Detector Readout Research Articles

Design of the SPT-SLIM Focal Plane: A Spectroscopic Imaging Array for the South Pole Telescope

The Summertime Line Intensity Mapper (SLIM) is a mm-wave line-intensity mapping (mm-LIM) experiment for the South Pole Telescope (SPT). The goal of SPT-SLIM is to serve as a technical and scientific pathfinder for the demonstration of the suitability and in-field performance of multi-pixel superconducting filterbank spectrometers for future mm-LIM experiments. Scheduled to deploy in the 2023-24 austral summer, the SPT-SLIM focal plane will include 18 dual-polarisation pixels, each coupled to an R = lambda / Delta lambda = 300 thin-film microstrip filterbank spectrometer that spans the 2 mm atmospheric window (120–180 GHz). Each individual spectral channel feeds a microstrip-coupled lumped-element kinetic inductance detector, which provides the highly multiplexed readout for the 10k detectors needed for SPT-SLIM. Here, we present an overview of the preliminary design of key aspects of the SPT-SLIM focal plane array, a description of the detector architecture and predicted performance, and initial test results that will be used to inform the final design of the SPT-SLIM spectrometer array.

Comparing different methods of position reconstruction considering 1D readout of GEM detectors

Gas Electron Multiplier (GEM) based detectors contain microstructures that provide amplification, via avalanche multiplication, for the charges generated due to ionizing radiation. The readout of the detector is responsible for collecting electrons multiplied by the GEM structure and it may be position sensitive. In this preliminary study, we created algorithms to compare the error of three different methods for position reconstruction. All these methods are based on weighted averages. In the algorithm we modeled an electron cloud as a normalized Gaussian function that is collected by a 1D readout of strips affected by white noise, then we made a clustering algorithm to identify the strips that collected the electron cloud. The method that uses the weight equal to squared charges shows the highest errors for narrow clouds, when the σ value (standard deviation of a Gaussian function) is closer to the strip width. Nonetheless, the errors of the three methods get similar results for a σ approximately equal to the width of one and a half strips.

A charge-integration pixel readout chip features IR-drop effect mitigation by distributed LDOs

HYLITE (High dYnamic range free electron Laser Imaging deTEctor) is a charge-integration pixel detector readout chip, which is designed for SHINE (Shanghai high repetition rate XFEL and extreme light facility). The targeting pixel array of a full-size chip is 128 × 128 with a pixel pitch of 100 μm. The dynamic range of HYLITE is 1 ∼ 10000 photons at 12 keV, and the frame rate is 10 kHz. Large array size, high dynamic range, and high readout speed result in a big challenge of large power consumption and a significant IR-Drop effect. We implemented HYLITE0.2, which is the second prototype chip fabricated in a CMOS 130 nm process. Compared with HYLITE0.1, HYLITE0.2 aims to implement a full-function chip with a further shrunk pixel size, while the foreseen problem of severe IR-Drop effect of the full-size chip must be solved. To mitigate the IR-Drop effect, we proposed a novel architecture of distributed in-array Low-Dropout Regulators (LDOs). The pixel array consists of 16 × 24 pixels, and the full functionality was implemented within a pixel pitch of 100 μm. Measurements show that pixels powered by the proposed architecture work well, and the gain gradient of those pixels is 31.8% of the pixels powered by the conventional architecture.

How innovations in methodology offer new prospects for volume electron microscopy

Detailed knowledge of biological structure has been key in understanding biology at several levels of organisation, from organs to cells and proteins. Volume electron microscopy (volume EM) provides high resolution 3D structural information about tissues on the nanometre scale. However, the throughput rate of conventional electron microscopes has limited the volume size and number of samples that can be imaged. Recent improvements in methodology are currently driving a revolution in volume EM, making possible the structural imaging of whole organs and small organisms. In turn, these recent developments in image acquisition have created or stressed bottlenecks in other parts of the pipeline, like sample preparation, image analysis and data management. While the progress in image analysis is stunning due to the advent of automatic segmentation and server‐based annotation tools, several challenges remain. Here we discuss recent trends in volume EM, emerging methods for increasing throughput and implications for sample preparation, image analysis and data management.

