The SiD Digital ECal Based on Monolithic Active Pixel Sensors

ALICE (A Large Ion Collider Experiment) is the heavy-ion experiment at the Large Hadron Collider (LHC) at CERN. As an important part of its upgrade plans, the ALICE experiment will schedule the installation of a new Inner Tracking System (ITS) during the Long Shutdown 2 (LS2) of the LHC. The new ITS layout will consist of seven concentric layers, $\approx$ 12.5 Gigapixel camera covering about 10m$^2$ with Monolithic Active Pixel Sensors (MAPS). This choice of technology has been guided by the tight requirements on the material budget of 0.3$\%$ X/X$_0$ per layer for the three innermost layers and backed by the significant progress in the field of MAPS in recent years. The technology initially chosen for the ITS upgrade is the TowerJazz 180 nm CMOS Technology. It offers a standard epitaxial layer of 15 - 18 $\mu$m with a resistivity between 1 and 5 k$\Omega$~cm$^{-1}$ and a gate oxide thickness below 4 nm, thus being more robust to Total Ionizing Dose (TID). The main subject of this thesis is to implement a novel digital pixel readout architecture for MAPS. This thesis aims to study this novel readout architecture as an alternative to the rolling-shutter readout. However, this must be investigated through the study of several chip readout architectures during the R$\&$D phase. Another objective of this thesis is the study and characterization of TowerJazz, if it meets the Non-Ionizing Energy Loss (NIEL) and Single Event Effects (SEE) of the ALICE ITS upgrade program. Other goals of this thesis are: Implementation of the top-down flow for this CMOS process and the design of multiple readouts for different prototypes up to the assembly of a full-scale prototype. Characterization of the radiation hardness and SEE of the chips submitted to fabrication. Characterization of full custom designs using analog simulations and the generation of digital models for the simulation chain needed for the verification process. \item Implementation and study of different digital readouts to meet the ITS upgrade program in integration time, pixel size and power consumption, from the conceptual idea, production and fabrication phase. SChapter 1 is a brief overview of CERN, the LHC and the detectors complex. The ALICE ITS will be explained, focusing on the ITS upgrade in terms of detector needs and design constraints. Chapter 2 explains the properties of silicon detectors and the detector material and the principles of operation for MAPS. Chapters 3 and 4 describe the ALPIDE prototypes and their readout based on MAPS; this forms the central part of this work, including the multiple families of pixel detectors fabricated in order to reach the final design for the ITS. The ALPIDE3/pALPIDE3B chip, the latest MAPS chip designed, will be explained in detail, as well focusing in the matrix digital readout. In chapter 5 the noise measurements and its characterization are presented including a brief summary of detector response to irradiation with soft X-rays, sources and particle beams. on the ITS upgrade in terms of detector needs and design constraints. Chapter 2 explains the properties of silicon detectors and the detector material and the principles of operation for MAPS. Chapters 3 and 4 describe the ALPIDE prototypes and their readout based on MAPS; this forms the central part of this work, including the multiple families of pixel detectors fabricated in order to reach the final design for the ITS. The ALPIDE3/pALPIDE3B chip, the latest MAPS chip designed, will be explained in detail, as well focusing in the matrix digital readout. In chapter 5 the noise measurements and its characterization are presented including a brief summary of detector response to irradiation with soft X-rays, sources and particle beams.

ID: 139 Monte Carlo simulations for imaging in proton therapy

The features of the 180nm TowerJazz1 CMOS technology allow for the first time the use of CMOS Monolithic Active Pixel Sensors (MAPS) under the harsh operational conditions of the LHC experiments. The stringent requirements of the ALICE Inner Tracking System (ITS) in terms of material budget, radiation hardness, readout speed and a low power consumption have thus lead to the choice of MAPS as baseline technology option for the recently approved upgrade of the ITS and are the key drivers for R&D efforts on basic transistor and Explorer and MIMOSA pixel sensor prototypes produced in TowerJazz technology. Though the radiation loads expected for the ITS are below those of ATLAS and CMS, it is however necessary to assess the radiation hardness for ITS MAPS prototypes. Total Ionizing Dose (TID) radiation hardness has been established for basic transistor structures using a 60keV X-ray machine. The main operational characteristics and detection properties such as noise, charge collection efficiency and signal over noise ratio of Explorer-0 and MIMOSA32 and MIMOSA34 pixel sensor prototypes have been studied using X-rays (55Fe) and test beams at CERN and DESY before and after Non Ionizing Energy Loss (NIEL) and TID irradiation. In this paper the results of these R&D activities will be presented and discussed.

