Readout Electrodes Research Articles

ALLEGRO FCC-ee detector concept & Noble liquid calorimetry

ALLEGRO is a proposed FCC-ee general-purpose detector concept with a noble liquid (NL) electromagnetic calorimeter (ECAL) as a central feature. Calorimetry based on liquified noble gases is a well-proven technology that has been successfully applied in numerous high-energy physics (HEP) experiments. This technology provides excellent energy resolution, linearity, stability, uniformity and timing properties at a reasonable cost, making it a strong candidate for future HEP experiments. By using multi-layer printed circuit boards as readout electrodes, we can build a calorimeter with almost arbitrarily high granularity. This in turn allows for four-dimensional imaging, machine learning algorithms and particle-flow reconstruction to be fully exploited. In this proceedings contribution we give an overview to the ALLEGRO concept and present the ongoing R&D work for adapting NL calorimetry to an ECAL of a lepton collider experiment. In addition to simulation studies and expected performance, we show results on signal extraction and noise mitigation studies made with readout electrode prototypes and compare the measurements to simulations, as well as discuss test results of absorber prototypes. In addition we present progress of the mechanical design project and status of the barrel ECAL test-beam prototype module development.

All‐Screen‐Coatable Photo‐Thermoelectric Imagers for Physical and Thermal Durability Enhancement

AbstractCarbon nanotube (CNT) film photo‐thermoelectric (PTE) imagers are suitable for non‐destructive inspection techniques owing to their functionalities. Simultaneously, their practical application remains a crucial bottleneck due to low yield handling in the device fabrication (e.g., disconnections between photo absorbent channels and readout electrodes). However, studies clarifying the above malfunction mechanism and associated dominant factors in device handling, such as specific fabrication or material selection steps, still need to be completed. To address this issue, this work introduces all‐screen‐coatable fabrication techniques for CNT film PTE imagers to enhance their physical and thermal durabilities. First, this work determined that the transfer of CNT films on supporting substrates dominantly governs the mechanical robustness of the channels and that thermal curing in the subsequent fabrication process is an essential factor in the yields of channel‐electrode connections. The proposed approach ensures a transfer‐free direct coating of the CNT film on diverse substrates and is sufficiently durable against thermal curing‐induced disconnections at the channel‐electrode interfaces. The screen‐coating technique is also available for whole device materials of solution‐processable CNT film PTE imagers, simplifying fabrication processes. All‐screen‐coatable CNT film PTE imagers synergize their inherent functional sensing and high‐yield operations toward versatile applications.

The industrial production of Micro Pattern Gaseous Detector: experience from the ATLAS Micromegas

Resistive Micromegas is one of the detector technologies chosen by ATLAS for the Phase-1 upgrade of the Muon Spectrometer, completed in 2022 in view of the LHC Run3 start.It is the largest MPGD-based detector system ever built, covering an active area of 1280 m2, providing trigger and precise tracking capabilities to the ATLAS Muon system and able to stand a radiation background rate up to 20 kHz/cm2.The heart of the ATLAS Micromegas detectors is the anode board, which carries the resistive protection layer, the readout electrodes and the insulating spacers supporting the micro-mesh.The production of the 2048 readout boards of size up to 0.5×2.2 m2 has been assigned to high-technology PCB industries and required dedicated efforts for technology transfer, production follow-up and quality assurance and control.The paper reviews the main challenges from the design phase to the completion of the project which spanned over several years. Emphasis is also put on the thorough quality assurance and quality control protocol established, the achieved results, as well as on the logistic, supply and schedule constraints.The lessons learned from this unprecedented MPGD project are also discussed.

