205 research outputs found
Design and standalone characterisation of a capacitively coupled HV-CMOS sensor chip for the CLIC vertex detector
The concept of capacitive coupling between sensors and readout chips is under
study for the vertex detector at the proposed high-energy CLIC electron
positron collider. The CLICpix Capacitively Coupled Pixel Detector (C3PD) is an
active High-Voltage CMOS sensor, designed to be capacitively coupled to the
CLICpix2 readout chip. The chip is implemented in a commercial nm HV-CMOS
process and contains a matrix of square pixels with m
pitch. First prototypes have been produced with a standard resistivity of
cm for the substrate and tested in standalone mode. The
results show a rise time of ns, charge gain of mV/ke and
e RMS noise for a power consumption of W/pixel. The
main design aspects, as well as standalone measurement results, are presented.Comment: 13 pages, 13 figures, 2 tables. Work carried out in the framework of
the CLICdp collaboratio
Characterisation of the Medipix3 detector for 60 and 80 keV electrons
In this paper we report quantitative measurements of the imaging performance for the current generation of hybrid pixel detector, Medipix3, used as a direct electron detector. We have measured the modulation transfer function and detective quantum efficiency at beam energies of 60 and 80 keV. In single pixel mode, energy threshold values can be chosen to maximize either the modulation transfer function or the detective quantum efficiency, obtaining values near to, or exceeding those for a theoretical detector with square pixels. The Medipix3 charge summing mode delivers simultaneous, high values of both modulation transfer function and detective quantum efficiency. We have also characterized the detector response to single electron events and describe an empirical model that predicts the detector modulation transfer function and detective quantum efficiency based on energy threshold. Exemplifying our findings we demonstrate the Medipix3 imaging performance recording a fully exposed electron diffraction pattern at 24-bit depth together with images in single pixel and charge summing modes. Our findings highlight that for transmission electron microscopy performed at low energies (energies <100 keV) thick hybrid pixel detectors provide an advantageous architecture for direct electron imaging
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
CliCTD: A monolithic HR-CMOS sensor chip for the CLIC silicon tracker
The CLIC Tracker Detector (CLICTD) is a monolithic pixelated sensor chip produced in a 180 nm imaging CMOS process built on a high-resistivity epitaxial layer. The chip, designed in the context of the CLIC tracking detector study, comprises a matrix of 16 x 128 elongated pixels, each measuring 300 x 30 μm. To ensure prompt charge collection, every elongated pixel is segmented in eight sub-pixels, each containing a collection diode and a separate analog front-end. A simultaneous 8-bit time measurement with 10 ns time bins and 5-bit energy measurement with programmable range is performed in the on-pixel digital logic. The main design aspects as well as the first results from laboratory measurements with the CLICTD chip are presented
Medipix3 Demonstration and understanding of near ideal detector performance for 60 & 80 keV electrons
In our article we report first quantitative measurements of imaging
performance for the current generation of hybrid pixel detector, Medipix3, as
direct electron detector. Utilising beam energies of 60 & 80 keV, measurements
of modulation transfer function (MTF) and detective quantum efficiency (DQE)
have revealed that, in single pixel mode (SPM), energy threshold values can be
chosen to maximize either the MTF or DQE, obtaining values near to, or even
exceeding, those for an ideal detector. We have demonstrated that the Medipix3
charge summing mode (CSM) can deliver simultaneous, near ideal values of both
MTF and DQE. To understand direct detection performance further we have
characterized the detector response to single electron events, building an
empirical model which can predict detector MTF and DQE performance based on
energy threshold. Exemplifying our findings we demonstrate the Medipix3 imaging
performance, recording a fully exposed electron diffraction pattern at 24-bit
depth and images in SPM and CSM modes. Taken together our findings highlight
that for transmission electron microscopy performed at low energies (energies
<100 keV) thick hybrid pixel detectors provide an advantageous and alternative
architecture for direct electron imagin
Validating Regulatory Sensory Processing Disorders Using the Sensory Profile and Child Behavior Checklist (CBCL 1 –5)
The objective was to validate Regulatory Sensory Processing Disorders’ criteria (DC:0-3R, 2005) using empirical data on the presence and severity of sensory modulation deficits and specific psychiatric symptoms in clinical samples. Sixty toddlers who attended a child mental health unit were diagnosed by a clinical team. The
following two groups were created: toddlers with RSPD(N = 14) and those with ‘‘other diagnoses in Axis I/II of the DC:0-3R00(OD3R) (N = 46). Independently of the
clinical process, parents completed the Infant Toddler Sensory Profile (as a checklist for sensory symptoms) and
the Achenbach Behavior Checklist for ages 1/2–5 (CBCL 1/2–5). The scores from the two groups were compared. The results showed the following for the RSPD group: a higher number of affected sensory areas and patterns than in the OD3R group; a higher percentage of sensory deficits in specific sensory categories; and a higher severity of
behavioral symptoms such as withdrawal, inattention, other externalizing problems and pervasive developmental problems in CBCL 1/2–5. The results confirmed our hypotheses by indicating a higher severity of sensory
symptoms and identifying specific behavioral problems in children with RSPD. The results revealed convergent validity between the instruments and the diagnostic criteria
for RSPD and supported the validity of RSPD as a unique diagnosis. The findings also suggested the importance of identifying sensory modulation deficits in order to develop an early intervention to enhance the sensory capacities of children who do not fully satisfy the criteria for some DSM-IV-TR disorders
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
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