Monolithic active pixel sensors (MAPS) in a VLSI CMOS technology

Development of a triple well CMOS MAPS device with in-pixel signal processing and sparsified readout capabilities

Silicon pixel detectors are widely used as vertex detectors or inner trackers in high-energy collider experiments because of their excellent spatial resolution, extremely high counting capability and low power consumption. The study of the silicon pixel detector based on the monolithic active pixel sensor (MAPS) is one of the R&D schemes for upgrading the inner chamber of the Beijing spectrometer Ⅲ (BESⅢ) drift chamber (MDC). It is planned to build a 1/10 scale prototype of the inner chamber. The detector module is the basic component of the prototype, consisting of ten MIMOSA28 chips thinned to 50 μm, a flexible cable and a carbon fiber support. In order to study the performance of the module, a test system is set up. The system is composed mainly of five-layer modules, readout electronics and data acquisition system. This article focuses on the realization of the continuous data readout method with trigger marking function, the measurement of the noise level of the detector modules, the module response test by a radioactive source, and the study of the hit reconstruction algorithm. The test of trigger readout logic verifies the correctness of the continuous readout method with trigger marking. It can be concluded that analyzing consecutive three frames data (the previous frame, the current frame and the next frame) of each valid trigger will not lead to effective hit data loss. The noise level of the detector module is tested. The results show that the fixed pattern noise (FPN) is 0.253 mV, and the temporal noise (TN) is 1.65 mV. The fake hit rate is less than <inline-formula><tex-math id="M1">\begin{document}$ {10}^{-5} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20210464_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20210464_M1.png"/></alternatives></inline-formula> that can be ignored when the chip threshold is set to be above 4σ of noise. Two algorithms for hit reconstruction (i.e. adjacent method and comparison method) are studied and compared. When the average number of fired pixels caused by each hit is 2.562 and more than four hits in each frame of data, the adjacent method can find all of the fired pixels to be faster. During the test, the detector module and the electronics are proved to work well. These studies lay a foundation for further testing the performance of the detector prototype.

A high resolution beam telescope, based on CMOS Monolithic Active Pixels Sensors (MAPS), is being developed within the EUDET collaboration, a coordinated detector R&D program for a future international linear collider. A very good spatial resolution ≪ 5 μm, a fast readout time of 100 μs for whole array and a high granularity can be obtained with this technology. A recent fast MAPS chip, designed on AMS CMOS 0.35 μm Opto process and called MIMOSA22, was submitted to foundry in October 2007. MIMOSA22 has an active area of 26.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with a pixel pitch of 18.4 μm arranged in an array of 576 rows by 136 columns where 8 columns have analog test outputs and 128 have their outputs connected to offset compensated discriminator stages. The pixel array is divided in seventeen blocks of pixels, with different amplification gain, diode size, pixel architecture and is addressed row-wise through a serially programmable (JTAG) sequencer. The sequencer operates as a pattern generator which delivers control signals both to the pixels and to the column-level discriminators. Discriminators have a common adjustable threshold, with internal DAC, controlled by the JTAG. MIMOSA22 is the last chip (IDC-Intermediate Digital Chip), before the final sensor of the EUDET-JRA1 beam telescope, which will be installed at the 6 GeV electron beam line at DESY in spring 2009. In this paper, laboratory tests results on analog and digital parts are presented. For this purpose, a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">55</sup> Fe source is used for calibration of pixels. Test beam results, obtained with a 120 GeV pions beam at CERN in summer 2008, are also presented. In the last part of the paper, a new chip MIMOSA22-bis, with radiation tolerant pixel architectures (evolution of MIMOSA22) will be discussed.

