Article

# Performance of the ATLASPix1 pixel sensor prototype in ams aH18 CMOS technology for the ATLAS ITk upgrade

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... First results from ATLASPix1 characterisation studies at CERN and FERMILAB have been reported in [5,6]. More results were obtained at recent test beam campaigns at DESY and PSI. ...
... Single hit efficiencies for a fully monolithic HV-MAPS 1 irradiated with protons and neutrons were reported first for the MuPix7 predecessor [14] which has no radiation hard design. These performance studies have been repeated for the ATLASPix1_Simple prototype and first results were reported in [5]. Results from a more comprehensive study are summarized in the following. ...
... First results from ATLASPix1 characterisation studies at CERN and FERMILAB have been reported in [5,6]. More results were obtained at recent test beam campaigns at DESY and PSI. ...
... Single hit efficiencies for a fully monolithic HV-MAPS 1 irradiated with protons and neutrons were reported first for the MuPix7 predecessor [14] which has no radiation hard design. These performance studies have been repeated for the ATLASPix1_Simple prototype and first results were reported in [5]. Results from a more comprehensive study are summarized in the following. ...
Preprint
High Voltage Monolithic Active Pixel Sensors (HV-MAPS) are based on a commercial High Voltage CMOS process and collect charge by drift inside a reversely biased diode. HV-MAPS represent a promising technology for future pixel tracking detectors. Two recent developments are presented. The MuPix has a continuous readout and is being developed for the Mu3e experiment whereas the ATLASPix is being developed for LHC applications with a triggered readout. Both variants have a fully monolithic design including state machines, clock circuitries and serial drivers. Several prototypes and design variants were characterised in the lab and in testbeam campaigns to measure efficiencies, noise, time resolution and radiation tolerance. Results from recent MuPix and ATLASPix prototypes are presented and prospects for future improvements are discussed.
... Active silicon tracking detectors with fully integrated readout electronics manufactured in a large volume industrial CMOS process are a potential alternative for hybrid silicon detectors at future particle colliders, promising similar performance at a simplified production and a smaller amount of material in the tracking volume. In recent years several prototypes capable of withstanding high radiation fields of the order of 10 15 n eq /cm 2 have been developed [1][2][3]. These designs, called depleted monolithic active pixel sensors (DMAPS), feature a depleted sensing layer providing a drift based, fast and radiation tolerant charge collection. ...
Preprint
In this work we investigated a method to determine time walk in an active silicon pixel sensor prototype using Edge-TCT with infrared laser charge injection. Samples were investigated before and after neutron irradiation to 5e14 neq/cm2. Threshold, noise and calibration of the analogue front end were determined with external charge injection. A spatially sensitive measurement of collected charge and time walk was carried out with Edge-TCT, showing a uniform charge collection and output delay in pixel centre. On pixel edges charge sharing was observed due to finite beam width resulting in smaller signals and larger output delay. Time walk below 25 ns was observed for charge above 2000 electrons at a threshold above the noise level. Time walk measurement with external charge injection yielded identical results.
... The HV-CMOS process has been qualified for fluences of up to 2 · 10 15 (1 MeV) neq in the context of the ATLAS high luminosity upgrade[59][60][61][62]. ...
Preprint
Full-text available
Technical design report of the Mu3e experiment phase 1.
... These two critical components are shown in Figure 7. With the predecessor of ATLASPix-1 [16], the measured position resolution of σ x = 11.3 µm, the time resolution of 6.8 ns after the time walk and row delay corrections, and the power consumption below 300 mW/cm 2 are already close to the expected CEPC tracker requirements. ATLASPix-3 should provide improved performance and enriched functional-ities. ...
... Hence, during the last decade, there has been a trend to improve the depletion within the sensitive layer of CMOS pixels [4], leading eventually to designs with fast charge collection through drift, namely DMAPS. Recently, significant progress has been made for DMAPS devices with several large-scale demonstrator chips developed in different CMOS technologies [5][6][7][8][9]. These devices combine a fully depleted sensitive layer with on-chip fast readout electronics, and are expected to tolerate particle fluences of at least 10 15 n eq /cm 2 and total ionization doses of at least 80 Mrad, while being able to cope with a particle rate higher than 100 MHz/cm 2 and distinguish hits from different LHC bunch crossings (25 ns). ...