Testing station for fast screening of through silicon via-enabled application-specific integrated circuits for hard x-ray imaging detectors

Application-specific integrated circuits (ASICs) are used in space-borne instruments for signal processing and detector readout. The electrical interface of these ASICs to frontend printed circuit boards is commonly accomplished with wire bonds. Through silicon via (TSV) technology has been proposed as an alternative interconnect technique that will reduce assembly complexity of ASIC packaging by replacing wire bonding with flip-chip bonding. TSV technology is advantageous in large detector arrays where TSVs enable close detector tiling on all sides. Wafer-level probe card testing of TSV ASICs is frustrated by solder balls introduced onto the ASIC surface for flip-chip bonding that hamper alignment. Therefore, we developed the ASIC test stand (ATS) to enable rapid screening and characterization of individual ASIC die. We successfully demonstrated ATS operation on ASICs originally developed for CdZnTe detectors on the Nuclear Spectroscopic and Telescope Array (NuSTAR) mission that were later modified with TSVs in a via-last process. We tested both backside blind-TSVs and frontside through-TSVs, with results from internal test pulser measurements that demonstrate performance equal to or exceeding the probe card wafer-level testing data. The ATS can easily be expanded or duplicated to parallelize ASIC screening for large area imaging detectors of future space programs.

A family of transient recorder ASICs for detector readout

A set of highly integrated read out ASICs with a common digitising and data acquisition back end but different front ends is currently under development at the GSI electronics department. The concept consists in using an analogue transient recorder stage for an efficient application of the area and power consuming analogue to digital converter. A focus of these ASICs is the read out of detectors with a large dynamic range. Possible applications could be the electromagnetic calorimeter of the PANDA detector or the GEM TPC of the Super-FRS at FAIR.

COMAP Early Science. III. CO Data Processing

We describe the first-season CO Mapping Array Project (COMAP) analysis pipeline that converts raw detector readouts to calibrated sky maps. This pipeline implements four main steps: gain calibration, filtering, data selection, and mapmaking. Absolute gain calibration relies on a combination of instrumental and astrophysical sources, while relative gain calibration exploits real-time total-power variations. High-efficiency filtering is achieved through spectroscopic common-mode rejection within and across receivers, resulting in nearly uncorrelated white noise within single-frequency channels. Consequently, near-optimal but biased maps are produced by binning the filtered time stream into pixelized maps; the corresponding signal bias transfer function is estimated through simulations. Data selection is performed automatically through a series of goodness-of-fit statistics, including χ 2 and multiscale correlation tests. Applying this pipeline to the first-season COMAP data, we produce a data set with very low levels of correlated noise. We find that one of our two scanning strategies (the Lissajous type) is sensitive to residual instrumental systematics. As a result, we no longer use this type of scan and exclude data taken this way from our Season 1 power spectrum estimates. We perform a careful analysis of our data processing and observing efficiencies and take account of planned improvements to estimate our future performance. Power spectrum results derived from the first-season COMAP maps are presented and discussed in companion papers.

The ultrafast pixel array camera system and its applications in high energy density physics.

Diagnostics in high energy density physics, shock physics, and related fields are primarily driven by a need to record rapidly time-evolving signals in single-shot events. These measurements are often limited by channel count and signal degradation issues on cable links between the detector and digitizer. We present the Ultrafast Pixel Array Camera (UPAC), a compact and flexible detector readout system with 32 waveform-recording channels at up to 10 Gsample/s and 1.8GHz analog bandwidth. The compact footprint allows the UPAC to be directly embedded in the detector environment. A key enabling technology is the PSEC4A chip, an eight-channel switch-capacitor array sampling device with up to 1056 samples/channel. The UPAC system includes a high-density input connector that can plug directly into an application-specific detector board, programmable control, and serial readout, with less than 5W of power consumption in full operation. We present the UPAC design and characterization, including a measured timing resolution of ∼20ps or better on acquisitions of sub-nanosecond pulses with minimal system calibrations. Example applications of the UPAC are also shown to demonstrate operation of a solid-state streak camera, an ultrafast imaging array, and a neutron time-of-flight spectrometer.

