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3D trench silicon pixel sensors, recently developed by the TimeSPOT collaboration, have shown excellent performance in terms of spatial resolution, timing precision and detection efficiency. The combination of these three features make them one of the best candidate for inner tracking detectors operating in high luminosity hadron colliders experiments. This article presents systematic characterisations of these devices made with minimum ionising particles on irradiated sensors with neutrons up to 2.5 · 1016 1 MeV neq cm-2. The results show that 3D trench pixels have extremely high resistance to radiation. The measured time resolution and the detection efficiency of irradiated sensors match those of non-irradiated ones if a slightly higher bias voltage, few tens of Volts, is applied to the pixels. As of today, 3D trench pixels are the only sensors capable of achieving 10 ps time resolution after being irradiated at extremely high fluences, extending by far the capabilities of future tracking systems of HEP experiments operating under extreme conditions. [ABSTRACT FROM AUTHOR]

3D trench silicon pixel sensors, recently developed by the TimeSPOT collaboration, have shown excellent performance in terms of spatial resolution, timing precision and detection efficiency. The combination of these three features make them one of the best candidate for inner tracking detectors operating in high luminosity hadron colliders experiments. This article presents systematic characterisations of these devices made with minimum ionising particles on irradiated sensors with neutrons up to 2.5 ⋅ 1016 1 MeV neq cm−2. The results show that 3D trench pixels have extremely high resistance to radiation. The measured time resolution and the detection efficiency of irradiated sensors match those of non-irradiated ones if a slightly higher bias voltage, few tens of Volts, is applied to the pixels. As of today, 3D trench pixels are the only sensors capable of achieving 10 ps time resolution after being irradiated at extremely high fluences, extending by far the capabilities of future tracking systems of HEP experiments operating under extreme conditions.

For the Phase-II Upgrade of the ATLAS Detector [1], its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100% silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: An early program using readout chips designed using a 250 nm fabrication process (ABCN-250) [2,2] and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests.

Pixelated LGADs have been established as the baseline technology for timing detectors for the High Granularity Timing Detector (HGTD) and the Endcap Timing Layer (ETL) of the ATLAS and CMS experiments, respectively. The drawback of segmenting an LGAD is the non-gain area present between pixels and the consequent reduction in the fill factor. To overcome this issue, the inverse LGAD (iLGAD) technology has been proposed by IMB-CNM to enhance the fill factor and provide excellent tracking capabilities. In this work, we explore the use of iLGAD sensors for surface damage irradiation by developing a new generation of iLGADs, the periphery of which is optimized to improve the performance of irradiated sensors. The fabricated iLGAD sensors exhibit good electrical performances before and after X-ray irradiation. [ABSTRACT FROM AUTHOR]

Silicon pixel detectors are at the core of the current and planned upgrade of the ATLAS experiment at the LHC. Given their close proximity to the interaction point, these detectors will be exposed to an unprecedented amount of radiation over their lifetime. The current pixel detector will receive damage from non-ionizing radiation in excess of 1015 1 MeV neq/cm2, while the pixel detector designed for the high-luminosity LHC must cope with an order of magnitude larger fluence. This paper presents a digitization model incorporating effects of radiation damage to the pixel sensors. The model is described in detail and predictions for the charge collection efficiency and Lorentz angle are compared with collision data collected between 2015 and 2017 (≤ 10 1 MeV neq/cm2).

Intensity-modulated radiotherapy is a widely used technique for accurately targeting cancerous tumours in difficult locations using dynamically shaped beams. This is ideally accompanied by real-time independent verification. Monolithic active pixel sensors are a viable candidate for providing upstream beam monitoring during treatment. We have already demonstrated that a Monolithic Active Pixel Sensor (MAPS)-based system can fulfill all clinical requirements except for the minimum required size. Here, we report the performance of a large-scale demonstrator system consisting of a matrix of 2 × 2 sensors, which is large enough to cover almost all radiotherapy treatment fields when affixed to the shadow tray of the LINAC head. When building a matrix structure, a small dead area is inevitable. Here, we report that with a newly developed position algorithm, leaf positions can be reconstructed over the entire range with a position resolution of below ∼200 μm in the centre of the sensor, which worsens to just below 300 μm in the middle of the gap between two sensors. A leaf position resolution below 300 μm results in a dose error below 2%, which is good enough for clinical deployment. [ABSTRACT FROM AUTHOR]