Study of RPC ionic signal properties with different read-out methods

The simultaneous measurement of the ionic charge (induced by the slow motion of positive ions inside the gas gap) and of the fast/prompt charge (induced on the read-out electrodes by the drift of electrons) is fundamental for the understanding of the working principles of the RPC detector. Typical RPC electrodes are made of resistive material with the voltage applied on a thin graphite layer, which however alters the reading of the ionic charge depending on the discharge position. We have therefore realized a small RPC detector with a metallic grid deployed in one of the resistive electrodes. The prompt charge is measured by means of typical read-out copper strips with 1.4 cm pitch. The purpose of the study described in this presentation is to test different ion signal read-out systems and the comparison with the prompt signal read out with traditional techniques, to improve the detector knowledge and for possible future applications.

Analysis of interstrip capacitance of p+n MCz Si microstrip detector using TCAD simulation combining surface and bulk damage effects by mixed irradiation

Interstrip capacitance plays a crucial role on the detector electronic noise performance at the readout electrode of the irradiated detectors in the harsh radiation environment of the high luminosity Large Hadron Collider experiments. The major challenge is to optimize the design of the detector to get the low interstrip capacitance in the real ‘mixed’ irradiation environment of the experiment. A few of experimental studies have been performed within CERN RDD0 collaboration on the n-MCz Si detectors to extract the microscopic parameters for the surface and bulk damage effects especially by mixed irradiations in the detectors. The results on the microscopic parameters are fed into ATLAS TCAD commercial simulation program to compare the experimental data and simulation result. A very good agreement has been recorded between the data and simulation result. In this paper, the microscopic model parameters are used to investigate the effects of mixed irradiation up to a fluence of 8.82× 1014 neq./cm2 on the interstrip capacitance in n-MCz 〈100〉 silicon microstrip detectors. The results are discussed in detail using electric field distribution, electron concentration profile in the irradiated detectors for the different metal overhang width, and an optimized p+n-MCz Si microstrip design is proposed for the future collider experiment.

Timing resolution in double-sided silicon photon-counting computed tomography detectors.

Our purpose is to investigate the timing resolution in edge-on silicon strip detectors for photon-counting spectral computed tomography. Today, the timing for detection of individual x-rays is not measured, but in the future, timing information can be valuable to accurately reconstruct the interactions caused by each primary photon. We assume a pixel size of and a detector with double-sided readout with low-noise CMOS electronics for pulse processing for every pixel on each side. Due to the electrode width in relation to the wafer thickness, the induced current signals are largely dominated by charge movement close to the collecting electrodes. By employing double-sided readout electrodes, at least two signals are generated for each interaction. By comparing the timing of the induced current pulses, the time of the interaction can be determined and used to identify interactions that originate from the same incident photon. Using a Monte Carlo simulation of photon interactions in combination with a charge transport model, we evaluate the performance of estimating the time of the interaction for different interaction positions. Our simulations indicate that a time resolution of 1ns can be achieved with a noise level of 0.5keV. In a detector with no electronic noise, the corresponding time resolution is . Time resolution in edge-on silicon strip CT detectors can potentially be used to increase the signal-to-noise-ratio and energy resolution by helping in identifying Compton scattered photons in the detector.

Skin-Inspired Bimodal Magneto-Dielectric-Based Flexible and Sensitive Capacitive Sensor for Limb Motion Tracking

Flexible devices featuring bimodality finds wide application in wearable electronics for tracking simple-to-complex human activities. Such tracking requires high sensitivity and broad working range which is still a concern for wearable electronics. Herein, a magneto-dielectric layer (MDL)-based bimodal sensing (strain and proximity) device with a broad working range and higher sensitivity is proposed. Nanoparticles in MDL (magnetic nanoparticles (MNP) within the PDMS matrix) change their position dynamically ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}{\rightarrow }{g}^{\prime }$ </tex-math></inline-formula> ) according to different bending load conditions. Increased sensitivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{ST}~\approx ~4\text{x}$ </tex-math></inline-formula> -times and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{Prox}~\approx ~1.5\text{x}$ </tex-math></inline-formula> -times) and wider working range (from 6 to 20 mm) are achieved in contrast to regular devices with PDMS as a dielectric. Linear device response (0.99 coefficient of linearity), long-endurance (1000 cycles), and rapid detection (200 and 250 ms) features add further advantages. Single capacitive readout and standard interdigitated electrodes (IDEs) simplify the device implementation. Moreover, IDE design automates contactless sensing along with identification of the nature of the sensing object (conducting/nonconducting), which is applied directly when it comes to object-sensitive human perception (e.g., visually impaired person).