Intensity threshold variation method in the post-irradiation analysis of Fluorescent Nuclear Track Detectors for neutron dosimetry

Fluorescent Nuclear Track Detectors (FNTDs) are biocompatible passive detectors and a promising tool for neutron dosimetry applications, such as in-phantom measurements within the scope of ion therapy. Sensitivity differences between individual detectors however complicate the post-irradiation analysis process, making detector comparability and consequently dose assessment challenging. Therefore, improvements in the analysis method are needed to account for the observed sensitivity effects. In this work, the FNTD technology was implemented for neutron dosimetry using a standard Am-241/Be neutron source for irradiation and a confocal laser scanning microscope for detector readout. Acquired images were evaluated in terms of the track number of recoil proton signals behind a polyethylene converter, which was found to be related to dose. This study presents a new methodology for the post-irradiation data analysis, based on the variation of the intensity threshold parameter during the proton track identification process. The procedure was tested within individual detectors in stepwise irradiation experiments, validating the consistency of the proposed methodology. The application of the method to an extended number of FNTDs was able to account for sensitivity impacts and enabled comparability between the different detectors. A calibration curve based on the observed linear relation between dose and the number of identify tracks was obtained, that can be used for future implementation of FNTDs in neutron dosimetry.

Technical note: Comparison of arithmetic mean and energy-weighted mean flood histogram generation methods for dual-ended readout positron emission tomography detectors.

Dual-ended readout pixelated scintillator array detectors can provide a suitable crystal resolvability and satisfactory depth of interaction (DOI), energy, and timing resolutions. Usually, the flood histogram measured by one-sided readout is depth dependent, and the flood histogram quality degrades as the distance between the interaction site and photodetector increases. Information measured by two photodetectors must be combined to obtain an improved flood histogram yielding a better PET scanner spatial resolution. Two flood histogram generation algorithms for dual-ended readout of pixelated scintillator array detectors were compared by theoretical calculations and experimental measurements. The first algorithm is the arithmetic mean (AM) algorithm, which assigns the same weight to the flood histograms measured by photodetectors 1 and 2. The second algorithm is the energy-weighted mean (EWM) algorithm, which assigns each flood histogram a certain weight proportional to the energy measured by the photodetector. Theoretical equations were derived to determine the quality of the flood histograms obtained with these two algorithms. Experimental measurements were performed with an 18 × 18 lutetium-yttrium oxyorthosilicate (LYSO) array with a crystal size of 0.62 × 0.62 × 20 mm3 read out by two multi-anode photomultiplier tubes at both ends. Flood histograms of the whole array and five specific depths were compared between the above two algorithms. The theoretical results indicated that the flood histograms obtained with the EWM method matched those obtained with the AM method at the middle detector depth and were better at other detector depths when the distance (S) between the locations of the same crystal in the flood histograms measured by photodetectors 1 and 2 reached 0. The advantage of the EWM method decreased with increasing S value since the crystal position in the flood histogram obtained with the EWM method varies with the depth when S does not equal 0. The advantage of the EWM method decreased with increasing S value. The experimental results generally agreed with the theoretical predictions. Compared to the AM method, the EWM method provided a similar flood histogram at a depth of 10 mm but generated a better flood histogram at depths of 2 and 18 mm. Although an inverse correlation between Q (a quality factor representing the advantage of the EWM method) and S was observed, the variation in Q given the same S value was high. The average Q value at the same S still agreed with the theoretical predictions. Theoretical equations were derived, and experimental measurements were performed to compare two flood histogram generation algorithms for dual-ended readout PET detectors. The results indicated that the EWM method based on inverse variance weighting theory could provide better flood histograms than those provided by the AM method.

