled device (EBCCD) has been developed. The diameter of its photocathode is 10 cm and it is the first EBCCD with such a large aperture. Its gain shows good linearity as a function of applied voltage up to −12 kV, where the gain is 2400. The spatial resolution was measured using ladder pattern charts. It is better than 2 line pairs/mm, which corresponds to 3.5 times the CCD pixel size. The spatial resolution was also measured with a copper foil pattern on a fluorescent screen irradiated with X-rays (14 and 18 keV) and a 60 keV gamma-ray from an americium source. The result was consistent with the measurement using ladder pattern charts. The output signal as a function of input light intensity shows better linearity than that of image intensifier tubes (IIT) as expected. We could detect cosmic rays passing through a scintillating fiber block and a plastic scintillator as a demonstration for a practical use in particle physics experiments. This kind of large aperture EBCCD can, for example, be used as an image sensor for a detector with a large number of readout channels and is expected to be additionally applied to other physics experiments.

Front-end electronics with large dynamic range for space-borne cosmic ray experiments

The next generation of space-based or balloon-borne experiments, dedicated to the study of high energy cosmic rays, are designed to identify the primary particle and to record electronically in flight its charge and energy. The large number of readout channels drives the front-end electronics design toward low power devices with the additional requirement of a large dynamic range. This turns out to be mandatory both for charge detectors dedicated to the identification of high-Z nuclei and for calorimeters designed to operate in the multi-TeV range. The development of new front-end electronics designed according to the above requirements will be reported.

A pipelined front-end, timing, and amplitude digitizing system

A front-end digitizing system is needed for the straw tracking-detector of the MECO experiment. This detector has 24 000 channels of time and amplitude readout. The system operates in a high singles count-rate environment, and continuously digitizes the incoming pulses of every channel, using a latency buffer to temporarily hold this information. For each event, channel occupancy signals are sent to a local logic analyzer. Thus, the system can be self-triggered or triggered by a coincidence of the internally generated occupancy signal with an external gate. Upon presentation of a valid trigger, all data stored in the latency buffer are then read with zero-suppression to local RAM. The readout can provide sub-nanosecond timing and 6-9-bit amplitude resolution. This digitizer design will be implemented in an ASIC due to the large number of readout channels, the requirement that the data initially flow in parallel because of high single rates, and the large number of memory buffers. The digitizer is controlled by an FPGA, and the system clock can be varied between 15-60 MHz. This paper presents the conceptual design for the MECO readout system, but we anticipate that it can be used for many other applications requiring the acquisition of time and waveform signals in high counting rate environments.

The ATLAS trigger system

ATLAS is one of two general-purpose detectors at the next-generation proton–proton collider, the LHC. The high rate of interactions and the large number of read-out channels make the trigger system for ATLAS a challenging task. The initial bunch-crossing rate of 40 MHz has to be reduced to about 200 Hz while preserving the physics signals against a large background. ATLAS uses a three level trigger system, with the first level implemented in custom hardware, while the high level trigger systems are implemented in software on commodity hardware. This note describes the physics motivation, the various selection strategies for different channel and the physical implementation of the trigger system. PACS: 25.70.Ef – 21.60.Gx – 27.30.+t

Design and operation of front-end electronics for the HERA-B muon detector

We have implemented a cost-effective design for the readout electronics of both the anode wires and the cathode pads of large area proportional wire chambers for the HERA-B muon system based on the ASD-08 integrated circuit. To control and monitor the large number of readout channels, we have built a distributed control system based on Philips Semiconductors' I2C bus and microcontrollers. To date we have installed about 10800 channels of muon chambers and electronics. The average single channel noise occupancy is less than 10**-5, and the detectors have been operated with target interaction rates as high as 70 MHz.