Performance of the MALTA Telescope

MALTA is part of the Depleted Monolithic Active Pixel sensors designed in Tower 180nm CMOS imaging technology. A custom telescope with six MALTA planes has been developed for test beam campaigns at SPS, CERN, with the ability to host several devices under test. The telescope system has a dedicated custom readout, online monitoring integrated into DAQ with realtime hit map, time distribution and event hit multiplicity. It hosts a dedicated fully configurable trigger system enabling to trigger on coincidence between telescope planes and timing reference from a scintillator. The excellent time resolution performance allows for fast track reconstruction, due to the possibility to retain a low hit multiplicity per event which reduces the combinatorics. This paper reviews the architecture of the system and its performance during the 2021 and 2022 test beam campaign at the SPS North Area

Recent results with radiation-tolerant TowerJazz 180 nm MALTA sensors

To achieve the physics goals of future colliders, it is necessary to develop novel, radiation-hard silicon sensors for their tracking detectors. We target the replacement of hybrid pixel detectors with Depleted Monolithic Active Pixel Sensors (DMAPS) that are radiation-hard, monolithic CMOS sensors. We have designed, manufactured and tested the MALTA series of sensors, which are DMAPS in the 180 nm TowerJazz CMOS imaging technology. MALTA have a pixel pitch well below current hybrid pixel detectors, high time resolution (<2 ns) and excellent charge collection efficiency across pixel geometries. These sensors have a total silicon thickness of between 50–300 m, implying reduced material budgets and multiple scattering rates for future detectors which utilize such technology. Furthermore, their monolithic design bypasses the costly stage of bump-bonding in hybrid sensors and can substantially reduce detector costs. This contribution presents the latest results from characterization studies of the MALTA2 sensors, including results demonstrating the radiation tolerance of these sensors

Performance of the MALTA telescope

MALTA is part of the Depleted Monolithic Active Pixel sensors designed in Tower 180 nm CMOS imaging technology. A custom telescope with six MALTA planes has been developed for test beam campaigns at SPS, CERN, with the ability to host several devices under test. The telescope system has a dedicated custom readout, online monitoring integrated into DAQ with realtime hit map, time distribution and event hit multiplicity. It hosts a dedicated fully configurable trigger system enabling to trigger on coincidence between telescope planes and timing reference from a scintillator. The excellent time resolution performance allows for fast track reconstruction, due to the possibility to retain a low hit multiplicity per event which reduces the combinatorics. This paper reviews the architecture of the system and its performance during the 2021 and 2022 test beam campaign at the SPS North Area

Radiation hardness of MALTA2 monolithic CMOS imaging sensors on Czochralski substrates

MALTA2 is the latest full-scale prototype of the MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) produced in Tower Semiconductor 180 nm CMOS sensor imaging technology. In order to comply with the requirements of high energy physics (HEP) experiments, various process modifications and front-end changes have been implemented to achieve low power consumption, reduce random telegraph signal (RTS) noise, and optimise the charge collection geometry. Compared to its predecessors, MALTA2 targets the use of a high-resistivity, thick Czochralski (Cz) substrates in order to demonstrate radiation hardness in terms of detection efficiency and timing resolution up to 3 × 1015 1 MeV neq/cm2 with backside metallisation to achieve good propagation of the bias voltage. This manuscript shows the results that were obtained with non-irradiated and irradiated MALTA2 samples on Cz substrates from the CERN SPS test beam campaign from 2021 to 2023 using the MALTA telescope

Radiation hardness characterization of CMOS sensors for the ATLAS ITK pixel at HL-LHC and Future Trackers

Diese Arbeit beschäftigt sich mit der Entwicklung eines neuartigen monolithischen Silizium-Pixeldetektors names `MALTA' in Kooperation mit dem Halbleiterhersteller TowerJazz. Ergebnisse aus Strahltests zeigen, dass erste Prototypen nach Bestrahlung eine unzureichende Detektionseffizienz am Pixelrand aufweisen. Dies wird durch eine starke Verringerung der Ladungssammlungseffizienz aufgrund eines unerwartet schwachen lateralen elektrischen Feldes erklärt. Die Wirksamkeit der anschließenden Änderungen an den Doping-Profilen und der CMOS Schaltung im MALTA-Pixel wird ebenfalls durch Strahltests bestätigt und es kann gezeigt werden, dass neue Versionen von MALTA die durch den ITk gestellten Anforderungen an die Detektionseffizienz nach Bestrahlung erfüllen können.Due to the installation of the `High Luminosity' upgrade at the LHC, ATLAS will be extensively upgraded as well in 2025. This includes an area of 12m2 which must be covered by silicon pixels and motivates the development of monolithic active pixel sensors manufactured via industrial CMOS processes to reduce production cost and increase production throughput. Further, monolithic detectors can be built with less material budget compared to state-of-the-art hybrid detectors which reduces the scattering of collision products by the detector.This work focuses on the development of a novel monolithic silicon pixel detector called `MALTA' in cooperation with the TowerJazz foundry. Results from beam tests show that first prototypes have a much reduced detection efficiency at pixel borders after irradiation. This is explained by a significantly reduced charge collection efficiency at pixel borders due to an unexpectedly weak lateral electric field. The effectiveness of the following modifications to the doping profiles and CMOS circuitry in the MALTA pixel is confirmed in further beam tests and it can be shown that later MALTA prototypes fulfill the detection efficiency requirements of the ITk after irradiation.14

