The edge transient-current technique (Edge-TCT) and charge-collection measurements with passive test structures made with the LFoundry 150-nm CMOS process on a p-type substrate with an initial ...resistivity of over 3 kΩcm are presented. The measurements were made before and after irradiation with reactor neutrons up to 2⋅1015 neq/cm2. Two sets of devices were investigated: unthinned (700 μm) with the substrate biased through the implant on top and thinned (200 μm) with a processed and metallised backplane.
The depletion depth was estimated with the Edge-TCT and the collected charge was measured with a 90Sr source using an external amplifier having a 25-ns shaping time. The depletion depth for a given bias voltage decreased with the increasing neutron fluence, but it was still larger than 70 μm at 250 V after the highest fluence. After irradiation a much higher collected charge was measured for the thinned detectors with a processed backplane compared to the unthinned devices, although the same or an even larger depletion depth was measured in the unthinned devices. The most probable value of the collected charge of over 5000 electrons was measured with a thinned device also after irradiation to 2⋅1015 neq/cm2. This is sufficient to ensure the successful operation of these detectors at the outer layer of the pixel detector in the ATLAS experiment at the upgraded HL-LHC.
We report on the design, production, and performance of compact 40-cm3 Time Projection Chambers (TPCs) that detect fast neutrons by measuring the three-dimensional (3D) ionization distribution of ...nuclear recoils in 4He:CO2 gas at atmospheric pressure. We use these detectors to characterize the fast-neutron flux inside the Belle II detector at the SuperKEKB electron–positron collider in Tsukuba, Japan, where the primary design constraint is a small form factor. We find that the TPCs meet or exceed all design specifications, and are capable of measuring the 3D surface shape and charge density profile of ionization clouds from nuclear recoils and charged tracks in exquisite detail. Scaled-up detectors based on the detection principle demonstrated here may be suitable for directional dark matter searches, measurements of coherent neutrino–nucleus scattering, and other experiments requiring precise detection of neutrons or nuclear recoils.
Depleted Monolithic Active Pixel Sensors (DMAPS) are monolithic pixel detectors with high-resistivity substrates designed for use in high-rate and high-radiation environments. They are produced in ...commercial CMOS processes, resulting in relatively low production costs and short turnaround times, and offer a low material budget. LF-Monopix1 and TJ-Monopix1 are large DMAPS prototypes produced in 150 nm LFoundry and 180 nm TowerJazz technology, respectively, that follow two different design concepts regarding the charge collection electrode. Prototypes of both development lines have been extensively tested and characterized over the last years. The second-generation Monopix prototypes, Monopix2, were recently produced. They were designed to address the shortcomings of their predecessors, in particular related to radiation hardness and cross talk, and further improve upon their performance. The latest measurements with LF-Monopix1 and TJ-Monopix1 concerning hit efficiency, depletion, and radiation hardness as well as the initial test results of the new Monopix2 prototypes are presented.
The MALTA monolithic silicon pixel sensors have been used to study dicing and thinning of monolithic silicon pixel detectors for large area and low mass modules. Dicing as close as possible to the ...active circuitry will allow to build modules with very narrow inactive regions between the sensors. Inactive edge regions of less than 5μ m to the electronic circuitry could be achieved for 100μm thick sensors. The MALTA chip (Cardella et al., 2019) also offers the possibility to transfer data and power directly from chip to chip. Tests have been carried out connecting two MALTA chips directly using ultrasonic wedge wire bonding. Results from lab tests show that the data accumulated in one chip can be transferred via the second chip to the readout system, without the need of a flexible circuit to route the signals. The concept of chip to chip data and power transfer to achieve low mass modules has also been studied on prototype wafers using Cu-stud interconnection bridges. First results are presented, outlining technical challenges and possible future steps to achieve a low mass large area monolithic pixel sensor module.
Depleted Monolithic Active Pixel Sensors (DMAPS) constitute a promising low cost alternative for the outer layers of the ATLAS experiment Inner Tracker (ITk). Realizations in modern, high resistivity ...CMOS technologies enhance their radiation tolerance by achieving substantial depletion of the sensing volume. Two DMAPS prototypes that use the same “column-drain” readout architecture and are based on different sensor implementation concepts named LF-Monopix and TJ-Monopix have been developed for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC).
LF-Monopix was fabricated in the LFoundry 150 nm technology and features pixel size of 50×250μm2 and large collection electrode opted for high radiation tolerance. Detection efficiency up to 99% has been measured after irradiation to 1⋅1015neq∕cm2. TJ-Monopix is a large scale (1×2cm2) prototype featuring pixels of 36×40μm2 size. It was fabricated in a novel TowerJazz 180 nm modified process that enables full depletion of the sensitive layer, while employing a small collection electrode that is less sensitive to crosstalk. The resulting small sensor capacitance (≤3 fF) is exploited by a compact, low power front end optimized to meet the 25 ns timing requirement. Measurement results demonstrate the sensor performance in terms of Equivalent Noise Charge (ENC) ≈11e−, threshold ≈300e−, threshold dispersion ≈30e− and total power consumption lower than 120 mW/cm2.
