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Abstract: This study describes the development of a CdTe pixel detector for high-energy X-ray diffraction experiments at synchrotron radiation facilities. We have developed three prototypes. The third prototype detector (SP8-02B) was designed with a pixel size of and a matrix of 20×50 pixels. The sensor was bonded to an application-specific integrated circuit with a preamplifier, shaper, window-type discriminator, and a 20-bit counter for each pixel. The SP8-02B detector improved the uniformity between pixels in one chip in comparison with the previous prototypes. The long-term stability was measured at various temperatures. A moderate cooling achieved good stability that was not affected by the polarization effect. [Copyright &y& Elsevier]

Abstract: We have developed a photon-counting-type CdTe pixel detector (SP8-01). SP8-01 was designed as a prototype of a high-energy X-ray imaging detector for experiments using synchrotron radiation. SP8-01 has a CdTe sensor of thickness, which has an absorption efficiency of almost 100% up to 50keV and 45% even at 100keV. A full-custom application specific integrated circuit (ASIC) was designed as a readout circuit of SP8-01, which is equipped with a window-type discriminator. The upper discriminator realizes a low-background measurement, because X-ray beams from the monochromator contain higher-order components beside the fundamental X-rays in general. ASIC chips were fabricated with a TSMC CMOS process, and CdTe sensors were bump-bonded to the ASIC chips by a gold-stud bonding technique. Beam tests were performed at SPring-8. SP8-01 detected X-rays up to 120keV. The capability of SP8-01 as an imaging detector for high-energy X-ray synchrotron radiation was evaluated with its performance characteristics. [Copyright &y& Elsevier]

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 × 250 μ m 2 and large collection electrode opted for high radiation tolerance. Detection efficiency up to 99% has been measured after irradiation to 1 ⋅ 1 0 15 n e q ∕ cm 2. TJ-Monopix is a large scale (1 × 2 cm 2) prototype featuring pixels of 36 × 40 μ m 2 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) ≈ 11 e − , threshold ≈ 300 e − , threshold dispersion ≈ 30 e − and total power consumption lower than 120 mW/cm 2. • 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 FROM AUTHOR]

The LF-Monopix chips are depleted monolithic active pixel sensors that follow the large-electrode design approach and implement a fast synchronous read-out architecture. They are designed in a 150 nm CMOS process and make use of large voltages (> 250 V) and highly resistive substrates (> 2 kΩ ⋅ cm) to collect charge through drift and enhance their radiation hardness. Samples of the first prototype ("LF-Monopix1") with a thickness of 100 μ m were irradiated to assess the tolerance of the chip's substrate and front-end circuitry to the surface and bulk damage doses expected at modern collider experiments. The device remained fully operational, with only a very small gain degradation and an increase in noise by less than 25 % after a total ionizing dose of 100 Mrad. Efficiency measurements in a sample exposed to a neutron fluence of 1 × 1 0 15 n eq / cm 2 showed that at least 96 % of all minimum ionizing particles going through a fully depleted detector are recorded in less than 25 ns. In the latest design ("LF-Monopix2") the column length was tripled and the pixel pitch reduced by 40 % with respect to its predecessor. The chip was successfully thinned down while keeping its breakdown voltage above 400 V and achieving a front-end threshold dispersion of ∼ 100 e − after tuning. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Single X-ray photon counting pixel detectors have become the most advanced detector technology in synchrotron radiation experiments recently. In particular, the PILATUS detector based on a silicon sensor has reached a very mature state and represents the world’s largest detector in this field. This paper first reports on threshold energy calibrations and the capability of applying an energy-resolved X-ray imaging with PILATUS. Second the design of a cadmium telluride (CdTe) pixel detector is described. A high density and high-atomic number sensor material is required in high energy X-ray applications available at SPring-8. For this purpose we are developing a CdTe pixel detector with the SP8-01 readout ASIC covering a wide dynamic range between 10 and 100keV and containing lower and upper discriminators. [Copyright &y& Elsevier]

This work reports on design and performance of a depleted monolithic active pixel sensor (DMAPS) prototype manufactured in the LFoundry 150 nm CMOS process. DMAPS exploit high voltage and/or high resistivity inclusion of modern CMOS technologies to achieve substantial depletion in the sensing volume. The device used in this work, named LF-Monopix, was designed as a proof of concept of a fully monolithic sensor capable of operating in the environment of outer layers of the ATLAS Inner Tracker upgrade in 2025 for the High Luminosity Large Hadron Collider (HL-LHC). This type of devices has a lower production cost and lower material budget compared to presently used hybrid designs. In this work, the chip architecture will be described followed by the characterization of the different pixel flavors with an external injection signal and an iron source (5.9 keV x-rays). [ABSTRACT FROM AUTHOR]

Abstract: A monolithic pixel detector with silicon-on-insulator (SOI) CMOS technology has been developed. It has both a thick high-resistivity sensor layer and thin LSI circuit layer on a single chip. Integration-type and counting-type pixel detectors are fabricated and tested with light and X-rays. The process is open to many researchers through Multi Project Wafer (MPW) runs operated by KEK. Further improvements of the fabrication technologies are also under investigation by using a buried p-well and 3D integration technologies. [ABSTRACT FROM AUTHOR]

The last couple of years have seen the development of Depleted Monolithic Active Pixel Sensors (DMAPS) fabricated with a process modification to increase the radiation tolerance. Two large scale prototypes, Monopix with a column drain synchronous readout, and MALTA with a novel asynchronous architecture, have been fully tested and characterized both in the laboratory and in test beams. This showed that certain aspects have to be improved such as charge collection after irradiation and the output data rate. Some improvements resulting from extensive TCAD simulations were verified on a small test chip, Mini-MALTA. A detailed cluster analysis, using data from laboratory and test beam studies, at different biases, for high and low thresholds and before and after irradiation is presented, followed by detailed simulations showing that the digital architecture for both chips is capable of dealing with data rates of around 80 MHz/cm2 similar to what it is expected in the outer layer of the ATLAS inner tracker upgrade for the HL-LHC. The data rate capability and output bandwidth are studied using realistic hits generated by the ATLAS detector simulation framework. [ABSTRACT FROM AUTHOR]

LF-Monopix1 and TJ-Monopix1 are depleted monolithic active pixel sensors (DMAPS) in 150 nm LFoundry and 180 nm 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. [ABSTRACT FROM AUTHOR]

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 μ m 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. [ABSTRACT FROM AUTHOR]

We present the recent development of DMAPS (Depleted Monolithic Active Pixel Sensor), implemented with a Toshiba 130 nm CMOS process. Unlike in the case of standard MAPS technologies which are based on an epi-layer, this process provides a high-resistive substrate that enables larger signal and faster charge collection by drift in a 50 − 300 μ m thick depleted layer. Since this process also enables the use of deep n-wells to isolate the collection electrodes from the thin active device layer, NMOS and PMOS transistors are available for the readout electronics in each pixel cell. In order to characterize the technology, we implemented a simple three transistor readout with a variety of pixel pitches and input FET sizes. This layout variety gives us a clue on sensor characteristics for future optimization, such as the input detector capacitance or leakage current. In the initial measurement, the radiation spectra were obtained from 55 Fe with an energy resolution of 770 eV (FWHM) and 90 Sr with the MVP of 4165 e − . [ABSTRACT FROM AUTHOR]