Monte-Carlo Simulation eines neuen ultra-schnellen Gamma-Detektor Designs in Geant4

As part of the PALADIN project which aims to develop a gamma photon detector with 100 ps FWHM time resolution, 1mm FWHM spatial resolution, 10 % FWHM energy resolution and a detection efficiency of about 90%, this thesis aims to provide an accurate simulation of the proposed detector system and to enable a first analysis of its properties. The new design features a central cube shaped scintillation crystal with its sides in direct optical contact to up to 6 dSiPMs developed by Philips. The goal is to improve on current designs in terms of spatial and temporal resolution, energy resolution and photon detection efficiency. To this end, a GEANT4 (GEometry ANd Tracking) application was developed in this work to simulate the new detector system and produce output of resulting scintillation photon emissions from 511keV annihilation photons interacting with a monolithic LYSO:Ce:Ca (Lutetium Yttrium Oxy-Orthosilicate, co-doped with Cerium and Calcium) scintillation crystal. The goal of the simulations presented in this thesis is to determine whether or not the new detector system can be expected to improve on already existing designs where only one or two DPCs were used for readout. These older designs showed, i.e., varying performance for spatial reconstruction along different directions which was inherent in their asymmetric design. Possible improvements in performance for the 6-sided readout will be studied by first discussing the plausibility of the data and then analyzing a few first results such as the probabilities of various processes, the distribution of detection times for photons, the number of Cherenkov photons produced per event, and the performance of a spatial reconstruction algorithm. The data analysis is performed with a self developed ROOT script.8

Radiation hard monolithic CMOS sensors with small electrodes for the HL-LHC and beyond

The upgrade of tracking detectors for experiments at the HL-LHC and future colliders requires the development of novel radiation hard silicon sensors. We target the replacement of hybrid pixel detectors with Depleted Monolithic Active Pixel Sensors (DMAPS) that are radiation hard monolithic CMOS sensors. We designed, manufactured and tested DMAPS in the TowerJazz 180 nm CMOS imaging technology with small electrodes pixel designs, that have a pixel pitch well below the current hybrid pixel detectors, and less multiple scattering due to a reduced total silicon thickness. In this document we present the recent results from these sensors manufactured on Czochralski silicon substrates in terms of cluster size, impact on tracking and time resolution from measurements carried out at beam tests on irradiated samples at 1e15 1 MeV $\mathrm{n}_\mathrm{eq}/\mathrm{cm}^{2}$

MALTA: a CMOS pixel sensor with asynchronous readout for the ATLAS High-Luminosity upgrade

Radiation hard silicon sensors are required for the upgrade of the ATLAS tracking detector for the High-Luminosity Large Hadron Collider (HL-LHC) at CERN. A process modification in a standard 0.18 μm CMOS imaging technology combines small, low-capacitance electrodes (~2 fF for the sensor) with a fully depleted active sensor volume. This results in a radiation hardness promising to meet the requirements of the ATLAS ITk outer pixel layers (1.5×10$^{15

MALTA3: concepts for a new radiation tolerant sensor in the TowerJazz 180 nm technology

The upgrade of the MALTA DMAPS designed in Tower 180 nm CMOS Imaging process will implement the numerous modifications, as well as front-end changes in order to boost the charge collection efficiency after the targeted fluence of 1x10^15 1 MeVneq/cm2. The effectiveness of these changes have been demonstrated in recent measurements with a small-scale Mini-MALTA demonstrator chip. Multiple changes in the digital periphery are proposed: The asynchronous address generator will be revised to provide more control over the pulse length. The Synchronisation memory will be upgraded with the goal of achieving a sub-nanosecond timing resolution. Serial chip to chip data transfer will be prototyped, in order to gauge the plausibility of implementation on a future full sized chip. Apart from these changes, research of the overall sensor architecture will be discussed as well

Österreichischer Forschungs- und Technologiebericht 2018 Bericht der Bundesregierung an den Nationalrat gem. § 8 (2) FOG über die Lage und Bedürfnisse von Forschung, Technologie und Innovation in Österreich

Österreichischer Forschungs- und Technologiebericht 201