•Depleted monolithic pixel sensors developed for the ATLAS ITk.•Different implemenation concepts featuring large and small collection electrodes.•Process modification to combine small capacitance with enhanced radiation tolerance.•Full functionality after irradiation.•High efficiency (LF-Monopix), High analog performance (TJ-Monopix).
Abstract
An x-ray imager is being developed for use in diffraction-limited synchrotron rings and continuous wave free electron lasers. The imager is named CoRDIA (COntinuous Readout Digitising Imager ...Array) and aims at achieving continuous operation at a frame rate in excess of 100kHz. Other goals include single-photon sensitivity at 12 keV (or below), a full well in excess of 10k photon/pixel/image, and a 100μm pixel pitch. The detector ASIC will be compatible with multiple sensor materials to cover different energy ranges. Exploratory prototypes of the readout ASIC (basic circuital blocks) have been manufactured in TSMC 65nm technology: they are presently under test.
DMAPS Monopix developments in large and small electrode designs Bespin, C.; Barbero, M.; Barrillon, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2020, Letnik:
978
Journal Article
Recenzirano
LF-Monopix1 and TJ-Monopix1 are depleted monolithic active pixel sensors (DMAPS) in 150nm LFoundry and 180nm TowerJazz CMOS technologies respectively. They are designed for usage in high-rate and ...high-radiation environments such as the ATLAS Inner Tracker at the High-Luminosity Large Hadron Collider (HL-LHC). Both chips are read out using a column-drain readout architecture. LF-Monopix1 follows a design with large charge collection electrode where readout electronics are placed inside. Generally, this offers a homogeneous electrical field in the sensor and short drift distances. TJ-Monopix1 employs a small charge collection electrode with readout electronics separated from the electrode and an additional n-type implant to achieve full depletion of the sensitive volume. This approach offers a low sensor capacitance and therefore low noise and is typically implemented with small pixel size. Both detectors have been characterized before and after irradiation using lab tests and particle beams.
Charge collection properties of depleted CMOS pixel detector prototypes produced on p-type substrate of 2 kOmega cm initial resistivity (by LFoundry 150 nm process) were studied using Edge-TCT method ...before and after neutron irradiation. The test structures were produced for investigation of CMOS technology in tracking detectors for experiments at HL-LHC upgrade. Measurements were made with passive detector structures in which current pulses induced on charge collecting electrodes could be directly observed. Thickness of depleted layer was estimated and studied as function of neutron irradiation fluence. An increase of depletion thickness was observed after first two irradiation steps to 1 middot 10 super(13) n/cm super(2) and 5 middot 10 super(13) n/cm super(2) and attributed to initial acceptor removal. At higher fluences the depletion thickness at given voltage decreases with increasing fluence because of radiation induced defects contributing to the effective space charge concentration. The behaviour is consistent with that of high resistivity silicon used for standard particle detectors. The measured thickness of the depleted layer after irradiation with 1 middot 10 super(15) n/cm super(2) is more than 50 mum at 100 V bias. This is sufficient to guarantee satisfactory signal/noise performance on outer layers of pixel trackers in HL-LHC experiments.
Measurement results of the MALTA monolithic pixel detector Schioppa, E.J.; Asensi Tortajada, I.; Berdalovic, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
Journal Article
Recenzirano
MALTA is a full scale monolithic pixel detector implemented in TowerJazz 180 nm CMOS technology. The small pixel electrode allowed for the implementation of a fast, low noise and low power front-end, ...which is sensitive to the charge released by ionizing radiation in a 20–25 μm deep depleted region. The novel asynchronous matrix architecture is designed to ensure low power consumption and high rate capability. Such features make MALTA a possible candidate for the outer layer of ATLAS Inner Tracker (ITk) upgrade. Unirradiated and irradiated MALTA sensors have been extensively tested in laboratory and with high energy particle beams. Results of this measurements campaign are shown, and the further improvements that are being implemented in the next versions of the chip are discussed.
The ATLAS collaboration is currently investigating CMOS monolithic pixel sensors for the outermost layer of the upgrade of its Inner Tracker (ITk). For this application, two large scale prototypes ...featuring small collection electrode have been produced in a radiation-hard process modification of a standard 0.18 μm CMOS imaging technology: the MALTA, with a novel asynchronous readout, and the TJ MONOPIX, based on the well established “column-drain” architecture. The MALTA chip is the first full-scale prototype suitable for the development of a monolithic module for the ITk. It features a fast and low-power front-end, an architecture designed to cope with an hit-rate up to 2 MHz/mm2 without clock distribution over the matrix, hence reducing total power consumption, and LVDS drivers. Laboratory tests confirmed the performance of the asynchronous architecture expected from simulations. Extensive testbeam measurements have proved an average detection efficiency of 96% before irradiation at a threshold of ∼230 e− with dispersion of ∼36 e− and ENC lower than 10 e−. A non fully functional pixel masking scheme, forces operation at relatively high thresholds, causing inefficiency. A severe degradation of efficiency has been measured after neutron irradiation at a fluence 1×10151 MeVneq/cm2. Consistent results have been produced with the TJ MONOPIX. A correlation with inefficiency plots and pixel layout has triggered TCAD simulations, ending up to two possible solutions, implemented in a new prototype, the MiniMALTA.
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