FastIC: a fast integrated circuit for the readout of high performance detectors

This work presents the 8-channel FastIC ASIC developed in CMOS 65 nm technology suitable for the readout of positive and negative polarity sensors in high energy physics experiments, Cherenkov detectors and time-of-flight systems. The front-end can be configured to perform analog summation of up to 4 single-ended channels before discrimination in view of improving time resolution when segmenting a SiPM. The outputs encode the time-of-arrival information and linear energy measurement which captures the peak amplitude of the input signal in the 5 µA–25 mA input peak current range. Power consumption of the ASIC is 12 mW/ch with default settings. Measurements of single photon time resolution with a red-light laser source and a HPK SiPM S13360-3050CS are ≈140 ps FWHM.

A Method Based on Muon System to Monitor LHCb Luminosity

LHCb is one of the four main experiments running at the Large Hadron Collider (LHC) of the European Organization for Nuclear Research. Since 2010, it has been collecting data to study the Physics of b and c quarks. For the past three years, the experimental apparatus underwent significant upgrades to be ready for a new round of data collection, expected to start in June 2022. The new apparatus is designed to be able to run at an instantaneous luminosity five times larger than the previous one, which was 2.0×1032 cm−2s−1, and the whole detector readout will be at a 40 MHz rate. It is worth noticing that the luminosity at the LHCb interaction point, for the characteristics of the detector, needs to be reduced with respect to the luminosity provided by LHC. Major changes in the different subdetectors were required, along with complete modifications of the trigger schemes. The LHCb collaboration is developing and studying different methods for the on-line measurement of luminosity at the LHCb impact point, crucial for the monitoring of correct machine operation and for most experimental physics studies. The present work describes a procedure based on hit counting in the muon detector for an on-line luminosity monitor. The performance and the precision achieved with this method in tests carried out on past data collected are presented, together with proposals for future upgrades.

High resolution detectors for whole-body PET scanners by using dual-ended readout

BackgroundMost current whole-body positron emission tomography (PET) scanners use detectors with high timing resolution to measure the time-of-flight of two 511 keV photons, improving the signal-to-noise ratio of PET images. However, almost all current whole-body PET scanners use detectors without depth-encoding capability; therefore, their spatial resolution can be affected by the parallax effect.MethodsIn this work, four depth-encoding detectors consisting of LYSO arrays with crystals of 2.98 × 2.98 × 20 mm3, 2.98 × 2.98 × 30 mm3, 1.95 × 1.95 × 20 mm3, and 1.95 × 1.95 × 30 mm3, respectively, were read at both ends, with 6 × 6 mm2 silicon photomultiplier (SiPM) pixels in a 4 × 4 array being used. The timing signals of the detectors were processed individually using an ultrafast NINO application-specific integrated circuit (ASIC) to obtain good timing resolution. The 16 energy signals of the SiPM array were read using a row and column summing circuit to obtain four position-encoding energy signals.ResultsThe four PET detectors provided good flood histograms in which all crystals could be clearly resolved, the crystal energy resolutions measured being 10.2, 12.1, 11.4 and 11.7% full width at half maximum (FWHM), at an average crystal depth of interaction (DOI) resolution of 3.5, 3.9, 2.7, and 3.0 mm, respectively. The depth dependence of the timing of each SiPM was measured and corrected, the timing of the two SiPMs being used as the timing of the dual-ended readout detector. The four detectors provided coincidence time resolutions of 180, 214, 239, and 263 ps, respectively.ConclusionsThe timing resolution of the dual-ended readout PET detector was approximately 20% better than that of the single-ended readout detector using the same LYSO array, SiPM array, and readout electronics. The detectors developed in this work used long crystals with small cross-sections and provided good flood histograms, DOI, energy, and timing resolutions, suggesting that they could be used to develop whole-body PET scanners with high sensitivity, uniform high spatial resolution, and high timing resolution.