Tracking particles at extreme fluences requires the accurate measurement of the charged particle timing at the pixel level in order to cope with the increased occupancy of HL-LHC experiments. Maintaining this precision throughout the operational life of the detector is crucial. This work demonstrates that the 55 × 55 μ m 2 wide 150 μ m thick 3D trench-type pixels, developed by the TimeSPOT Collaboration, maintain the performance of non-irradiated sensors even after exposure to fluences as high as 1 ⋅ 1 0 17 1 MeV n eq cm − 2 . The preliminary results of a beam test characterization using minimum ionizing particles at the SPS North area beam facility reveal that the charge collection and the time resolution of the irradiated sensors are comparable to those of non-irradiated ones, by increasing the operational bias voltage. A minor reduction in detection efficiency, approximately 4%, is observed post-irradiation. Currently, 3D trench-type pixels are among the fastest pixel detectors available for tracking charged particles and hold significant promise for future tracking system upgrades. This preliminary evaluation suggests their suitability for use in even harsher radiation environments than High Luminosity Large Hadron Collider (HL-LHC) such as future experiments at the Future Circular Hadron Collider (FCC-hh). [ABSTRACT FROM AUTHOR]

ATLAS is currently preparing for the HL-LHC upgrade, with an all-silicon Inner Tracker (ITk) that will replace the current Inner Detector. The ITk will feature a pixel detector surrounded by a strip detector, with the strip system consisting of four Barrel layers and six endcap disks. After completion of final design reviews in key areas, such as Sensors, Modules, Front-End electronics and ASICs, a large scale prototyping program has been completed successfully. We present an overview of the Strip System, and highlight the final design choices of sensors, modules and ASICs. We will summarise results achieved during prototyping and the current status of production and pre-production on various detector components, with an emphasis on QA and QC procedures. [ABSTRACT FROM AUTHOR]

The EXFLU1 batch of LGAD sensors on substrates of thickness between 15 and 45 μ m were exposed to various radiation grades between 1 × 1014 and 5 × 1015 n eq cm−2 using the TRIGA Mark II research nuclear reactor at the Jozef Stefan Institute. The sensor designs are optimised to preserve characteristics at high fluences. These sensors are manufactured by Fondazione Bruno Kessler. The latest studies of the effects of radiation have been performed, with particular focus on acceptor removal and gain evolution. [ABSTRACT FROM AUTHOR]

The Phase-2 upgrades of ATLAS and CMS for the High-Luminosity LHC (HL-LHC), require a new tracker with robust readout electronics capable of withstanding extreme radiation (1 Grad), a high hit rate (3 GHz/cm2), and a high data rate readout (5 Gb/s). In a joint effort between ATLAS and CMS, pixel detector readout chips have been designed by the RD53 collaboration in 65 nm CMOS technology. Based on a half-sized demonstrator (RD53A), two chip variants were designed for ATLAS and CMS, respectively. The ATLAS pre-production readout chip, ITkPixV1, was characterised in detail, and informed by the results, the final ATLAS pixel readout chip, ITkPixV2, has been designed, submitted, and the first wafers were received in July 2023. This contribution provides an overview of the characterisation measurements performed on the ITkPixV2 chip so far, focusing on bench-top testing of chip functionality, and first results of X-ray irradiation studies to assess the radiation tolerance of the chip. [ABSTRACT FROM AUTHOR]

The OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) is currently developed for the upgrade of the vertex detector of the Belle II experiment located at Tsukuba/Japan. The pixel matrix of OBELIX is inherited from the TJ-Monopix2 chip, but the periphery includes additional features to improve performance and allow the integration into a larger detector system. The new features include a trigger unit to process trigger signals, a precision timing module and a possibility to transmit low granularity hit information with low latency to contribute to the Belle II trigger. Additionally, low dropout voltage regulators and an ADC to monitor power consumption and substrate temperature is developed. This paper will focus on the trigger contribution capabilities of the OBELIX chip. [ABSTRACT FROM AUTHOR]

