Quad-module characterization with the MALTA monolithic pixel chip Dachs, F.; Zoubir, A.M.; Sharma, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2024, Letnik:
1064
Journal Article
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The MALTA silicon pixel detector combines a depleted monolithic active pixel sensor (DMAPS) with a fully asynchronous front-end and readout. It features a high granularity pixel matrix with a 36.4 μm ...symmetric pixel pitch, low power consumption of <1 μW/pixel and low material budget with detector thicknesses as little as 50 μm. It achieves a radiation hardness to 100MRad TID and more than 1 × 10E15 1 MeV neq/cm2 with a time resolution of <2 ns (Pernegger et al., 2023).
In order to cover large sensitive areas efficiently with a minimum of power and data connections the development of modules, comprising of up to 4 MALTA detectors, is studied.
This contribution presents the beam test performance of parallel and serial powered MALTA 4-chip modules in an effort to characterize the sensor’s chip-to-chip data and power transmission and prepare the production of a first prototype of an ultra-light weight 4-chip module on a flexible circuit with next generation MALTA2 sensors.
MALTA2 is a depleted monolithic active pixel sensor (DMAPS) developed in the Tower 180 nm CMOS imaging process. Monolithic CMOS sensors offer advantages over current hybrid imaging sensors both in ...terms of increased tracking performance due to lower material budget but also in terms of ease of integration and construction costs due to the monolithic design. Current research and development efforts are aimed towards radiation-hard designs up to 100 Mrad in Total Ionizing Dose and 3×1015 1 MeV neq/cm2 in Non-Ionizing Energy Loss. One important property of a sensor’s radiation hardness is the depletion depth at which efficient charge collection is achieved via drift movement. Grazing angle test-beam data was taken during the 2023 SPS CERN test beam with the MALTA telescope and Edge Transient Current Technique studies were performed at DESY in order to develop a quantitative study of the depletion depth for un-irradiated, epitaxial MALTA2 samples. The study is planned to be extended for irradiated and Czochralski MALTA2 samples.
In this article, a low-power, radiation-hard front-end circuit for monolithic pixel sensors, designed to meet the requirements of low noise and low pixel-to-pixel variability, the key features to ...achieve high detection efficiencies, is presented. The sensor features a small collection electrode to achieve a small capacitance (<5 fF) and allows full CMOS in-pixel circuitry. The circuit is implemented in the 180-nm CMOS imaging technology from the TowerJazz foundry and integrated into the MALTA2 chip, which is part of a development that targets the specifications of the outer pixel layer of the ATLAS Inner Tracker upgrade at the LHC. One of the main challenges for monolithic sensors is a radiation hardness up to 10 15 1-MeV <inline-formula> <tex-math notation="LaTeX">\text {n}_{\text {eq}}/\text {cm}^{{2}} </tex-math></inline-formula> non-ionizing energy loss (NIEL) and 80 Mrad total ionizing dose (TID) required for this application. Tests up to <inline-formula> <tex-math notation="LaTeX">{3} \cdot {10}^{15} </tex-math></inline-formula> 1-MeV <inline-formula> <tex-math notation="LaTeX">\text {n}_{\text {eq}}/\text {cm}^{{2}} </tex-math></inline-formula> and 100 Mrad were performed on the MALTA2 sensor and front-end circuit, which still show good performance even after these levels of irradiation, promising for even more demanding applications such as the future experiments at the high-luminosity large hadron collider (HL-LHC).