... The HV-CMOS process has been qualified for fluences of up to 2 · 10 15 (1 MeV) neq in the context of the ATLAS high luminosity upgrade[50][51][52][53]. ...
Preprint
Full-text available
The Mu3e experiment aims to find or exclude the lepton flavour violating decay $\mu \rightarrow eee$ at branching fractions above $10^{-16}$. A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of $2\cdot 10^{-15}$. We present an overview of all aspects of the technical design and expected performance of the phase~I Mu3e detector. The high rate of up to $10^{8}$ muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.
... In order to cope with conditions such as those expected at the future HL-LHC, charge collection has to be done by drift in a depleted sensor volume, leading to depleted monolithic active pixel sensors (DMAPS). Large-scale prototype chips employing high resistivity substrates and high bias voltages have been designed in various CMOS technologies with integrated fast readout electronics on the sensor substrate [3,4,5]. ...
Preprint
Full-text available
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.
... Three generations of High Voltage CMOS (HVCMOS) monolithic sensor chips [1] have been designed in AMS/TSI 180 nm process to meet the requirements of ATLAS Inner Tracker (ITk) layer 4. The first generation ATLASpix prototype has proven high radiation tolerance of 1 × 10 15 n eq /cm 2 with 99.4% detection efficiency in a test beam study [2]. The design of ATLASpix sensors follows the large charge collection electrode topology. ...
Article
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.
Article
In this work we investigated a method to determine time walk in an active silicon pixel sensor prototype using Edge-TCT with infrared laser charge injection. Samples were investigated before and after neutron irradiation to 5· 10^14n_ eq/cm^2. Threshold, noise and calibration of the analogue front end were determined with external charge injection. A spatially sensitive measurement of collected charge and time walk was carried out with Edge-TCT, showing a uniform charge collection and output delay in pixel centre. On pixel edges charge sharing was observed due to finite beam width resulting in smaller signals and larger output delay. Time walk below 25 ns was observed for charge above 2000 e^- at a threshold above the noise level. Time walk measurement with external charge injection yielded identical results.
Article
Full-text available
The Mu3e experiment aims to find or exclude the lepton flavour violating decay μ→eee at branching fractions above 10−16. A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of 2⋅10−15. We present an overview of all aspects of the technical design and expected performance of the phase I Mu3e detector. The high rate of up to 108 muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.
Article
The high-voltage CMOS (HVCMOS) sensors are a novel type of CMOS active pixel sensors for ionizing particles that can be implemented in CMOS processes with deep n-well option. The pixel contains one sensor electrode formed with a deep n-well implanted in a p-type substrate. CMOS pixel electronics, embedded in shallow wells, are placed inside the deep n-well. By biasing the substrate with a high negative voltage and by the use of a lowly doped substrate, a depleted region depth of at least 30 $\mu \text{m}$ can be achieved. The electrons generated by a particle are collected by drift, which induces fast detectable signals. This publication presents a 4.2-cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> large HVCMOS pixel sensor implemented in a commercial 180-nm process on a lowly doped substrate and its characterization.
Article
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.
Article
Full-text available
This paper reports on the characterisation with Transient Current Technique measurements of the charge collection and depletion depth of a radiation-hard high-voltage CMOS pixel sensor produced at ams AG. Several substrate resistivities were tested before and after proton irradiation with two different sources: the 24 GeV Proton Synchrotron at CERN and the 16.7 MeV Cyclotron at Bern Inselspital.