To address the challenges of providing high-performance calorimetry in future hadron collider experiments under conditions of high luminosity and high radiation (FCC-hh environments), we conducted R&D on advanced calorimetry techniques suitable for such operation, based on scintillation and wavelength-shifting technologies and photosensor (SiPM and SiPM-like) technology. In particular, we focused our attention on ultra-compact radiation-hard EM calorimeters based on modular structures (RADiCAL modules) consisting of alternating layers of the very dense absorber and scintillating plates, read out via radiation hard wavelength shifting (WLS) solid fiber or capillary elements to photosensors positioned either proximately or remotely, depending upon their radiation tolerance. RADiCAL modules provide the capability to measure simultaneously and with high precision the position, energy and timing of EM showers. This paper provides an overview of the instrumentation and photosensor R&D associated with the RADiCAL program. [ABSTRACT FROM AUTHOR]

The Belle II experiment at KEK in Japan considers an upgrade for the vertex detector system in line with the accelerator upgrade for higher luminosity at long shutdown 2 planned for 2028. One proposal for the upgrade of the vertex detector called VTX aims to improve background robustness and reduce occupancy using small and fast pixels. VTX accommodates the OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) on all five proposed layers. OBELIX is specifically developed for the VTX application and based on the TJ-Monopix2 chip initially developed to meet the requirements of the outer layers of the ATLAS inner tracker (ITk). This paper will review recent tests of the TJ-Monopix2 chip as well as various design aspects of the OBELIX-1 chip currently under development. [ABSTRACT FROM AUTHOR]

Pixelated LGADs have been established as the baseline technology for timing detectors for the High Granularity Timing Detector (HGTD) and the Endcap Timing Layer (ETL) of the ATLAS and CMS experiments, respectively. The drawback of segmenting an LGAD is the non-gain area present between pixels and the consequent reduction in the fill factor. To overcome this issue, the inverse LGAD (iLGAD) technology has been proposed by IMB-CNM to enhance the fill factor and provide excellent tracking capabilities. In this work, we explore the use of iLGAD sensors for surface damage irradiation by developing a new generation of iLGADs, the periphery of which is optimized to improve the performance of irradiated sensors. The fabricated iLGAD sensors exhibit good electrical performances before and after X-ray irradiation.

Intensity-modulated radiotherapy is a widely used technique for accurately targeting cancerous tumours in difficult locations using dynamically shaped beams. This is ideally accompanied by real-time independent verification. Monolithic active pixel sensors are a viable candidate for providing upstream beam monitoring during treatment. We have already demonstrated that a Monolithic Active Pixel Sensor (MAPS)-based system can fulfill all clinical requirements except for the minimum required size. Here, we report the performance of a large-scale demonstrator system consisting of a matrix of 2 × 2 sensors, which is large enough to cover almost all radiotherapy treatment fields when affixed to the shadow tray of the LINAC head. When building a matrix structure, a small dead area is inevitable. Here, we report that with a newly developed position algorithm, leaf positions can be reconstructed over the entire range with a position resolution of below ∼200 μm in the centre of the sensor, which worsens to just below 300 μm in the middle of the gap between two sensors. A leaf position resolution below 300 μm results in a dose error below 2%, which is good enough for clinical deployment.

Experimental fission studies for reaction physics or nuclear spectroscopy can profit from fast, efficient, and radiation-resistant fission fragment (FF) detectors. When such experiments are performed in-beam in intense thermal neutron beams, additional constraints arise in terms of target-detector interface, beam-induced background, etc. Therefore, wide gap semi-conductor detectors were tested with the aim of developing innovative instrumentation for such applications. The detector characterization was performed with mass- and energy-separated fission fragment beams at the ILL (Institut Laue Langevin) LOHENGRIN spectrometer. Two single crystal diamonds, three polycrystalline and one diamond-on-iridium as well as a silicon carbide detector were characterized as solid state ionization chamber for FF detection. Timing measurements were performed with a 500-µm thick single crystal diamond detector read out by a broadband amplifier. A timing resolution of ∼10.2 ps RMS was obtained for FF with mass A = 98 at 90 MeV kinetic energy. Using a spectroscopic preamplifier developed at INFN-Milano, the energy resolution measured for the same FF was found to be slightly better for a ∼50-µm thin single crystal diamond detector (∼1.4% RMS) than for the 500-µm thick one (∼1.6% RMS), while a value of 3.4% RMS was obtained with the 400-µm silicon carbide detector. The Pulse Height Defect (PHD), which is significant in silicon detectors, was also investigated with the two single crystal diamond detectors. The comparison with results from α and triton measurements enabled us to conclude that PHD leads to ∼50% loss of the initial generated charge carriers for FF. In view of these results, a possible detector configuration and integration for in-beam experiments has been discussed.

