Measurement of Radiation Damage to 130nm Hybrid Pixel Detector Readout Chips

We present the first measurements of the performance of the Medipix3 hybrid pixel readout chip after exposure to significant x-ray flux. Specifically the changes in performance of the mixed mode pixel architecture, the digital periphery, digital to analogue converters and the e-fuse technology were characterised. A high intensity, calibrated x- ray source was used to incrementally irradiate the separate regions of the detector whilst it was powered. This is the first total ionizing dose study of a large area pixel detector fabricated using the 130nm CMOS technology

Application of Weather Generation to High Frequency and High Resolution Gridded Datasets in Sao Paulo.

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Timing performance of the Timepix4 front-end

A characterisation of the Timepix4 pixel front-end with a strong focus on timing performance is presented. Externally generated test pulses were used to probe the per-pixel time-to-digital converter (TDC) and measure the time-bin sizes by precisely controlling the test-pulse arrival time in steps of 10 ps. The results indicate that the TDC can achieve a time resolution of 60 ps, provided that a calibration is performed to compensate for frequency variation in the voltage controlled oscillators of the pixel TDCs. The internal clock distribution system of Timepix4 was used to control the arrival time of internally generated analog test pulses in steps of about 20 ps. The analog test pulse mechanism injects a controlled amount of charge directly into the analog front-end (AFE) of the pixel, and was used to measure the time resolution as a function of signal charge, independently of the TDC. It was shown that for the default configuration, the AFE time resolution in the hole-collecting mode is limited to 105 ps. However, this can be improved up to about 60 ps by increasing the preamplifier bias-current at the cost of increased power dissipation. For the electron-collecting mode, an AFE time resolution of 47 ps was measured for a bare Timepix4 device at a signal charge of 21 ke. It was observed that additional input capacitance from a bonded sensor reduces this figure to 62 ps

20-ps resolution Clock Distribution Network for a fast-timing single photon detector

The time resolution of active pixel sensors whose timestamp mechanism is based on Time-to-Digital Converters is critically linked to the accuracy in the distribution of the master clock signal that latches the timestamp values across the detector. The Clock Distribution Network that delivers the master clock signal must compensate process-voltage-temperature variations to reduce static time errors (skew), and minimize the power supply bounce to prevent dynamic time errors (jitter). To achieve sub-100ps time resolution within pixel detectors and thus enable a step forward in multiple imaging applications, the network latencies must be adjusted in steps well below that value. Power consumption must be kept as low as possible. In this work, a self-regulated Clock Distribution Network that fulfills these requirements is presented for the FastICpix single photon detector ¿ aiming at a 65nm process. A 40 MHz master clock is distributed to 64x64 pixels over an area of 2.4x2.4 cm2 using digital Delay-Locked Loops, achieving clock leaf skew below 20 ps with a power consumption of 26 mW. Guidelines are provided to adapt the system to arbitrary chip area and pixel pitch values, yielding a versatile design with very fine time resolution

Precision scans of the pixel cell response of double sided 3D pixel detectors to pion and x-ray beams

hree-dimensional (3D) silicon sensors offer potential advantages over standard planar sensors for radiation hardness in future high energy physics experiments and reduced charge-sharing for X-ray applications, but may introduce inefficiencies due to the columnar electrodes. These inefficiencies are probed by studying variations in response across a unit pixel cell in a 55μm pitch double-sided 3D pixel sensor bump bonded to TimePix and Medipix2 readout ASICs. Two complementary characterisation techniques are discussed: the first uses a custom built telescope and a 120GeV pion beam from the Super Proton Synchrotron (SPS) at CERN; the second employs a novel technique to illuminate the sensor with a micro-focused synchrotron X-ray beam at the Diamond Light Source, UK. For a pion beam incident perpendicular to the sensor plane an overall pixel efficiency of 93.0±0.5% is measured. After a 10o rotation of the device the effect of the columnar region becomes negligible and the overall efficiency rises to 99.8±0.5%. The double-sided 3D sensor shows significantly reduced charge sharing to neighbouring pixels compared to the planar device. The charge sharing results obtained from the X-ray beam study of the 3D sensor are shown to agree with a simple simulation in which charge diffusion is neglected. The devices tested are found to be compatible with having a region in which no charge is collected centred on the electrode columns and of radius 7.6±0.6μm. Charge collection above and below the columnar electrodes in the double-sided 3D sensor is observed

Bioaccesibilidad de hierro de fortificación y zinc endógeno de fideos comerciales tipo spaghetti

Introduction: The aims were to assess the bioaccessibility and Potential Supply (PS) of Fe and Zn from Commercial Fortified Spaghettis (CFS), and the relationship between cooking time and losses of solids, Fe and Zn of these samples.Material and Methods: Four samples of different trades were analyzed. Solid, Fe, and Zn losses were evaluated at to cooking times (optimum cooking time and optimum time plus 10 min overcooking). Fe and Zn bioaccessibility was estimated through mineral dialyzability. Potential Supply (PS) was determined as the product of mineral concentration and dialyzability.Results: Solids losses were lower than 7%, still with overcooking. Three of the four fortified samples did not meet the declared values of Fe content. There were high losses of Fe and Zn during cooking, which increased when extended cooking time (from 43.7% to 64.7% for Fe, and from 7.7% to 15.2% for Zn). Fe losses (fortification mineral), being greater than Zn (endogenous mineral). Fe and Zn bioaccessibility were very low (0.82±0.27% and 0.90±0.45%, respectively) and the PS of 80 g portion of CFS only cover approximately 0.65% and 0.71% of Fe and Zn requirements, respectively.Conclusions: The results show that the fortification of spaghetti makes little contribution to meet the requirements of the analyzed minerals.Introducción: El presente trabajo tiene por objetivo evaluar la bioaccesibilidad y Aporte Potencial (AP) de Fe y Zn de Fideos Comerciales Fortificados (FCF), y la relación entre el tiempo de cocción y la pérdida de sólidos, Fe y Zn de dichos fideos.Material y métodos: Se analizaron cuatro diferentes marcas de FCF. Se evaluó la pérdida de sólidos, Fe y Zn, a dos tiempos de cocción (tiempo óptimo indicado por el fabricante y una sobrecocción de 10 minutos). La bioaccesibilidad de Fe y Zn se estimó a través del porcentaje del mineral dializado. El AP de minerales se determinó como el producto de la concentración y la dializabilidad de cada mineral.Resultados: Las pérdidas de sólidos resultaron inferiores al 7%, aún con sobrecocción. Tres de los cuatro FCF no cumplían con los valores declarados de contenido de Fe. Se produjeron grandes pérdidas de Fe y Zn durante la cocción, las cuales aumentaron al prolongarse el tiempo de cocción (de 43,7% a 64,7% para Fe; y de 7,7% a 15,2% para el Zn), siendo mayores las pérdidas de Fe (mineral de fortificación), que de Zn (mineral endógeno). La bioaccesibilidad de Fe y Zn resultó baja (0,82±0,27% y 0,90±0,45%, respectivamente) y el AP de una porción de 80 g de FCF sólo cubriría en promedio 0,646% de los requerimientos de Fe y 0,708% de los requerimientos de Zn.Conclusiones: Los resultados muestran que la fortificación de fideos contribuye muy poco a cubrir los requerimientos de los minerales analizados ya que gran parte se pierde en el agua de cocción