A Radiation hard bandgap reference circuit in a standard 0.13um CMOS Technology

With ongoing CMOS evolution, the gate-oxide thickness steadily decreases, resulting in an increased radiation tolerance of MOS transistors. Combined with special layout techniques, this yields circuits with a high inherent robustness against X-rays and other ionizing radiation. In bandgap voltage references, the dominant radiation-susceptibility is then no longer associated with the MOS transistors, but is dominated by the diodes. This paper gives an analysis of radiation effects in both MOSdevices and diodes and presents a solution to realize a radiation-hard voltage reference circuit in a standard CMOS technology. A demonstrator circuit was implemented in a standard 0.13 m CMOS technology. Measurements show correct operation with supply voltages in the range from 1.4 V down to 0.85 V, a reference voltage of 405 mV 7.5 mV ( = 6mVchip-to-chip statistical spread), and a reference voltage shift of only 1.5 mV (around 0.8%) under irradiation up to 44 Mrad (Si)

Two-dimensional Markov chains with geometric jumps

Several queueing problems lead to Markov chains with jumps of unbounded length, particularly with geometric behaviour in one or more directions. In the present paper the equilibrium behaviour is analysed for two-dimensional nearest neighbour random walks, which may make geometric jumps in one direction. The first step in the analysis consists of searching for product forms satisfying the equilibrium equations for inner states. This is made possible by simplifying the equations by taking differences of equations for neighbouring states in a well-chosen direction. Such a difference is called \Delta-equation. It appears that the \Delta-equation is state-independent. Therefore one obtains two equations, the starting equation and the \Delta-equation; these equations have a large set of product form solutions S. It appears that, in the case of no transitions from inner states to the North, North-East and East, plus some restrictions on the horizontal boundary, there is a linear combination of countably many product forms from S which satisfies the boundary equations. This linear ombination may be constructed with a compensation procedure. In other cases there is a finite linear combination from S satisfying the boundary equations, if the boundary equations satisfy some rather severe extra conditions

Sum of product forms solutions to MSCCC queues with job type dependent processing times

Queueing models with simultaneous resource possession can be used to model production systems at which the production process occupies two or more resources(machines, operators, product carriers etc.) at the same time. A special class of these queueing models is the class of MSCCC queues, for which the stationary distribution has a product form. This was shown by Berezner et al. whose result depends on one special characteristic of MSCCC queues, being the processing times are job type independent exponentially distributed. However in many production situations processing times are job type dependent. Therefore we examined MSCCC queues with job type dependent exponentially distributed processing times. We determined the equilibrium probabilities of two special models using a detailed state description for which a solution using an aggregated state description is known. Comparing these two solutions we gained more insight in the structure of the solution to more general models for which such an aggregated state description no longer has the Markov property

Photocathodes for a post-processed imaging array

Preliminary results of a photon detector combining a Micromegas like multiplier coated with a UV-sensitive CsI photocathode are described. The multiplier is made in the CMOS compatible InGrid technology, which allows to post-process it directly on the surface of an imaging IC. This method is aimed at building light-sensitive imaging detectors where all elements are monolithically integrated. We show that the CsI photocathode deposited in the InGrid mesh does not alter the device performance. Maximum gains of ~6000 were reached in a singlegrid element operated in Ar/CH4, with a 2% Ion Back Flow fraction returning to the photocathode

The detection of single electrons by means of a Micromegas-covered MediPix2 pixel CMOS readout circuit

A small drift chamber was read out by means of a MediPix2 readout chip as direct anode. A Micromegas foil was placed 50 $\mu$m above the chip, and electron multiplication occurred in the gap. With a He/Isobutane 80/20 mixture, gas multiplication factors up to tens of thousands were achieved, resulting in an efficiency for detecting single electrons of better than 90% . We recorded many frames containing 2D images with tracks from cosmic muons. Along these tracks, electron clusters were observed, as well as delta-rays.Comment: 15 pages, 9 included postscript figures, 5 separate jpeg figures, submitted to Nucl. Instr. and Meth. A. A complete postscript version with high resolution figures 1, 3, 11, 12 and 14 can be found at http://www.nikhef.nl/~i06/RandD/final/letter4.p

Effect of Pulsed or Continuous Delivery of Salt on Sensory Perception Over Short Time Intervals

Salt in the human diet is a major risk factor for hypertension and many countries have set targets to reduce salt consumption. Technological solutions are being sought to lower the salt content of processed foods without altering their taste. In this study, the approach was to deliver salt solutions in pulses of different concentrations to determine whether a pulsed delivery profile affected sensory perception of salt. Nine different salt profiles were delivered by a Dynataste device and a trained panel assessed their saltiness using time–intensity and single-score sensory techniques. The profile duration (15 s) was designed to match eating conditions and the effects of intensity and duration of the pulses on sensory perception were investigated. Sensory results from the profiles delivered in either water or in a bouillon base were not statistically different. Maximum perceived salt intensities and the area under the time– intensity curves correlated well with the overall perceived saltiness intensity despite the stimulus being delivered as several pulses. The overall saltiness scores for profiles delivering the same overall amount of sodium were statistically not different from one another suggesting that, in this system, pulsed delivery did not enhance salt perception but the overall amount of salt delivered in each profile did affect sensory perception

The performance of GridPix detectors

A GridPix detector is a gaseous detector capable of detecting individual single primary electrons from ionizing particles. Such a detector consists of a pixel chip as active anode covered with a thin layer of silicon rich silicon nitride (SiRN) for protection against discharges, an integrated amplification grid (InGrid), applied on top of the chip by wafer post processing techniques, and a cathode plane. The drift region is between the grid and cathode while the gas gain occurs between the chip and the grid. The discharge quenching properties of the SiRN layer have been determined as well as the relation on grid capacitance, grid voltage and gas mixture. Part of the detectors in this report were of the type Gossip, a GridPix detector with a drift gap of ∼1 mm. Using such thin drift layer, one may consider this detector as a replacement for a silicon pixel detector. The performance of three Gossip detectors has been investigated by measurements in a test beam at CERN