In the passive CMOS Strips Project, strip sensors were designed at the University of Bonn and produced by LFoundry in 150 nm technology, with an additional backside processing from IZM Berlin. Up to five individual reticules were connected by stitching at the foundry in order to obtain the typical strip lengths required for the LHC Phase-II upgrade of ATLAS or CMS trackers. Sensors electrical properties were simulated using Sentaurus TCAD and the results were compared to experimentally measured data. Detector modules were also constructed from several sensors and thoroughly studied in two beam campaigns at DESY. All of these measurements were performed before and after irradiation. This contribution provides an overview of simulation results, its comparison to measured data and in particular presents first test beam results for irradiated and unirradiated passive CMOS strip sensors. We are demonstrating that large area sensors with sufficient radiation hardness can be obtained by stitching during the CMOS process, and presenting our plans for the next submission in the framework of this project. [ABSTRACT FROM AUTHOR]

To address the challenges of providing high-performance calorimetry in future hadron collider experiments under conditions of high luminosity and high radiation (FCC-hh environments), we conducted R&D on advanced calorimetry techniques suitable for such operation, based on scintillation and wavelength-shifting technologies and photosensor (SiPM and SiPM-like) technology. In particular, we focused our attention on ultra-compact radiation-hard EM calorimeters based on modular structures (RADiCAL modules) consisting of alternating layers of the very dense absorber and scintillating plates, read out via radiation hard wavelength shifting (WLS) solid fiber or capillary elements to photosensors positioned either proximately or remotely, depending upon their radiation tolerance. RADiCAL modules provide the capability to measure simultaneously and with high precision the position, energy and timing of EM showers. This paper provides an overview of the instrumentation and photosensor R&D associated with the RADiCAL program.

Third-generation semiconductor materials have a wide band gap, high thermal conductivity, high chemical stability and strong radiation resistance. These materials have broad application prospects in optoelectronics, high-temperature and high-power equipment and radiation detectors. In this work, thin-film solid state neutron detectors made of four third-generation semiconductor materials are studied. Geant4 10.7 was used to analyze and optimize detectors. The optimal thicknesses required to achieve the highest detection efficiency for the four materials are studied. The optimized materials include diamond, silicon carbide (SiC), gallium oxide (Ga2O3) and gallium nitride (GaN), and the converter layer materials are boron carbide (B4C) and lithium fluoride (LiF) with a natural enrichment of boron and lithium. With optimal thickness, the primary knock-on atom (PKA) energy spectrum and displacements per atom (DPA) are studied to provide an indication of the radiation hardness of the four materials. The gamma rejection capabilities and electron collection efficiency (ECE) of these materials have also been studied. This work will contribute to manufacturing radiation-resistant, high-temperature-resistant and fast response neutron detectors. It will facilitate reactor monitoring, high-energy physics experiments and nuclear fusion research.

Abstract The upgrade of the ATLAS (The ATLAS Collaboration, 2008) tracking detector for the High-Luminosity Large Hadron Collider (LHC) at CERN requires novel radiation hard silicon sensor technologies. Significant effort has been put into the development of monolithic CMOS sensors but it has been a challenge to combine a low capacitance of the sensing node with full depletion of the sensitive layer. Low capacitance brings fast signal response at low noise combined with low analog power. Depletion of the sensitive layer causes the signal charge to be collected by drift sufficiently fast to separate hits from consecutive bunch crossings (25 ns at the LHC) and to avoid losing the charge by trapping after irradiation. This paper focuses on the characterization of charge collection properties and detection efficiency of prototype sensors originally designed in the framework of the ALICE Inner Tracking System (ITS) upgrade. The prototypes are fabricated both in the standard TowerJazz 1 1 Manufactured by Tower Semiconductor Ltd, Israel. 180 nm CMOS imager process (Senyukov et al., 2013) and in an innovative modification of this process developed in collaboration with the foundry, aimed to fully deplete the sensitive epitaxial layer and enhance the tolerance to non-ionizing energy loss. Sensors fabricated in standard and modified process variants were characterized using radioactive sources, X-ray beam and test beams before and after irradiation. Contrary to sensors manufactured in the standard process, sensors from the modified process remain fully functional even after 1 0 15 n eq /cm 2 which is the expected NIEL radiation fluence for the outer pixel layers in the future ATLAS Inner Tracker (ITk). [ABSTRACT FROM AUTHOR]