Study of depth-dependent charge collection profiles in irradiated pad diodes

In this work, charge collection profiles of non-irradiated and irradiated 150µm thick p-type pad diodes were measured using a 5.2GeV electron beam traversing the diode parallel to the readout electrode. Four diodes were irradiated to 1MeV neutron equivalent fluences of 2, 4, 8, and 12 × 1015cm−2 with 23MeV protons. The Charge Collection Efficiency profiles as a function of depth are extracted by unfolding the data. The results of the measurements are compared to the TCAD device simulation using three radiation damage models from literature which were tuned to different irradiation types and fluences.

Test of ITk 3D sensor pre-production modules with ITkPixV1.1 chip

ITk detector, the new ATLAS tracking system at High Luminosity LHC, will be equipped with 3D pixel sensor modules in the innermost layer (L0). The pixel cell dimensions will be either 25 × 100 μm2 (barrel) or 50 × 50 μm2 (endcap), with one read-out electrode at the centre of a pixel and four bias electrodes at the corners. Sensors from pre-production wafers (50 × 50 μm2) produced by FBK have been bump bonded to ITkPixV1.1 chips at IZM. Bare modules have been assembled in Genoa on Single Chip Cards and characterized in laboratory and on beam.

Nonpatterned Soft Piezoresistive Films with Filamentous Conduction Paths for Mimicking Multiple-Resolution Receptors of Human Skin.

Soft pressure sensors play key roles as input devices of electronic skin (E-skin) to imitate real human skin. For efficient data acquisition according to stimulus types such as detailed pressure images or macroscopic strength of stimuli, soft pressure sensors can have variable spatial resolution, just like the uneven spatial distribution of pressure-sensing receptors on the human body. However, previous methods on soft pressure sensors cannot achieve such tunability of spatial resolution because their sensor materials and read-out electrodes need to be elaborately patterned for a specific sensor density. Here, we report a universal soft pressure-sensitive platform based on anisotropically self-assembled ferromagnetic particles embedded in elastomer matrices whose spatial resolution can be facilely tuned. Various spatial densities of pressure-sensing receptors of human body parts can be implemented by simply sandwiching the film between soft electrodes with different pitches. Since the anisotropically aligned nickel particles form independent filamentous conductive paths, the pressure sensors show spatial sensing ability without crosstalk, whose spatial resolution up to 100 dpi can be achieved from a single platform. The sensor array shows a wide dynamic range capable of detecting various pressure levels, such as liquid drops (∼30 Pa) and plantar (∼300 kPa) pressures. Our universal soft pressure-sensing platform would be a key enabling technology for actually imitating the receptor systems of human skin in robot and biomedical applications.

Inductive Superconducting Quantum Interference Proximity Transistor: The L-SQUIPT

The design for an inductive superconducting quantum interference proximity transistor with enhanced performance, the L-SQUIPT, is presented and analyzed. The interferometer is based on a double-loop structure, where each ring comprises a superconductor-normal metal-superconductor mesoscopic Josephson weak-link and the read-out electrode is implemented in the form of a superconducting tunnel probe. Our design allows both to improve the coupling of the transistor to the external magnetic field and to increase the characteristic magnetic flux transfer functions, thereby leading to an improved ultrasensitive quantum limited magnetometer. The L-SQUIPT behavior is analyzed in both the dissipative and the dissipationless Josephson-like operation modes, in the dissipative or in the dissipationless Josephson-like operation mode in the latter case by exploiting both an inductive and a dispersive readout scheme. The improved performance makes the L-SQUIPT promising for magnetic field detection as well as for specific applications in quantum technology, where a responsive dispersive magnetometry at milliKelvin temperatures is required.