SEBAT-Based Readout for FET THz Detectors With Intrinsic Power-to-Frequency Conversion

TeraHertz (THz) detection with Field-Effect Transistor-based (FET-based) detectors requires low-noise amplification, which typically involves trade-offs in terms of complexity, power, and area, resulting in severe scalability constraints for pixel integration into imaging arrays. The purpose of this paper is to describe a novel approach, from design to experimental validation, that enables active device-level amplification of the signal generated by a FET detector and converts it to a frequency suitable for digital processing. This has been done by exploiting a Single-Electron Bipolar Avalanche Transistor (SEBAT) to build a low-noise compact front-end circuit. The FET output is connected to the SEBAT forming a circuit element that here is defined as a TeraHertz Single-Electron Transistor (THzSET). The FET generates a detection current when it senses the THz signal; this current is then injected into the SEBAT, which generates an avalanche current pulse for each single electron, achieving a device-level amplification. The avalanche pulse rate is then evaluated from the signal measured at the SEBAT collector, and performing an FFT of the counts-per-second curve over time it is possible to measure the modulated THz signal applied to the device. The obtained Responsivity <inline-formula> <tex-math notation="LaTeX">$\text {R}_{\text {F}}$ </tex-math></inline-formula> and the Noise Equivalent Power NEP are respectively <inline-formula> <tex-math notation="LaTeX">$\frac {\text {4.61Gcps}}{\text {W}}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\frac {\text {88nW}}{\sqrt {\text {Hz}}} $ </tex-math></inline-formula> at 330GHz illumination frequency. This is achieved with sub-<inline-formula> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> power consumption and minimal area overhead: indeed, the pixel and the interface have a total area of 0.146mm², where the antenna area is <inline-formula> <tex-math notation="LaTeX">${455} \times {320}\mu \text{m}^{{2}}$ </tex-math></inline-formula> and the SEBAT area is <inline-formula> <tex-math notation="LaTeX">${27} \times {22}\mu \text{m}^{{2}}$ </tex-math></inline-formula>.

The QICK (Quantum Instrumentation Control Kit): Readout and control for qubits and detectors.

We introduce a Xilinx RF System-on-Chip (RFSoC)-based qubit controller (called the Quantum Instrumentation Control Kit, or QICK for short), which supports the direct synthesis of control pulses with carrier frequencies of up to 6GHz. The QICK can control multiple qubits or other quantum devices. The QICK consists of a digital board hosting an RFSoC field-programmable gate array, custom firmware, and software and an optional companion custom-designed analog front-end board. We characterize the analog performance of the system as well as its digital latency, important for quantum error correction and feedback protocols. We benchmark the controller by performing standard characterizations of a transmon qubit. We achieve an average gate fidelity of Favg=99.93%. All of the schematics, firmware, and software are open-source.

Rate-capability of the VMM3a front-end in the RD51 Scalable Readout System

The VMM3a is an Application Specific Integrated Circuit (ASIC), specifically developed for the readout of gaseous detectors. Originally developed within the ATLAS New Small Wheel (NSW) upgrade, it has been successfully integrated into the Scalable Readout System (SRS) of the RD51 collaboration. This allows, to use the VMM3a also in small laboratory set-ups and mid-scale experiments, which make use of Micro-Pattern Gaseous Detectors (MPGDs). As part of the integration of the VMM3a into the SRS, the readout and data transfer scheme was optimised to reach a high rate-capability of the entire readout system and profit from the VMM3a’s high single-channel rate-capability of 3.6Mhits/s. The optimisation focused mainly on the handling of the data output stream of the VMM3a, but also on the development of a trigger-logic between the front-end cards and the DAQ computer. In this article, two firmware implementations of the non-ATLAS continuous readout mode are presented, as well as the implementation of the trigger-logic. Afterwards, a short overview on X-ray imaging results is presented, to illustrate the high rate-capability from an application point-of-view.