The upgrade of the ALICE Inner Tracking System (ITS) aims at improving the capabilities of ALICE in terms of read-out rate as well as track pointing resolution and track finding efficiency, especially for particles with low transverse momenta. The new ITS will be a low material budget detector with high granularity and read-out speed. It comprises seven concentric layers of Monolithic Active Pixel Sensors (MAPS) with a total active surface of about 10 m$^2$. The developed MAPS are based on the TowerJazz 180 nm CMOS technology. The sensor is called ALPIDE. In this paper, we present the setup used for measurements with inclined tracks and we discuss the sensor efficiency obtained using $\pi$ beams with a momentum of 6 GeV/c at the Proton Synchrotron (PS) at CERN. Some sensors were irradiated before the beam test using the cyclotron facility of the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS) to induce radiation damage to the sensor. Measurements at different operating points (thresholds, bias voltages) provide important information about cluster-shape frequencies, needed to tune the ALICE Monte-Carlo generators. A very good agreement between test-beam data and simulations is obtained.

CMOS Monolithic Active Pixel Sensors (MAPS) demonstrated excellent performances in the field of charged particle tracking. Among their strong points are an single point resolution few μm, a light material budget of 0.05% X0 in combination with a good radiation tolerance and high rate capability. Those features make the sensors a valuable technology for vertex detectors of various experiments in heavy ion and particle physics. To reduce the load on the event builders and future mass storage systems, we have developed algorithms suited for preprocessing and reducing the data streams generated by the MAPS. This real-time processing employs remaining free resources of the FPGAs of the readout controllers of the detector and complements the on-chip data reduction circuits of the MAPS.

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.

A full on-chip, low noise, low power consumption reference generator in monolithic active pixel sensors

To extract the physics required at the International Linear Collider, the detectors will need a jet energy resolution of 30%/radicE (GeV). The most promising approach to reach that goal is the use of particle flow algorithms. Particle flow algorithms measure jet energies by combining both tracking and calorimeter information. This requires the use of highly granular calorimeter systems. For the electromagnetic calorimeter (ECAL) the choice is to use silicon-tungsten sampling calorimeters with a highly granular readout. We propose to use Monolithic Active Pixel Sensors (MAPS) as both sensor and readout for such a calorimeter. This novel design would have an extremely fine granularity of 50 x 50 mum2 with binary readout. With a total area of 2000 m2 of silicon this leads to a Tera-Pixel ECAL. An overview of the MAPS detector concept will be given along with the potential advantages of this design. For the optimization of the design detailed sensor simulations have been used. A first prototype sensor using MAPS has been produced and we show first results obtained with this sensor. We also address system level issues like the required DAQ bandwidth and the power consumption.

First results from the characterization of a three-dimensional deep N-well MAPS prototype for vertexing applications

This paper reviews the development of CMOS Monolithic Active Pixel Sensors (MAPS) for future vertex detectors. MAPS are developed in a standard CMOS technology. In the imaging field, where the technology found its first applications, they are also known as CMOS Image Sensors. The use of MAPS as a detector for particle physics was first proposed at the end of 1999. Since then, their good performance in terms of spatial resolution, efficiency, radiation hardness have been demonstrated and work is now well under way to deliver the first MAPS-based vertex detectors.

CMOS Monolithic Active Pixel Sensors (MAPS) demonstrate excellent performances in the field of charged particle tracking. A single point resolution of 1–2 μm and a detection efficiency close to 100% were routinely observed with various MAPS designs featuring up to 106 pixels on active areas as large as 4 cm2[1]. Those features make MAPS an interesting technology for vertex detectors in particle and heavy ion physics. In order to adapt the sensors to the high particle fluxes expected in this application, we designed a sensor with fast column parallel readout and partially depleted active volume. The latter feature was expected to increase the tolerance of the sensors to non-ionizing radiation by one order of magnitude with respect to the standard technology. This paper discusses the novel sensor and presents the results on its radiation tolerance.