Noble Liquid Calorimetry for FCC-ee

Noble liquid calorimeters have been successfully used in particle physics experiments for decades. The project presented in this article is that of a new noble liquid calorimeter concept, where a novel design allows us to fulfil the stringent requirements on calorimetry of the physics programme of the electron-positron Future Circular Collider at CERN. High granularity is achieved through the design of specific readout electrodes and high-density cryostat feedthroughs. Excellent performance can be reached through new very light cryostat design and low electronics noise. Preliminary promising performance is achieved in simulations, and ideas for further R&amp;D opportunities are discussed.

Creation of Ohmic contact on InGaAs/InAlAs quantum well detector for broad range photon detection

Several applications utilizing either synchrotron or conventional light sources require fastand efficient pixelated detectors. In order to cover a wide range of experiments, this workinvestigates the possibility to use InGaAs/InAlAs quantum well devices as photon detectorsfor a broad range of energies. Owing to their direct, low-energy band gap and high electron mobility, such devices may be used also at room temperature as multi-wavelength sensors from visible light to hard X-rays. Three different metal configurations were tested to create Ohmic contacts on quantum well detectors. The triple layers of Au/Ge/Ni is a suitable metal to create good Ohmic contacts for the readout electrode. When the beam is hitting from the readout side, Al could be involved as contacting metal with annealing without requiring the etching.

High-accuracy 4D particle trackers with resistive silicon detectors (AC-LGADs)

Future particle trackers will have to measure concurrently position and time with unprecedented accuracy, aiming at ∼5 μm and a few 10s ps resolution respectively. A promising good candidate for such a task are the resistive AC-LGADs, solid state silicon sensors of novel design, characterized by an internal moderate gain and an AC-coupled resistive read-out to achieve signal sharing among pads. The sensor design leads to a drastic reduction in the number of read-out channels, has an intrinsic 100% fill factor, and adapts easily to any read-out geometry. This report describes the design challenges, the signal formation and recent test results obtained with the first prototypes. A part is also dedicated to the reconstruction techniques that exploit the distributed nature of the signal, including machine learning. An outlook to a future development for optimized read-out electrodes and electronics is also presented.

Depth-dependent charge collection profile of pad diodes

The collected charge of two pad diodes is measured along the diode width using a 5.2GeV electron beam at the DESY II beam test facility. The electron beam enters parallel to the readout electrode plane and perpendicular to the edge of the diode. The position of the electron beam is reconstructed by three planes of an EUDET-type telescope. An in-situ procedure is developed to align the diode surface parallel to the electron beam. The result of these measurements is the charge collection efficiency profile as a function of depth for each diode. For a non-irradiated diode, the charge profile is uniform as a function of the beam position for bias voltages above the full-depletion, as expected. For the irradiated diode, the charge profile is non-uniform and changes as a function of bias voltage.

Optimization of GEM-based detector readout electrode structure for SXR imaging of tokamak plasma

The paper presents an optimization of a readout structure of the GEM-based detector designed for X-ray imaging for DTT tokamak in the energy range of 2–15 keV. The readout electrode of approximately 100 cm2 surface is composed of hexagonal pixels connected in a way that allows reducing the actual number of signal pixels (electronics channels). At the same time, based on time coincidence analysis, it makes possible to unambiguously identify the position of the recorded X-ray photon. For the input spectrum, the Detective Quantum Efficiency (DQE) of the detector was calculated using the Geant4 program and the spatial distributions of electron avalanches at the readout electrode were simulated using the Garfield++ program. These were conducted for a given energy range of radiation and a statistical distribution consistent with the shape of the spectrum considering the DQE of the detector. As a result, the size of a single hexagonal pixel was proposed to capture the position of the recorded radiation quanta in an optimal and effective way.