The upgrade of the tracking detectors for the High Luminosity-LHC (HL-LHC) requires the development of novel radiation hard silicon sensors. The development of Depleted Monolithic Active Pixel ...Sensors targets the replacement of hybrid pixel detectors with radiation hard monolithic CMOS sensors. We designed, manufactured and tested radiation hard monolithic CMOS sensors in the TowerJazz 180 nm CMOS imaging technology with small electrodes pixel designs. These designs can achieve pixel pitches well below current hybrid pixel sensors (typically 50 × 50μm) for improved spatial resolution. Monolithic sensors in our design allow to reduce multiple scattering by thinning to a total silicon thickness of only 50μm. Furthermore monolithic CMOS sensors can substantially reduce detector costs. These well-known advantages of CMOS sensor for performance and costs can only be exploited in pp-collisions at HL-LHC if the DMAPS sensors are designed to be radiation hard, capable of high hit rates and have a fast signal response to satisfy the 25 ns bunch crossing structure of LHC. Through the development of the MALTA and Mini-MALTA sensors we show the necessary steps to achieve radiation hardness at 1015 neq/cm2 for DMAPS with small electrode designs. The sensors combine high granularity (pitch 36.4x36.4μm2), low detector capacitance (<5fF/pixel) of the charge collection electrode (3μm), low noise (ENC≈10 e−) and low power operation (1μW/pixel) with a fast signal response (25 ns bunch crossing). The sensors feature arrays of 512 × 512 (MALTA) and 16 × 64 (Mini-MALTA) pixels. To cope with high hit rates expected at HL-LHC (>200 MHz/cm2) we have implemented a novel high-speed asynchronous readout architecture. The paper summarises the optimisation of the pixel design to achieve radiation hard pixel designs with full efficiency after irradiation at >98% after 1015 neq/cm2).
MALTA is a depleted monolithic active pixel sensor (DMAPS) developed in the Tower Semiconductor 180-nm CMOS imaging process. Monolithic CMOS sensors offer advantages over current hybrid imaging ...sensors in terms of both increased tracking performance due to lower material budget and ease of integration and construction costs due to the integration of read-out and active sensor into one ASIC. Current research and development efforts are aimed toward radiation hard designs up to 100 Mrad in total ionizing dose (TID) and <inline-formula> <tex-math notation="LaTeX">1\,\, \times 10 ^{15}~1~\text {MeV}\text {n}_{\text {eq}}/\text {cm}^{2} </tex-math></inline-formula> in nonionizing energy loss (NIEL). The design of the MALTA sensors was specifically chosen to achieve radiation hardness up to these requirements and satisfy current and future collider constraints. The current MALTA pixel architecture uses small electrodes which provide less noise, higher signal voltage, and a better power-to-performance ratio. To counteract the loss of efficiency in pixel corners, modifications to the Tower process have been implemented. The MALTA sensors have been tested during the 2021 and 2022 SPS CERN Test Beam in the MALTA telescope. The telescope ran for the whole duration of the beam time and took data to characterize the novel MALTA2 variant and the performance of irradiated samples in terms of efficiency and cluster size. These campaigns show that MALTA is an interesting prospect for HL-LHC and beyond collider experiments, providing both very good tracking capabilities and radiation hardness in harsh radiation environments.
The MALTA pixel chip is a 2 cm × 2 cm large monolithic pixel detector developed in the Tower 180 nm imaging process. The chip contains four CMOS transceiver blocks at its sides which allow ...chip-to-chip data transfer. The power pads are located mainly at the side edges on the chip which allows for chip-to-chip power transmission. The MALTA chip has been used to study module assembly using different interconnection techniques to transmit data and power from chip to chip and to minimize the overall material budget. Several 2-chip and 4-chip modules have been assembled using standard wire bonding, ACF (Anisotropic Conductive Films) and laser reflow interconnection techniques. These proceedings will summarize the experience with the different interconnection techniques and performance tests of MALTA modules with 2 and 4 chips tested in a cosmic muon telescope. They will also show first results on the effect of serial power tests on chip performance as well as the impact of the different interconnection techniques and the results of mechanical tests. Finally, a conceptual study for a flex based ultra-light weight monolithic pixel module based on the MALTA chip with minimum interconnections is presented.
In this report we investigate the models employed by PYTHIA and PHOJET Monte Carlo event generators used to describe soft interactions in hadron–hadron collisions. The aim of this study is to predict ...the important properties of minimum bias and the underlying event at the LHC energy scale. Focusing on a wide range of measurements dominated by soft interactions in proton–proton and proton–anti-proton collisions, one of the aims of this study is to check the consistency of these models when compared to data and evaluate the accuracy of their descriptions of low-pt processes. Based on comparisons to a wide range of minimum bias and underlying event data we present a tuning for PYTHIA6.214 and compare it to other PYTHIA tunings. Our proposed tuning for PYTHIA6.214 has been used for the ATLAS Data Challenge productions.
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.
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