Impact of X-ray induced radiation damage on FD-MAPS of the ARCADIA project

Recent advancements in Monolithic Active Pixel Sensors (MAPS) demonstrated the ability to operate in high radiation environments of up to multiple kGy’s, which increased their appeal as sensors for high-energy physics detectors. The most recent example in such application is the new ALICE inner tracking system, entirely instrumented with CMOS MAPS, that covers an area of about 10 m2. However, the full potential of such devices has not yet been fully exploited, especially in respect of the size of the active area, power consumption, and timing capabilities. The ARCADIA project is developing Fully Depleted (FD) MAPS with an innovative sensor design, that uses a proprietary processing of the backside to improve the charge collection efficiency and timing over a wide range of operational and environmental conditions. The innovative sensor design targets very low power consumption, of the order of 20 mW cm−2 at 100 MHz cm−2 hit flux, to enable air-cooled operations of the sensors. Another key design parameter is the ability to further reduce the power regime of the sensor, down to 5 mW cm−2 or better, for low hit rates like e.g. expected in space experiments. In this contribution, we present a comparison between the detector characteristics predicted with Technology Computer Aided Design (TCAD) simulations and the ones measured experimentally. The comparison focuses on the current-voltage (IV) and capacitance-voltage (CV) characteristics, as well as noise estimated from in-pixel capacitances of passive/active pixel matrices. In view of the targeted applications of this technology, an emphasis is set on the modeling of X-ray induced radiation damage at the Si-SiO2 interface and the impact on the in-pixel sensor capacitance. The so-called new Perugia model has been used in the simulations to predict the sensor performance after total ionizing doses of up to 10 Mrad.

Design of a 9-bit column-parallel ADC in the MAPS for real-time beam monitoring

This paper describes a 2 Msps 9-bit column-parallel ADC for monolithic active pixel sensor. It is designed in fully differential cyclic architecture and takes eight clock cycles to perform a 9-bit conversion. This ADC is fabricated in a 130 nm CMOS process. Each ADC covers a small area of 100 µm × 300 µm and consumes ∼5 mW. The measurement results show that this ADC has a signal-to-noise and distortion ratio (SNDR) of 46.8 dB. The DNL (Differential Nonlinearity) and (Integral Nonlinearity) INL are 0.168 LSB and 0.112 LSB, respectively. The effective number of bits (ENOB) is 7.48 bits.

Development of a serial link transmitter for monolithic active pixel sensors

In this paper, a 5-Gbps serial link transmitter has been designed for monolithic active pixel sensor. The serial link is designed in a commercial 130-nm CMOS technology with a power supply of 1.2 V. The transmitter consists of a 16b/20b encoder, a three-stage 20:1 serializer core, the CML driver with pre-emphasis function, and a high-speed receiver to deal with the external clock. The root mean square jitter of this serial link transmitter is 2.2 ps, indicating a bit error rate of 1 × 10−14. This paper will discuss the design and performance of this serial link transmitter.

Pixel chamber: a solid-state active-target for 3D imaging of charm and beauty

The aim of the pixel chamber project is to develop the first “solid-state bubble chamber” for high precision measurement of charm and beauty. In this paper we will describe the idea for the first silicon active target conceived as an ultra-high granular stack of hundreds of very thin monolithic active pixel sensors (MAPS), which provides continuous, high-resolution 3D tracking of all of the particles produced in proton-silicon interactions occurring inside the detector volume, including open charm and beauty. We will also discuss the high-precision tracking and vertexing performances, showing that the vertex resolution can be up to one order of magnitude better than state-of-the-art detectors like the LHCb one.

Characterisation of analogue front end and time walk in CMOS active pixel sensor

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.

Nonlinear approximation of wildfire front temperature on MODIS data for sub-pixel analysis of burning

An improved approach to evaluate thermal anomalies characteristics using the pixel-based analysis of the MODIS imagery was proposed. The approach allows us to improve the accuracy in estimating characteristics of active combustion zones comparing to the standard Dozier method. We used the imagery of active wildfires in Siberian forests from the MODIS radiometer acquired in the spectral ranges of 3.930–3.990 and 10.780–11.280 mm (bands 21 and 31, respectively). Nonlinear exponential function was used to describe the approximation of the temperature of combustion zones. Available data of field and numerical experiments were used for validating of the approximation accuracy. Nonlinear approximation of wildfire front temperature allows to determine the portion of the active pixel of the MODIS image with the given temperature excess comparing to the temperature of background cover. This improves the accuracy in extracting of active burning zones as well as in classifying the heat release rate at the sub-pixel level of analysis.

The Mu3e experiment

The experiment aims for a single event sensitivity of 2\cdot 10^{-15}2⋅10−15 on the charged lepton flavour violating \mu^+\rightarrow e^+ e^+ e^-μ+→e+e+e− decay. The experimental apparatus, a light-weight tracker based on custom High-Voltage Monolithic Active Pixel Sensors placed in a 1 T magnetic field is currently under construction at the Paul Scherrer Institute, where it will fully use the intense 10^88\mu^+μ+/s beam available. A final sensitivity of 1 \cdot 10^{-16}1⋅10−16 is envisioned for a phase II experiment, driving the development of a new high-intensity continuous muon source which will deliver >10^99\mu^+μ+/s to the experiment.