Article
Full-text available
HV-CMOS pixel sensors are a promising option for the tracker upgrade of the ATLAS experiment at the LHC, as well as for other future tracking applications in which large areas are to be instrumented with radiation-tolerant silicon pixel sensors. We present results of testbeam characterisations of the $4^{\mathrm{th}}$ generation of Capacitively Coupled Pixel Detectors (CCPDv4) produced with the ams H18 HV-CMOS process that have been irradiated with different particles (reactor neutrons and 18 MeV protons) to fluences between $1\cdot 10^{14}$ and $5\cdot 10^{15}$ 1-MeV-n$_\textrm{eq}$/cm$^2$. The sensors were glued to ATLAS FE-I4 pixel readout chips and measured at the CERN SPS H8 beamline using the FE-I4 beam telescope. Results for all fluences are very encouraging with all hit efficiencies being better than 97% for bias voltages of $85\,$V. The sample irradiated to a fluence of $1\cdot 10^{15}$ n$_\textrm{eq}$/cm$^2$ - a relevant value for a large volume of the upgraded tracker - exhibited 99.7% average hit efficiency. The results give strong evidence for the radiation tolerance of HV-CMOS sensors and their suitability as sensors for the experimental HL-LHC upgrades and future large-area silicon-based tracking detectors in high-radiation environments.
Article
Full-text available
High Voltage CMOS sensors are a promising technology for tracking detectors in collider experiments. Extensive R&D studies are being carried out by the ATLAS Collaboration for a possible use of HV-CMOS in the High Luminosity LHC upgrade of the Inner Tracker detector. CaRIBOu (Control and Readout Itk BOard) is a modular test system developed to test Silicon based detectors. It currently includes five custom designed boards, a Xilinx ZC706 development board, FELIX (Front-End LInk eXchange) PCIe card and a host computer. A software program has been developed in Python to control the CaRIBOu hardware. CaRIBOu has been used in the testbeam of the HV-CMOS sensor CCPDv4 at CERN. Preliminary results have shown that the test system is very versatile. Further development is ongoing to adapt to different sensors, and to make it available to various lab test stands.
Article
Full-text available
A testbeam telescope, based on ATLAS IBL silicon pixel modules, has been built. It comprises six planes of planar silicon sensors with 250 x 50 um^2 pitch, read out by ATLAS FE-I4 chips. In the CERN SPS H8 beamline (180 GeV pi+) a resolution of better than 8 x 12 um^2 at the position of the device under test was achieved. The telescope reached a trigger rate of 6kHz with two measured devices. It is mainly designed for studies using FE-I4 based prototypes, but has also been successfully run with independent DAQ systems. Specialised trigger schemes ensure data synchronisation between these external devices and the telescope. A region-of-interest trigger can be formed by setting masks on the first and the last pixel sensor planes. The setup infrastructure provides centrally controlled and monitored high and low voltage power supplies, silicon oil cooling, temperature and humidity sensors and movable stages.
Article
Particle pixel detectors in standard high-voltage CMOS technology are a new detector family that allows implementation of low-cost radiation-tolerant detectors with good time resolution. In order to test the concept we have implemented three detector variants. The first variant uses simple four-transistor pixel electronics that allows the rolling-shutter readout. The second variant implements complex CMOS pixel electronics with particle hit detection on pixel level and binary readout. The third variant uses the readout based on the capacitive chip-to-chip signal transmission.In this paper we will present the recent experimental results.
Article
A new concept for monolithic pixel detector with 100% fill-factor is presented. The detection is based on the charge collection in the depleted zone of the reverse biased diode. Complex pixel electronics, including charge sensitive amplifier, amplitude discriminator and digital storage element is placed completely inside the diode cathode (N-well). A test chip that comprises a small pixel matrix and test structures has been fabricated in a high-voltage CMOS process and successfully tested. The results of the electrical tests and measurements with X-ray and beta radioactive sources are presented.
• M Kiehn
M. Kiehn et al., Proteus beam telescope reconstruction, https://doi.org/10.5281/zenodo.2579153, 2017.
Testbeam results of irradiated ams H18 HV-CMOS pixel sensor prototypes
• M Benoit
M. Benoit et al., Testbeam results of irradiated ams H18 HV-CMOS pixel sensor prototypes, 2018 JINST 13 P02011 [arXiv:1611. 2669].