Studies of annealing at temperatures up to 450 °C with Low Gain Avalanche Detectors (LGAD) irradiated with neutrons are described. It was found that the performance of LGADs irradiated with 1.5e15 n/cm 2 was already improved at 5 min of annealing at 250 °C. Isochronal annealing for 30 min in 50 °C steps between 300 °C and 450 °C showed that the largest beneficial effect of annealing is at around 350 °C. Another set of devices was annealed for 60 min at 350 °C and this annealing significantly increased depletion voltage of the gain layer (V gl). The effect is equivalent to reducing the effective acceptor removal constant by a factor of ∼ 4. Increase of V gl is the consequence of increased effective space charge in the gain layer caused by formation of electrically active defects or re-activation of interstitial boron atoms. [ABSTRACT FROM AUTHOR]

This paper provides an overview of 3D detectors fabrication technology developed in the clean room of the Microelectronics Institute of Barcelona (IMB-CNM). Emphasis is put on manufacturability, especially on stress and bow issues. Some of the technological solutions proposed at IMB-CNM to improve manufacturability are presented. Results and solutions from other research institutes are also mentioned. Analogy with through-silicon-via technology is drawn. This article aims at giving hints of the technology improvements implemented to upgrade from a R&D process to a mature technology.

Abstract H igh- V oltage M onolithic A ctive P ixel S ensors (HV-MAPS) based on a 180 nm HV-CMOS process have been proposed to realize thin, fast and highly integrated pixel sensors. The MuPix7 prototype, fabricated in the commercial AMS H18 process, features a fully integrated on-chip readout, i.e. hit-digitization, zero suppression and data serialization. MuPix7 is the first fully monolithic HV-CMOS pixel sensor that has been tested for the use in high irradiation environments like HL-LHC. We present results from laboratory and test beam measurements of MuPix7 prototypes irradiated with neutrons (up to 5.0 × 1015 n eq /cm2) and 24 GeV protons (up to 7.8 × 1015 protons/cm2) and compare the performance with non-irradiated sensors. At sensor temperatures of about 8 °C efficiencies of ≥ 90% at noise rates below 40 Hz per pixel are measured for fluences of up to 1.5 × 1015 n eq /cm2. A time resolution better than 22 ns, expressed as Gaussian σ , is measured for all tested settings and sensors, even at the highest irradiation fluences. The data transmission at 1.25 Gbit/s and the on-chip PLL remain fully functional. [ABSTRACT FROM AUTHOR]

Abstract 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 k Ω cm are presented. The measurements were made before and after irradiation with reactor neutrons up to 2 ⋅ 10 15 n eq /cm 2. Two sets of devices were investigated: unthinned (700 μ m) with the substrate biased through the implant on top and thinned (200 μ m) 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 μ m 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 ⋅ 10 15 n eq /cm 2. 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. [ABSTRACT FROM AUTHOR]

The high luminosity upgraded LHC or Phase-II is expected to increase the instantaneous luminosity by a factor of 10 beyond the LHC's design value, expecting to deliver 250 fb −1 per year for a further 10 years of operation. Under these conditions the performance degradation due to integrated radiation dose will need to be addressed. The CMS collaboration is planning to upgrade the forward calorimeters. The replacement is called the High Granularity Calorimeter (HGC) and it will be realized as a sampling calorimeter with layers of silicon detectors interleaved. The sensors will be realized as pad detectors with sizes of less that ∼1.0 cm 2 and an active thickness between 100 and 300 μm depending on the position, respectively, the expected radiation levels. For an integrated luminosity of 3000 fb −1 , the electromagnetic calorimetry will sustain integrated doses of 1.5 MGy (150 Mrads) and neutron fluences up to 10 16 neq/cm 2 . A radiation tolerance study after neutron irradiation of 300, 200, and 100 μm n-on-p and p-on-n silicon pads irradiated to fluences up to 1.6×10 16 neq/cm 2 is presented. The properties of these diodes studied before and after irradiation were leakage current, capacitance, charge collection efficiency, annealing effects and timing capability. The results of these measurements validate these sensors as candidates for the HGC system. [ABSTRACT FROM AUTHOR]