Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

Hall sensor array

Integrated circuit Hall sensor system comprising a plurality of elementary blocks (EB), each elementary block including a Hall cell (4), a differential pair (8) of an input stage of a Differential Difference Amplifier (DDA), and terminals (12a, 12b), wherein the terminals (12a, 12b) are placed laterally on opposing outer sides of each elementary block parallel to a Y axis and the plurality of elementary blocks are arranged in a juxtaposed manner to form at least one row (6a, 6b) extending along an X axis orthogonal to the Y axis and interconnected by the terminals

Circular Hall transducer for angular position sensing

We developed a new integrated magnetic sensor based on the Hall effect, suitable for the application in magnetic contactless 360° absolute angle sensors. The device consists of a narrow n-well ring with a chain of 64 contacts equally distributed around the ring. The contacts are connected to an on-chip electronics with biasing and signal conditioning circuits providing the information about the magnitude and phase of in-plane component of the magnetic field. We characterized the sensor in homogenous magnetic field of 100 mT and measured the angular resolution of 0.01° in the frequency bandwidth of 1 kHz and the absolute angular accuracy of about 1° and 0.1° without and with output offset calibration of the sensor, respectively

Offset compensation based on distributed Hall system architecture

Integrated Hall devices have the great advantage, over other magnetic sensors, that they can be fully fabricated by a standard CMOS process. However they are known to have a relatively large offset (i.e. residual voltage at zero magnetic field). Techniques such as spinning current [1] or orthogonal coupling are effective to reduce this offset down to the 100 uT range. Still, in order to gain a real advantage over competing technologies [2], the offset of integrated Hall sensors should be reduced further, to the 10 uT range. The idea to achieve low offset performances is to reduce the sensor non-linearities. According to the reverse field reciprocity principle [3], the spinning current method completely cancels the offset in a linear system. It is now well understood that the major cause of non-linearity is either the junction field effect [4] or the carrier velocity saturation, depending on the device geometry. In both cases the non-linearity increases with the device bias voltage. However, reducing the bias voltage to reduce offset degrades the signal to noise ratio, since the noise depends mainly on device resistance. Therefore, the solution to maintain the signal-to-noise ratio is to integrate an array of Hall devices. This architecture allows finding a good trade-off between offset reduction, sensitivity, bandwidth, and current consumption. We have realized a system in 0.35 um CMOS standard technology to demonstrate the potential of this architecture. A primitive cell containing a Hall device, spinning current block and an amplification unit was designed in order to build an arbitrarily large array. This particular test system is built of 16 primitive cells, equally distributed over the layout. The Hall signal is processed in a differential way and can be demodulated using time continuous or switched capacitor technique, depending on required signal bandwidth. In addition, a switching scheme designed to reduce the problems of charge injection and the related switching spikes was implemented. Promising results are shown and the relation between parameters, such as the bias current, the number of cells, the layout distribution and the selected signal treatment technique, are discussed

True 2D CMOS integrated Hall sensor

We have designed and realized a new integrated Hall structure that converts the magnetic field vector in the chip plane, into an ac signal, whose amplitude and phase correspond to the magnitude and direction of the field, respectively. It is the first Hall sensor that provides the field angle without the need of computing an arctan function. The Hall element is formed by a n-well ring with a large number of contacts equally distributed along the ring, like a circular railroad track. Each contact is connected to the control electronics through switches. The measurement consists in activating a small portion of the ring at the time, forming a vertical Hall probe and acting on the switches to make this portion circulate. The measurement sequence suppresses the zero-field offset and the 1/f noise. Without calibration, in a 100 mT field, we obtain an angle resolution better than 1°. We propose a measurement scheme that further reduces the offset, in order to remove the need for calibration

Method for determining geometric characteristics of an anomaly in a test object and measuring apparatus for carrying out the method

In a method for determining geometrical characteristics (d) of an anomaly (12) which changes the electrical conductivity in the region near the surface of an electrically conducting, in particular a metallic test object (10), a considerable simplification is achieved in that, in the region of the anomaly (12) in the test object (10), eddy currents (13, 14) of different frequencies are excited, and the magnetic field (By,0), which is produced by the excited eddy currents, is scanned in the vicinity of the anomaly (12) and the geometric characteristics of the anomaly are exclusively deduced from the distribution of the magnetic field (By,0)

Offset Compensation Based on Distributed Hall Cell Architecture

A new offset reduction strategy for CMOS Hall devices is proposed. The novelty is to fragment the Hall device into multiple Hall blocks, distributed over the silicon area and easy to interconnect. The suitable number of Hall blocks and the bias current level in each block can be adjusted according to the requirements in terms of offset, offset drift and signal to noise ratio. A chip was fabricated in 0.35 µm CMOS standard technology to demonstrate the potential of this architecture. The chip shows promising results, and in particular, a very low offset drift was observed at the front-end output stage (of the order of 10 nT/°C)

Des usages aux pratiques : le Web a-t-il un sens ?

Cet ouvrage, issu des travaux du groupe TIC-IS de la Société Française des Sciences de l’Information et de la Communication, a pour objectif de mettre en évidence de nouvelles approches avec les théories des systèmes, de la non-linéarité et de la complexité, afin d’appréhender plus facilement le développement d’Internet et des réseaux numériques. En effet, l’extraordinaire développement de ces réseaux est marqué par un double mouvement d’expansion et de fragmentation Les relations entre acteurs évaluent, et s’il est aujourd’hui facile et rapide d’accéder à un large ensemble d’informations, le niveau de qualité des données « disponibles » est inégal. L’ambition de ce volume est d’approfondir la réflexion autour de plusieurs perspectives : comment les informations naissent-elles et circulent-elles ? Comment les réseaux évoluent-ils ? Quelles interactions pour favoriser les stratégies économiques, territoriales et/ou professionnelles ? Quelles pratiques et/ou usages pour favoriser l’émergence de projets durables ? Comment mettre en place une construction collective des connaissances ? Les textes réunis témoignent des enjeux de la recherche sur le numérique en sciences de l’information et de la communication : quelles directions ? quelles significations ? Le Web a-t-il un sens