Photon dosimetry using selective data sampling with Particle Swarm optimization algorithm based on NaI(Tl) scintillation detector

AbstractSodium Iodide doped with Thallium NaI(Tl) scintillation detectors have potential for the development of an active dosimeter for photon radiation. We aim to show that the photon dosimetry response for NaI(Tl) scintillation detector may be optimized by employing the Particle Swarm optimization algorithm, when the selective data sampling is applied for the detector readout. In this work, Sodium Iodide doped with Thallium NaI(Tl) scintillation detector is considered due to being highly sensitive to gamma radiation, and one of the affordable room temperature detectors. In this research, we intend to measure the dosimetry response of the NaI(Tl) detector for various gamma sources, as an example, by measuring the ambient dose equivalent H*(10) for different gamma radioactive sources. Furthermore, we demonstrate that the photon dosimetry response may be well optimized for various energies, especially at lower energies, by increasing the energy interval number in data sampling over the NaI(Tl) scintillation detector readout with the help of an optimization algorithm. The simulation software Geant4 has been used for determining the NaI(Tl) scintillation detector readout. To this end, experimental ambient dose equivalent measurements for gamma radiation sources are compared with the theoretical results. As three and six energy intervals are considered for the selective data sampling along with an optimization algorithm based on NaI(Tl) detector output, the error percentage will be less than 20 and 10%, respectively.

A laboratory course on detector readout for undergraduate students of experimental physics

The laboratory course program presented in this paper (96 h in total) aims to give undergraduate students of experimental physics the necessary knowledge to build and manage a complete experimental setup for the readout of a particle detector. Students learn to understand and operate silicon photosensors (SiPMs) in single photon regime; to amplify and shape their analogue signals with feedbacked operational amplifiers; to digitise and trigger them with a microcontroller; and to transmit waveforms via UART on a PC running MATLAB, where they can build typical ‘comb-like’ SiPM spectra that allow to discern single photoelectrons.

Simulation-based spectral analysis of X-ray CCD data affected by photon pile-up

Abstract We have developed a simulation-based method of spectral analysis for pile-up-affected data of X-ray CCDs without any loss of photon statistics. As effects of the photon pile-up appear as complicated nonlinear detector responses, we employ a detailed simulation to calculate the important processes in an X-ray observation including physical interactions, detector signal generation, detector readout, and a series of data reduction processes. This simulation naturally reproduces X-ray-like and background-like events as results of X-ray photon merging in a single pixel or in a chunk of adjacent pixels, allowing us to construct a nonlinear spectral analysis framework that can treat pile-up-affected observation data. For validation, we have performed data analysis of Suzaku X-ray Imaging Spectrometer (XIS) observations using this framework with various parameters of the detector simulation, all of which are optimized for that instrument. We present three cases of different pile-up degrees: PKS 2155−304 (negligible pile-up), Aquila X-1 (moderate pile-up), and the Crab Nebula (strong pile-up); we show that the nonlinear analysis method produces results consistent with a conventional linear analysis for the negligible pile-up condition, and accurately corrects well-known pile-up effects such as spectral hardening and flux decrease for the pile-up cases. These corrected results are consistent with those obtained by a widely used core-exclusion method or by other observatories with much higher timing resolutions (without pile-up). Our framework is applicable to any types of CCDs used for X-ray astronomy, including future missions such as X-ray Imaging and Spectroscopy Mission (XRISM), by appropriate optimization of the simulation parameters.

Optimized steering: Quantum state engineering and exceptional points

The state of a quantum system may be steered towards a predesignated target state, employing a sequence of weak $\textit{blind}$ measurements (where the detector's readouts are traced out). Here we analyze the steering of a two-level system using the interplay of a system Hamiltonian and weak measurements, and show that $\textit{any}$ pure or mixed state can be targeted. We show that the optimization of such a steering protocol is underlain by the presence of Liouvillian exceptional points. More specifically, for high purity target states, optimal steering implies purely relaxational dynamics marked by a second-order exceptional point, while for low purity target states, it implies an oscillatory approach to the target state. The dynamical phase transition between these two regimes is characterized by a third-order exceptional point.