Characterization of Modal Frequencies and Orientation of Axisymmetric Resonators in Coriolis Vibratory Gyroscopes

This paper presents the characterization of the modal frequencies and the modal orientation of the axisymmetric resonators in Coriolis vibratory gyroscopes based on the approaches of the frequency sweep and the ring down. The modal frequencies and the orientation of the stiffness axis are the key parameters for the mechanical correction of the stiffness imperfections. The frequency sweep method utilizes the zero and the poles in the magnitude-frequency responses of the two-dimensional transfer function to extract the modal orientation information within the frequency domain. The ring down method makes use of the peak and the valley values of the beat signals at the readout electrodes to obtain the modal orientation and the coefficient of the nonlinear stiffness directly within the time domain. The proposed approaches were verified via a silicon ring resonator designed for gyroscopic sensing and the modal information from the experiments exhibited a good agreement between the methods of the frequency sweep and the ring down.

A new technique to establish the uniformity of the induction gap in GEM based detectors

This work explores the use of multichannel readout electronics, already in use for quality assurance in gain uniformity studies, to measure the uniformity of the induction gap in Gas Electron Multipliers (GEM) based detectors. The devised procedure also provides a qualification of the readout electrodes in terms of disconnected or shorted channels. The measurement is based on inducing a signal on the readout strips by pulsing the bottom layer of the GEM foil, and measuring the amplitude of the induced signal. In this work, signals are readout using the analog APV25 front-end chip and the Scalable Readout System (SRS) developed by the RD51 collaboration at CERN. Studies on small and large area GEM detectors, effects of mechanical stress, and of electric fields are presented. Sensitivity to defects in the readout plane is also verified.

First measurements of ionization cluster-size distributions with a compact nanodosimeter.

A nanodosimeter is a type of detector which measures single ionizations in a small gaseous volume in order to obtain ionization cluster size probability distributions for characterization of radiation types. Working nanodosimeter detectors are usually bulky machines which require a lot of space. In this work, the authors present a compact ceramic nanodosimeter detector and report on first measurements of cluster size distributions of 5MeV alpha particles. Single ionization measurements are achieved by applying a weak electric field to collect positive ions in a hole in a ceramic plate. Inside the ceramic plate, due to a strong electric field, the ions are accelerated and produce impact-ionizations. The resulting electron avalanche is detected in a read-out electrode. A Bayesian unfolding algorithm is then applied to the experimentally obtained cluster size distributions to reconstruct the true cluster size distributions. Experimentally obtained cluster size distributions by the compact nanodosimeter detector are presented. The reconstructed cluster size distributions agreed well with Monte Carlo simulated cluster size distributions for small volumes (diameter=2.5nm). For larger volumes, discrepancies between the reconstructed cluster size distributions and cluster size distributions from Monte Carlo simulations were observed. For the first time, ionization cluster size probability distributions could be obtained by a small and compact nanodosimeter detector. This signifies the achievement of a critical step toward the wide application of nanodosimetric characterization of radiation types including in clinical environments.

Development of 2D GEM-based SXR plasma imaging for DTT device: Focus on readout structure

Creation and development of a new diagnostics useful for future thermonuclear reactors and helpful in studying impurity profiles, MHD modes/localization, and imaging are among urgent tasks in plasma research field. Global SXR imaging for DTT device in support of power exhaust programme and its consecutive impact for plasma core is an example of applicability of such diagnostics. This contribution presents the results of the ongoing development of the elaborated plasma X-ray imaging technology focusing on the design of the relevant structure of readout electrode. In order to achieve that, the details on the expected plasma radiation for the selected scenario for DTT machine were assessed. Then, the spatial distribution of plasma radiation intensity flux that will be reaching the detector window of the GEM based detector was simulated. Taking it into account along with the physical properties of the detector, the spatial and temporal distributions of charge cloud that will be reaching the readout plane were evaluated. The special design of the readout structure has been proposed that fulfil critical conditions originated from technological and physical constraints. The final effectiveness of the GEM based detector was evaluated proving that such detector is well suited for an effective plasma radiation imaging.